Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

39 files changed, 10996 insertions, 0 deletions

diff --git a/tools/testing/selftests/x86/.gitignore b/tools/testing/selftests/x86/.gitignore
new file mode 100644
index 000000000..7757f73ff
--- /dev/null
+++ b/tools/testing/selftests/x86/.gitignore
@@ -0,0 +1,15 @@
+*_32
+*_64
+single_step_syscall
+sysret_ss_attrs
+syscall_nt
+ptrace_syscall
+test_mremap_vdso
+check_initial_reg_state
+sigreturn
+ldt_gdt
+iopl
+mpx-mini-test
+ioperm
+protection_keys
+test_vdso
diff --git a/tools/testing/selftests/x86/Makefile b/tools/testing/selftests/x86/Makefile
new file mode 100644
index 000000000..186520198
--- /dev/null
+++ b/tools/testing/selftests/x86/Makefile
@@ -0,0 +1,105 @@
+# SPDX-License-Identifier: GPL-2.0
+all:
+
+include ../lib.mk
+
+.PHONY: all all_32 all_64 warn_32bit_failure clean
+
+UNAME_M := $(shell uname -m)
+CAN_BUILD_I386 := $(shell ./check_cc.sh $(CC) trivial_32bit_program.c -m32)
+CAN_BUILD_X86_64 := $(shell ./check_cc.sh $(CC) trivial_64bit_program.c)
+CAN_BUILD_WITH_NOPIE := $(shell ./check_cc.sh $(CC) trivial_program.c -no-pie)
+
+TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt test_mremap_vdso \
+			check_initial_reg_state sigreturn iopl mpx-mini-test ioperm \
+			protection_keys test_vdso test_vsyscall mov_ss_trap
+TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
+			test_FCMOV test_FCOMI test_FISTTP \
+			vdso_restorer
+TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip
+# Some selftests require 32bit support enabled also on 64bit systems
+TARGETS_C_32BIT_NEEDED := ldt_gdt ptrace_syscall
+
+TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY) $(TARGETS_C_32BIT_NEEDED)
+TARGETS_C_64BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_64BIT_ONLY)
+ifeq ($(CAN_BUILD_I386)$(CAN_BUILD_X86_64),11)
+TARGETS_C_64BIT_ALL += $(TARGETS_C_32BIT_NEEDED)
+endif
+
+BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)
+BINARIES_64 := $(TARGETS_C_64BIT_ALL:%=%_64)
+
+BINARIES_32 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_32))
+BINARIES_64 := $(patsubst %,$(OUTPUT)/%,$(BINARIES_64))
+
+CFLAGS := -O2 -g -std=gnu99 -pthread -Wall
+
+# call32_from_64 in thunks.S uses absolute addresses.
+ifeq ($(CAN_BUILD_WITH_NOPIE),1)
+CFLAGS += -no-pie
+endif
+
+define gen-target-rule-32
+$(1) $(1)_32: $(OUTPUT)/$(1)_32
+.PHONY: $(1) $(1)_32
+endef
+
+define gen-target-rule-64
+$(1) $(1)_64: $(OUTPUT)/$(1)_64
+.PHONY: $(1) $(1)_64
+endef
+
+ifeq ($(CAN_BUILD_I386),1)
+all: all_32
+TEST_PROGS += $(BINARIES_32)
+EXTRA_CFLAGS += -DCAN_BUILD_32
+$(foreach t,$(TARGETS_C_32BIT_ALL),$(eval $(call gen-target-rule-32,$(t))))
+endif
+
+ifeq ($(CAN_BUILD_X86_64),1)
+all: all_64
+TEST_PROGS += $(BINARIES_64)
+EXTRA_CFLAGS += -DCAN_BUILD_64
+$(foreach t,$(TARGETS_C_64BIT_ALL),$(eval $(call gen-target-rule-64,$(t))))
+endif
+
+all_32: $(BINARIES_32)
+
+all_64: $(BINARIES_64)
+
+EXTRA_CLEAN := $(BINARIES_32) $(BINARIES_64)
+
+$(BINARIES_32): $(OUTPUT)/%_32: %.c
+	$(CC) -m32 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl -lm
+
+$(BINARIES_64): $(OUTPUT)/%_64: %.c
+	$(CC) -m64 -o $@ $(CFLAGS) $(EXTRA_CFLAGS) $^ -lrt -ldl
+
+# x86_64 users should be encouraged to install 32-bit libraries
+ifeq ($(CAN_BUILD_I386)$(CAN_BUILD_X86_64),01)
+all: warn_32bit_failure
+
+warn_32bit_failure:
+	@echo "Warning: you seem to have a broken 32-bit build" 2>&1; 	\
+	echo "environment.  This will reduce test coverage of 64-bit" 2>&1; \
+	echo "kernels.  If you are using a Debian-like distribution," 2>&1; \
+	echo "try:"; 2>&1; \
+	echo "";							\
+	echo "  apt-get install gcc-multilib libc6-i386 libc6-dev-i386"; \
+	echo "";							\
+	echo "If you are using a Fedora-like distribution, try:";	\
+	echo "";							\
+	echo "  yum install glibc-devel.*i686";				\
+	exit 0;
+endif
+
+# Some tests have additional dependencies.
+$(OUTPUT)/sysret_ss_attrs_64: thunks.S
+$(OUTPUT)/ptrace_syscall_32: raw_syscall_helper_32.S
+$(OUTPUT)/test_syscall_vdso_32: thunks_32.S
+
+# check_initial_reg_state is special: it needs a custom entry, and it
+# needs to be static so that its interpreter doesn't destroy its initial
+# state.
+$(OUTPUT)/check_initial_reg_state_32: CFLAGS += -Wl,-ereal_start -static
+$(OUTPUT)/check_initial_reg_state_64: CFLAGS += -Wl,-ereal_start -static
diff --git a/tools/testing/selftests/x86/check_cc.sh b/tools/testing/selftests/x86/check_cc.sh
new file mode 100755
index 000000000..356689c56
--- /dev/null
+++ b/tools/testing/selftests/x86/check_cc.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+# check_cc.sh - Helper to test userspace compilation support
+# Copyright (c) 2015 Andrew Lutomirski
+# GPL v2
+
+CC="$1"
+TESTPROG="$2"
+shift 2
+
+if [ -n "$CC" ] && $CC -o /dev/null "$TESTPROG" -O0 "$@" 2>/dev/null; then
+    echo 1
+else
+    echo 0
+fi
+
+exit 0
diff --git a/tools/testing/selftests/x86/check_initial_reg_state.c b/tools/testing/selftests/x86/check_initial_reg_state.c
new file mode 100644
index 000000000..6aaed9b85
--- /dev/null
+++ b/tools/testing/selftests/x86/check_initial_reg_state.c
@@ -0,0 +1,109 @@
+/*
+ * check_initial_reg_state.c - check that execve sets the correct state
+ * Copyright (c) 2014-2016 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+
+unsigned long ax, bx, cx, dx, si, di, bp, sp, flags;
+unsigned long r8, r9, r10, r11, r12, r13, r14, r15;
+
+asm (
+	".pushsection .text\n\t"
+	".type real_start, @function\n\t"
+	".global real_start\n\t"
+	"real_start:\n\t"
+#ifdef __x86_64__
+	"mov %rax, ax\n\t"
+	"mov %rbx, bx\n\t"
+	"mov %rcx, cx\n\t"
+	"mov %rdx, dx\n\t"
+	"mov %rsi, si\n\t"
+	"mov %rdi, di\n\t"
+	"mov %rbp, bp\n\t"
+	"mov %rsp, sp\n\t"
+	"mov %r8, r8\n\t"
+	"mov %r9, r9\n\t"
+	"mov %r10, r10\n\t"
+	"mov %r11, r11\n\t"
+	"mov %r12, r12\n\t"
+	"mov %r13, r13\n\t"
+	"mov %r14, r14\n\t"
+	"mov %r15, r15\n\t"
+	"pushfq\n\t"
+	"popq flags\n\t"
+#else
+	"mov %eax, ax\n\t"
+	"mov %ebx, bx\n\t"
+	"mov %ecx, cx\n\t"
+	"mov %edx, dx\n\t"
+	"mov %esi, si\n\t"
+	"mov %edi, di\n\t"
+	"mov %ebp, bp\n\t"
+	"mov %esp, sp\n\t"
+	"pushfl\n\t"
+	"popl flags\n\t"
+#endif
+	"jmp _start\n\t"
+	".size real_start, . - real_start\n\t"
+	".popsection");
+
+int main()
+{
+	int nerrs = 0;
+
+	if (sp == 0) {
+		printf("[FAIL]\tTest was built incorrectly\n");
+		return 1;
+	}
+
+	if (ax || bx || cx || dx || si || di || bp
+#ifdef __x86_64__
+	    || r8 || r9 || r10 || r11 || r12 || r13 || r14 || r15
+#endif
+		) {
+		printf("[FAIL]\tAll GPRs except SP should be 0\n");
+#define SHOW(x) printf("\t" #x " = 0x%lx\n", x);
+		SHOW(ax);
+		SHOW(bx);
+		SHOW(cx);
+		SHOW(dx);
+		SHOW(si);
+		SHOW(di);
+		SHOW(bp);
+		SHOW(sp);
+#ifdef __x86_64__
+		SHOW(r8);
+		SHOW(r9);
+		SHOW(r10);
+		SHOW(r11);
+		SHOW(r12);
+		SHOW(r13);
+		SHOW(r14);
+		SHOW(r15);
+#endif
+		nerrs++;
+	} else {
+		printf("[OK]\tAll GPRs except SP are 0\n");
+	}
+
+	if (flags != 0x202) {
+		printf("[FAIL]\tFLAGS is 0x%lx, but it should be 0x202\n", flags);
+		nerrs++;
+	} else {
+		printf("[OK]\tFLAGS is 0x202\n");
+	}
+
+	return nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/entry_from_vm86.c b/tools/testing/selftests/x86/entry_from_vm86.c
new file mode 100644
index 000000000..ade443a88
--- /dev/null
+++ b/tools/testing/selftests/x86/entry_from_vm86.c
@@ -0,0 +1,349 @@
+/*
+ * entry_from_vm86.c - tests kernel entries from vm86 mode
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This exercises a few paths that need to special-case vm86 mode.
+ *
+ * GPL v2.
+ */
+
+#define _GNU_SOURCE
+
+#include <assert.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/signal.h>
+#include <sys/ucontext.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+#include <err.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <sys/vm86.h>
+
+static unsigned long load_addr = 0x10000;
+static int nerrs = 0;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static sig_atomic_t got_signal;
+
+static void sighandler(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (ctx->uc_mcontext.gregs[REG_EFL] & X86_EFLAGS_VM ||
+	    (ctx->uc_mcontext.gregs[REG_CS] & 3) != 3) {
+		printf("[FAIL]\tSignal frame should not reflect vm86 mode\n");
+		nerrs++;
+	}
+
+	const char *signame;
+	if (sig == SIGSEGV)
+		signame = "SIGSEGV";
+	else if (sig == SIGILL)
+		signame = "SIGILL";
+	else
+		signame = "unexpected signal";
+
+	printf("[INFO]\t%s: FLAGS = 0x%lx, CS = 0x%hx\n", signame,
+	       (unsigned long)ctx->uc_mcontext.gregs[REG_EFL],
+	       (unsigned short)ctx->uc_mcontext.gregs[REG_CS]);
+
+	got_signal = 1;
+}
+
+asm (
+	".pushsection .rodata\n\t"
+	".type vmcode_bound, @object\n\t"
+	"vmcode:\n\t"
+	"vmcode_bound:\n\t"
+	".code16\n\t"
+	"bound %ax, (2048)\n\t"
+	"int3\n\t"
+	"vmcode_sysenter:\n\t"
+	"sysenter\n\t"
+	"vmcode_syscall:\n\t"
+	"syscall\n\t"
+	"vmcode_sti:\n\t"
+	"sti\n\t"
+	"vmcode_int3:\n\t"
+	"int3\n\t"
+	"vmcode_int80:\n\t"
+	"int $0x80\n\t"
+	"vmcode_popf_hlt:\n\t"
+	"push %ax\n\t"
+	"popf\n\t"
+	"hlt\n\t"
+	"vmcode_umip:\n\t"
+	/* addressing via displacements */
+	"smsw (2052)\n\t"
+	"sidt (2054)\n\t"
+	"sgdt (2060)\n\t"
+	/* addressing via registers */
+	"mov $2066, %bx\n\t"
+	"smsw (%bx)\n\t"
+	"mov $2068, %bx\n\t"
+	"sidt (%bx)\n\t"
+	"mov $2074, %bx\n\t"
+	"sgdt (%bx)\n\t"
+	/* register operands, only for smsw */
+	"smsw %ax\n\t"
+	"mov %ax, (2080)\n\t"
+	"int3\n\t"
+	"vmcode_umip_str:\n\t"
+	"str %eax\n\t"
+	"vmcode_umip_sldt:\n\t"
+	"sldt %eax\n\t"
+	"int3\n\t"
+	".size vmcode, . - vmcode\n\t"
+	"end_vmcode:\n\t"
+	".code32\n\t"
+	".popsection"
+	);
+
+extern unsigned char vmcode[], end_vmcode[];
+extern unsigned char vmcode_bound[], vmcode_sysenter[], vmcode_syscall[],
+	vmcode_sti[], vmcode_int3[], vmcode_int80[], vmcode_popf_hlt[],
+	vmcode_umip[], vmcode_umip_str[], vmcode_umip_sldt[];
+
+/* Returns false if the test was skipped. */
+static bool do_test(struct vm86plus_struct *v86, unsigned long eip,
+		    unsigned int rettype, unsigned int retarg,
+		    const char *text)
+{
+	long ret;
+
+	printf("[RUN]\t%s from vm86 mode\n", text);
+	v86->regs.eip = eip;
+	ret = vm86(VM86_ENTER, v86);
+
+	if (ret == -1 && (errno == ENOSYS || errno == EPERM)) {
+		printf("[SKIP]\tvm86 %s\n",
+		       errno == ENOSYS ? "not supported" : "not allowed");
+		return false;
+	}
+
+	if (VM86_TYPE(ret) == VM86_INTx) {
+		char trapname[32];
+		int trapno = VM86_ARG(ret);
+		if (trapno == 13)
+			strcpy(trapname, "GP");
+		else if (trapno == 5)
+			strcpy(trapname, "BR");
+		else if (trapno == 14)
+			strcpy(trapname, "PF");
+		else
+			sprintf(trapname, "%d", trapno);
+
+		printf("[INFO]\tExited vm86 mode due to #%s\n", trapname);
+	} else if (VM86_TYPE(ret) == VM86_UNKNOWN) {
+		printf("[INFO]\tExited vm86 mode due to unhandled GP fault\n");
+	} else if (VM86_TYPE(ret) == VM86_TRAP) {
+		printf("[INFO]\tExited vm86 mode due to a trap (arg=%ld)\n",
+		       VM86_ARG(ret));
+	} else if (VM86_TYPE(ret) == VM86_SIGNAL) {
+		printf("[INFO]\tExited vm86 mode due to a signal\n");
+	} else if (VM86_TYPE(ret) == VM86_STI) {
+		printf("[INFO]\tExited vm86 mode due to STI\n");
+	} else {
+		printf("[INFO]\tExited vm86 mode due to type %ld, arg %ld\n",
+		       VM86_TYPE(ret), VM86_ARG(ret));
+	}
+
+	if (rettype == -1 ||
+	    (VM86_TYPE(ret) == rettype && VM86_ARG(ret) == retarg)) {
+		printf("[OK]\tReturned correctly\n");
+	} else {
+		printf("[FAIL]\tIncorrect return reason (started at eip = 0x%lx, ended at eip = 0x%lx)\n", eip, v86->regs.eip);
+		nerrs++;
+	}
+
+	return true;
+}
+
+void do_umip_tests(struct vm86plus_struct *vm86, unsigned char *test_mem)
+{
+	struct table_desc {
+		unsigned short limit;
+		unsigned long base;
+	} __attribute__((packed));
+
+	/* Initialize variables with arbitrary values */
+	struct table_desc gdt1 = { .base = 0x3c3c3c3c, .limit = 0x9999 };
+	struct table_desc gdt2 = { .base = 0x1a1a1a1a, .limit = 0xaeae };
+	struct table_desc idt1 = { .base = 0x7b7b7b7b, .limit = 0xf1f1 };
+	struct table_desc idt2 = { .base = 0x89898989, .limit = 0x1313 };
+	unsigned short msw1 = 0x1414, msw2 = 0x2525, msw3 = 3737;
+
+	/* UMIP -- exit with INT3 unless kernel emulation did not trap #GP */
+	do_test(vm86, vmcode_umip - vmcode, VM86_TRAP, 3, "UMIP tests");
+
+	/* Results from displacement-only addressing */
+	msw1 = *(unsigned short *)(test_mem + 2052);
+	memcpy(&idt1, test_mem + 2054, sizeof(idt1));
+	memcpy(&gdt1, test_mem + 2060, sizeof(gdt1));
+
+	/* Results from register-indirect addressing */
+	msw2 = *(unsigned short *)(test_mem + 2066);
+	memcpy(&idt2, test_mem + 2068, sizeof(idt2));
+	memcpy(&gdt2, test_mem + 2074, sizeof(gdt2));
+
+	/* Results when using register operands */
+	msw3 = *(unsigned short *)(test_mem + 2080);
+
+	printf("[INFO]\tResult from SMSW:[0x%04x]\n", msw1);
+	printf("[INFO]\tResult from SIDT: limit[0x%04x]base[0x%08lx]\n",
+	       idt1.limit, idt1.base);
+	printf("[INFO]\tResult from SGDT: limit[0x%04x]base[0x%08lx]\n",
+	       gdt1.limit, gdt1.base);
+
+	if (msw1 != msw2 || msw1 != msw3)
+		printf("[FAIL]\tAll the results of SMSW should be the same.\n");
+	else
+		printf("[PASS]\tAll the results from SMSW are identical.\n");
+
+	if (memcmp(&gdt1, &gdt2, sizeof(gdt1)))
+		printf("[FAIL]\tAll the results of SGDT should be the same.\n");
+	else
+		printf("[PASS]\tAll the results from SGDT are identical.\n");
+
+	if (memcmp(&idt1, &idt2, sizeof(idt1)))
+		printf("[FAIL]\tAll the results of SIDT should be the same.\n");
+	else
+		printf("[PASS]\tAll the results from SIDT are identical.\n");
+
+	sethandler(SIGILL, sighandler, 0);
+	do_test(vm86, vmcode_umip_str - vmcode, VM86_SIGNAL, 0,
+		"STR instruction");
+	clearhandler(SIGILL);
+
+	sethandler(SIGILL, sighandler, 0);
+	do_test(vm86, vmcode_umip_sldt - vmcode, VM86_SIGNAL, 0,
+		"SLDT instruction");
+	clearhandler(SIGILL);
+}
+
+int main(void)
+{
+	struct vm86plus_struct v86;
+	unsigned char *addr = mmap((void *)load_addr, 4096,
+				   PROT_READ | PROT_WRITE | PROT_EXEC,
+				   MAP_ANONYMOUS | MAP_PRIVATE, -1,0);
+	if (addr != (unsigned char *)load_addr)
+		err(1, "mmap");
+
+	memcpy(addr, vmcode, end_vmcode - vmcode);
+	addr[2048] = 2;
+	addr[2050] = 3;
+
+	memset(&v86, 0, sizeof(v86));
+
+	v86.regs.cs = load_addr / 16;
+	v86.regs.ss = load_addr / 16;
+	v86.regs.ds = load_addr / 16;
+	v86.regs.es = load_addr / 16;
+
+	/* Use the end of the page as our stack. */
+	v86.regs.esp = 4096;
+
+	assert((v86.regs.cs & 3) == 0);	/* Looks like RPL = 0 */
+
+	/* #BR -- should deliver SIG??? */
+	do_test(&v86, vmcode_bound - vmcode, VM86_INTx, 5, "#BR");
+
+	/*
+	 * SYSENTER -- should cause #GP or #UD depending on CPU.
+	 * Expected return type -1 means that we shouldn't validate
+	 * the vm86 return value.  This will avoid problems on non-SEP
+	 * CPUs.
+	 */
+	sethandler(SIGILL, sighandler, 0);
+	do_test(&v86, vmcode_sysenter - vmcode, -1, 0, "SYSENTER");
+	clearhandler(SIGILL);
+
+	/*
+	 * SYSCALL would be a disaster in VM86 mode.  Fortunately,
+	 * there is no kernel that both enables SYSCALL and sets
+	 * EFER.SCE, so it's #UD on all systems.  But vm86 is
+	 * buggy (or has a "feature"), so the SIGILL will actually
+	 * be delivered.
+	 */
+	sethandler(SIGILL, sighandler, 0);
+	do_test(&v86, vmcode_syscall - vmcode, VM86_SIGNAL, 0, "SYSCALL");
+	clearhandler(SIGILL);
+
+	/* STI with VIP set */
+	v86.regs.eflags |= X86_EFLAGS_VIP;
+	v86.regs.eflags &= ~X86_EFLAGS_IF;
+	do_test(&v86, vmcode_sti - vmcode, VM86_STI, 0, "STI with VIP set");
+
+	/* POPF with VIP set but IF clear: should not trap */
+	v86.regs.eflags = X86_EFLAGS_VIP;
+	v86.regs.eax = 0;
+	do_test(&v86, vmcode_popf_hlt - vmcode, VM86_UNKNOWN, 0, "POPF with VIP set and IF clear");
+
+	/* POPF with VIP set and IF set: should trap */
+	v86.regs.eflags = X86_EFLAGS_VIP;
+	v86.regs.eax = X86_EFLAGS_IF;
+	do_test(&v86, vmcode_popf_hlt - vmcode, VM86_STI, 0, "POPF with VIP and IF set");
+
+	/* POPF with VIP clear and IF set: should not trap */
+	v86.regs.eflags = 0;
+	v86.regs.eax = X86_EFLAGS_IF;
+	do_test(&v86, vmcode_popf_hlt - vmcode, VM86_UNKNOWN, 0, "POPF with VIP clear and IF set");
+
+	v86.regs.eflags = 0;
+
+	/* INT3 -- should cause #BP */
+	do_test(&v86, vmcode_int3 - vmcode, VM86_TRAP, 3, "INT3");
+
+	/* INT80 -- should exit with "INTx 0x80" */
+	v86.regs.eax = (unsigned int)-1;
+	do_test(&v86, vmcode_int80 - vmcode, VM86_INTx, 0x80, "int80");
+
+	/* UMIP -- should exit with INTx 0x80 unless UMIP was not disabled */
+	do_umip_tests(&v86, addr);
+
+	/* Execute a null pointer */
+	v86.regs.cs = 0;
+	v86.regs.ss = 0;
+	sethandler(SIGSEGV, sighandler, 0);
+	got_signal = 0;
+	if (do_test(&v86, 0, VM86_SIGNAL, 0, "Execute null pointer") &&
+	    !got_signal) {
+		printf("[FAIL]\tDid not receive SIGSEGV\n");
+		nerrs++;
+	}
+	clearhandler(SIGSEGV);
+
+	/* Make sure nothing explodes if we fork. */
+	if (fork() == 0)
+		return 0;
+
+	return (nerrs == 0 ? 0 : 1);
+}
diff --git a/tools/testing/selftests/x86/fsgsbase.c b/tools/testing/selftests/x86/fsgsbase.c
new file mode 100644
index 000000000..f249e042b
--- /dev/null
+++ b/tools/testing/selftests/x86/fsgsbase.c
@@ -0,0 +1,427 @@
+/*
+ * fsgsbase.c, an fsgsbase test
+ * Copyright (c) 2014-2016 Andy Lutomirski
+ * GPL v2
+ */
+
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <err.h>
+#include <sys/user.h>
+#include <asm/prctl.h>
+#include <sys/prctl.h>
+#include <signal.h>
+#include <limits.h>
+#include <sys/ucontext.h>
+#include <sched.h>
+#include <linux/futex.h>
+#include <pthread.h>
+#include <asm/ldt.h>
+#include <sys/mman.h>
+
+#ifndef __x86_64__
+# error This test is 64-bit only
+#endif
+
+static volatile sig_atomic_t want_segv;
+static volatile unsigned long segv_addr;
+
+static int nerrs;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (!want_segv) {
+		clearhandler(SIGSEGV);
+		return;  /* Crash cleanly. */
+	}
+
+	want_segv = false;
+	segv_addr = (unsigned long)si->si_addr;
+
+	ctx->uc_mcontext.gregs[REG_RIP] += 4;	/* Skip the faulting mov */
+
+}
+
+enum which_base { FS, GS };
+
+static unsigned long read_base(enum which_base which)
+{
+	unsigned long offset;
+	/*
+	 * Unless we have FSGSBASE, there's no direct way to do this from
+	 * user mode.  We can get at it indirectly using signals, though.
+	 */
+
+	want_segv = true;
+
+	offset = 0;
+	if (which == FS) {
+		/* Use a constant-length instruction here. */
+		asm volatile ("mov %%fs:(%%rcx), %%rax" : : "c" (offset) : "rax");
+	} else {
+		asm volatile ("mov %%gs:(%%rcx), %%rax" : : "c" (offset) : "rax");
+	}
+	if (!want_segv)
+		return segv_addr + offset;
+
+	/*
+	 * If that didn't segfault, try the other end of the address space.
+	 * Unless we get really unlucky and run into the vsyscall page, this
+	 * is guaranteed to segfault.
+	 */
+
+	offset = (ULONG_MAX >> 1) + 1;
+	if (which == FS) {
+		asm volatile ("mov %%fs:(%%rcx), %%rax"
+			      : : "c" (offset) : "rax");
+	} else {
+		asm volatile ("mov %%gs:(%%rcx), %%rax"
+			      : : "c" (offset) : "rax");
+	}
+	if (!want_segv)
+		return segv_addr + offset;
+
+	abort();
+}
+
+static void check_gs_value(unsigned long value)
+{
+	unsigned long base;
+	unsigned short sel;
+
+	printf("[RUN]\tARCH_SET_GS to 0x%lx\n", value);
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, value) != 0)
+		err(1, "ARCH_SET_GS");
+
+	asm volatile ("mov %%gs, %0" : "=rm" (sel));
+	base = read_base(GS);
+	if (base == value) {
+		printf("[OK]\tGSBASE was set as expected (selector 0x%hx)\n",
+		       sel);
+	} else {
+		nerrs++;
+		printf("[FAIL]\tGSBASE was not as expected: got 0x%lx (selector 0x%hx)\n",
+		       base, sel);
+	}
+
+	if (syscall(SYS_arch_prctl, ARCH_GET_GS, &base) != 0)
+		err(1, "ARCH_GET_GS");
+	if (base == value) {
+		printf("[OK]\tARCH_GET_GS worked as expected (selector 0x%hx)\n",
+		       sel);
+	} else {
+		nerrs++;
+		printf("[FAIL]\tARCH_GET_GS was not as expected: got 0x%lx (selector 0x%hx)\n",
+		       base, sel);
+	}
+}
+
+static void mov_0_gs(unsigned long initial_base, bool schedule)
+{
+	unsigned long base, arch_base;
+
+	printf("[RUN]\tARCH_SET_GS to 0x%lx then mov 0 to %%gs%s\n", initial_base, schedule ? " and schedule " : "");
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, initial_base) != 0)
+		err(1, "ARCH_SET_GS");
+
+	if (schedule)
+		usleep(10);
+
+	asm volatile ("mov %0, %%gs" : : "rm" (0));
+	base = read_base(GS);
+	if (syscall(SYS_arch_prctl, ARCH_GET_GS, &arch_base) != 0)
+		err(1, "ARCH_GET_GS");
+	if (base == arch_base) {
+		printf("[OK]\tGSBASE is 0x%lx\n", base);
+	} else {
+		nerrs++;
+		printf("[FAIL]\tGSBASE changed to 0x%lx but kernel reports 0x%lx\n", base, arch_base);
+	}
+}
+
+static volatile unsigned long remote_base;
+static volatile bool remote_hard_zero;
+static volatile unsigned int ftx;
+
+/*
+ * ARCH_SET_FS/GS(0) may or may not program a selector of zero.  HARD_ZERO
+ * means to force the selector to zero to improve test coverage.
+ */
+#define HARD_ZERO 0xa1fa5f343cb85fa4
+
+static void do_remote_base()
+{
+	unsigned long to_set = remote_base;
+	bool hard_zero = false;
+	if (to_set == HARD_ZERO) {
+		to_set = 0;
+		hard_zero = true;
+	}
+
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, to_set) != 0)
+		err(1, "ARCH_SET_GS");
+
+	if (hard_zero)
+		asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)0));
+
+	unsigned short sel;
+	asm volatile ("mov %%gs, %0" : "=rm" (sel));
+	printf("\tother thread: ARCH_SET_GS(0x%lx)%s -- sel is 0x%hx\n",
+	       to_set, hard_zero ? " and clear gs" : "", sel);
+}
+
+void do_unexpected_base(void)
+{
+	/*
+	 * The goal here is to try to arrange for GS == 0, GSBASE !=
+	 * 0, and for the the kernel the think that GSBASE == 0.
+	 *
+	 * To make the test as reliable as possible, this uses
+	 * explicit descriptorss.  (This is not the only way.  This
+	 * could use ARCH_SET_GS with a low, nonzero base, but the
+	 * relevant side effect of ARCH_SET_GS could change.)
+	 */
+
+	/* Step 1: tell the kernel that we have GSBASE == 0. */
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, 0) != 0)
+		err(1, "ARCH_SET_GS");
+
+	/* Step 2: change GSBASE without telling the kernel. */
+	struct user_desc desc = {
+		.entry_number    = 0,
+		.base_addr       = 0xBAADF00D,
+		.limit           = 0xfffff,
+		.seg_32bit       = 1,
+		.contents        = 0, /* Data, grow-up */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 1,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+	if (syscall(SYS_modify_ldt, 1, &desc, sizeof(desc)) == 0) {
+		printf("\tother thread: using LDT slot 0\n");
+		asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)0x7));
+	} else {
+		/* No modify_ldt for us (configured out, perhaps) */
+
+		struct user_desc *low_desc = mmap(
+			NULL, sizeof(desc),
+			PROT_READ | PROT_WRITE,
+			MAP_PRIVATE | MAP_ANONYMOUS | MAP_32BIT, -1, 0);
+		memcpy(low_desc, &desc, sizeof(desc));
+
+		low_desc->entry_number = -1;
+
+		/* 32-bit set_thread_area */
+		long ret;
+		asm volatile ("int $0x80"
+			      : "=a" (ret) : "a" (243), "b" (low_desc)
+			      : "r8", "r9", "r10", "r11");
+		memcpy(&desc, low_desc, sizeof(desc));
+		munmap(low_desc, sizeof(desc));
+
+		if (ret != 0) {
+			printf("[NOTE]\tcould not create a segment -- test won't do anything\n");
+			return;
+		}
+		printf("\tother thread: using GDT slot %d\n", desc.entry_number);
+		asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)((desc.entry_number << 3) | 0x3)));
+	}
+
+	/*
+	 * Step 3: set the selector back to zero.  On AMD chips, this will
+	 * preserve GSBASE.
+	 */
+
+	asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)0));
+}
+
+static void *threadproc(void *ctx)
+{
+	while (1) {
+		while (ftx == 0)
+			syscall(SYS_futex, &ftx, FUTEX_WAIT, 0, NULL, NULL, 0);
+		if (ftx == 3)
+			return NULL;
+
+		if (ftx == 1)
+			do_remote_base();
+		else if (ftx == 2)
+			do_unexpected_base();
+		else
+			errx(1, "helper thread got bad command");
+
+		ftx = 0;
+		syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+	}
+}
+
+static void set_gs_and_switch_to(unsigned long local,
+				 unsigned short force_sel,
+				 unsigned long remote)
+{
+	unsigned long base;
+	unsigned short sel_pre_sched, sel_post_sched;
+
+	bool hard_zero = false;
+	if (local == HARD_ZERO) {
+		hard_zero = true;
+		local = 0;
+	}
+
+	printf("[RUN]\tARCH_SET_GS(0x%lx)%s, then schedule to 0x%lx\n",
+	       local, hard_zero ? " and clear gs" : "", remote);
+	if (force_sel)
+		printf("\tBefore schedule, set selector to 0x%hx\n", force_sel);
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, local) != 0)
+		err(1, "ARCH_SET_GS");
+	if (hard_zero)
+		asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)0));
+
+	if (read_base(GS) != local) {
+		nerrs++;
+		printf("[FAIL]\tGSBASE wasn't set as expected\n");
+	}
+
+	if (force_sel) {
+		asm volatile ("mov %0, %%gs" : : "rm" (force_sel));
+		sel_pre_sched = force_sel;
+		local = read_base(GS);
+
+		/*
+		 * Signal delivery seems to mess up weird selectors.  Put it
+		 * back.
+		 */
+		asm volatile ("mov %0, %%gs" : : "rm" (force_sel));
+	} else {
+		asm volatile ("mov %%gs, %0" : "=rm" (sel_pre_sched));
+	}
+
+	remote_base = remote;
+	ftx = 1;
+	syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+	while (ftx != 0)
+		syscall(SYS_futex, &ftx, FUTEX_WAIT, 1, NULL, NULL, 0);
+
+	asm volatile ("mov %%gs, %0" : "=rm" (sel_post_sched));
+	base = read_base(GS);
+	if (base == local && sel_pre_sched == sel_post_sched) {
+		printf("[OK]\tGS/BASE remained 0x%hx/0x%lx\n",
+		       sel_pre_sched, local);
+	} else {
+		nerrs++;
+		printf("[FAIL]\tGS/BASE changed from 0x%hx/0x%lx to 0x%hx/0x%lx\n",
+		       sel_pre_sched, local, sel_post_sched, base);
+	}
+}
+
+static void test_unexpected_base(void)
+{
+	unsigned long base;
+
+	printf("[RUN]\tARCH_SET_GS(0), clear gs, then manipulate GSBASE in a different thread\n");
+	if (syscall(SYS_arch_prctl, ARCH_SET_GS, 0) != 0)
+		err(1, "ARCH_SET_GS");
+	asm volatile ("mov %0, %%gs" : : "rm" ((unsigned short)0));
+
+	ftx = 2;
+	syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+	while (ftx != 0)
+		syscall(SYS_futex, &ftx, FUTEX_WAIT, 1, NULL, NULL, 0);
+
+	base = read_base(GS);
+	if (base == 0) {
+		printf("[OK]\tGSBASE remained 0\n");
+	} else {
+		nerrs++;
+		printf("[FAIL]\tGSBASE changed to 0x%lx\n", base);
+	}
+}
+
+int main()
+{
+	pthread_t thread;
+
+	sethandler(SIGSEGV, sigsegv, 0);
+
+	check_gs_value(0);
+	check_gs_value(1);
+	check_gs_value(0x200000000);
+	check_gs_value(0);
+	check_gs_value(0x200000000);
+	check_gs_value(1);
+
+	for (int sched = 0; sched < 2; sched++) {
+		mov_0_gs(0, !!sched);
+		mov_0_gs(1, !!sched);
+		mov_0_gs(0x200000000, !!sched);
+	}
+
+	/* Set up for multithreading. */
+
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+		err(1, "sched_setaffinity to CPU 0");	/* should never fail */
+
+	if (pthread_create(&thread, 0, threadproc, 0) != 0)
+		err(1, "pthread_create");
+
+	static unsigned long bases_with_hard_zero[] = {
+		0, HARD_ZERO, 1, 0x200000000,
+	};
+
+	for (int local = 0; local < 4; local++) {
+		for (int remote = 0; remote < 4; remote++) {
+			for (unsigned short s = 0; s < 5; s++) {
+				unsigned short sel = s;
+				if (s == 4)
+					asm ("mov %%ss, %0" : "=rm" (sel));
+				set_gs_and_switch_to(
+					bases_with_hard_zero[local],
+					sel,
+					bases_with_hard_zero[remote]);
+			}
+		}
+	}
+
+	test_unexpected_base();
+
+	ftx = 3;  /* Kill the thread. */
+	syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+
+	if (pthread_join(thread, NULL) != 0)
+		err(1, "pthread_join");
+
+	return nerrs == 0 ? 0 : 1;
+}
diff --git a/tools/testing/selftests/x86/ioperm.c b/tools/testing/selftests/x86/ioperm.c
new file mode 100644
index 000000000..01de41c1b
--- /dev/null
+++ b/tools/testing/selftests/x86/ioperm.c
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ioperm.c - Test case for ioperm(2)
+ * Copyright (c) 2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <sys/io.h>
+
+static int nerrs = 0;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
+{
+	siglongjmp(jmpbuf, 1);
+}
+
+static bool try_outb(unsigned short port)
+{
+	sethandler(SIGSEGV, sigsegv, SA_RESETHAND);
+	if (sigsetjmp(jmpbuf, 1) != 0) {
+		return false;
+	} else {
+		asm volatile ("outb %%al, %w[port]"
+			      : : [port] "Nd" (port), "a" (0));
+		return true;
+	}
+	clearhandler(SIGSEGV);
+}
+
+static void expect_ok(unsigned short port)
+{
+	if (!try_outb(port)) {
+		printf("[FAIL]\toutb to 0x%02hx failed\n", port);
+		exit(1);
+	}
+
+	printf("[OK]\toutb to 0x%02hx worked\n", port);
+}
+
+static void expect_gp(unsigned short port)
+{
+	if (try_outb(port)) {
+		printf("[FAIL]\toutb to 0x%02hx worked\n", port);
+		exit(1);
+	}
+
+	printf("[OK]\toutb to 0x%02hx failed\n", port);
+}
+
+int main(void)
+{
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+		err(1, "sched_setaffinity to CPU 0");
+
+	expect_gp(0x80);
+	expect_gp(0xed);
+
+	/*
+	 * Probe for ioperm support.  Note that clearing ioperm bits
+	 * works even as nonroot.
+	 */
+	printf("[RUN]\tenable 0x80\n");
+	if (ioperm(0x80, 1, 1) != 0) {
+		printf("[OK]\tioperm(0x80, 1, 1) failed (%d) -- try running as root\n",
+		       errno);
+		return 0;
+	}
+	expect_ok(0x80);
+	expect_gp(0xed);
+
+	printf("[RUN]\tdisable 0x80\n");
+	if (ioperm(0x80, 1, 0) != 0) {
+		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+		return 1;
+	}
+	expect_gp(0x80);
+	expect_gp(0xed);
+
+	/* Make sure that fork() preserves ioperm. */
+	if (ioperm(0x80, 1, 1) != 0) {
+		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+		return 1;
+	}
+
+	pid_t child = fork();
+	if (child == -1)
+		err(1, "fork");
+
+	if (child == 0) {
+		printf("[RUN]\tchild: check that we inherited permissions\n");
+		expect_ok(0x80);
+		expect_gp(0xed);
+		return 0;
+	} else {
+		int status;
+		if (waitpid(child, &status, 0) != child ||
+		    !WIFEXITED(status)) {
+			printf("[FAIL]\tChild died\n");
+			nerrs++;
+		} else if (WEXITSTATUS(status) != 0) {
+			printf("[FAIL]\tChild failed\n");
+			nerrs++;
+		} else {
+			printf("[OK]\tChild succeeded\n");
+		}
+	}
+
+	/* Test the capability checks. */
+
+	printf("\tDrop privileges\n");
+	if (setresuid(1, 1, 1) != 0) {
+		printf("[WARN]\tDropping privileges failed\n");
+		return 0;
+	}
+
+	printf("[RUN]\tdisable 0x80\n");
+	if (ioperm(0x80, 1, 0) != 0) {
+		printf("[FAIL]\tioperm(0x80, 1, 0) failed (%d)", errno);
+		return 1;
+	}
+	printf("[OK]\tit worked\n");
+
+	printf("[RUN]\tenable 0x80 again\n");
+	if (ioperm(0x80, 1, 1) == 0) {
+		printf("[FAIL]\tit succeeded but should have failed.\n");
+		return 1;
+	}
+	printf("[OK]\tit failed\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/iopl.c b/tools/testing/selftests/x86/iopl.c
new file mode 100644
index 000000000..6aa27f346
--- /dev/null
+++ b/tools/testing/selftests/x86/iopl.c
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * iopl.c - Test case for a Linux on Xen 64-bit bug
+ * Copyright (c) 2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <sched.h>
+#include <sys/io.h>
+
+static int nerrs = 0;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *si, void *ctx_void)
+{
+	siglongjmp(jmpbuf, 1);
+}
+
+int main(void)
+{
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+		err(1, "sched_setaffinity to CPU 0");
+
+	/* Probe for iopl support.  Note that iopl(0) works even as nonroot. */
+	if (iopl(3) != 0) {
+		printf("[OK]\tiopl(3) failed (%d) -- try running as root\n",
+		       errno);
+		return 0;
+	}
+
+	/* Restore our original state prior to starting the test. */
+	if (iopl(0) != 0)
+		err(1, "iopl(0)");
+
+	pid_t child = fork();
+	if (child == -1)
+		err(1, "fork");
+
+	if (child == 0) {
+		printf("\tchild: set IOPL to 3\n");
+		if (iopl(3) != 0)
+			err(1, "iopl");
+
+		printf("[RUN]\tchild: write to 0x80\n");
+		asm volatile ("outb %%al, $0x80" : : "a" (0));
+
+		return 0;
+	} else {
+		int status;
+		if (waitpid(child, &status, 0) != child ||
+		    !WIFEXITED(status)) {
+			printf("[FAIL]\tChild died\n");
+			nerrs++;
+		} else if (WEXITSTATUS(status) != 0) {
+			printf("[FAIL]\tChild failed\n");
+			nerrs++;
+		} else {
+			printf("[OK]\tChild succeeded\n");
+		}
+	}
+
+	printf("[RUN]\tparent: write to 0x80 (should fail)\n");
+
+	sethandler(SIGSEGV, sigsegv, 0);
+	if (sigsetjmp(jmpbuf, 1) != 0) {
+		printf("[OK]\twrite was denied\n");
+	} else {
+		asm volatile ("outb %%al, $0x80" : : "a" (0));
+		printf("[FAIL]\twrite was allowed\n");
+		nerrs++;
+	}
+
+	/* Test the capability checks. */
+	printf("\tiopl(3)\n");
+	if (iopl(3) != 0)
+		err(1, "iopl(3)");
+
+	printf("\tDrop privileges\n");
+	if (setresuid(1, 1, 1) != 0) {
+		printf("[WARN]\tDropping privileges failed\n");
+		goto done;
+	}
+
+	printf("[RUN]\tiopl(3) unprivileged but with IOPL==3\n");
+	if (iopl(3) != 0) {
+		printf("[FAIL]\tiopl(3) should work if iopl is already 3 even if unprivileged\n");
+		nerrs++;
+	}
+
+	printf("[RUN]\tiopl(0) unprivileged\n");
+	if (iopl(0) != 0) {
+		printf("[FAIL]\tiopl(0) should work if iopl is already 3 even if unprivileged\n");
+		nerrs++;
+	}
+
+	printf("[RUN]\tiopl(3) unprivileged\n");
+	if (iopl(3) == 0) {
+		printf("[FAIL]\tiopl(3) should fail if when unprivileged if iopl==0\n");
+		nerrs++;
+	} else {
+		printf("[OK]\tFailed as expected\n");
+	}
+
+done:
+	return nerrs ? 1 : 0;
+}
+
diff --git a/tools/testing/selftests/x86/ldt_gdt.c b/tools/testing/selftests/x86/ldt_gdt.c
new file mode 100644
index 000000000..1aef72df2
--- /dev/null
+++ b/tools/testing/selftests/x86/ldt_gdt.c
@@ -0,0 +1,927 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ldt_gdt.c - Test cases for LDT and GDT access
+ * Copyright (c) 2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <asm/ldt.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <stdbool.h>
+#include <pthread.h>
+#include <sched.h>
+#include <linux/futex.h>
+#include <sys/mman.h>
+#include <asm/prctl.h>
+#include <sys/prctl.h>
+
+#define AR_ACCESSED		(1<<8)
+
+#define AR_TYPE_RODATA		(0 * (1<<9))
+#define AR_TYPE_RWDATA		(1 * (1<<9))
+#define AR_TYPE_RODATA_EXPDOWN	(2 * (1<<9))
+#define AR_TYPE_RWDATA_EXPDOWN	(3 * (1<<9))
+#define AR_TYPE_XOCODE		(4 * (1<<9))
+#define AR_TYPE_XRCODE		(5 * (1<<9))
+#define AR_TYPE_XOCODE_CONF	(6 * (1<<9))
+#define AR_TYPE_XRCODE_CONF	(7 * (1<<9))
+
+#define AR_DPL3			(3 * (1<<13))
+
+#define AR_S			(1 << 12)
+#define AR_P			(1 << 15)
+#define AR_AVL			(1 << 20)
+#define AR_L			(1 << 21)
+#define AR_DB			(1 << 22)
+#define AR_G			(1 << 23)
+
+#ifdef __x86_64__
+# define INT80_CLOBBERS "r8", "r9", "r10", "r11"
+#else
+# define INT80_CLOBBERS
+#endif
+
+static int nerrs;
+
+/* Points to an array of 1024 ints, each holding its own index. */
+static const unsigned int *counter_page;
+static struct user_desc *low_user_desc;
+static struct user_desc *low_user_desc_clear;  /* Use to delete GDT entry */
+static int gdt_entry_num;
+
+static void check_invalid_segment(uint16_t index, int ldt)
+{
+	uint32_t has_limit = 0, has_ar = 0, limit, ar;
+	uint32_t selector = (index << 3) | (ldt << 2) | 3;
+
+	asm ("lsl %[selector], %[limit]\n\t"
+	     "jnz 1f\n\t"
+	     "movl $1, %[has_limit]\n\t"
+	     "1:"
+	     : [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
+	     : [selector] "r" (selector));
+	asm ("larl %[selector], %[ar]\n\t"
+	     "jnz 1f\n\t"
+	     "movl $1, %[has_ar]\n\t"
+	     "1:"
+	     : [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
+	     : [selector] "r" (selector));
+
+	if (has_limit || has_ar) {
+		printf("[FAIL]\t%s entry %hu is valid but should be invalid\n",
+		       (ldt ? "LDT" : "GDT"), index);
+		nerrs++;
+	} else {
+		printf("[OK]\t%s entry %hu is invalid\n",
+		       (ldt ? "LDT" : "GDT"), index);
+	}
+}
+
+static void check_valid_segment(uint16_t index, int ldt,
+				uint32_t expected_ar, uint32_t expected_limit,
+				bool verbose)
+{
+	uint32_t has_limit = 0, has_ar = 0, limit, ar;
+	uint32_t selector = (index << 3) | (ldt << 2) | 3;
+
+	asm ("lsl %[selector], %[limit]\n\t"
+	     "jnz 1f\n\t"
+	     "movl $1, %[has_limit]\n\t"
+	     "1:"
+	     : [limit] "=r" (limit), [has_limit] "+rm" (has_limit)
+	     : [selector] "r" (selector));
+	asm ("larl %[selector], %[ar]\n\t"
+	     "jnz 1f\n\t"
+	     "movl $1, %[has_ar]\n\t"
+	     "1:"
+	     : [ar] "=r" (ar), [has_ar] "+rm" (has_ar)
+	     : [selector] "r" (selector));
+
+	if (!has_limit || !has_ar) {
+		printf("[FAIL]\t%s entry %hu is invalid but should be valid\n",
+		       (ldt ? "LDT" : "GDT"), index);
+		nerrs++;
+		return;
+	}
+
+	/* The SDM says "bits 19:16 are undefined".  Thanks. */
+	ar &= ~0xF0000;
+
+	/*
+	 * NB: Different Linux versions do different things with the
+	 * accessed bit in set_thread_area().
+	 */
+	if (ar != expected_ar && ar != (expected_ar | AR_ACCESSED)) {
+		printf("[FAIL]\t%s entry %hu has AR 0x%08X but expected 0x%08X\n",
+		       (ldt ? "LDT" : "GDT"), index, ar, expected_ar);
+		nerrs++;
+	} else if (limit != expected_limit) {
+		printf("[FAIL]\t%s entry %hu has limit 0x%08X but expected 0x%08X\n",
+		       (ldt ? "LDT" : "GDT"), index, limit, expected_limit);
+		nerrs++;
+	} else if (verbose) {
+		printf("[OK]\t%s entry %hu has AR 0x%08X and limit 0x%08X\n",
+		       (ldt ? "LDT" : "GDT"), index, ar, limit);
+	}
+}
+
+static bool install_valid_mode(const struct user_desc *d, uint32_t ar,
+			       bool oldmode, bool ldt)
+{
+	struct user_desc desc = *d;
+	int ret;
+
+	if (!ldt) {
+#ifndef __i386__
+		/* No point testing set_thread_area in a 64-bit build */
+		return false;
+#endif
+		if (!gdt_entry_num)
+			return false;
+		desc.entry_number = gdt_entry_num;
+
+		ret = syscall(SYS_set_thread_area, &desc);
+	} else {
+		ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
+			      &desc, sizeof(desc));
+
+		if (ret < -1)
+			errno = -ret;
+
+		if (ret != 0 && errno == ENOSYS) {
+			printf("[OK]\tmodify_ldt returned -ENOSYS\n");
+			return false;
+		}
+	}
+
+	if (ret == 0) {
+		uint32_t limit = desc.limit;
+		if (desc.limit_in_pages)
+			limit = (limit << 12) + 4095;
+		check_valid_segment(desc.entry_number, ldt, ar, limit, true);
+		return true;
+	} else {
+		if (desc.seg_32bit) {
+			printf("[FAIL]\tUnexpected %s failure %d\n",
+			       ldt ? "modify_ldt" : "set_thread_area",
+			       errno);
+			nerrs++;
+			return false;
+		} else {
+			printf("[OK]\t%s rejected 16 bit segment\n",
+			       ldt ? "modify_ldt" : "set_thread_area");
+			return false;
+		}
+	}
+}
+
+static bool install_valid(const struct user_desc *desc, uint32_t ar)
+{
+	bool ret = install_valid_mode(desc, ar, false, true);
+
+	if (desc->contents <= 1 && desc->seg_32bit &&
+	    !desc->seg_not_present) {
+		/* Should work in the GDT, too. */
+		install_valid_mode(desc, ar, false, false);
+	}
+
+	return ret;
+}
+
+static void install_invalid(const struct user_desc *desc, bool oldmode)
+{
+	int ret = syscall(SYS_modify_ldt, oldmode ? 1 : 0x11,
+			  desc, sizeof(*desc));
+	if (ret < -1)
+		errno = -ret;
+	if (ret == 0) {
+		check_invalid_segment(desc->entry_number, 1);
+	} else if (errno == ENOSYS) {
+		printf("[OK]\tmodify_ldt returned -ENOSYS\n");
+	} else {
+		if (desc->seg_32bit) {
+			printf("[FAIL]\tUnexpected modify_ldt failure %d\n",
+			       errno);
+			nerrs++;
+		} else {
+			printf("[OK]\tmodify_ldt rejected 16 bit segment\n");
+		}
+	}
+}
+
+static int safe_modify_ldt(int func, struct user_desc *ptr,
+			   unsigned long bytecount)
+{
+	int ret = syscall(SYS_modify_ldt, 0x11, ptr, bytecount);
+	if (ret < -1)
+		errno = -ret;
+	return ret;
+}
+
+static void fail_install(struct user_desc *desc)
+{
+	if (safe_modify_ldt(0x11, desc, sizeof(*desc)) == 0) {
+		printf("[FAIL]\tmodify_ldt accepted a bad descriptor\n");
+		nerrs++;
+	} else if (errno == ENOSYS) {
+		printf("[OK]\tmodify_ldt returned -ENOSYS\n");
+	} else {
+		printf("[OK]\tmodify_ldt failure %d\n", errno);
+	}
+}
+
+static void do_simple_tests(void)
+{
+	struct user_desc desc = {
+		.entry_number    = 0,
+		.base_addr       = 0,
+		.limit           = 10,
+		.seg_32bit       = 1,
+		.contents        = 2, /* Code, not conforming */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
+
+	desc.limit_in_pages = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_P | AR_DB | AR_G);
+
+	check_invalid_segment(1, 1);
+
+	desc.entry_number = 2;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_P | AR_DB | AR_G);
+
+	check_invalid_segment(1, 1);
+
+	desc.base_addr = 0xf0000000;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_P | AR_DB | AR_G);
+
+	desc.useable = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_P | AR_DB | AR_G | AR_AVL);
+
+	desc.seg_not_present = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_DB | AR_G | AR_AVL);
+
+	desc.seg_32bit = 0;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_G | AR_AVL);
+
+	desc.seg_32bit = 1;
+	desc.contents = 0;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA |
+		      AR_S | AR_DB | AR_G | AR_AVL);
+
+	desc.read_exec_only = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA |
+		      AR_S | AR_DB | AR_G | AR_AVL);
+
+	desc.contents = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN |
+		      AR_S | AR_DB | AR_G | AR_AVL);
+
+	desc.read_exec_only = 0;
+	desc.limit_in_pages = 0;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN |
+		      AR_S | AR_DB | AR_AVL);
+
+	desc.contents = 3;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE_CONF |
+		      AR_S | AR_DB | AR_AVL);
+
+	desc.read_exec_only = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE_CONF |
+		      AR_S | AR_DB | AR_AVL);
+
+	desc.read_exec_only = 0;
+	desc.contents = 2;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE |
+		      AR_S | AR_DB | AR_AVL);
+
+	desc.read_exec_only = 1;
+
+#ifdef __x86_64__
+	desc.lm = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
+		      AR_S | AR_DB | AR_AVL);
+	desc.lm = 0;
+#endif
+
+	bool entry1_okay = install_valid(&desc, AR_DPL3 | AR_TYPE_XOCODE |
+					 AR_S | AR_DB | AR_AVL);
+
+	if (entry1_okay) {
+		printf("[RUN]\tTest fork\n");
+		pid_t child = fork();
+		if (child == 0) {
+			nerrs = 0;
+			check_valid_segment(desc.entry_number, 1,
+					    AR_DPL3 | AR_TYPE_XOCODE |
+					    AR_S | AR_DB | AR_AVL, desc.limit,
+					    true);
+			check_invalid_segment(1, 1);
+			exit(nerrs ? 1 : 0);
+		} else {
+			int status;
+			if (waitpid(child, &status, 0) != child ||
+			    !WIFEXITED(status)) {
+				printf("[FAIL]\tChild died\n");
+				nerrs++;
+			} else if (WEXITSTATUS(status) != 0) {
+				printf("[FAIL]\tChild failed\n");
+				nerrs++;
+			} else {
+				printf("[OK]\tChild succeeded\n");
+			}
+		}
+
+		printf("[RUN]\tTest size\n");
+		int i;
+		for (i = 0; i < 8192; i++) {
+			desc.entry_number = i;
+			desc.limit = i;
+			if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
+				printf("[FAIL]\tFailed to install entry %d\n", i);
+				nerrs++;
+				break;
+			}
+		}
+		for (int j = 0; j < i; j++) {
+			check_valid_segment(j, 1, AR_DPL3 | AR_TYPE_XOCODE |
+					    AR_S | AR_DB | AR_AVL, j, false);
+		}
+		printf("[DONE]\tSize test\n");
+	} else {
+		printf("[SKIP]\tSkipping fork and size tests because we have no LDT\n");
+	}
+
+	/* Test entry_number too high. */
+	desc.entry_number = 8192;
+	fail_install(&desc);
+
+	/* Test deletion and actions mistakeable for deletion. */
+	memset(&desc, 0, sizeof(desc));
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P);
+
+	desc.seg_not_present = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
+
+	desc.seg_not_present = 0;
+	desc.read_exec_only = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P);
+
+	desc.read_exec_only = 0;
+	desc.seg_not_present = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S);
+
+	desc.read_exec_only = 1;
+	desc.limit = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
+
+	desc.limit = 0;
+	desc.base_addr = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S);
+
+	desc.base_addr = 0;
+	install_invalid(&desc, false);
+
+	desc.seg_not_present = 0;
+	desc.seg_32bit = 1;
+	desc.read_exec_only = 0;
+	desc.limit = 0xfffff;
+
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB);
+
+	desc.limit_in_pages = 1;
+
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA | AR_S | AR_P | AR_DB | AR_G);
+	desc.read_exec_only = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA | AR_S | AR_P | AR_DB | AR_G);
+	desc.contents = 1;
+	desc.read_exec_only = 0;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RWDATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
+	desc.read_exec_only = 1;
+	install_valid(&desc, AR_DPL3 | AR_TYPE_RODATA_EXPDOWN | AR_S | AR_P | AR_DB | AR_G);
+
+	desc.limit = 0;
+	install_invalid(&desc, true);
+}
+
+/*
+ * 0: thread is idle
+ * 1: thread armed
+ * 2: thread should clear LDT entry 0
+ * 3: thread should exit
+ */
+static volatile unsigned int ftx;
+
+static void *threadproc(void *ctx)
+{
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(1, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+		err(1, "sched_setaffinity to CPU 1");	/* should never fail */
+
+	while (1) {
+		syscall(SYS_futex, &ftx, FUTEX_WAIT, 0, NULL, NULL, 0);
+		while (ftx != 2) {
+			if (ftx >= 3)
+				return NULL;
+		}
+
+		/* clear LDT entry 0 */
+		const struct user_desc desc = {};
+		if (syscall(SYS_modify_ldt, 1, &desc, sizeof(desc)) != 0)
+			err(1, "modify_ldt");
+
+		/* If ftx == 2, set it to zero.  If ftx == 100, quit. */
+		unsigned int x = -2;
+		asm volatile ("lock xaddl %[x], %[ftx]" :
+			      [x] "+r" (x), [ftx] "+m" (ftx));
+		if (x != 2)
+			return NULL;
+	}
+}
+
+#ifdef __i386__
+
+#ifndef SA_RESTORE
+#define SA_RESTORER 0x04000000
+#endif
+
+/*
+ * The UAPI header calls this 'struct sigaction', which conflicts with
+ * glibc.  Sigh.
+ */
+struct fake_ksigaction {
+	void *handler;  /* the real type is nasty */
+	unsigned long sa_flags;
+	void (*sa_restorer)(void);
+	unsigned char sigset[8];
+};
+
+static void fix_sa_restorer(int sig)
+{
+	struct fake_ksigaction ksa;
+
+	if (syscall(SYS_rt_sigaction, sig, NULL, &ksa, 8) == 0) {
+		/*
+		 * glibc has a nasty bug: it sometimes writes garbage to
+		 * sa_restorer.  This interacts quite badly with anything
+		 * that fiddles with SS because it can trigger legacy
+		 * stack switching.  Patch it up.  See:
+		 *
+		 * https://sourceware.org/bugzilla/show_bug.cgi?id=21269
+		 */
+		if (!(ksa.sa_flags & SA_RESTORER) && ksa.sa_restorer) {
+			ksa.sa_restorer = NULL;
+			if (syscall(SYS_rt_sigaction, sig, &ksa, NULL,
+				    sizeof(ksa.sigset)) != 0)
+				err(1, "rt_sigaction");
+		}
+	}
+}
+#else
+static void fix_sa_restorer(int sig)
+{
+	/* 64-bit glibc works fine. */
+}
+#endif
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+
+	fix_sa_restorer(sig);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+	siglongjmp(jmpbuf, 1);
+}
+
+static void do_multicpu_tests(void)
+{
+	cpu_set_t cpuset;
+	pthread_t thread;
+	int failures = 0, iters = 5, i;
+	unsigned short orig_ss;
+
+	CPU_ZERO(&cpuset);
+	CPU_SET(1, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+		printf("[SKIP]\tCannot set affinity to CPU 1\n");
+		return;
+	}
+
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+		printf("[SKIP]\tCannot set affinity to CPU 0\n");
+		return;
+	}
+
+	sethandler(SIGSEGV, sigsegv, 0);
+#ifdef __i386__
+	/* True 32-bit kernels send SIGILL instead of SIGSEGV on IRET faults. */
+	sethandler(SIGILL, sigsegv, 0);
+#endif
+
+	printf("[RUN]\tCross-CPU LDT invalidation\n");
+
+	if (pthread_create(&thread, 0, threadproc, 0) != 0)
+		err(1, "pthread_create");
+
+	asm volatile ("mov %%ss, %0" : "=rm" (orig_ss));
+
+	for (i = 0; i < 5; i++) {
+		if (sigsetjmp(jmpbuf, 1) != 0)
+			continue;
+
+		/* Make sure the thread is ready after the last test. */
+		while (ftx != 0)
+			;
+
+		struct user_desc desc = {
+			.entry_number    = 0,
+			.base_addr       = 0,
+			.limit           = 0xfffff,
+			.seg_32bit       = 1,
+			.contents        = 0, /* Data */
+			.read_exec_only  = 0,
+			.limit_in_pages  = 1,
+			.seg_not_present = 0,
+			.useable         = 0
+		};
+
+		if (safe_modify_ldt(0x11, &desc, sizeof(desc)) != 0) {
+			if (errno != ENOSYS)
+				err(1, "modify_ldt");
+			printf("[SKIP]\tmodify_ldt unavailable\n");
+			break;
+		}
+
+		/* Arm the thread. */
+		ftx = 1;
+		syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+
+		asm volatile ("mov %0, %%ss" : : "r" (0x7));
+
+		/* Go! */
+		ftx = 2;
+
+		while (ftx != 0)
+			;
+
+		/*
+		 * On success, modify_ldt will segfault us synchronously,
+		 * and we'll escape via siglongjmp.
+		 */
+
+		failures++;
+		asm volatile ("mov %0, %%ss" : : "rm" (orig_ss));
+	};
+
+	ftx = 100;  /* Kill the thread. */
+	syscall(SYS_futex, &ftx, FUTEX_WAKE, 0, NULL, NULL, 0);
+
+	if (pthread_join(thread, NULL) != 0)
+		err(1, "pthread_join");
+
+	if (failures) {
+		printf("[FAIL]\t%d of %d iterations failed\n", failures, iters);
+		nerrs++;
+	} else {
+		printf("[OK]\tAll %d iterations succeeded\n", iters);
+	}
+}
+
+static int finish_exec_test(void)
+{
+	/*
+	 * Older kernel versions did inherit the LDT on exec() which is
+	 * wrong because exec() starts from a clean state.
+	 */
+	check_invalid_segment(0, 1);
+
+	return nerrs ? 1 : 0;
+}
+
+static void do_exec_test(void)
+{
+	printf("[RUN]\tTest exec\n");
+
+	struct user_desc desc = {
+		.entry_number    = 0,
+		.base_addr       = 0,
+		.limit           = 42,
+		.seg_32bit       = 1,
+		.contents        = 2, /* Code, not conforming */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+	install_valid(&desc, AR_DPL3 | AR_TYPE_XRCODE | AR_S | AR_P | AR_DB);
+
+	pid_t child = fork();
+	if (child == 0) {
+		execl("/proc/self/exe", "ldt_gdt_test_exec", NULL);
+		printf("[FAIL]\tCould not exec self\n");
+		exit(1);	/* exec failed */
+	} else {
+		int status;
+		if (waitpid(child, &status, 0) != child ||
+		    !WIFEXITED(status)) {
+			printf("[FAIL]\tChild died\n");
+			nerrs++;
+		} else if (WEXITSTATUS(status) != 0) {
+			printf("[FAIL]\tChild failed\n");
+			nerrs++;
+		} else {
+			printf("[OK]\tChild succeeded\n");
+		}
+	}
+}
+
+static void setup_counter_page(void)
+{
+	unsigned int *page = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
+			 MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1, 0);
+	if (page == MAP_FAILED)
+		err(1, "mmap");
+
+	for (int i = 0; i < 1024; i++)
+		page[i] = i;
+	counter_page = page;
+}
+
+static int invoke_set_thread_area(void)
+{
+	int ret;
+	asm volatile ("int $0x80"
+		      : "=a" (ret), "+m" (low_user_desc) :
+			"a" (243), "b" (low_user_desc)
+		      : INT80_CLOBBERS);
+	return ret;
+}
+
+static void setup_low_user_desc(void)
+{
+	low_user_desc = mmap(NULL, 2 * sizeof(struct user_desc),
+			     PROT_READ | PROT_WRITE,
+			     MAP_ANONYMOUS | MAP_PRIVATE | MAP_32BIT, -1, 0);
+	if (low_user_desc == MAP_FAILED)
+		err(1, "mmap");
+
+	low_user_desc->entry_number	= -1;
+	low_user_desc->base_addr	= (unsigned long)&counter_page[1];
+	low_user_desc->limit		= 0xfffff;
+	low_user_desc->seg_32bit	= 1;
+	low_user_desc->contents		= 0; /* Data, grow-up*/
+	low_user_desc->read_exec_only	= 0;
+	low_user_desc->limit_in_pages	= 1;
+	low_user_desc->seg_not_present	= 0;
+	low_user_desc->useable		= 0;
+
+	if (invoke_set_thread_area() == 0) {
+		gdt_entry_num = low_user_desc->entry_number;
+		printf("[NOTE]\tset_thread_area is available; will use GDT index %d\n", gdt_entry_num);
+	} else {
+		printf("[NOTE]\tset_thread_area is unavailable\n");
+	}
+
+	low_user_desc_clear = low_user_desc + 1;
+	low_user_desc_clear->entry_number = gdt_entry_num;
+	low_user_desc_clear->read_exec_only = 1;
+	low_user_desc_clear->seg_not_present = 1;
+}
+
+static void test_gdt_invalidation(void)
+{
+	if (!gdt_entry_num)
+		return;	/* 64-bit only system -- we can't use set_thread_area */
+
+	unsigned short prev_sel;
+	unsigned short sel;
+	unsigned int eax;
+	const char *result;
+#ifdef __x86_64__
+	unsigned long saved_base;
+	unsigned long new_base;
+#endif
+
+	/* Test DS */
+	invoke_set_thread_area();
+	eax = 243;
+	sel = (gdt_entry_num << 3) | 3;
+	asm volatile ("movw %%ds, %[prev_sel]\n\t"
+		      "movw %[sel], %%ds\n\t"
+#ifdef __i386__
+		      "pushl %%ebx\n\t"
+#endif
+		      "movl %[arg1], %%ebx\n\t"
+		      "int $0x80\n\t"	/* Should invalidate ds */
+#ifdef __i386__
+		      "popl %%ebx\n\t"
+#endif
+		      "movw %%ds, %[sel]\n\t"
+		      "movw %[prev_sel], %%ds"
+		      : [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
+			"+a" (eax)
+		      : "m" (low_user_desc_clear),
+			[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
+		      : INT80_CLOBBERS);
+
+	if (sel != 0) {
+		result = "FAIL";
+		nerrs++;
+	} else {
+		result = "OK";
+	}
+	printf("[%s]\tInvalidate DS with set_thread_area: new DS = 0x%hx\n",
+	       result, sel);
+
+	/* Test ES */
+	invoke_set_thread_area();
+	eax = 243;
+	sel = (gdt_entry_num << 3) | 3;
+	asm volatile ("movw %%es, %[prev_sel]\n\t"
+		      "movw %[sel], %%es\n\t"
+#ifdef __i386__
+		      "pushl %%ebx\n\t"
+#endif
+		      "movl %[arg1], %%ebx\n\t"
+		      "int $0x80\n\t"	/* Should invalidate es */
+#ifdef __i386__
+		      "popl %%ebx\n\t"
+#endif
+		      "movw %%es, %[sel]\n\t"
+		      "movw %[prev_sel], %%es"
+		      : [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
+			"+a" (eax)
+		      : "m" (low_user_desc_clear),
+			[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
+		      : INT80_CLOBBERS);
+
+	if (sel != 0) {
+		result = "FAIL";
+		nerrs++;
+	} else {
+		result = "OK";
+	}
+	printf("[%s]\tInvalidate ES with set_thread_area: new ES = 0x%hx\n",
+	       result, sel);
+
+	/* Test FS */
+	invoke_set_thread_area();
+	eax = 243;
+	sel = (gdt_entry_num << 3) | 3;
+#ifdef __x86_64__
+	syscall(SYS_arch_prctl, ARCH_GET_FS, &saved_base);
+#endif
+	asm volatile ("movw %%fs, %[prev_sel]\n\t"
+		      "movw %[sel], %%fs\n\t"
+#ifdef __i386__
+		      "pushl %%ebx\n\t"
+#endif
+		      "movl %[arg1], %%ebx\n\t"
+		      "int $0x80\n\t"	/* Should invalidate fs */
+#ifdef __i386__
+		      "popl %%ebx\n\t"
+#endif
+		      "movw %%fs, %[sel]\n\t"
+		      : [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
+			"+a" (eax)
+		      : "m" (low_user_desc_clear),
+			[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
+		      : INT80_CLOBBERS);
+
+#ifdef __x86_64__
+	syscall(SYS_arch_prctl, ARCH_GET_FS, &new_base);
+#endif
+
+	/* Restore FS/BASE for glibc */
+	asm volatile ("movw %[prev_sel], %%fs" : : [prev_sel] "rm" (prev_sel));
+#ifdef __x86_64__
+	if (saved_base)
+		syscall(SYS_arch_prctl, ARCH_SET_FS, saved_base);
+#endif
+
+	if (sel != 0) {
+		result = "FAIL";
+		nerrs++;
+	} else {
+		result = "OK";
+	}
+	printf("[%s]\tInvalidate FS with set_thread_area: new FS = 0x%hx\n",
+	       result, sel);
+
+#ifdef __x86_64__
+	if (sel == 0 && new_base != 0) {
+		nerrs++;
+		printf("[FAIL]\tNew FSBASE was 0x%lx\n", new_base);
+	} else {
+		printf("[OK]\tNew FSBASE was zero\n");
+	}
+#endif
+
+	/* Test GS */
+	invoke_set_thread_area();
+	eax = 243;
+	sel = (gdt_entry_num << 3) | 3;
+#ifdef __x86_64__
+	syscall(SYS_arch_prctl, ARCH_GET_GS, &saved_base);
+#endif
+	asm volatile ("movw %%gs, %[prev_sel]\n\t"
+		      "movw %[sel], %%gs\n\t"
+#ifdef __i386__
+		      "pushl %%ebx\n\t"
+#endif
+		      "movl %[arg1], %%ebx\n\t"
+		      "int $0x80\n\t"	/* Should invalidate gs */
+#ifdef __i386__
+		      "popl %%ebx\n\t"
+#endif
+		      "movw %%gs, %[sel]\n\t"
+		      : [prev_sel] "=&r" (prev_sel), [sel] "+r" (sel),
+			"+a" (eax)
+		      : "m" (low_user_desc_clear),
+			[arg1] "r" ((unsigned int)(unsigned long)low_user_desc_clear)
+		      : INT80_CLOBBERS);
+
+#ifdef __x86_64__
+	syscall(SYS_arch_prctl, ARCH_GET_GS, &new_base);
+#endif
+
+	/* Restore GS/BASE for glibc */
+	asm volatile ("movw %[prev_sel], %%gs" : : [prev_sel] "rm" (prev_sel));
+#ifdef __x86_64__
+	if (saved_base)
+		syscall(SYS_arch_prctl, ARCH_SET_GS, saved_base);
+#endif
+
+	if (sel != 0) {
+		result = "FAIL";
+		nerrs++;
+	} else {
+		result = "OK";
+	}
+	printf("[%s]\tInvalidate GS with set_thread_area: new GS = 0x%hx\n",
+	       result, sel);
+
+#ifdef __x86_64__
+	if (sel == 0 && new_base != 0) {
+		nerrs++;
+		printf("[FAIL]\tNew GSBASE was 0x%lx\n", new_base);
+	} else {
+		printf("[OK]\tNew GSBASE was zero\n");
+	}
+#endif
+}
+
+int main(int argc, char **argv)
+{
+	if (argc == 1 && !strcmp(argv[0], "ldt_gdt_test_exec"))
+		return finish_exec_test();
+
+	setup_counter_page();
+	setup_low_user_desc();
+
+	do_simple_tests();
+
+	do_multicpu_tests();
+
+	do_exec_test();
+
+	test_gdt_invalidation();
+
+	return nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/mov_ss_trap.c b/tools/testing/selftests/x86/mov_ss_trap.c
new file mode 100644
index 000000000..3c3a02265
--- /dev/null
+++ b/tools/testing/selftests/x86/mov_ss_trap.c
@@ -0,0 +1,285 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * mov_ss_trap.c: Exercise the bizarre side effects of a watchpoint on MOV SS
+ *
+ * This does MOV SS from a watchpointed address followed by various
+ * types of kernel entries.  A MOV SS that hits a watchpoint will queue
+ * up a #DB trap but will not actually deliver that trap.  The trap
+ * will be delivered after the next instruction instead.  The CPU's logic
+ * seems to be:
+ *
+ *  - Any fault: drop the pending #DB trap.
+ *  - INT $N, INT3, INTO, SYSCALL, SYSENTER: enter the kernel and then
+ *    deliver #DB.
+ *  - ICEBP: enter the kernel but do not deliver the watchpoint trap
+ *  - breakpoint: only one #DB is delivered (phew!)
+ *
+ * There are plenty of ways for a kernel to handle this incorrectly.  This
+ * test tries to exercise all the cases.
+ *
+ * This should mostly cover CVE-2018-1087 and CVE-2018-8897.
+ */
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/user.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <err.h>
+#include <string.h>
+#include <setjmp.h>
+#include <sys/prctl.h>
+
+#define X86_EFLAGS_RF (1UL << 16)
+
+#if __x86_64__
+# define REG_IP REG_RIP
+#else
+# define REG_IP REG_EIP
+#endif
+
+unsigned short ss;
+extern unsigned char breakpoint_insn[];
+sigjmp_buf jmpbuf;
+static unsigned char altstack_data[SIGSTKSZ];
+
+static void enable_watchpoint(void)
+{
+	pid_t parent = getpid();
+	int status;
+
+	pid_t child = fork();
+	if (child < 0)
+		err(1, "fork");
+
+	if (child) {
+		if (waitpid(child, &status, 0) != child)
+			err(1, "waitpid for child");
+	} else {
+		unsigned long dr0, dr1, dr7;
+
+		dr0 = (unsigned long)&ss;
+		dr1 = (unsigned long)breakpoint_insn;
+		dr7 = ((1UL << 1) |	/* G0 */
+		       (3UL << 16) |	/* RW0 = read or write */
+		       (1UL << 18) |	/* LEN0 = 2 bytes */
+		       (1UL << 3));	/* G1, RW1 = insn */
+
+		if (ptrace(PTRACE_ATTACH, parent, NULL, NULL) != 0)
+			err(1, "PTRACE_ATTACH");
+
+		if (waitpid(parent, &status, 0) != parent)
+			err(1, "waitpid for child");
+
+		if (ptrace(PTRACE_POKEUSER, parent, (void *)offsetof(struct user, u_debugreg[0]), dr0) != 0)
+			err(1, "PTRACE_POKEUSER DR0");
+
+		if (ptrace(PTRACE_POKEUSER, parent, (void *)offsetof(struct user, u_debugreg[1]), dr1) != 0)
+			err(1, "PTRACE_POKEUSER DR1");
+
+		if (ptrace(PTRACE_POKEUSER, parent, (void *)offsetof(struct user, u_debugreg[7]), dr7) != 0)
+			err(1, "PTRACE_POKEUSER DR7");
+
+		printf("\tDR0 = %lx, DR1 = %lx, DR7 = %lx\n", dr0, dr1, dr7);
+
+		if (ptrace(PTRACE_DETACH, parent, NULL, NULL) != 0)
+			err(1, "PTRACE_DETACH");
+
+		exit(0);
+	}
+}
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static char const * const signames[] = {
+	[SIGSEGV] = "SIGSEGV",
+	[SIGBUS] = "SIBGUS",
+	[SIGTRAP] = "SIGTRAP",
+	[SIGILL] = "SIGILL",
+};
+
+static void sigtrap(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = ctx_void;
+
+	printf("\tGot SIGTRAP with RIP=%lx, EFLAGS.RF=%d\n",
+	       (unsigned long)ctx->uc_mcontext.gregs[REG_IP],
+	       !!(ctx->uc_mcontext.gregs[REG_EFL] & X86_EFLAGS_RF));
+}
+
+static void handle_and_return(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = ctx_void;
+
+	printf("\tGot %s with RIP=%lx\n", signames[sig],
+	       (unsigned long)ctx->uc_mcontext.gregs[REG_IP]);
+}
+
+static void handle_and_longjmp(int sig, siginfo_t *si, void *ctx_void)
+{
+	ucontext_t *ctx = ctx_void;
+
+	printf("\tGot %s with RIP=%lx\n", signames[sig],
+	       (unsigned long)ctx->uc_mcontext.gregs[REG_IP]);
+
+	siglongjmp(jmpbuf, 1);
+}
+
+int main()
+{
+	unsigned long nr;
+
+	asm volatile ("mov %%ss, %[ss]" : [ss] "=m" (ss));
+	printf("\tSS = 0x%hx, &SS = 0x%p\n", ss, &ss);
+
+	if (prctl(PR_SET_PTRACER, PR_SET_PTRACER_ANY, 0, 0, 0) == 0)
+		printf("\tPR_SET_PTRACER_ANY succeeded\n");
+
+	printf("\tSet up a watchpoint\n");
+	sethandler(SIGTRAP, sigtrap, 0);
+	enable_watchpoint();
+
+	printf("[RUN]\tRead from watched memory (should get SIGTRAP)\n");
+	asm volatile ("mov %[ss], %[tmp]" : [tmp] "=r" (nr) : [ss] "m" (ss));
+
+	printf("[RUN]\tMOV SS; INT3\n");
+	asm volatile ("mov %[ss], %%ss; int3" :: [ss] "m" (ss));
+
+	printf("[RUN]\tMOV SS; INT 3\n");
+	asm volatile ("mov %[ss], %%ss; .byte 0xcd, 0x3" :: [ss] "m" (ss));
+
+	printf("[RUN]\tMOV SS; CS CS INT3\n");
+	asm volatile ("mov %[ss], %%ss; .byte 0x2e, 0x2e; int3" :: [ss] "m" (ss));
+
+	printf("[RUN]\tMOV SS; CSx14 INT3\n");
+	asm volatile ("mov %[ss], %%ss; .fill 14,1,0x2e; int3" :: [ss] "m" (ss));
+
+	printf("[RUN]\tMOV SS; INT 4\n");
+	sethandler(SIGSEGV, handle_and_return, SA_RESETHAND);
+	asm volatile ("mov %[ss], %%ss; int $4" :: [ss] "m" (ss));
+
+#ifdef __i386__
+	printf("[RUN]\tMOV SS; INTO\n");
+	sethandler(SIGSEGV, handle_and_return, SA_RESETHAND);
+	nr = -1;
+	asm volatile ("add $1, %[tmp]; mov %[ss], %%ss; into"
+		      : [tmp] "+r" (nr) : [ss] "m" (ss));
+#endif
+
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; ICEBP\n");
+
+		/* Some emulators (e.g. QEMU TCG) don't emulate ICEBP. */
+		sethandler(SIGILL, handle_and_longjmp, SA_RESETHAND);
+
+		asm volatile ("mov %[ss], %%ss; .byte 0xf1" :: [ss] "m" (ss));
+	}
+
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; CLI\n");
+		sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND);
+		asm volatile ("mov %[ss], %%ss; cli" :: [ss] "m" (ss));
+	}
+
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; #PF\n");
+		sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND);
+		asm volatile ("mov %[ss], %%ss; mov (-1), %[tmp]"
+			      : [tmp] "=r" (nr) : [ss] "m" (ss));
+	}
+
+	/*
+	 * INT $1: if #DB has DPL=3 and there isn't special handling,
+	 * then the kernel will die.
+	 */
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; INT 1\n");
+		sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND);
+		asm volatile ("mov %[ss], %%ss; int $1" :: [ss] "m" (ss));
+	}
+
+#ifdef __x86_64__
+	/*
+	 * In principle, we should test 32-bit SYSCALL as well, but
+	 * the calling convention is so unpredictable that it's
+	 * not obviously worth the effort.
+	 */
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; SYSCALL\n");
+		sethandler(SIGILL, handle_and_longjmp, SA_RESETHAND);
+		nr = SYS_getpid;
+		/*
+		 * Toggle the high bit of RSP to make it noncanonical to
+		 * strengthen this test on non-SMAP systems.
+		 */
+		asm volatile ("btc $63, %%rsp\n\t"
+			      "mov %[ss], %%ss; syscall\n\t"
+			      "btc $63, %%rsp"
+			      : "+a" (nr) : [ss] "m" (ss)
+			      : "rcx"
+#ifdef __x86_64__
+				, "r11"
+#endif
+			);
+	}
+#endif
+
+	printf("[RUN]\tMOV SS; breakpointed NOP\n");
+	asm volatile ("mov %[ss], %%ss; breakpoint_insn: nop" :: [ss] "m" (ss));
+
+	/*
+	 * Invoking SYSENTER directly breaks all the rules.  Just handle
+	 * the SIGSEGV.
+	 */
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; SYSENTER\n");
+		stack_t stack = {
+			.ss_sp = altstack_data,
+			.ss_size = SIGSTKSZ,
+		};
+		if (sigaltstack(&stack, NULL) != 0)
+			err(1, "sigaltstack");
+		sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND | SA_ONSTACK);
+		nr = SYS_getpid;
+		asm volatile ("mov %[ss], %%ss; SYSENTER" : "+a" (nr)
+			      : [ss] "m" (ss) : "flags", "rcx"
+#ifdef __x86_64__
+				, "r11"
+#endif
+			);
+
+		/* We're unreachable here.  SYSENTER forgets RIP. */
+	}
+
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		printf("[RUN]\tMOV SS; INT $0x80\n");
+		sethandler(SIGSEGV, handle_and_longjmp, SA_RESETHAND);
+		nr = 20;	/* compat getpid */
+		asm volatile ("mov %[ss], %%ss; int $0x80"
+			      : "+a" (nr) : [ss] "m" (ss)
+			      : "flags"
+#ifdef __x86_64__
+				, "r8", "r9", "r10", "r11"
+#endif
+			);
+	}
+
+	printf("[OK]\tI aten't dead\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/mpx-debug.h b/tools/testing/selftests/x86/mpx-debug.h
new file mode 100644
index 000000000..7546eba7f
--- /dev/null
+++ b/tools/testing/selftests/x86/mpx-debug.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MPX_DEBUG_H
+#define _MPX_DEBUG_H
+
+#ifndef DEBUG_LEVEL
+#define DEBUG_LEVEL 0
+#endif
+#define dprintf_level(level, args...) do { if(level <= DEBUG_LEVEL) printf(args); } while(0)
+#define dprintf1(args...) dprintf_level(1, args)
+#define dprintf2(args...) dprintf_level(2, args)
+#define dprintf3(args...) dprintf_level(3, args)
+#define dprintf4(args...) dprintf_level(4, args)
+#define dprintf5(args...) dprintf_level(5, args)
+
+#endif /* _MPX_DEBUG_H */
diff --git a/tools/testing/selftests/x86/mpx-dig.c b/tools/testing/selftests/x86/mpx-dig.c
new file mode 100644
index 000000000..c13607ef5
--- /dev/null
+++ b/tools/testing/selftests/x86/mpx-dig.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Written by Dave Hansen <dave.hansen@intel.com>
+ */
+
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <fcntl.h>
+#include "mpx-debug.h"
+#include "mpx-mm.h"
+#include "mpx-hw.h"
+
+unsigned long bounds_dir_global;
+
+#define mpx_dig_abort()	__mpx_dig_abort(__FILE__, __func__, __LINE__)
+static void inline __mpx_dig_abort(const char *file, const char *func, int line)
+{
+	fprintf(stderr, "MPX dig abort @ %s::%d in %s()\n", file, line, func);
+	printf("MPX dig abort @ %s::%d in %s()\n", file, line, func);
+	abort();
+}
+
+/*
+ * run like this (BDIR finds the probably bounds directory):
+ *
+ *	BDIR="$(cat /proc/$pid/smaps | grep -B1 2097152 \
+ *		| head -1 | awk -F- '{print $1}')";
+ *	./mpx-dig $pid 0x$BDIR
+ *
+ * NOTE:
+ *	assumes that the only 2097152-kb VMA is the bounds dir
+ */
+
+long nr_incore(void *ptr, unsigned long size_bytes)
+{
+	int i;
+	long ret = 0;
+	long vec_len = size_bytes / PAGE_SIZE;
+	unsigned char *vec = malloc(vec_len);
+	int incore_ret;
+
+	if (!vec)
+		mpx_dig_abort();
+
+	incore_ret = mincore(ptr, size_bytes, vec);
+	if (incore_ret) {
+		printf("mincore ret: %d\n", incore_ret);
+		perror("mincore");
+		mpx_dig_abort();
+	}
+	for (i = 0; i < vec_len; i++)
+		ret += vec[i];
+	free(vec);
+	return ret;
+}
+
+int open_proc(int pid, char *file)
+{
+	static char buf[100];
+	int fd;
+
+	snprintf(&buf[0], sizeof(buf), "/proc/%d/%s", pid, file);
+	fd = open(&buf[0], O_RDONLY);
+	if (fd < 0)
+		perror(buf);
+
+	return fd;
+}
+
+struct vaddr_range {
+	unsigned long start;
+	unsigned long end;
+};
+struct vaddr_range *ranges;
+int nr_ranges_allocated;
+int nr_ranges_populated;
+int last_range = -1;
+
+int __pid_load_vaddrs(int pid)
+{
+	int ret = 0;
+	int proc_maps_fd = open_proc(pid, "maps");
+	char linebuf[10000];
+	unsigned long start;
+	unsigned long end;
+	char rest[1000];
+	FILE *f = fdopen(proc_maps_fd, "r");
+
+	if (!f)
+		mpx_dig_abort();
+	nr_ranges_populated = 0;
+	while (!feof(f)) {
+		char *readret = fgets(linebuf, sizeof(linebuf), f);
+		int parsed;
+
+		if (readret == NULL) {
+			if (feof(f))
+				break;
+			mpx_dig_abort();
+		}
+
+		parsed = sscanf(linebuf, "%lx-%lx%s", &start, &end, rest);
+		if (parsed != 3)
+			mpx_dig_abort();
+
+		dprintf4("result[%d]: %lx-%lx<->%s\n", parsed, start, end, rest);
+		if (nr_ranges_populated >= nr_ranges_allocated) {
+			ret = -E2BIG;
+			break;
+		}
+		ranges[nr_ranges_populated].start = start;
+		ranges[nr_ranges_populated].end = end;
+		nr_ranges_populated++;
+	}
+	last_range = -1;
+	fclose(f);
+	close(proc_maps_fd);
+	return ret;
+}
+
+int pid_load_vaddrs(int pid)
+{
+	int ret;
+
+	dprintf2("%s(%d)\n", __func__, pid);
+	if (!ranges) {
+		nr_ranges_allocated = 4;
+		ranges = malloc(nr_ranges_allocated * sizeof(ranges[0]));
+		dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__, pid,
+			 nr_ranges_allocated, ranges);
+		assert(ranges != NULL);
+	}
+	do {
+		ret = __pid_load_vaddrs(pid);
+		if (!ret)
+			break;
+		if (ret == -E2BIG) {
+			dprintf2("%s(%d) need to realloc\n", __func__, pid);
+			nr_ranges_allocated *= 2;
+			ranges = realloc(ranges,
+					nr_ranges_allocated * sizeof(ranges[0]));
+			dprintf2("%s(%d) allocated %d ranges @ %p\n", __func__,
+					pid, nr_ranges_allocated, ranges);
+			assert(ranges != NULL);
+			dprintf1("reallocating to hold %d ranges\n", nr_ranges_allocated);
+		}
+	} while (1);
+
+	dprintf2("%s(%d) done\n", __func__, pid);
+
+	return ret;
+}
+
+static inline int vaddr_in_range(unsigned long vaddr, struct vaddr_range *r)
+{
+	if (vaddr < r->start)
+		return 0;
+	if (vaddr >= r->end)
+		return 0;
+	return 1;
+}
+
+static inline int vaddr_mapped_by_range(unsigned long vaddr)
+{
+	int i;
+
+	if (last_range > 0 && vaddr_in_range(vaddr, &ranges[last_range]))
+		return 1;
+
+	for (i = 0; i < nr_ranges_populated; i++) {
+		struct vaddr_range *r = &ranges[i];
+
+		if (vaddr_in_range(vaddr, r))
+			continue;
+		last_range = i;
+		return 1;
+	}
+	return 0;
+}
+
+const int bt_entry_size_bytes = sizeof(unsigned long) * 4;
+
+void *read_bounds_table_into_buf(unsigned long table_vaddr)
+{
+#ifdef MPX_DIG_STANDALONE
+	static char bt_buf[MPX_BOUNDS_TABLE_SIZE_BYTES];
+	off_t seek_ret = lseek(fd, table_vaddr, SEEK_SET);
+	if (seek_ret != table_vaddr)
+		mpx_dig_abort();
+
+	int read_ret = read(fd, &bt_buf, sizeof(bt_buf));
+	if (read_ret != sizeof(bt_buf))
+		mpx_dig_abort();
+	return &bt_buf;
+#else
+	return (void *)table_vaddr;
+#endif
+}
+
+int dump_table(unsigned long table_vaddr, unsigned long base_controlled_vaddr,
+		unsigned long bde_vaddr)
+{
+	unsigned long offset_inside_bt;
+	int nr_entries = 0;
+	int do_abort = 0;
+	char *bt_buf;
+
+	dprintf3("%s() base_controlled_vaddr: 0x%012lx bde_vaddr: 0x%012lx\n",
+			__func__, base_controlled_vaddr, bde_vaddr);
+
+	bt_buf = read_bounds_table_into_buf(table_vaddr);
+
+	dprintf4("%s() read done\n", __func__);
+
+	for (offset_inside_bt = 0;
+	     offset_inside_bt < MPX_BOUNDS_TABLE_SIZE_BYTES;
+	     offset_inside_bt += bt_entry_size_bytes) {
+		unsigned long bt_entry_index;
+		unsigned long bt_entry_controls;
+		unsigned long this_bt_entry_for_vaddr;
+		unsigned long *bt_entry_buf;
+		int i;
+
+		dprintf4("%s() offset_inside_bt: 0x%lx of 0x%llx\n", __func__,
+			offset_inside_bt, MPX_BOUNDS_TABLE_SIZE_BYTES);
+		bt_entry_buf = (void *)&bt_buf[offset_inside_bt];
+		if (!bt_buf) {
+			printf("null bt_buf\n");
+			mpx_dig_abort();
+		}
+		if (!bt_entry_buf) {
+			printf("null bt_entry_buf\n");
+			mpx_dig_abort();
+		}
+		dprintf4("%s() reading *bt_entry_buf @ %p\n", __func__,
+				bt_entry_buf);
+		if (!bt_entry_buf[0] &&
+		    !bt_entry_buf[1] &&
+		    !bt_entry_buf[2] &&
+		    !bt_entry_buf[3])
+			continue;
+
+		nr_entries++;
+
+		bt_entry_index = offset_inside_bt/bt_entry_size_bytes;
+		bt_entry_controls = sizeof(void *);
+		this_bt_entry_for_vaddr =
+			base_controlled_vaddr + bt_entry_index*bt_entry_controls;
+		/*
+		 * We sign extend vaddr bits 48->63 which effectively
+		 * creates a hole in the virtual address space.
+		 * This calculation corrects for the hole.
+		 */
+		if (this_bt_entry_for_vaddr > 0x00007fffffffffffUL)
+			this_bt_entry_for_vaddr |= 0xffff800000000000;
+
+		if (!vaddr_mapped_by_range(this_bt_entry_for_vaddr)) {
+			printf("bt_entry_buf: %p\n", bt_entry_buf);
+			printf("there is a bte for %lx but no mapping\n",
+					this_bt_entry_for_vaddr);
+			printf("	  bde   vaddr: %016lx\n", bde_vaddr);
+			printf("base_controlled_vaddr: %016lx\n", base_controlled_vaddr);
+			printf("	  table_vaddr: %016lx\n", table_vaddr);
+			printf("	  entry vaddr: %016lx @ offset %lx\n",
+				table_vaddr + offset_inside_bt, offset_inside_bt);
+			do_abort = 1;
+			mpx_dig_abort();
+		}
+		if (DEBUG_LEVEL < 4)
+			continue;
+
+		printf("table entry[%lx]: ", offset_inside_bt);
+		for (i = 0; i < bt_entry_size_bytes; i += sizeof(unsigned long))
+			printf("0x%016lx ", bt_entry_buf[i]);
+		printf("\n");
+	}
+	if (do_abort)
+		mpx_dig_abort();
+	dprintf4("%s() done\n",  __func__);
+	return nr_entries;
+}
+
+int search_bd_buf(char *buf, int len_bytes, unsigned long bd_offset_bytes,
+		int *nr_populated_bdes)
+{
+	unsigned long i;
+	int total_entries = 0;
+
+	dprintf3("%s(%p, %x, %lx, ...) buf end: %p\n", __func__, buf,
+			len_bytes, bd_offset_bytes, buf + len_bytes);
+
+	for (i = 0; i < len_bytes; i += sizeof(unsigned long)) {
+		unsigned long bd_index = (bd_offset_bytes + i) / sizeof(unsigned long);
+		unsigned long *bounds_dir_entry_ptr = (unsigned long *)&buf[i];
+		unsigned long bounds_dir_entry;
+		unsigned long bd_for_vaddr;
+		unsigned long bt_start;
+		unsigned long bt_tail;
+		int nr_entries;
+
+		dprintf4("%s() loop i: %ld bounds_dir_entry_ptr: %p\n", __func__, i,
+				bounds_dir_entry_ptr);
+
+		bounds_dir_entry = *bounds_dir_entry_ptr;
+		if (!bounds_dir_entry) {
+			dprintf4("no bounds dir at index 0x%lx / 0x%lx "
+				 "start at offset:%lx %lx\n", bd_index, bd_index,
+					bd_offset_bytes, i);
+			continue;
+		}
+		dprintf3("found bounds_dir_entry: 0x%lx @ "
+			 "index 0x%lx buf ptr: %p\n", bounds_dir_entry, i,
+					&buf[i]);
+		/* mask off the enable bit: */
+		bounds_dir_entry &= ~0x1;
+		(*nr_populated_bdes)++;
+		dprintf4("nr_populated_bdes: %p\n", nr_populated_bdes);
+		dprintf4("*nr_populated_bdes: %d\n", *nr_populated_bdes);
+
+		bt_start = bounds_dir_entry;
+		bt_tail = bounds_dir_entry + MPX_BOUNDS_TABLE_SIZE_BYTES - 1;
+		if (!vaddr_mapped_by_range(bt_start)) {
+			printf("bounds directory 0x%lx points to nowhere\n",
+					bounds_dir_entry);
+			mpx_dig_abort();
+		}
+		if (!vaddr_mapped_by_range(bt_tail)) {
+			printf("bounds directory end 0x%lx points to nowhere\n",
+					bt_tail);
+			mpx_dig_abort();
+		}
+		/*
+		 * Each bounds directory entry controls 1MB of virtual address
+		 * space.  This variable is the virtual address in the process
+		 * of the beginning of the area controlled by this bounds_dir.
+		 */
+		bd_for_vaddr = bd_index * (1UL<<20);
+
+		nr_entries = dump_table(bounds_dir_entry, bd_for_vaddr,
+				bounds_dir_global+bd_offset_bytes+i);
+		total_entries += nr_entries;
+		dprintf5("dir entry[%4ld @ %p]: 0x%lx %6d entries "
+			 "total this buf: %7d bd_for_vaddrs: 0x%lx -> 0x%lx\n",
+				bd_index, buf+i,
+				bounds_dir_entry, nr_entries, total_entries,
+				bd_for_vaddr, bd_for_vaddr + (1UL<<20));
+	}
+	dprintf3("%s(%p, %x, %lx, ...) done\n", __func__, buf, len_bytes,
+			bd_offset_bytes);
+	return total_entries;
+}
+
+int proc_pid_mem_fd = -1;
+
+void *fill_bounds_dir_buf_other(long byte_offset_inside_bounds_dir,
+			   long buffer_size_bytes, void *buffer)
+{
+	unsigned long seekto = bounds_dir_global + byte_offset_inside_bounds_dir;
+	int read_ret;
+	off_t seek_ret = lseek(proc_pid_mem_fd, seekto, SEEK_SET);
+
+	if (seek_ret != seekto)
+		mpx_dig_abort();
+
+	read_ret = read(proc_pid_mem_fd, buffer, buffer_size_bytes);
+	/* there shouldn't practically be short reads of /proc/$pid/mem */
+	if (read_ret != buffer_size_bytes)
+		mpx_dig_abort();
+
+	return buffer;
+}
+void *fill_bounds_dir_buf_self(long byte_offset_inside_bounds_dir,
+			   long buffer_size_bytes, void *buffer)
+
+{
+	unsigned char vec[buffer_size_bytes / PAGE_SIZE];
+	char *dig_bounds_dir_ptr =
+		(void *)(bounds_dir_global + byte_offset_inside_bounds_dir);
+	/*
+	 * use mincore() to quickly find the areas of the bounds directory
+	 * that have memory and thus will be worth scanning.
+	 */
+	int incore_ret;
+
+	int incore = 0;
+	int i;
+
+	dprintf4("%s() dig_bounds_dir_ptr: %p\n", __func__, dig_bounds_dir_ptr);
+
+	incore_ret = mincore(dig_bounds_dir_ptr, buffer_size_bytes, &vec[0]);
+	if (incore_ret) {
+		printf("mincore ret: %d\n", incore_ret);
+		perror("mincore");
+		mpx_dig_abort();
+	}
+	for (i = 0; i < sizeof(vec); i++)
+		incore += vec[i];
+	dprintf4("%s() total incore: %d\n", __func__, incore);
+	if (!incore)
+		return NULL;
+	dprintf3("%s() total incore: %d\n", __func__, incore);
+	return dig_bounds_dir_ptr;
+}
+
+int inspect_pid(int pid)
+{
+	static int dig_nr;
+	long offset_inside_bounds_dir;
+	char bounds_dir_buf[sizeof(unsigned long) * (1UL << 15)];
+	char *dig_bounds_dir_ptr;
+	int total_entries = 0;
+	int nr_populated_bdes = 0;
+	int inspect_self;
+
+	if (getpid() == pid) {
+		dprintf4("inspecting self\n");
+		inspect_self = 1;
+	} else {
+		dprintf4("inspecting pid %d\n", pid);
+		mpx_dig_abort();
+	}
+
+	for (offset_inside_bounds_dir = 0;
+	     offset_inside_bounds_dir < MPX_BOUNDS_TABLE_SIZE_BYTES;
+	     offset_inside_bounds_dir += sizeof(bounds_dir_buf)) {
+		static int bufs_skipped;
+		int this_entries;
+
+		if (inspect_self) {
+			dig_bounds_dir_ptr =
+				fill_bounds_dir_buf_self(offset_inside_bounds_dir,
+							 sizeof(bounds_dir_buf),
+							 &bounds_dir_buf[0]);
+		} else {
+			dig_bounds_dir_ptr =
+				fill_bounds_dir_buf_other(offset_inside_bounds_dir,
+							  sizeof(bounds_dir_buf),
+							  &bounds_dir_buf[0]);
+		}
+		if (!dig_bounds_dir_ptr) {
+			bufs_skipped++;
+			continue;
+		}
+		this_entries = search_bd_buf(dig_bounds_dir_ptr,
+					sizeof(bounds_dir_buf),
+					offset_inside_bounds_dir,
+					&nr_populated_bdes);
+		total_entries += this_entries;
+	}
+	printf("mpx dig (%3d) complete, SUCCESS (%8d / %4d)\n", ++dig_nr,
+			total_entries, nr_populated_bdes);
+	return total_entries + nr_populated_bdes;
+}
+
+#ifdef MPX_DIG_REMOTE
+int main(int argc, char **argv)
+{
+	int err;
+	char *c;
+	unsigned long bounds_dir_entry;
+	int pid;
+
+	printf("mpx-dig starting...\n");
+	err = sscanf(argv[1], "%d", &pid);
+	printf("parsing: '%s', err: %d\n", argv[1], err);
+	if (err != 1)
+		mpx_dig_abort();
+
+	err = sscanf(argv[2], "%lx", &bounds_dir_global);
+	printf("parsing: '%s': %d\n", argv[2], err);
+	if (err != 1)
+		mpx_dig_abort();
+
+	proc_pid_mem_fd = open_proc(pid, "mem");
+	if (proc_pid_mem_fd < 0)
+		mpx_dig_abort();
+
+	inspect_pid(pid);
+	return 0;
+}
+#endif
+
+long inspect_me(struct mpx_bounds_dir *bounds_dir)
+{
+	int pid = getpid();
+
+	pid_load_vaddrs(pid);
+	bounds_dir_global = (unsigned long)bounds_dir;
+	dprintf4("enter %s() bounds dir: %p\n", __func__, bounds_dir);
+	return inspect_pid(pid);
+}
diff --git a/tools/testing/selftests/x86/mpx-hw.h b/tools/testing/selftests/x86/mpx-hw.h
new file mode 100644
index 000000000..d1b61ab87
--- /dev/null
+++ b/tools/testing/selftests/x86/mpx-hw.h
@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MPX_HW_H
+#define _MPX_HW_H
+
+#include <assert.h>
+
+/* Describe the MPX Hardware Layout in here */
+
+#define NR_MPX_BOUNDS_REGISTERS 4
+
+#ifdef __i386__
+
+#define MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES	16 /* 4 * 32-bits */
+#define MPX_BOUNDS_TABLE_SIZE_BYTES		(1ULL << 14) /* 16k */
+#define MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES		4
+#define MPX_BOUNDS_DIR_SIZE_BYTES		(1ULL << 22) /* 4MB */
+
+#define MPX_BOUNDS_TABLE_BOTTOM_BIT		2
+#define MPX_BOUNDS_TABLE_TOP_BIT		11
+#define MPX_BOUNDS_DIR_BOTTOM_BIT		12
+#define MPX_BOUNDS_DIR_TOP_BIT			31
+
+#else
+
+/*
+ * Linear Address of "pointer" (LAp)
+ *   0 ->  2: ignored
+ *   3 -> 19: index in to bounds table
+ *  20 -> 47: index in to bounds directory
+ *  48 -> 63: ignored
+ */
+
+#define MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES	32
+#define MPX_BOUNDS_TABLE_SIZE_BYTES		(1ULL << 22) /* 4MB */
+#define MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES		8
+#define MPX_BOUNDS_DIR_SIZE_BYTES		(1ULL << 31) /* 2GB */
+
+#define MPX_BOUNDS_TABLE_BOTTOM_BIT		3
+#define MPX_BOUNDS_TABLE_TOP_BIT		19
+#define MPX_BOUNDS_DIR_BOTTOM_BIT		20
+#define MPX_BOUNDS_DIR_TOP_BIT			47
+
+#endif
+
+#define MPX_BOUNDS_DIR_NR_ENTRIES	\
+	(MPX_BOUNDS_DIR_SIZE_BYTES/MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES)
+#define MPX_BOUNDS_TABLE_NR_ENTRIES	\
+	(MPX_BOUNDS_TABLE_SIZE_BYTES/MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES)
+
+#define MPX_BOUNDS_TABLE_ENTRY_VALID_BIT	0x1
+
+struct mpx_bd_entry {
+	union {
+		char x[MPX_BOUNDS_DIR_ENTRY_SIZE_BYTES];
+		void *contents[0];
+	};
+} __attribute__((packed));
+
+struct mpx_bt_entry {
+	union {
+		char x[MPX_BOUNDS_TABLE_ENTRY_SIZE_BYTES];
+		unsigned long contents[0];
+	};
+} __attribute__((packed));
+
+struct mpx_bounds_dir {
+	struct mpx_bd_entry entries[MPX_BOUNDS_DIR_NR_ENTRIES];
+} __attribute__((packed));
+
+struct mpx_bounds_table {
+	struct mpx_bt_entry entries[MPX_BOUNDS_TABLE_NR_ENTRIES];
+} __attribute__((packed));
+
+static inline unsigned long GET_BITS(unsigned long val, int bottombit, int topbit)
+{
+	int total_nr_bits = topbit - bottombit;
+	unsigned long mask = (1UL << total_nr_bits)-1;
+	return (val >> bottombit) & mask;
+}
+
+static inline unsigned long __vaddr_bounds_table_index(void *vaddr)
+{
+	return GET_BITS((unsigned long)vaddr, MPX_BOUNDS_TABLE_BOTTOM_BIT,
+					      MPX_BOUNDS_TABLE_TOP_BIT);
+}
+
+static inline unsigned long __vaddr_bounds_directory_index(void *vaddr)
+{
+	return GET_BITS((unsigned long)vaddr, MPX_BOUNDS_DIR_BOTTOM_BIT,
+					      MPX_BOUNDS_DIR_TOP_BIT);
+}
+
+static inline struct mpx_bd_entry *mpx_vaddr_to_bd_entry(void *vaddr,
+		struct mpx_bounds_dir *bounds_dir)
+{
+	unsigned long index = __vaddr_bounds_directory_index(vaddr);
+	return &bounds_dir->entries[index];
+}
+
+static inline int bd_entry_valid(struct mpx_bd_entry *bounds_dir_entry)
+{
+	unsigned long __bd_entry = (unsigned long)bounds_dir_entry->contents;
+	return (__bd_entry & MPX_BOUNDS_TABLE_ENTRY_VALID_BIT);
+}
+
+static inline struct mpx_bounds_table *
+__bd_entry_to_bounds_table(struct mpx_bd_entry *bounds_dir_entry)
+{
+	unsigned long __bd_entry = (unsigned long)bounds_dir_entry->contents;
+	assert(__bd_entry & MPX_BOUNDS_TABLE_ENTRY_VALID_BIT);
+	__bd_entry &= ~MPX_BOUNDS_TABLE_ENTRY_VALID_BIT;
+	return (struct mpx_bounds_table *)__bd_entry;
+}
+
+static inline struct mpx_bt_entry *
+mpx_vaddr_to_bt_entry(void *vaddr, struct mpx_bounds_dir *bounds_dir)
+{
+	struct mpx_bd_entry *bde = mpx_vaddr_to_bd_entry(vaddr, bounds_dir);
+	struct mpx_bounds_table *bt = __bd_entry_to_bounds_table(bde);
+	unsigned long index = __vaddr_bounds_table_index(vaddr);
+	return &bt->entries[index];
+}
+
+#endif /* _MPX_HW_H */
diff --git a/tools/testing/selftests/x86/mpx-mini-test.c b/tools/testing/selftests/x86/mpx-mini-test.c
new file mode 100644
index 000000000..50f7e9272
--- /dev/null
+++ b/tools/testing/selftests/x86/mpx-mini-test.c
@@ -0,0 +1,1616 @@
+/*
+ * mpx-mini-test.c: routines to test Intel MPX (Memory Protection eXtentions)
+ *
+ * Written by:
+ * "Ren, Qiaowei" <qiaowei.ren@intel.com>
+ * "Wei, Gang" <gang.wei@intel.com>
+ * "Hansen, Dave" <dave.hansen@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2.
+ */
+
+/*
+ * 2014-12-05: Dave Hansen: fixed all of the compiler warnings, and made sure
+ *	       it works on 32-bit.
+ */
+
+int inspect_every_this_many_mallocs = 100;
+int zap_all_every_this_many_mallocs = 1000;
+
+#define _GNU_SOURCE
+#define _LARGEFILE64_SOURCE
+
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "mpx-hw.h"
+#include "mpx-debug.h"
+#include "mpx-mm.h"
+
+#ifndef __always_inline
+#define __always_inline inline __attribute__((always_inline)
+#endif
+
+#ifndef TEST_DURATION_SECS
+#define TEST_DURATION_SECS 3
+#endif
+
+void write_int_to(char *prefix, char *file, int int_to_write)
+{
+	char buf[100];
+	int fd = open(file, O_RDWR);
+	int len;
+	int ret;
+
+	assert(fd >= 0);
+	len = snprintf(buf, sizeof(buf), "%s%d", prefix, int_to_write);
+	assert(len >= 0);
+	assert(len < sizeof(buf));
+	ret = write(fd, buf, len);
+	assert(ret == len);
+	ret = close(fd);
+	assert(!ret);
+}
+
+void write_pid_to(char *prefix, char *file)
+{
+	write_int_to(prefix, file, getpid());
+}
+
+void trace_me(void)
+{
+/* tracing events dir */
+#define TED "/sys/kernel/debug/tracing/events/"
+/*
+	write_pid_to("common_pid=", TED "signal/filter");
+	write_pid_to("common_pid=", TED "exceptions/filter");
+	write_int_to("", TED "signal/enable", 1);
+	write_int_to("", TED "exceptions/enable", 1);
+*/
+	write_pid_to("", "/sys/kernel/debug/tracing/set_ftrace_pid");
+	write_int_to("", "/sys/kernel/debug/tracing/trace", 0);
+}
+
+#define test_failed() __test_failed(__FILE__, __LINE__)
+static void __test_failed(char *f, int l)
+{
+	fprintf(stderr, "abort @ %s::%d\n", f, l);
+	abort();
+}
+
+/* Error Printf */
+#define eprintf(args...)	fprintf(stderr, args)
+
+#ifdef __i386__
+
+/* i386 directory size is 4MB */
+#define REG_IP_IDX	REG_EIP
+#define REX_PREFIX
+
+#define XSAVE_OFFSET_IN_FPMEM	sizeof(struct _libc_fpstate)
+
+/*
+ * __cpuid() is from the Linux Kernel:
+ */
+static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
+		unsigned int *ecx, unsigned int *edx)
+{
+	/* ecx is often an input as well as an output. */
+	asm volatile(
+		"push %%ebx;"
+		"cpuid;"
+		"mov %%ebx, %1;"
+		"pop %%ebx"
+		: "=a" (*eax),
+		  "=g" (*ebx),
+		  "=c" (*ecx),
+		  "=d" (*edx)
+		: "0" (*eax), "2" (*ecx));
+}
+
+#else /* __i386__ */
+
+#define REG_IP_IDX	REG_RIP
+#define REX_PREFIX "0x48, "
+
+#define XSAVE_OFFSET_IN_FPMEM	0
+
+/*
+ * __cpuid() is from the Linux Kernel:
+ */
+static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
+		unsigned int *ecx, unsigned int *edx)
+{
+	/* ecx is often an input as well as an output. */
+	asm volatile(
+		"cpuid;"
+		: "=a" (*eax),
+		  "=b" (*ebx),
+		  "=c" (*ecx),
+		  "=d" (*edx)
+		: "0" (*eax), "2" (*ecx));
+}
+
+#endif /* !__i386__ */
+
+struct xsave_hdr_struct {
+	uint64_t xstate_bv;
+	uint64_t reserved1[2];
+	uint64_t reserved2[5];
+} __attribute__((packed));
+
+struct bndregs_struct {
+	uint64_t bndregs[8];
+} __attribute__((packed));
+
+struct bndcsr_struct {
+	uint64_t cfg_reg_u;
+	uint64_t status_reg;
+} __attribute__((packed));
+
+struct xsave_struct {
+	uint8_t fpu_sse[512];
+	struct xsave_hdr_struct xsave_hdr;
+	uint8_t ymm[256];
+	uint8_t lwp[128];
+	struct bndregs_struct bndregs;
+	struct bndcsr_struct bndcsr;
+} __attribute__((packed));
+
+uint8_t __attribute__((__aligned__(64))) buffer[4096];
+struct xsave_struct *xsave_buf = (struct xsave_struct *)buffer;
+
+uint8_t __attribute__((__aligned__(64))) test_buffer[4096];
+struct xsave_struct *xsave_test_buf = (struct xsave_struct *)test_buffer;
+
+uint64_t num_bnd_chk;
+
+static __always_inline void xrstor_state(struct xsave_struct *fx, uint64_t mask)
+{
+	uint32_t lmask = mask;
+	uint32_t hmask = mask >> 32;
+
+	asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x2f\n\t"
+		     : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+		     :   "memory");
+}
+
+static __always_inline void xsave_state_1(void *_fx, uint64_t mask)
+{
+	uint32_t lmask = mask;
+	uint32_t hmask = mask >> 32;
+	unsigned char *fx = _fx;
+
+	asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x27\n\t"
+		     : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+		     :   "memory");
+}
+
+static inline uint64_t xgetbv(uint32_t index)
+{
+	uint32_t eax, edx;
+
+	asm volatile(".byte 0x0f,0x01,0xd0" /* xgetbv */
+		     : "=a" (eax), "=d" (edx)
+		     : "c" (index));
+	return eax + ((uint64_t)edx << 32);
+}
+
+static uint64_t read_mpx_status_sig(ucontext_t *uctxt)
+{
+	memset(buffer, 0, sizeof(buffer));
+	memcpy(buffer,
+		(uint8_t *)uctxt->uc_mcontext.fpregs + XSAVE_OFFSET_IN_FPMEM,
+		sizeof(struct xsave_struct));
+
+	return xsave_buf->bndcsr.status_reg;
+}
+
+#include <pthread.h>
+
+static uint8_t *get_next_inst_ip(uint8_t *addr)
+{
+	uint8_t *ip = addr;
+	uint8_t sib;
+	uint8_t rm;
+	uint8_t mod;
+	uint8_t base;
+	uint8_t modrm;
+
+	/* determine the prefix. */
+	switch(*ip) {
+	case 0xf2:
+	case 0xf3:
+	case 0x66:
+		ip++;
+		break;
+	}
+
+	/* look for rex prefix */
+	if ((*ip & 0x40) == 0x40)
+		ip++;
+
+	/* Make sure we have a MPX instruction. */
+	if (*ip++ != 0x0f)
+		return addr;
+
+	/* Skip the op code byte. */
+	ip++;
+
+	/* Get the modrm byte. */
+	modrm = *ip++;
+
+	/* Break it down into parts. */
+	rm = modrm & 7;
+	mod = (modrm >> 6);
+
+	/* Init the parts of the address mode. */
+	base = 8;
+
+	/* Is it a mem mode? */
+	if (mod != 3) {
+		/* look for scaled indexed addressing */
+		if (rm == 4) {
+			/* SIB addressing */
+			sib = *ip++;
+			base = sib & 7;
+			switch (mod) {
+			case 0:
+				if (base == 5)
+					ip += 4;
+				break;
+
+			case 1:
+				ip++;
+				break;
+
+			case 2:
+				ip += 4;
+				break;
+			}
+
+		} else {
+			/* MODRM addressing */
+			switch (mod) {
+			case 0:
+				/* DISP32 addressing, no base */
+				if (rm == 5)
+					ip += 4;
+				break;
+
+			case 1:
+				ip++;
+				break;
+
+			case 2:
+				ip += 4;
+				break;
+			}
+		}
+	}
+	return ip;
+}
+
+#ifdef si_lower
+static inline void *__si_bounds_lower(siginfo_t *si)
+{
+	return si->si_lower;
+}
+
+static inline void *__si_bounds_upper(siginfo_t *si)
+{
+	return si->si_upper;
+}
+#else
+
+/*
+ * This deals with old version of _sigfault in some distros:
+ *
+
+old _sigfault:
+        struct {
+            void *si_addr;
+	} _sigfault;
+
+new _sigfault:
+	struct {
+		void __user *_addr;
+		int _trapno;
+		short _addr_lsb;
+		union {
+			struct {
+				void __user *_lower;
+				void __user *_upper;
+			} _addr_bnd;
+			__u32 _pkey;
+		};
+	} _sigfault;
+ *
+ */
+
+static inline void **__si_bounds_hack(siginfo_t *si)
+{
+	void *sigfault = &si->_sifields._sigfault;
+	void *end_sigfault = sigfault + sizeof(si->_sifields._sigfault);
+	int *trapno = (int*)end_sigfault;
+	/* skip _trapno and _addr_lsb */
+	void **__si_lower = (void**)(trapno + 2);
+
+	return __si_lower;
+}
+
+static inline void *__si_bounds_lower(siginfo_t *si)
+{
+	return *__si_bounds_hack(si);
+}
+
+static inline void *__si_bounds_upper(siginfo_t *si)
+{
+	return *(__si_bounds_hack(si) + 1);
+}
+#endif
+
+static int br_count;
+static int expected_bnd_index = -1;
+uint64_t shadow_plb[NR_MPX_BOUNDS_REGISTERS][2]; /* shadow MPX bound registers */
+unsigned long shadow_map[NR_MPX_BOUNDS_REGISTERS];
+
+/* Failed address bound checks: */
+#ifndef SEGV_BNDERR
+# define SEGV_BNDERR	3
+#endif
+
+/*
+ * The kernel is supposed to provide some information about the bounds
+ * exception in the siginfo.  It should match what we have in the bounds
+ * registers that we are checking against.  Just check against the shadow copy
+ * since it is easily available, and we also check that *it* matches the real
+ * registers.
+ */
+void check_siginfo_vs_shadow(siginfo_t* si)
+{
+	int siginfo_ok = 1;
+	void *shadow_lower = (void *)(unsigned long)shadow_plb[expected_bnd_index][0];
+	void *shadow_upper = (void *)(unsigned long)shadow_plb[expected_bnd_index][1];
+
+	if ((expected_bnd_index < 0) ||
+	    (expected_bnd_index >= NR_MPX_BOUNDS_REGISTERS)) {
+		fprintf(stderr, "ERROR: invalid expected_bnd_index: %d\n",
+			expected_bnd_index);
+		exit(6);
+	}
+	if (__si_bounds_lower(si) != shadow_lower)
+		siginfo_ok = 0;
+	if (__si_bounds_upper(si) != shadow_upper)
+		siginfo_ok = 0;
+
+	if (!siginfo_ok) {
+		fprintf(stderr, "ERROR: siginfo bounds do not match "
+			"shadow bounds for register %d\n", expected_bnd_index);
+		exit(7);
+	}
+}
+
+void handler(int signum, siginfo_t *si, void *vucontext)
+{
+	int i;
+	ucontext_t *uctxt = vucontext;
+	int trapno;
+	unsigned long ip;
+
+	dprintf1("entered signal handler\n");
+
+	trapno = uctxt->uc_mcontext.gregs[REG_TRAPNO];
+	ip = uctxt->uc_mcontext.gregs[REG_IP_IDX];
+
+	if (trapno == 5) {
+		typeof(si->si_addr) *si_addr_ptr = &si->si_addr;
+		uint64_t status = read_mpx_status_sig(uctxt);
+		uint64_t br_reason =  status & 0x3;
+
+		br_count++;
+		dprintf1("#BR 0x%jx (total seen: %d)\n", status, br_count);
+
+		dprintf2("Saw a #BR! status 0x%jx at %016lx br_reason: %jx\n",
+				status, ip, br_reason);
+		dprintf2("si_signo: %d\n", si->si_signo);
+		dprintf2("  signum: %d\n", signum);
+		dprintf2("info->si_code == SEGV_BNDERR: %d\n",
+				(si->si_code == SEGV_BNDERR));
+		dprintf2("info->si_code: %d\n", si->si_code);
+		dprintf2("info->si_lower: %p\n", __si_bounds_lower(si));
+		dprintf2("info->si_upper: %p\n", __si_bounds_upper(si));
+
+		for (i = 0; i < 8; i++)
+			dprintf3("[%d]: %p\n", i, si_addr_ptr[i]);
+		switch (br_reason) {
+		case 0: /* traditional BR */
+			fprintf(stderr,
+				"Undefined status with bound exception:%jx\n",
+				 status);
+			exit(5);
+		case 1: /* #BR MPX bounds exception */
+			/* these are normal and we expect to see them */
+
+			check_siginfo_vs_shadow(si);
+
+			dprintf1("bounds exception (normal): status 0x%jx at %p si_addr: %p\n",
+				status, (void *)ip, si->si_addr);
+			num_bnd_chk++;
+			uctxt->uc_mcontext.gregs[REG_IP_IDX] =
+				(greg_t)get_next_inst_ip((uint8_t *)ip);
+			break;
+		case 2:
+			fprintf(stderr, "#BR status == 2, missing bounds table,"
+					"kernel should have handled!!\n");
+			exit(4);
+			break;
+		default:
+			fprintf(stderr, "bound check error: status 0x%jx at %p\n",
+				status, (void *)ip);
+			num_bnd_chk++;
+			uctxt->uc_mcontext.gregs[REG_IP_IDX] =
+				(greg_t)get_next_inst_ip((uint8_t *)ip);
+			fprintf(stderr, "bound check error: si_addr %p\n", si->si_addr);
+			exit(3);
+		}
+	} else if (trapno == 14) {
+		eprintf("ERROR: In signal handler, page fault, trapno = %d, ip = %016lx\n",
+			trapno, ip);
+		eprintf("si_addr %p\n", si->si_addr);
+		eprintf("REG_ERR: %lx\n", (unsigned long)uctxt->uc_mcontext.gregs[REG_ERR]);
+		test_failed();
+	} else {
+		eprintf("unexpected trap %d! at 0x%lx\n", trapno, ip);
+		eprintf("si_addr %p\n", si->si_addr);
+		eprintf("REG_ERR: %lx\n", (unsigned long)uctxt->uc_mcontext.gregs[REG_ERR]);
+		test_failed();
+	}
+}
+
+static inline void cpuid_count(unsigned int op, int count,
+			       unsigned int *eax, unsigned int *ebx,
+			       unsigned int *ecx, unsigned int *edx)
+{
+	*eax = op;
+	*ecx = count;
+	__cpuid(eax, ebx, ecx, edx);
+}
+
+#define XSTATE_CPUID	    0x0000000d
+
+/*
+ * List of XSAVE features Linux knows about:
+ */
+enum xfeature_bit {
+	XSTATE_BIT_FP,
+	XSTATE_BIT_SSE,
+	XSTATE_BIT_YMM,
+	XSTATE_BIT_BNDREGS,
+	XSTATE_BIT_BNDCSR,
+	XSTATE_BIT_OPMASK,
+	XSTATE_BIT_ZMM_Hi256,
+	XSTATE_BIT_Hi16_ZMM,
+
+	XFEATURES_NR_MAX,
+};
+
+#define XSTATE_FP	       (1 << XSTATE_BIT_FP)
+#define XSTATE_SSE	      (1 << XSTATE_BIT_SSE)
+#define XSTATE_YMM	      (1 << XSTATE_BIT_YMM)
+#define XSTATE_BNDREGS	  (1 << XSTATE_BIT_BNDREGS)
+#define XSTATE_BNDCSR	   (1 << XSTATE_BIT_BNDCSR)
+#define XSTATE_OPMASK	   (1 << XSTATE_BIT_OPMASK)
+#define XSTATE_ZMM_Hi256	(1 << XSTATE_BIT_ZMM_Hi256)
+#define XSTATE_Hi16_ZMM	 (1 << XSTATE_BIT_Hi16_ZMM)
+
+#define MPX_XSTATES		(XSTATE_BNDREGS | XSTATE_BNDCSR) /* 0x18 */
+
+bool one_bit(unsigned int x, int bit)
+{
+	return !!(x & (1<<bit));
+}
+
+void print_state_component(int state_bit_nr, char *name)
+{
+	unsigned int eax, ebx, ecx, edx;
+	unsigned int state_component_size;
+	unsigned int state_component_supervisor;
+	unsigned int state_component_user;
+	unsigned int state_component_aligned;
+
+	/* See SDM Section 13.2 */
+	cpuid_count(XSTATE_CPUID, state_bit_nr, &eax, &ebx, &ecx, &edx);
+	assert(eax || ebx || ecx);
+	state_component_size = eax;
+	state_component_supervisor = ((!ebx) && one_bit(ecx, 0));
+	state_component_user = !one_bit(ecx, 0);
+	state_component_aligned = one_bit(ecx, 1);
+	printf("%8s: size: %d user: %d supervisor: %d aligned: %d\n",
+		name,
+		state_component_size,	    state_component_user,
+		state_component_supervisor, state_component_aligned);
+
+}
+
+/* Intel-defined CPU features, CPUID level 0x00000001 (ecx) */
+#define XSAVE_FEATURE_BIT       (26)  /* XSAVE/XRSTOR/XSETBV/XGETBV */
+#define OSXSAVE_FEATURE_BIT     (27) /* XSAVE enabled in the OS */
+
+bool check_mpx_support(void)
+{
+	unsigned int eax, ebx, ecx, edx;
+
+	cpuid_count(1, 0, &eax, &ebx, &ecx, &edx);
+
+	/* We can't do much without XSAVE, so just make these assert()'s */
+	if (!one_bit(ecx, XSAVE_FEATURE_BIT)) {
+		fprintf(stderr, "processor lacks XSAVE, can not run MPX tests\n");
+		exit(0);
+	}
+
+	if (!one_bit(ecx, OSXSAVE_FEATURE_BIT)) {
+		fprintf(stderr, "processor lacks OSXSAVE, can not run MPX tests\n");
+		exit(0);
+	}
+
+	/* CPUs not supporting the XSTATE CPUID leaf do not support MPX */
+	/* Is this redundant with the feature bit checks? */
+	cpuid_count(0, 0, &eax, &ebx, &ecx, &edx);
+	if (eax < XSTATE_CPUID) {
+		fprintf(stderr, "processor lacks XSTATE CPUID leaf,"
+				" can not run MPX tests\n");
+		exit(0);
+	}
+
+	printf("XSAVE is supported by HW & OS\n");
+
+	cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx);
+
+	printf("XSAVE processor supported state mask: 0x%x\n", eax);
+	printf("XSAVE OS supported state mask: 0x%jx\n", xgetbv(0));
+
+	/* Make sure that the MPX states are enabled in in XCR0 */
+	if ((eax & MPX_XSTATES) != MPX_XSTATES) {
+		fprintf(stderr, "processor lacks MPX XSTATE(s), can not run MPX tests\n");
+		exit(0);
+	}
+
+	/* Make sure the MPX states are supported by XSAVE* */
+	if ((xgetbv(0) & MPX_XSTATES) != MPX_XSTATES) {
+		fprintf(stderr, "MPX XSTATE(s) no enabled in XCR0, "
+				"can not run MPX tests\n");
+		exit(0);
+	}
+
+	print_state_component(XSTATE_BIT_BNDREGS, "BNDREGS");
+	print_state_component(XSTATE_BIT_BNDCSR,  "BNDCSR");
+
+	return true;
+}
+
+void enable_mpx(void *l1base)
+{
+	/* enable point lookup */
+	memset(buffer, 0, sizeof(buffer));
+	xrstor_state(xsave_buf, 0x18);
+
+	xsave_buf->xsave_hdr.xstate_bv = 0x10;
+	xsave_buf->bndcsr.cfg_reg_u = (unsigned long)l1base | 1;
+	xsave_buf->bndcsr.status_reg = 0;
+
+	dprintf2("bf xrstor\n");
+	dprintf2("xsave cndcsr: status %jx, configu %jx\n",
+	       xsave_buf->bndcsr.status_reg, xsave_buf->bndcsr.cfg_reg_u);
+	xrstor_state(xsave_buf, 0x18);
+	dprintf2("after xrstor\n");
+
+	xsave_state_1(xsave_buf, 0x18);
+
+	dprintf1("xsave bndcsr: status %jx, configu %jx\n",
+	       xsave_buf->bndcsr.status_reg, xsave_buf->bndcsr.cfg_reg_u);
+}
+
+#include <sys/prctl.h>
+
+struct mpx_bounds_dir *bounds_dir_ptr;
+
+unsigned long __bd_incore(const char *func, int line)
+{
+	unsigned long ret = nr_incore(bounds_dir_ptr, MPX_BOUNDS_DIR_SIZE_BYTES);
+	return ret;
+}
+#define bd_incore() __bd_incore(__func__, __LINE__)
+
+void check_clear(void *ptr, unsigned long sz)
+{
+	unsigned long *i;
+
+	for (i = ptr; (void *)i < ptr + sz; i++) {
+		if (*i) {
+			dprintf1("%p is NOT clear at %p\n", ptr, i);
+			assert(0);
+		}
+	}
+	dprintf1("%p is clear for %lx\n", ptr, sz);
+}
+
+void check_clear_bd(void)
+{
+	check_clear(bounds_dir_ptr, 2UL << 30);
+}
+
+#define USE_MALLOC_FOR_BOUNDS_DIR 1
+bool process_specific_init(void)
+{
+	unsigned long size;
+	unsigned long *dir;
+	/* Guarantee we have the space to align it, add padding: */
+	unsigned long pad = getpagesize();
+
+	size = 2UL << 30; /* 2GB */
+	if (sizeof(unsigned long) == 4)
+		size = 4UL << 20; /* 4MB */
+	dprintf1("trying to allocate %ld MB bounds directory\n", (size >> 20));
+
+	if (USE_MALLOC_FOR_BOUNDS_DIR) {
+		unsigned long _dir;
+
+		dir = malloc(size + pad);
+		assert(dir);
+		_dir = (unsigned long)dir;
+		_dir += 0xfffUL;
+		_dir &= ~0xfffUL;
+		dir = (void *)_dir;
+	} else {
+		/*
+		 * This makes debugging easier because the address
+		 * calculations are simpler:
+		 */
+		dir = mmap((void *)0x200000000000, size + pad,
+				PROT_READ|PROT_WRITE,
+				MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		if (dir == (void *)-1) {
+			perror("unable to allocate bounds directory");
+			abort();
+		}
+		check_clear(dir, size);
+	}
+	bounds_dir_ptr = (void *)dir;
+	madvise(bounds_dir_ptr, size, MADV_NOHUGEPAGE);
+	bd_incore();
+	dprintf1("bounds directory: 0x%p -> 0x%p\n", bounds_dir_ptr,
+			(char *)bounds_dir_ptr + size);
+	check_clear(dir, size);
+	enable_mpx(dir);
+	check_clear(dir, size);
+	if (prctl(43, 0, 0, 0, 0)) {
+		printf("no MPX support\n");
+		abort();
+		return false;
+	}
+	return true;
+}
+
+bool process_specific_finish(void)
+{
+	if (prctl(44)) {
+		printf("no MPX support\n");
+		return false;
+	}
+	return true;
+}
+
+void setup_handler()
+{
+	int r, rs;
+	struct sigaction newact;
+	struct sigaction oldact;
+
+	/* #BR is mapped to sigsegv */
+	int signum  = SIGSEGV;
+
+	newact.sa_handler = 0;   /* void(*)(int)*/
+	newact.sa_sigaction = handler; /* void (*)(int, siginfo_t*, void *) */
+
+	/*sigset_t - signals to block while in the handler */
+	/* get the old signal mask. */
+	rs = sigprocmask(SIG_SETMASK, 0, &newact.sa_mask);
+	assert(rs == 0);
+
+	/* call sa_sigaction, not sa_handler*/
+	newact.sa_flags = SA_SIGINFO;
+
+	newact.sa_restorer = 0;  /* void(*)(), obsolete */
+	r = sigaction(signum, &newact, &oldact);
+	assert(r == 0);
+}
+
+void mpx_prepare(void)
+{
+	dprintf2("%s()\n", __func__);
+	setup_handler();
+	process_specific_init();
+}
+
+void mpx_cleanup(void)
+{
+	printf("%s(): %jd BRs. bye...\n", __func__, num_bnd_chk);
+	process_specific_finish();
+}
+
+/*-------------- the following is test case ---------------*/
+#include <stdint.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <time.h>
+
+uint64_t num_lower_brs;
+uint64_t num_upper_brs;
+
+#define MPX_CONFIG_OFFSET 1024
+#define MPX_BOUNDS_OFFSET 960
+#define MPX_HEADER_OFFSET 512
+#define MAX_ADDR_TESTED (1<<28)
+#define TEST_ROUNDS 100
+
+/*
+      0F 1A /r BNDLDX-Load
+      0F 1B /r BNDSTX-Store Extended Bounds Using Address Translation
+   66 0F 1A /r BNDMOV bnd1, bnd2/m128
+   66 0F 1B /r BNDMOV bnd1/m128, bnd2
+   F2 0F 1A /r BNDCU bnd, r/m64
+   F2 0F 1B /r BNDCN bnd, r/m64
+   F3 0F 1A /r BNDCL bnd, r/m64
+   F3 0F 1B /r BNDMK bnd, m64
+*/
+
+static __always_inline void xsave_state(void *_fx, uint64_t mask)
+{
+	uint32_t lmask = mask;
+	uint32_t hmask = mask >> 32;
+	unsigned char *fx = _fx;
+
+	asm volatile(".byte " REX_PREFIX "0x0f,0xae,0x27\n\t"
+		     : : "D" (fx), "m" (*fx), "a" (lmask), "d" (hmask)
+		     :   "memory");
+}
+
+static __always_inline void mpx_clear_bnd0(void)
+{
+	long size = 0;
+	void *ptr = NULL;
+	/* F3 0F 1B /r BNDMK bnd, m64			*/
+	/* f3 0f 1b 04 11    bndmk  (%rcx,%rdx,1),%bnd0	*/
+	asm volatile(".byte 0xf3,0x0f,0x1b,0x04,0x11\n\t"
+		     : : "c" (ptr), "d" (size-1)
+		     :   "memory");
+}
+
+static __always_inline void mpx_make_bound_helper(unsigned long ptr,
+		unsigned long size)
+{
+	/* F3 0F 1B /r		BNDMK bnd, m64			*/
+	/* f3 0f 1b 04 11       bndmk  (%rcx,%rdx,1),%bnd0	*/
+	asm volatile(".byte 0xf3,0x0f,0x1b,0x04,0x11\n\t"
+		     : : "c" (ptr), "d" (size-1)
+		     :   "memory");
+}
+
+static __always_inline void mpx_check_lowerbound_helper(unsigned long ptr)
+{
+	/* F3 0F 1A /r	NDCL bnd, r/m64			*/
+	/* f3 0f 1a 01	bndcl  (%rcx),%bnd0		*/
+	asm volatile(".byte 0xf3,0x0f,0x1a,0x01\n\t"
+		     : : "c" (ptr)
+		     :   "memory");
+}
+
+static __always_inline void mpx_check_upperbound_helper(unsigned long ptr)
+{
+	/* F2 0F 1A /r	BNDCU bnd, r/m64	*/
+	/* f2 0f 1a 01	bndcu  (%rcx),%bnd0	*/
+	asm volatile(".byte 0xf2,0x0f,0x1a,0x01\n\t"
+		     : : "c" (ptr)
+		     :   "memory");
+}
+
+static __always_inline void mpx_movbndreg_helper()
+{
+	/* 66 0F 1B /r	BNDMOV bnd1/m128, bnd2	*/
+	/* 66 0f 1b c2	bndmov %bnd0,%bnd2	*/
+
+	asm volatile(".byte 0x66,0x0f,0x1b,0xc2\n\t");
+}
+
+static __always_inline void mpx_movbnd2mem_helper(uint8_t *mem)
+{
+	/* 66 0F 1B /r	BNDMOV bnd1/m128, bnd2	*/
+	/* 66 0f 1b 01	bndmov %bnd0,(%rcx)	*/
+	asm volatile(".byte 0x66,0x0f,0x1b,0x01\n\t"
+		     : : "c" (mem)
+		     :   "memory");
+}
+
+static __always_inline void mpx_movbnd_from_mem_helper(uint8_t *mem)
+{
+	/* 66 0F 1A /r	BNDMOV bnd1, bnd2/m128	*/
+	/* 66 0f 1a 01	bndmov (%rcx),%bnd0	*/
+	asm volatile(".byte 0x66,0x0f,0x1a,0x01\n\t"
+		     : : "c" (mem)
+		     :   "memory");
+}
+
+static __always_inline void mpx_store_dsc_helper(unsigned long ptr_addr,
+		unsigned long ptr_val)
+{
+	/* 0F 1B /r	BNDSTX-Store Extended Bounds Using Address Translation	*/
+	/* 0f 1b 04 11	bndstx %bnd0,(%rcx,%rdx,1)				*/
+	asm volatile(".byte 0x0f,0x1b,0x04,0x11\n\t"
+		     : : "c" (ptr_addr), "d" (ptr_val)
+		     :   "memory");
+}
+
+static __always_inline void mpx_load_dsc_helper(unsigned long ptr_addr,
+		unsigned long ptr_val)
+{
+	/* 0F 1A /r	BNDLDX-Load			*/
+	/*/ 0f 1a 04 11	bndldx (%rcx,%rdx,1),%bnd0	*/
+	asm volatile(".byte 0x0f,0x1a,0x04,0x11\n\t"
+		     : : "c" (ptr_addr), "d" (ptr_val)
+		     :   "memory");
+}
+
+void __print_context(void *__print_xsave_buffer, int line)
+{
+	uint64_t *bounds = (uint64_t *)(__print_xsave_buffer + MPX_BOUNDS_OFFSET);
+	uint64_t *cfg    = (uint64_t *)(__print_xsave_buffer + MPX_CONFIG_OFFSET);
+
+	int i;
+	eprintf("%s()::%d\n", "print_context", line);
+	for (i = 0; i < 4; i++) {
+		eprintf("bound[%d]: 0x%016lx 0x%016lx(0x%016lx)\n", i,
+		       (unsigned long)bounds[i*2],
+		       ~(unsigned long)bounds[i*2+1],
+			(unsigned long)bounds[i*2+1]);
+	}
+
+	eprintf("cpcfg: %jx  cpstatus: %jx\n", cfg[0], cfg[1]);
+}
+#define print_context(x) __print_context(x, __LINE__)
+#ifdef DEBUG
+#define dprint_context(x) print_context(x)
+#else
+#define dprint_context(x) do{}while(0)
+#endif
+
+void init()
+{
+	int i;
+
+	srand((unsigned int)time(NULL));
+
+	for (i = 0; i < 4; i++) {
+		shadow_plb[i][0] = 0;
+		shadow_plb[i][1] = ~(unsigned long)0;
+	}
+}
+
+long int __mpx_random(int line)
+{
+#ifdef NOT_SO_RANDOM
+	static long fake = 722122311;
+	fake += 563792075;
+	return fakse;
+#else
+	return random();
+#endif
+}
+#define mpx_random() __mpx_random(__LINE__)
+
+uint8_t *get_random_addr()
+{
+	uint8_t*addr = (uint8_t *)(unsigned long)(rand() % MAX_ADDR_TESTED);
+	return (addr - (unsigned long)addr % sizeof(uint8_t *));
+}
+
+static inline bool compare_context(void *__xsave_buffer)
+{
+	uint64_t *bounds = (uint64_t *)(__xsave_buffer + MPX_BOUNDS_OFFSET);
+
+	int i;
+	for (i = 0; i < 4; i++) {
+		dprintf3("shadow[%d]{%016lx/%016lx}\nbounds[%d]{%016lx/%016lx}\n",
+		       i, (unsigned long)shadow_plb[i][0], (unsigned long)shadow_plb[i][1],
+		       i, (unsigned long)bounds[i*2],     ~(unsigned long)bounds[i*2+1]);
+		if ((shadow_plb[i][0] != bounds[i*2]) ||
+		    (shadow_plb[i][1] != ~(unsigned long)bounds[i*2+1])) {
+			eprintf("ERROR comparing shadow to real bound register %d\n", i);
+			eprintf("shadow{0x%016lx/0x%016lx}\nbounds{0x%016lx/0x%016lx}\n",
+			       (unsigned long)shadow_plb[i][0], (unsigned long)shadow_plb[i][1],
+			       (unsigned long)bounds[i*2], (unsigned long)bounds[i*2+1]);
+			return false;
+		}
+	}
+
+	return true;
+}
+
+void mkbnd_shadow(uint8_t *ptr, int index, long offset)
+{
+	uint64_t *lower = (uint64_t *)&(shadow_plb[index][0]);
+	uint64_t *upper = (uint64_t *)&(shadow_plb[index][1]);
+	*lower = (unsigned long)ptr;
+	*upper = (unsigned long)ptr + offset - 1;
+}
+
+void check_lowerbound_shadow(uint8_t *ptr, int index)
+{
+	uint64_t *lower = (uint64_t *)&(shadow_plb[index][0]);
+	if (*lower > (uint64_t)(unsigned long)ptr)
+		num_lower_brs++;
+	else
+		dprintf1("LowerBoundChk passed:%p\n", ptr);
+}
+
+void check_upperbound_shadow(uint8_t *ptr, int index)
+{
+	uint64_t upper = *(uint64_t *)&(shadow_plb[index][1]);
+	if (upper < (uint64_t)(unsigned long)ptr)
+		num_upper_brs++;
+	else
+		dprintf1("UpperBoundChk passed:%p\n", ptr);
+}
+
+__always_inline void movbndreg_shadow(int src, int dest)
+{
+	shadow_plb[dest][0] = shadow_plb[src][0];
+	shadow_plb[dest][1] = shadow_plb[src][1];
+}
+
+__always_inline void movbnd2mem_shadow(int src, unsigned long *dest)
+{
+	unsigned long *lower = (unsigned long *)&(shadow_plb[src][0]);
+	unsigned long *upper = (unsigned long *)&(shadow_plb[src][1]);
+	*dest = *lower;
+	*(dest+1) = *upper;
+}
+
+__always_inline void movbnd_from_mem_shadow(unsigned long *src, int dest)
+{
+	unsigned long *lower = (unsigned long *)&(shadow_plb[dest][0]);
+	unsigned long *upper = (unsigned long *)&(shadow_plb[dest][1]);
+	*lower = *src;
+	*upper = *(src+1);
+}
+
+__always_inline void stdsc_shadow(int index, uint8_t *ptr, uint8_t *ptr_val)
+{
+	shadow_map[0] = (unsigned long)shadow_plb[index][0];
+	shadow_map[1] = (unsigned long)shadow_plb[index][1];
+	shadow_map[2] = (unsigned long)ptr_val;
+	dprintf3("%s(%d, %p, %p) set shadow map[2]: %p\n", __func__,
+			index, ptr, ptr_val, ptr_val);
+	/*ptr ignored */
+}
+
+void lddsc_shadow(int index, uint8_t *ptr, uint8_t *ptr_val)
+{
+	uint64_t lower = shadow_map[0];
+	uint64_t upper = shadow_map[1];
+	uint8_t *value = (uint8_t *)shadow_map[2];
+
+	if (value != ptr_val) {
+		dprintf2("%s(%d, %p, %p) init shadow bounds[%d] "
+			 "because %p != %p\n", __func__, index, ptr,
+			 ptr_val, index, value, ptr_val);
+		shadow_plb[index][0] = 0;
+		shadow_plb[index][1] = ~(unsigned long)0;
+	} else {
+		shadow_plb[index][0] = lower;
+		shadow_plb[index][1] = upper;
+	}
+	/* ptr ignored */
+}
+
+static __always_inline void mpx_test_helper0(uint8_t *buf, uint8_t *ptr)
+{
+	mpx_make_bound_helper((unsigned long)ptr, 0x1800);
+}
+
+static __always_inline void mpx_test_helper0_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	mkbnd_shadow(ptr, 0, 0x1800);
+}
+
+static __always_inline void mpx_test_helper1(uint8_t *buf, uint8_t *ptr)
+{
+	/* these are hard-coded to check bnd0 */
+	expected_bnd_index = 0;
+	mpx_check_lowerbound_helper((unsigned long)(ptr-1));
+	mpx_check_upperbound_helper((unsigned long)(ptr+0x1800));
+	/* reset this since we do not expect any more bounds exceptions */
+	expected_bnd_index = -1;
+}
+
+static __always_inline void mpx_test_helper1_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	check_lowerbound_shadow(ptr-1, 0);
+	check_upperbound_shadow(ptr+0x1800, 0);
+}
+
+static __always_inline void mpx_test_helper2(uint8_t *buf, uint8_t *ptr)
+{
+	mpx_make_bound_helper((unsigned long)ptr, 0x1800);
+	mpx_movbndreg_helper();
+	mpx_movbnd2mem_helper(buf);
+	mpx_make_bound_helper((unsigned long)(ptr+0x12), 0x1800);
+}
+
+static __always_inline void mpx_test_helper2_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	mkbnd_shadow(ptr, 0, 0x1800);
+	movbndreg_shadow(0, 2);
+	movbnd2mem_shadow(0, (unsigned long *)buf);
+	mkbnd_shadow(ptr+0x12, 0, 0x1800);
+}
+
+static __always_inline void mpx_test_helper3(uint8_t *buf, uint8_t *ptr)
+{
+	mpx_movbnd_from_mem_helper(buf);
+}
+
+static __always_inline void mpx_test_helper3_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	movbnd_from_mem_shadow((unsigned long *)buf, 0);
+}
+
+static __always_inline void mpx_test_helper4(uint8_t *buf, uint8_t *ptr)
+{
+	mpx_store_dsc_helper((unsigned long)buf, (unsigned long)ptr);
+	mpx_make_bound_helper((unsigned long)(ptr+0x12), 0x1800);
+}
+
+static __always_inline void mpx_test_helper4_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	stdsc_shadow(0, buf, ptr);
+	mkbnd_shadow(ptr+0x12, 0, 0x1800);
+}
+
+static __always_inline void mpx_test_helper5(uint8_t *buf, uint8_t *ptr)
+{
+	mpx_load_dsc_helper((unsigned long)buf, (unsigned long)ptr);
+}
+
+static __always_inline void mpx_test_helper5_shadow(uint8_t *buf, uint8_t *ptr)
+{
+	lddsc_shadow(0, buf, ptr);
+}
+
+#define NR_MPX_TEST_FUNCTIONS 6
+
+/*
+ * For compatibility reasons, MPX will clear the bounds registers
+ * when you make function calls (among other things).  We have to
+ * preserve the registers in between calls to the "helpers" since
+ * they build on each other.
+ *
+ * Be very careful not to make any function calls inside the
+ * helpers, or anywhere else beween the xrstor and xsave.
+ */
+#define run_helper(helper_nr, buf, buf_shadow, ptr)	do {	\
+	xrstor_state(xsave_test_buf, flags);			\
+	mpx_test_helper##helper_nr(buf, ptr);			\
+	xsave_state(xsave_test_buf, flags);			\
+	mpx_test_helper##helper_nr##_shadow(buf_shadow, ptr);	\
+} while (0)
+
+static void run_helpers(int nr, uint8_t *buf, uint8_t *buf_shadow, uint8_t *ptr)
+{
+	uint64_t flags = 0x18;
+
+	dprint_context(xsave_test_buf);
+	switch (nr) {
+	case 0:
+		run_helper(0, buf, buf_shadow, ptr);
+		break;
+	case 1:
+		run_helper(1, buf, buf_shadow, ptr);
+		break;
+	case 2:
+		run_helper(2, buf, buf_shadow, ptr);
+		break;
+	case 3:
+		run_helper(3, buf, buf_shadow, ptr);
+		break;
+	case 4:
+		run_helper(4, buf, buf_shadow, ptr);
+		break;
+	case 5:
+		run_helper(5, buf, buf_shadow, ptr);
+		break;
+	default:
+		test_failed();
+		break;
+	}
+	dprint_context(xsave_test_buf);
+}
+
+unsigned long buf_shadow[1024]; /* used to check load / store descriptors */
+extern long inspect_me(struct mpx_bounds_dir *bounds_dir);
+
+long cover_buf_with_bt_entries(void *buf, long buf_len)
+{
+	int i;
+	long nr_to_fill;
+	int ratio = 1000;
+	unsigned long buf_len_in_ptrs;
+
+	/* Fill about 1/100 of the space with bt entries */
+	nr_to_fill = buf_len / (sizeof(unsigned long) * ratio);
+
+	if (!nr_to_fill)
+		dprintf3("%s() nr_to_fill: %ld\n", __func__, nr_to_fill);
+
+	/* Align the buffer to pointer size */
+	while (((unsigned long)buf) % sizeof(void *)) {
+		buf++;
+		buf_len--;
+	}
+	/* We are storing pointers, so make */
+	buf_len_in_ptrs = buf_len / sizeof(void *);
+
+	for (i = 0; i < nr_to_fill; i++) {
+		long index = (mpx_random() % buf_len_in_ptrs);
+		void *ptr = buf + index * sizeof(unsigned long);
+		unsigned long ptr_addr = (unsigned long)ptr;
+
+		/* ptr and size can be anything */
+		mpx_make_bound_helper((unsigned long)ptr, 8);
+
+		/*
+		 * take bnd0 and put it in to bounds tables "buf + index" is an
+		 * address inside the buffer where we are pretending that we
+		 * are going to put a pointer We do not, though because we will
+		 * never load entries from the table, so it doesn't matter.
+		 */
+		mpx_store_dsc_helper(ptr_addr, (unsigned long)ptr);
+		dprintf4("storing bound table entry for %lx (buf start @ %p)\n",
+				ptr_addr, buf);
+	}
+	return nr_to_fill;
+}
+
+unsigned long align_down(unsigned long alignme, unsigned long align_to)
+{
+	return alignme & ~(align_to-1);
+}
+
+unsigned long align_up(unsigned long alignme, unsigned long align_to)
+{
+	return (alignme + align_to - 1) & ~(align_to-1);
+}
+
+/*
+ * Using 1MB alignment guarantees that each no allocation
+ * will overlap with another's bounds tables.
+ *
+ * We have to cook our own allocator here.  malloc() can
+ * mix other allocation with ours which means that even
+ * if we free all of our allocations, there might still
+ * be bounds tables for the *areas* since there is other
+ * valid memory there.
+ *
+ * We also can't use malloc() because a free() of an area
+ * might not free it back to the kernel.  We want it
+ * completely unmapped an malloc() does not guarantee
+ * that.
+ */
+#ifdef __i386__
+long alignment = 4096;
+long sz_alignment = 4096;
+#else
+long alignment = 1 * MB;
+long sz_alignment = 1 * MB;
+#endif
+void *mpx_mini_alloc(unsigned long sz)
+{
+	unsigned long long tries = 0;
+	static void *last;
+	void *ptr;
+	void *try_at;
+
+	sz = align_up(sz, sz_alignment);
+
+	try_at = last + alignment;
+	while (1) {
+		ptr = mmap(try_at, sz, PROT_READ|PROT_WRITE,
+				MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		if (ptr == (void *)-1)
+			return NULL;
+		if (ptr == try_at)
+			break;
+
+		munmap(ptr, sz);
+		try_at += alignment;
+#ifdef __i386__
+		/*
+		 * This isn't quite correct for 32-bit binaries
+		 * on 64-bit kernels since they can use the
+		 * entire 32-bit address space, but it's close
+		 * enough.
+		 */
+		if (try_at > (void *)0xC0000000)
+#else
+		if (try_at > (void *)0x0000800000000000)
+#endif
+			try_at = (void *)0x0;
+		if (!(++tries % 10000))
+			dprintf1("stuck in %s(), tries: %lld\n", __func__, tries);
+		continue;
+	}
+	last = ptr;
+	dprintf3("mpx_mini_alloc(0x%lx) returning: %p\n", sz, ptr);
+	return ptr;
+}
+void mpx_mini_free(void *ptr, long sz)
+{
+	dprintf2("%s() ptr: %p\n", __func__, ptr);
+	if ((unsigned long)ptr > 0x100000000000) {
+		dprintf1("uh oh !!!!!!!!!!!!!!! pointer too high: %p\n", ptr);
+		test_failed();
+	}
+	sz = align_up(sz, sz_alignment);
+	dprintf3("%s() ptr: %p before munmap\n", __func__, ptr);
+	munmap(ptr, sz);
+	dprintf3("%s() ptr: %p DONE\n", __func__, ptr);
+}
+
+#define NR_MALLOCS 100
+struct one_malloc {
+	char *ptr;
+	int nr_filled_btes;
+	unsigned long size;
+};
+struct one_malloc mallocs[NR_MALLOCS];
+
+void free_one_malloc(int index)
+{
+	unsigned long free_ptr;
+	unsigned long mask;
+
+	if (!mallocs[index].ptr)
+		return;
+
+	mpx_mini_free(mallocs[index].ptr, mallocs[index].size);
+	dprintf4("freed[%d]:  %p\n", index, mallocs[index].ptr);
+
+	free_ptr = (unsigned long)mallocs[index].ptr;
+	mask = alignment-1;
+	dprintf4("lowerbits: %lx / %lx mask: %lx\n", free_ptr,
+			(free_ptr & mask), mask);
+	assert((free_ptr & mask) == 0);
+
+	mallocs[index].ptr = NULL;
+}
+
+#ifdef __i386__
+#define MPX_BOUNDS_TABLE_COVERS 4096
+#else
+#define MPX_BOUNDS_TABLE_COVERS (1 * MB)
+#endif
+void zap_everything(void)
+{
+	long after_zap;
+	long before_zap;
+	int i;
+
+	before_zap = inspect_me(bounds_dir_ptr);
+	dprintf1("zapping everything start: %ld\n", before_zap);
+	for (i = 0; i < NR_MALLOCS; i++)
+		free_one_malloc(i);
+
+	after_zap = inspect_me(bounds_dir_ptr);
+	dprintf1("zapping everything done: %ld\n", after_zap);
+	/*
+	 * We only guarantee to empty the thing out if our allocations are
+	 * exactly aligned on the boundaries of a boudns table.
+	 */
+	if ((alignment >= MPX_BOUNDS_TABLE_COVERS) &&
+	    (sz_alignment >= MPX_BOUNDS_TABLE_COVERS)) {
+		if (after_zap != 0)
+			test_failed();
+
+		assert(after_zap == 0);
+	}
+}
+
+void do_one_malloc(void)
+{
+	static int malloc_counter;
+	long sz;
+	int rand_index = (mpx_random() % NR_MALLOCS);
+	void *ptr = mallocs[rand_index].ptr;
+
+	dprintf3("%s() enter\n", __func__);
+
+	if (ptr) {
+		dprintf3("freeing one malloc at index: %d\n", rand_index);
+		free_one_malloc(rand_index);
+		if (mpx_random() % (NR_MALLOCS*3) == 3) {
+			int i;
+			dprintf3("zapping some more\n");
+			for (i = rand_index; i < NR_MALLOCS; i++)
+				free_one_malloc(i);
+		}
+		if ((mpx_random() % zap_all_every_this_many_mallocs) == 4)
+			zap_everything();
+	}
+
+	/* 1->~1M */
+	sz = (1 + mpx_random() % 1000) * 1000;
+	ptr = mpx_mini_alloc(sz);
+	if (!ptr) {
+		/*
+		 * If we are failing allocations, just assume we
+		 * are out of memory and zap everything.
+		 */
+		dprintf3("zapping everything because out of memory\n");
+		zap_everything();
+		goto out;
+	}
+
+	dprintf3("malloc: %p size: 0x%lx\n", ptr, sz);
+	mallocs[rand_index].nr_filled_btes = cover_buf_with_bt_entries(ptr, sz);
+	mallocs[rand_index].ptr = ptr;
+	mallocs[rand_index].size = sz;
+out:
+	if ((++malloc_counter) % inspect_every_this_many_mallocs == 0)
+		inspect_me(bounds_dir_ptr);
+}
+
+void run_timed_test(void (*test_func)(void))
+{
+	int done = 0;
+	long iteration = 0;
+	static time_t last_print;
+	time_t now;
+	time_t start;
+
+	time(&start);
+	while (!done) {
+		time(&now);
+		if ((now - start) > TEST_DURATION_SECS)
+			done = 1;
+
+		test_func();
+		iteration++;
+
+		if ((now - last_print > 1) || done) {
+			printf("iteration %ld complete, OK so far\n", iteration);
+			last_print = now;
+		}
+	}
+}
+
+void check_bounds_table_frees(void)
+{
+	printf("executing unmaptest\n");
+	inspect_me(bounds_dir_ptr);
+	run_timed_test(&do_one_malloc);
+	printf("done with malloc() fun\n");
+}
+
+void insn_test_failed(int test_nr, int test_round, void *buf,
+		void *buf_shadow, void *ptr)
+{
+	print_context(xsave_test_buf);
+	eprintf("ERROR: test %d round %d failed\n", test_nr, test_round);
+	while (test_nr == 5) {
+		struct mpx_bt_entry *bte;
+		struct mpx_bounds_dir *bd = (void *)bounds_dir_ptr;
+		struct mpx_bd_entry *bde = mpx_vaddr_to_bd_entry(buf, bd);
+
+		printf("  bd: %p\n", bd);
+		printf("&bde: %p\n", bde);
+		printf("*bde: %lx\n", *(unsigned long *)bde);
+		if (!bd_entry_valid(bde))
+			break;
+
+		bte = mpx_vaddr_to_bt_entry(buf, bd);
+		printf(" te: %p\n", bte);
+		printf("bte[0]: %lx\n", bte->contents[0]);
+		printf("bte[1]: %lx\n", bte->contents[1]);
+		printf("bte[2]: %lx\n", bte->contents[2]);
+		printf("bte[3]: %lx\n", bte->contents[3]);
+		break;
+	}
+	test_failed();
+}
+
+void check_mpx_insns_and_tables(void)
+{
+	int successes = 0;
+	int failures  = 0;
+	int buf_size = (1024*1024);
+	unsigned long *buf = malloc(buf_size);
+	const int total_nr_tests = NR_MPX_TEST_FUNCTIONS * TEST_ROUNDS;
+	int i, j;
+
+	memset(buf, 0, buf_size);
+	memset(buf_shadow, 0, sizeof(buf_shadow));
+
+	for (i = 0; i < TEST_ROUNDS; i++) {
+		uint8_t *ptr = get_random_addr() + 8;
+
+		for (j = 0; j < NR_MPX_TEST_FUNCTIONS; j++) {
+			if (0 && j != 5) {
+				successes++;
+				continue;
+			}
+			dprintf2("starting test %d round %d\n", j, i);
+			dprint_context(xsave_test_buf);
+			/*
+			 * test5 loads an address from the bounds tables.
+			 * The load will only complete if 'ptr' matches
+			 * the load and the store, so with random addrs,
+			 * the odds of this are very small.  Make it
+			 * higher by only moving 'ptr' 1/10 times.
+			 */
+			if (random() % 10 <= 0)
+				ptr = get_random_addr() + 8;
+			dprintf3("random ptr{%p}\n", ptr);
+			dprint_context(xsave_test_buf);
+			run_helpers(j, (void *)buf, (void *)buf_shadow, ptr);
+			dprint_context(xsave_test_buf);
+			if (!compare_context(xsave_test_buf)) {
+				insn_test_failed(j, i, buf, buf_shadow, ptr);
+				failures++;
+				goto exit;
+			}
+			successes++;
+			dprint_context(xsave_test_buf);
+			dprintf2("finished test %d round %d\n", j, i);
+			dprintf3("\n");
+			dprint_context(xsave_test_buf);
+		}
+	}
+
+exit:
+	dprintf2("\nabout to free:\n");
+	free(buf);
+	dprintf1("successes: %d\n", successes);
+	dprintf1(" failures: %d\n", failures);
+	dprintf1("    tests: %d\n", total_nr_tests);
+	dprintf1(" expected: %jd #BRs\n", num_upper_brs + num_lower_brs);
+	dprintf1("      saw: %d #BRs\n", br_count);
+	if (failures) {
+		eprintf("ERROR: non-zero number of failures\n");
+		exit(20);
+	}
+	if (successes != total_nr_tests) {
+		eprintf("ERROR: succeded fewer than number of tries (%d != %d)\n",
+				successes, total_nr_tests);
+		exit(21);
+	}
+	if (num_upper_brs + num_lower_brs != br_count) {
+		eprintf("ERROR: unexpected number of #BRs: %jd %jd %d\n",
+				num_upper_brs, num_lower_brs, br_count);
+		eprintf("successes: %d\n", successes);
+		eprintf(" failures: %d\n", failures);
+		eprintf("    tests: %d\n", total_nr_tests);
+		eprintf(" expected: %jd #BRs\n", num_upper_brs + num_lower_brs);
+		eprintf("      saw: %d #BRs\n", br_count);
+		exit(22);
+	}
+}
+
+/*
+ * This is supposed to SIGSEGV nicely once the kernel
+ * can no longer allocate vaddr space.
+ */
+void exhaust_vaddr_space(void)
+{
+	unsigned long ptr;
+	/* Try to make sure there is no room for a bounds table anywhere */
+	unsigned long skip = MPX_BOUNDS_TABLE_SIZE_BYTES - PAGE_SIZE;
+#ifdef __i386__
+	unsigned long max_vaddr = 0xf7788000UL;
+#else
+	unsigned long max_vaddr = 0x800000000000UL;
+#endif
+
+	dprintf1("%s() start\n", __func__);
+	/* do not start at 0, we aren't allowed to map there */
+	for (ptr = PAGE_SIZE; ptr < max_vaddr; ptr += skip) {
+		void *ptr_ret;
+		int ret = madvise((void *)ptr, PAGE_SIZE, MADV_NORMAL);
+
+		if (!ret) {
+			dprintf1("madvise() %lx ret: %d\n", ptr, ret);
+			continue;
+		}
+		ptr_ret = mmap((void *)ptr, PAGE_SIZE, PROT_READ|PROT_WRITE,
+				MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		if (ptr_ret != (void *)ptr) {
+			perror("mmap");
+			dprintf1("mmap(%lx) ret: %p\n", ptr, ptr_ret);
+			break;
+		}
+		if (!(ptr & 0xffffff))
+			dprintf1("mmap(%lx) ret: %p\n", ptr, ptr_ret);
+	}
+	for (ptr = PAGE_SIZE; ptr < max_vaddr; ptr += skip) {
+		dprintf2("covering 0x%lx with bounds table entries\n", ptr);
+		cover_buf_with_bt_entries((void *)ptr, PAGE_SIZE);
+	}
+	dprintf1("%s() end\n", __func__);
+	printf("done with vaddr space fun\n");
+}
+
+void mpx_table_test(void)
+{
+	printf("starting mpx bounds table test\n");
+	run_timed_test(check_mpx_insns_and_tables);
+	printf("done with mpx bounds table test\n");
+}
+
+int main(int argc, char **argv)
+{
+	int unmaptest = 0;
+	int vaddrexhaust = 0;
+	int tabletest = 0;
+	int i;
+
+	check_mpx_support();
+	mpx_prepare();
+	srandom(11179);
+
+	bd_incore();
+	init();
+	bd_incore();
+
+	trace_me();
+
+	xsave_state((void *)xsave_test_buf, 0x1f);
+	if (!compare_context(xsave_test_buf))
+		printf("Init failed\n");
+
+	for (i = 1; i < argc; i++) {
+		if (!strcmp(argv[i], "unmaptest"))
+			unmaptest = 1;
+		if (!strcmp(argv[i], "vaddrexhaust"))
+			vaddrexhaust = 1;
+		if (!strcmp(argv[i], "tabletest"))
+			tabletest = 1;
+	}
+	if (!(unmaptest || vaddrexhaust || tabletest)) {
+		unmaptest = 1;
+		/* vaddrexhaust = 1; */
+		tabletest = 1;
+	}
+	if (unmaptest)
+		check_bounds_table_frees();
+	if (tabletest)
+		mpx_table_test();
+	if (vaddrexhaust)
+		exhaust_vaddr_space();
+	printf("%s completed successfully\n", argv[0]);
+	exit(0);
+}
+
+#include "mpx-dig.c"
diff --git a/tools/testing/selftests/x86/mpx-mm.h b/tools/testing/selftests/x86/mpx-mm.h
new file mode 100644
index 000000000..6dbdd66b8
--- /dev/null
+++ b/tools/testing/selftests/x86/mpx-mm.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _MPX_MM_H
+#define _MPX_MM_H
+
+#define PAGE_SIZE 4096
+#define MB (1UL<<20)
+
+extern long nr_incore(void *ptr, unsigned long size_bytes);
+
+#endif /* _MPX_MM_H */
diff --git a/tools/testing/selftests/x86/pkey-helpers.h b/tools/testing/selftests/x86/pkey-helpers.h
new file mode 100644
index 000000000..254e5436b
--- /dev/null
+++ b/tools/testing/selftests/x86/pkey-helpers.h
@@ -0,0 +1,219 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PKEYS_HELPER_H
+#define _PKEYS_HELPER_H
+#define _GNU_SOURCE
+#include <string.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+
+#define NR_PKEYS 16
+#define PKRU_BITS_PER_PKEY 2
+
+#ifndef DEBUG_LEVEL
+#define DEBUG_LEVEL 0
+#endif
+#define DPRINT_IN_SIGNAL_BUF_SIZE 4096
+extern int dprint_in_signal;
+extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+static inline void sigsafe_printf(const char *format, ...)
+{
+	va_list ap;
+
+	if (!dprint_in_signal) {
+		va_start(ap, format);
+		vprintf(format, ap);
+		va_end(ap);
+	} else {
+		int ret;
+		/*
+		 * No printf() functions are signal-safe.
+		 * They deadlock easily. Write the format
+		 * string to get some output, even if
+		 * incomplete.
+		 */
+		ret = write(1, format, strlen(format));
+		if (ret < 0)
+			exit(1);
+	}
+}
+#define dprintf_level(level, args...) do {	\
+	if (level <= DEBUG_LEVEL)		\
+		sigsafe_printf(args);		\
+} while (0)
+#define dprintf0(args...) dprintf_level(0, args)
+#define dprintf1(args...) dprintf_level(1, args)
+#define dprintf2(args...) dprintf_level(2, args)
+#define dprintf3(args...) dprintf_level(3, args)
+#define dprintf4(args...) dprintf_level(4, args)
+
+extern unsigned int shadow_pkru;
+static inline unsigned int __rdpkru(void)
+{
+	unsigned int eax, edx;
+	unsigned int ecx = 0;
+	unsigned int pkru;
+
+	asm volatile(".byte 0x0f,0x01,0xee\n\t"
+		     : "=a" (eax), "=d" (edx)
+		     : "c" (ecx));
+	pkru = eax;
+	return pkru;
+}
+
+static inline unsigned int _rdpkru(int line)
+{
+	unsigned int pkru = __rdpkru();
+
+	dprintf4("rdpkru(line=%d) pkru: %x shadow: %x\n",
+			line, pkru, shadow_pkru);
+	assert(pkru == shadow_pkru);
+
+	return pkru;
+}
+
+#define rdpkru() _rdpkru(__LINE__)
+
+static inline void __wrpkru(unsigned int pkru)
+{
+	unsigned int eax = pkru;
+	unsigned int ecx = 0;
+	unsigned int edx = 0;
+
+	dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
+	asm volatile(".byte 0x0f,0x01,0xef\n\t"
+		     : : "a" (eax), "c" (ecx), "d" (edx));
+	assert(pkru == __rdpkru());
+}
+
+static inline void wrpkru(unsigned int pkru)
+{
+	dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
+	/* will do the shadow check for us: */
+	rdpkru();
+	__wrpkru(pkru);
+	shadow_pkru = pkru;
+	dprintf4("%s(%08x) pkru: %08x\n", __func__, pkru, __rdpkru());
+}
+
+/*
+ * These are technically racy. since something could
+ * change PKRU between the read and the write.
+ */
+static inline void __pkey_access_allow(int pkey, int do_allow)
+{
+	unsigned int pkru = rdpkru();
+	int bit = pkey * 2;
+
+	if (do_allow)
+		pkru &= (1<<bit);
+	else
+		pkru |= (1<<bit);
+
+	dprintf4("pkru now: %08x\n", rdpkru());
+	wrpkru(pkru);
+}
+
+static inline void __pkey_write_allow(int pkey, int do_allow_write)
+{
+	long pkru = rdpkru();
+	int bit = pkey * 2 + 1;
+
+	if (do_allow_write)
+		pkru &= (1<<bit);
+	else
+		pkru |= (1<<bit);
+
+	wrpkru(pkru);
+	dprintf4("pkru now: %08x\n", rdpkru());
+}
+
+#define PROT_PKEY0     0x10            /* protection key value (bit 0) */
+#define PROT_PKEY1     0x20            /* protection key value (bit 1) */
+#define PROT_PKEY2     0x40            /* protection key value (bit 2) */
+#define PROT_PKEY3     0x80            /* protection key value (bit 3) */
+
+#define PAGE_SIZE 4096
+#define MB	(1<<20)
+
+static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
+		unsigned int *ecx, unsigned int *edx)
+{
+	/* ecx is often an input as well as an output. */
+	asm volatile(
+		"cpuid;"
+		: "=a" (*eax),
+		  "=b" (*ebx),
+		  "=c" (*ecx),
+		  "=d" (*edx)
+		: "0" (*eax), "2" (*ecx));
+}
+
+/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
+#define X86_FEATURE_PKU        (1<<3) /* Protection Keys for Userspace */
+#define X86_FEATURE_OSPKE      (1<<4) /* OS Protection Keys Enable */
+
+static inline int cpu_has_pku(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+
+	eax = 0x7;
+	ecx = 0x0;
+	__cpuid(&eax, &ebx, &ecx, &edx);
+
+	if (!(ecx & X86_FEATURE_PKU)) {
+		dprintf2("cpu does not have PKU\n");
+		return 0;
+	}
+	if (!(ecx & X86_FEATURE_OSPKE)) {
+		dprintf2("cpu does not have OSPKE\n");
+		return 0;
+	}
+	return 1;
+}
+
+#define XSTATE_PKRU_BIT	(9)
+#define XSTATE_PKRU	0x200
+
+int pkru_xstate_offset(void)
+{
+	unsigned int eax;
+	unsigned int ebx;
+	unsigned int ecx;
+	unsigned int edx;
+	int xstate_offset;
+	int xstate_size;
+	unsigned long XSTATE_CPUID = 0xd;
+	int leaf;
+
+	/* assume that XSTATE_PKRU is set in XCR0 */
+	leaf = XSTATE_PKRU_BIT;
+	{
+		eax = XSTATE_CPUID;
+		ecx = leaf;
+		__cpuid(&eax, &ebx, &ecx, &edx);
+
+		if (leaf == XSTATE_PKRU_BIT) {
+			xstate_offset = ebx;
+			xstate_size = eax;
+		}
+	}
+
+	if (xstate_size == 0) {
+		printf("could not find size/offset of PKRU in xsave state\n");
+		return 0;
+	}
+
+	return xstate_offset;
+}
+
+#endif /* _PKEYS_HELPER_H */
diff --git a/tools/testing/selftests/x86/protection_keys.c b/tools/testing/selftests/x86/protection_keys.c
new file mode 100644
index 000000000..27661302a
--- /dev/null
+++ b/tools/testing/selftests/x86/protection_keys.c
@@ -0,0 +1,1508 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Tests x86 Memory Protection Keys (see Documentation/x86/protection-keys.txt)
+ *
+ * There are examples in here of:
+ *  * how to set protection keys on memory
+ *  * how to set/clear bits in PKRU (the rights register)
+ *  * how to handle SEGV_PKRU signals and extract pkey-relevant
+ *    information from the siginfo
+ *
+ * Things to add:
+ *	make sure KSM and KSM COW breaking works
+ *	prefault pages in at malloc, or not
+ *	protect MPX bounds tables with protection keys?
+ *	make sure VMA splitting/merging is working correctly
+ *	OOMs can destroy mm->mmap (see exit_mmap()), so make sure it is immune to pkeys
+ *	look for pkey "leaks" where it is still set on a VMA but "freed" back to the kernel
+ *	do a plain mprotect() to a mprotect_pkey() area and make sure the pkey sticks
+ *
+ * Compile like this:
+ *	gcc      -o protection_keys    -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
+ *	gcc -m32 -o protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall protection_keys.c -lrt -ldl -lm
+ */
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/futex.h>
+#include <time.h>
+#include <sys/time.h>
+#include <sys/syscall.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <signal.h>
+#include <assert.h>
+#include <stdlib.h>
+#include <ucontext.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <sys/ptrace.h>
+#include <setjmp.h>
+
+#include "pkey-helpers.h"
+
+int iteration_nr = 1;
+int test_nr;
+
+unsigned int shadow_pkru;
+
+#define HPAGE_SIZE	(1UL<<21)
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+#define ALIGN_UP(x, align_to)	(((x) + ((align_to)-1)) & ~((align_to)-1))
+#define ALIGN_DOWN(x, align_to) ((x) & ~((align_to)-1))
+#define ALIGN_PTR_UP(p, ptr_align_to)	((typeof(p))ALIGN_UP((unsigned long)(p),	ptr_align_to))
+#define ALIGN_PTR_DOWN(p, ptr_align_to)	((typeof(p))ALIGN_DOWN((unsigned long)(p),	ptr_align_to))
+#define __stringify_1(x...)     #x
+#define __stringify(x...)       __stringify_1(x)
+
+#define PTR_ERR_ENOTSUP ((void *)-ENOTSUP)
+
+int dprint_in_signal;
+char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
+
+extern void abort_hooks(void);
+#define pkey_assert(condition) do {		\
+	if (!(condition)) {			\
+		dprintf0("assert() at %s::%d test_nr: %d iteration: %d\n", \
+				__FILE__, __LINE__,	\
+				test_nr, iteration_nr);	\
+		dprintf0("errno at assert: %d", errno);	\
+		abort_hooks();			\
+		exit(__LINE__);			\
+	}					\
+} while (0)
+
+void cat_into_file(char *str, char *file)
+{
+	int fd = open(file, O_RDWR);
+	int ret;
+
+	dprintf2("%s(): writing '%s' to '%s'\n", __func__, str, file);
+	/*
+	 * these need to be raw because they are called under
+	 * pkey_assert()
+	 */
+	if (fd < 0) {
+		fprintf(stderr, "error opening '%s'\n", str);
+		perror("error: ");
+		exit(__LINE__);
+	}
+
+	ret = write(fd, str, strlen(str));
+	if (ret != strlen(str)) {
+		perror("write to file failed");
+		fprintf(stderr, "filename: '%s' str: '%s'\n", file, str);
+		exit(__LINE__);
+	}
+	close(fd);
+}
+
+#if CONTROL_TRACING > 0
+static int warned_tracing;
+int tracing_root_ok(void)
+{
+	if (geteuid() != 0) {
+		if (!warned_tracing)
+			fprintf(stderr, "WARNING: not run as root, "
+					"can not do tracing control\n");
+		warned_tracing = 1;
+		return 0;
+	}
+	return 1;
+}
+#endif
+
+void tracing_on(void)
+{
+#if CONTROL_TRACING > 0
+#define TRACEDIR "/sys/kernel/debug/tracing"
+	char pidstr[32];
+
+	if (!tracing_root_ok())
+		return;
+
+	sprintf(pidstr, "%d", getpid());
+	cat_into_file("0", TRACEDIR "/tracing_on");
+	cat_into_file("\n", TRACEDIR "/trace");
+	if (1) {
+		cat_into_file("function_graph", TRACEDIR "/current_tracer");
+		cat_into_file("1", TRACEDIR "/options/funcgraph-proc");
+	} else {
+		cat_into_file("nop", TRACEDIR "/current_tracer");
+	}
+	cat_into_file(pidstr, TRACEDIR "/set_ftrace_pid");
+	cat_into_file("1", TRACEDIR "/tracing_on");
+	dprintf1("enabled tracing\n");
+#endif
+}
+
+void tracing_off(void)
+{
+#if CONTROL_TRACING > 0
+	if (!tracing_root_ok())
+		return;
+	cat_into_file("0", "/sys/kernel/debug/tracing/tracing_on");
+#endif
+}
+
+void abort_hooks(void)
+{
+	fprintf(stderr, "running %s()...\n", __func__);
+	tracing_off();
+#ifdef SLEEP_ON_ABORT
+	sleep(SLEEP_ON_ABORT);
+#endif
+}
+
+static inline void __page_o_noops(void)
+{
+	/* 8-bytes of instruction * 512 bytes = 1 page */
+	asm(".rept 512 ; nopl 0x7eeeeeee(%eax) ; .endr");
+}
+
+/*
+ * This attempts to have roughly a page of instructions followed by a few
+ * instructions that do a write, and another page of instructions.  That
+ * way, we are pretty sure that the write is in the second page of
+ * instructions and has at least a page of padding behind it.
+ *
+ * *That* lets us be sure to madvise() away the write instruction, which
+ * will then fault, which makes sure that the fault code handles
+ * execute-only memory properly.
+ */
+__attribute__((__aligned__(PAGE_SIZE)))
+void lots_o_noops_around_write(int *write_to_me)
+{
+	dprintf3("running %s()\n", __func__);
+	__page_o_noops();
+	/* Assume this happens in the second page of instructions: */
+	*write_to_me = __LINE__;
+	/* pad out by another page: */
+	__page_o_noops();
+	dprintf3("%s() done\n", __func__);
+}
+
+/* Define some kernel-like types */
+#define  u8 uint8_t
+#define u16 uint16_t
+#define u32 uint32_t
+#define u64 uint64_t
+
+#ifdef __i386__
+
+#ifndef SYS_mprotect_key
+# define SYS_mprotect_key	380
+#endif
+
+#ifndef SYS_pkey_alloc
+# define SYS_pkey_alloc		381
+# define SYS_pkey_free		382
+#endif
+
+#define REG_IP_IDX		REG_EIP
+#define si_pkey_offset		0x14
+
+#else
+
+#ifndef SYS_mprotect_key
+# define SYS_mprotect_key	329
+#endif
+
+#ifndef SYS_pkey_alloc
+# define SYS_pkey_alloc		330
+# define SYS_pkey_free		331
+#endif
+
+#define REG_IP_IDX		REG_RIP
+#define si_pkey_offset		0x20
+
+#endif
+
+void dump_mem(void *dumpme, int len_bytes)
+{
+	char *c = (void *)dumpme;
+	int i;
+
+	for (i = 0; i < len_bytes; i += sizeof(u64)) {
+		u64 *ptr = (u64 *)(c + i);
+		dprintf1("dump[%03d][@%p]: %016jx\n", i, ptr, *ptr);
+	}
+}
+
+/* Failed address bound checks: */
+#ifndef SEGV_BNDERR
+# define SEGV_BNDERR		3
+#endif
+
+#ifndef SEGV_PKUERR
+# define SEGV_PKUERR		4
+#endif
+
+static char *si_code_str(int si_code)
+{
+	if (si_code == SEGV_MAPERR)
+		return "SEGV_MAPERR";
+	if (si_code == SEGV_ACCERR)
+		return "SEGV_ACCERR";
+	if (si_code == SEGV_BNDERR)
+		return "SEGV_BNDERR";
+	if (si_code == SEGV_PKUERR)
+		return "SEGV_PKUERR";
+	return "UNKNOWN";
+}
+
+int pkru_faults;
+int last_si_pkey = -1;
+void signal_handler(int signum, siginfo_t *si, void *vucontext)
+{
+	ucontext_t *uctxt = vucontext;
+	int trapno;
+	unsigned long ip;
+	char *fpregs;
+	u32 *pkru_ptr;
+	u64 siginfo_pkey;
+	u32 *si_pkey_ptr;
+	int pkru_offset;
+	fpregset_t fpregset;
+
+	dprint_in_signal = 1;
+	dprintf1(">>>>===============SIGSEGV============================\n");
+	dprintf1("%s()::%d, pkru: 0x%x shadow: %x\n", __func__, __LINE__,
+			__rdpkru(), shadow_pkru);
+
+	trapno = uctxt->uc_mcontext.gregs[REG_TRAPNO];
+	ip = uctxt->uc_mcontext.gregs[REG_IP_IDX];
+	fpregset = uctxt->uc_mcontext.fpregs;
+	fpregs = (void *)fpregset;
+
+	dprintf2("%s() trapno: %d ip: 0x%lx info->si_code: %s/%d\n", __func__,
+			trapno, ip, si_code_str(si->si_code), si->si_code);
+#ifdef __i386__
+	/*
+	 * 32-bit has some extra padding so that userspace can tell whether
+	 * the XSTATE header is present in addition to the "legacy" FPU
+	 * state.  We just assume that it is here.
+	 */
+	fpregs += 0x70;
+#endif
+	pkru_offset = pkru_xstate_offset();
+	pkru_ptr = (void *)(&fpregs[pkru_offset]);
+
+	dprintf1("siginfo: %p\n", si);
+	dprintf1(" fpregs: %p\n", fpregs);
+	/*
+	 * If we got a PKRU fault, we *HAVE* to have at least one bit set in
+	 * here.
+	 */
+	dprintf1("pkru_xstate_offset: %d\n", pkru_xstate_offset());
+	if (DEBUG_LEVEL > 4)
+		dump_mem(pkru_ptr - 128, 256);
+	pkey_assert(*pkru_ptr);
+
+	if ((si->si_code == SEGV_MAPERR) ||
+	    (si->si_code == SEGV_ACCERR) ||
+	    (si->si_code == SEGV_BNDERR)) {
+		printf("non-PK si_code, exiting...\n");
+		exit(4);
+	}
+
+	si_pkey_ptr = (u32 *)(((u8 *)si) + si_pkey_offset);
+	dprintf1("si_pkey_ptr: %p\n", si_pkey_ptr);
+	dump_mem((u8 *)si_pkey_ptr - 8, 24);
+	siginfo_pkey = *si_pkey_ptr;
+	pkey_assert(siginfo_pkey < NR_PKEYS);
+	last_si_pkey = siginfo_pkey;
+
+	dprintf1("signal pkru from xsave: %08x\n", *pkru_ptr);
+	/* need __rdpkru() version so we do not do shadow_pkru checking */
+	dprintf1("signal pkru from  pkru: %08x\n", __rdpkru());
+	dprintf1("pkey from siginfo: %jx\n", siginfo_pkey);
+	*(u64 *)pkru_ptr = 0x00000000;
+	dprintf1("WARNING: set PRKU=0 to allow faulting instruction to continue\n");
+	pkru_faults++;
+	dprintf1("<<<<==================================================\n");
+	dprint_in_signal = 0;
+}
+
+int wait_all_children(void)
+{
+	int status;
+	return waitpid(-1, &status, 0);
+}
+
+void sig_chld(int x)
+{
+	dprint_in_signal = 1;
+	dprintf2("[%d] SIGCHLD: %d\n", getpid(), x);
+	dprint_in_signal = 0;
+}
+
+void setup_sigsegv_handler(void)
+{
+	int r, rs;
+	struct sigaction newact;
+	struct sigaction oldact;
+
+	/* #PF is mapped to sigsegv */
+	int signum  = SIGSEGV;
+
+	newact.sa_handler = 0;
+	newact.sa_sigaction = signal_handler;
+
+	/*sigset_t - signals to block while in the handler */
+	/* get the old signal mask. */
+	rs = sigprocmask(SIG_SETMASK, 0, &newact.sa_mask);
+	pkey_assert(rs == 0);
+
+	/* call sa_sigaction, not sa_handler*/
+	newact.sa_flags = SA_SIGINFO;
+
+	newact.sa_restorer = 0;  /* void(*)(), obsolete */
+	r = sigaction(signum, &newact, &oldact);
+	r = sigaction(SIGALRM, &newact, &oldact);
+	pkey_assert(r == 0);
+}
+
+void setup_handlers(void)
+{
+	signal(SIGCHLD, &sig_chld);
+	setup_sigsegv_handler();
+}
+
+pid_t fork_lazy_child(void)
+{
+	pid_t forkret;
+
+	forkret = fork();
+	pkey_assert(forkret >= 0);
+	dprintf3("[%d] fork() ret: %d\n", getpid(), forkret);
+
+	if (!forkret) {
+		/* in the child */
+		while (1) {
+			dprintf1("child sleeping...\n");
+			sleep(30);
+		}
+	}
+	return forkret;
+}
+
+#ifndef PKEY_DISABLE_ACCESS
+# define PKEY_DISABLE_ACCESS	0x1
+#endif
+
+#ifndef PKEY_DISABLE_WRITE
+# define PKEY_DISABLE_WRITE	0x2
+#endif
+
+static u32 hw_pkey_get(int pkey, unsigned long flags)
+{
+	u32 mask = (PKEY_DISABLE_ACCESS|PKEY_DISABLE_WRITE);
+	u32 pkru = __rdpkru();
+	u32 shifted_pkru;
+	u32 masked_pkru;
+
+	dprintf1("%s(pkey=%d, flags=%lx) = %x / %d\n",
+			__func__, pkey, flags, 0, 0);
+	dprintf2("%s() raw pkru: %x\n", __func__, pkru);
+
+	shifted_pkru = (pkru >> (pkey * PKRU_BITS_PER_PKEY));
+	dprintf2("%s() shifted_pkru: %x\n", __func__, shifted_pkru);
+	masked_pkru = shifted_pkru & mask;
+	dprintf2("%s() masked  pkru: %x\n", __func__, masked_pkru);
+	/*
+	 * shift down the relevant bits to the lowest two, then
+	 * mask off all the other high bits.
+	 */
+	return masked_pkru;
+}
+
+static int hw_pkey_set(int pkey, unsigned long rights, unsigned long flags)
+{
+	u32 mask = (PKEY_DISABLE_ACCESS|PKEY_DISABLE_WRITE);
+	u32 old_pkru = __rdpkru();
+	u32 new_pkru;
+
+	/* make sure that 'rights' only contains the bits we expect: */
+	assert(!(rights & ~mask));
+
+	/* copy old pkru */
+	new_pkru = old_pkru;
+	/* mask out bits from pkey in old value: */
+	new_pkru &= ~(mask << (pkey * PKRU_BITS_PER_PKEY));
+	/* OR in new bits for pkey: */
+	new_pkru |= (rights << (pkey * PKRU_BITS_PER_PKEY));
+
+	__wrpkru(new_pkru);
+
+	dprintf3("%s(pkey=%d, rights=%lx, flags=%lx) = %x pkru now: %x old_pkru: %x\n",
+			__func__, pkey, rights, flags, 0, __rdpkru(), old_pkru);
+	return 0;
+}
+
+void pkey_disable_set(int pkey, int flags)
+{
+	unsigned long syscall_flags = 0;
+	int ret;
+	int pkey_rights;
+	u32 orig_pkru = rdpkru();
+
+	dprintf1("START->%s(%d, 0x%x)\n", __func__,
+		pkey, flags);
+	pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+	pkey_assert(pkey_rights >= 0);
+
+	pkey_rights |= flags;
+
+	ret = hw_pkey_set(pkey, pkey_rights, syscall_flags);
+	assert(!ret);
+	/*pkru and flags have the same format */
+	shadow_pkru |= flags << (pkey * 2);
+	dprintf1("%s(%d) shadow: 0x%x\n", __func__, pkey, shadow_pkru);
+
+	pkey_assert(ret >= 0);
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+
+	dprintf1("%s(%d) pkru: 0x%x\n", __func__, pkey, rdpkru());
+	if (flags)
+		pkey_assert(rdpkru() > orig_pkru);
+	dprintf1("END<---%s(%d, 0x%x)\n", __func__,
+		pkey, flags);
+}
+
+void pkey_disable_clear(int pkey, int flags)
+{
+	unsigned long syscall_flags = 0;
+	int ret;
+	int pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	u32 orig_pkru = rdpkru();
+
+	pkey_assert(flags & (PKEY_DISABLE_ACCESS | PKEY_DISABLE_WRITE));
+
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+	pkey_assert(pkey_rights >= 0);
+
+	pkey_rights |= flags;
+
+	ret = hw_pkey_set(pkey, pkey_rights, 0);
+	/* pkru and flags have the same format */
+	shadow_pkru &= ~(flags << (pkey * 2));
+	pkey_assert(ret >= 0);
+
+	pkey_rights = hw_pkey_get(pkey, syscall_flags);
+	dprintf1("%s(%d) hw_pkey_get(%d): %x\n", __func__,
+			pkey, pkey, pkey_rights);
+
+	dprintf1("%s(%d) pkru: 0x%x\n", __func__, pkey, rdpkru());
+	if (flags)
+		assert(rdpkru() > orig_pkru);
+}
+
+void pkey_write_allow(int pkey)
+{
+	pkey_disable_clear(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_write_deny(int pkey)
+{
+	pkey_disable_set(pkey, PKEY_DISABLE_WRITE);
+}
+void pkey_access_allow(int pkey)
+{
+	pkey_disable_clear(pkey, PKEY_DISABLE_ACCESS);
+}
+void pkey_access_deny(int pkey)
+{
+	pkey_disable_set(pkey, PKEY_DISABLE_ACCESS);
+}
+
+int sys_mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey)
+{
+	int sret;
+
+	dprintf2("%s(0x%p, %zx, prot=%lx, pkey=%lx)\n", __func__,
+			ptr, size, orig_prot, pkey);
+
+	errno = 0;
+	sret = syscall(SYS_mprotect_key, ptr, size, orig_prot, pkey);
+	if (errno) {
+		dprintf2("SYS_mprotect_key sret: %d\n", sret);
+		dprintf2("SYS_mprotect_key prot: 0x%lx\n", orig_prot);
+		dprintf2("SYS_mprotect_key failed, errno: %d\n", errno);
+		if (DEBUG_LEVEL >= 2)
+			perror("SYS_mprotect_pkey");
+	}
+	return sret;
+}
+
+int sys_pkey_alloc(unsigned long flags, unsigned long init_val)
+{
+	int ret = syscall(SYS_pkey_alloc, flags, init_val);
+	dprintf1("%s(flags=%lx, init_val=%lx) syscall ret: %d errno: %d\n",
+			__func__, flags, init_val, ret, errno);
+	return ret;
+}
+
+int alloc_pkey(void)
+{
+	int ret;
+	unsigned long init_val = 0x0;
+
+	dprintf1("alloc_pkey()::%d, pkru: 0x%x shadow: %x\n",
+			__LINE__, __rdpkru(), shadow_pkru);
+	ret = sys_pkey_alloc(0, init_val);
+	/*
+	 * pkey_alloc() sets PKRU, so we need to reflect it in
+	 * shadow_pkru:
+	 */
+	dprintf4("alloc_pkey()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n",
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	if (ret) {
+		/* clear both the bits: */
+		shadow_pkru &= ~(0x3      << (ret * 2));
+		dprintf4("alloc_pkey()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n",
+				__LINE__, ret, __rdpkru(), shadow_pkru);
+		/*
+		 * move the new state in from init_val
+		 * (remember, we cheated and init_val == pkru format)
+		 */
+		shadow_pkru |=  (init_val << (ret * 2));
+	}
+	dprintf4("alloc_pkey()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n",
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	dprintf1("alloc_pkey()::%d errno: %d\n", __LINE__, errno);
+	/* for shadow checking: */
+	rdpkru();
+	dprintf4("alloc_pkey()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n",
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	return ret;
+}
+
+int sys_pkey_free(unsigned long pkey)
+{
+	int ret = syscall(SYS_pkey_free, pkey);
+	dprintf1("%s(pkey=%ld) syscall ret: %d\n", __func__, pkey, ret);
+	return ret;
+}
+
+/*
+ * I had a bug where pkey bits could be set by mprotect() but
+ * not cleared.  This ensures we get lots of random bit sets
+ * and clears on the vma and pte pkey bits.
+ */
+int alloc_random_pkey(void)
+{
+	int max_nr_pkey_allocs;
+	int ret;
+	int i;
+	int alloced_pkeys[NR_PKEYS];
+	int nr_alloced = 0;
+	int random_index;
+	memset(alloced_pkeys, 0, sizeof(alloced_pkeys));
+
+	/* allocate every possible key and make a note of which ones we got */
+	max_nr_pkey_allocs = NR_PKEYS;
+	for (i = 0; i < max_nr_pkey_allocs; i++) {
+		int new_pkey = alloc_pkey();
+		if (new_pkey < 0)
+			break;
+		alloced_pkeys[nr_alloced++] = new_pkey;
+	}
+
+	pkey_assert(nr_alloced > 0);
+	/* select a random one out of the allocated ones */
+	random_index = rand() % nr_alloced;
+	ret = alloced_pkeys[random_index];
+	/* now zero it out so we don't free it next */
+	alloced_pkeys[random_index] = 0;
+
+	/* go through the allocated ones that we did not want and free them */
+	for (i = 0; i < nr_alloced; i++) {
+		int free_ret;
+		if (!alloced_pkeys[i])
+			continue;
+		free_ret = sys_pkey_free(alloced_pkeys[i]);
+		pkey_assert(!free_ret);
+	}
+	dprintf1("%s()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n", __func__,
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	return ret;
+}
+
+int mprotect_pkey(void *ptr, size_t size, unsigned long orig_prot,
+		unsigned long pkey)
+{
+	int nr_iterations = random() % 100;
+	int ret;
+
+	while (0) {
+		int rpkey = alloc_random_pkey();
+		ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey);
+		dprintf1("sys_mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n",
+				ptr, size, orig_prot, pkey, ret);
+		if (nr_iterations-- < 0)
+			break;
+
+		dprintf1("%s()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n", __func__,
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+		sys_pkey_free(rpkey);
+		dprintf1("%s()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n", __func__,
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	}
+	pkey_assert(pkey < NR_PKEYS);
+
+	ret = sys_mprotect_pkey(ptr, size, orig_prot, pkey);
+	dprintf1("mprotect_pkey(%p, %zx, prot=0x%lx, pkey=%ld) ret: %d\n",
+			ptr, size, orig_prot, pkey, ret);
+	pkey_assert(!ret);
+	dprintf1("%s()::%d, ret: %d pkru: 0x%x shadow: 0x%x\n", __func__,
+			__LINE__, ret, __rdpkru(), shadow_pkru);
+	return ret;
+}
+
+struct pkey_malloc_record {
+	void *ptr;
+	long size;
+	int prot;
+};
+struct pkey_malloc_record *pkey_malloc_records;
+struct pkey_malloc_record *pkey_last_malloc_record;
+long nr_pkey_malloc_records;
+void record_pkey_malloc(void *ptr, long size, int prot)
+{
+	long i;
+	struct pkey_malloc_record *rec = NULL;
+
+	for (i = 0; i < nr_pkey_malloc_records; i++) {
+		rec = &pkey_malloc_records[i];
+		/* find a free record */
+		if (rec)
+			break;
+	}
+	if (!rec) {
+		/* every record is full */
+		size_t old_nr_records = nr_pkey_malloc_records;
+		size_t new_nr_records = (nr_pkey_malloc_records * 2 + 1);
+		size_t new_size = new_nr_records * sizeof(struct pkey_malloc_record);
+		dprintf2("new_nr_records: %zd\n", new_nr_records);
+		dprintf2("new_size: %zd\n", new_size);
+		pkey_malloc_records = realloc(pkey_malloc_records, new_size);
+		pkey_assert(pkey_malloc_records != NULL);
+		rec = &pkey_malloc_records[nr_pkey_malloc_records];
+		/*
+		 * realloc() does not initialize memory, so zero it from
+		 * the first new record all the way to the end.
+		 */
+		for (i = 0; i < new_nr_records - old_nr_records; i++)
+			memset(rec + i, 0, sizeof(*rec));
+	}
+	dprintf3("filling malloc record[%d/%p]: {%p, %ld}\n",
+		(int)(rec - pkey_malloc_records), rec, ptr, size);
+	rec->ptr = ptr;
+	rec->size = size;
+	rec->prot = prot;
+	pkey_last_malloc_record = rec;
+	nr_pkey_malloc_records++;
+}
+
+void free_pkey_malloc(void *ptr)
+{
+	long i;
+	int ret;
+	dprintf3("%s(%p)\n", __func__, ptr);
+	for (i = 0; i < nr_pkey_malloc_records; i++) {
+		struct pkey_malloc_record *rec = &pkey_malloc_records[i];
+		dprintf4("looking for ptr %p at record[%ld/%p]: {%p, %ld}\n",
+				ptr, i, rec, rec->ptr, rec->size);
+		if ((ptr <  rec->ptr) ||
+		    (ptr >= rec->ptr + rec->size))
+			continue;
+
+		dprintf3("found ptr %p at record[%ld/%p]: {%p, %ld}\n",
+				ptr, i, rec, rec->ptr, rec->size);
+		nr_pkey_malloc_records--;
+		ret = munmap(rec->ptr, rec->size);
+		dprintf3("munmap ret: %d\n", ret);
+		pkey_assert(!ret);
+		dprintf3("clearing rec->ptr, rec: %p\n", rec);
+		rec->ptr = NULL;
+		dprintf3("done clearing rec->ptr, rec: %p\n", rec);
+		return;
+	}
+	pkey_assert(false);
+}
+
+
+void *malloc_pkey_with_mprotect(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int ret;
+
+	rdpkru();
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
+	pkey_assert(!ret);
+	record_pkey_malloc(ptr, size, prot);
+	rdpkru();
+
+	dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
+	return ptr;
+}
+
+void *malloc_pkey_anon_huge(long size, int prot, u16 pkey)
+{
+	int ret;
+	void *ptr;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	/*
+	 * Guarantee we can fit at least one huge page in the resulting
+	 * allocation by allocating space for 2:
+	 */
+	size = ALIGN_UP(size, HPAGE_SIZE * 2);
+	ptr = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	record_pkey_malloc(ptr, size, prot);
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	dprintf1("unaligned ptr: %p\n", ptr);
+	ptr = ALIGN_PTR_UP(ptr, HPAGE_SIZE);
+	dprintf1("  aligned ptr: %p\n", ptr);
+	ret = madvise(ptr, HPAGE_SIZE, MADV_HUGEPAGE);
+	dprintf1("MADV_HUGEPAGE ret: %d\n", ret);
+	ret = madvise(ptr, HPAGE_SIZE, MADV_WILLNEED);
+	dprintf1("MADV_WILLNEED ret: %d\n", ret);
+	memset(ptr, 0, HPAGE_SIZE);
+
+	dprintf1("mmap()'d thp for pkey %d @ %p\n", pkey, ptr);
+	return ptr;
+}
+
+int hugetlb_setup_ok;
+#define GET_NR_HUGE_PAGES 10
+void setup_hugetlbfs(void)
+{
+	int err;
+	int fd;
+	char buf[] = "123";
+
+	if (geteuid() != 0) {
+		fprintf(stderr, "WARNING: not run as root, can not do hugetlb test\n");
+		return;
+	}
+
+	cat_into_file(__stringify(GET_NR_HUGE_PAGES), "/proc/sys/vm/nr_hugepages");
+
+	/*
+	 * Now go make sure that we got the pages and that they
+	 * are 2M pages.  Someone might have made 1G the default.
+	 */
+	fd = open("/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages", O_RDONLY);
+	if (fd < 0) {
+		perror("opening sysfs 2M hugetlb config");
+		return;
+	}
+
+	/* -1 to guarantee leaving the trailing \0 */
+	err = read(fd, buf, sizeof(buf)-1);
+	close(fd);
+	if (err <= 0) {
+		perror("reading sysfs 2M hugetlb config");
+		return;
+	}
+
+	if (atoi(buf) != GET_NR_HUGE_PAGES) {
+		fprintf(stderr, "could not confirm 2M pages, got: '%s' expected %d\n",
+			buf, GET_NR_HUGE_PAGES);
+		return;
+	}
+
+	hugetlb_setup_ok = 1;
+}
+
+void *malloc_pkey_hugetlb(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int flags = MAP_ANONYMOUS|MAP_PRIVATE|MAP_HUGETLB;
+
+	if (!hugetlb_setup_ok)
+		return PTR_ERR_ENOTSUP;
+
+	dprintf1("doing %s(%ld, %x, %x)\n", __func__, size, prot, pkey);
+	size = ALIGN_UP(size, HPAGE_SIZE * 2);
+	pkey_assert(pkey < NR_PKEYS);
+	ptr = mmap(NULL, size, PROT_NONE, flags, -1, 0);
+	pkey_assert(ptr != (void *)-1);
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("mmap()'d hugetlbfs for pkey %d @ %p\n", pkey, ptr);
+	return ptr;
+}
+
+void *malloc_pkey_mmap_dax(long size, int prot, u16 pkey)
+{
+	void *ptr;
+	int fd;
+
+	dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
+			size, prot, pkey);
+	pkey_assert(pkey < NR_PKEYS);
+	fd = open("/dax/foo", O_RDWR);
+	pkey_assert(fd >= 0);
+
+	ptr = mmap(0, size, prot, MAP_SHARED, fd, 0);
+	pkey_assert(ptr != (void *)-1);
+
+	mprotect_pkey(ptr, size, prot, pkey);
+
+	record_pkey_malloc(ptr, size, prot);
+
+	dprintf1("mmap()'d for pkey %d @ %p\n", pkey, ptr);
+	close(fd);
+	return ptr;
+}
+
+void *(*pkey_malloc[])(long size, int prot, u16 pkey) = {
+
+	malloc_pkey_with_mprotect,
+	malloc_pkey_anon_huge,
+	malloc_pkey_hugetlb
+/* can not do direct with the pkey_mprotect() API:
+	malloc_pkey_mmap_direct,
+	malloc_pkey_mmap_dax,
+*/
+};
+
+void *malloc_pkey(long size, int prot, u16 pkey)
+{
+	void *ret;
+	static int malloc_type;
+	int nr_malloc_types = ARRAY_SIZE(pkey_malloc);
+
+	pkey_assert(pkey < NR_PKEYS);
+
+	while (1) {
+		pkey_assert(malloc_type < nr_malloc_types);
+
+		ret = pkey_malloc[malloc_type](size, prot, pkey);
+		pkey_assert(ret != (void *)-1);
+
+		malloc_type++;
+		if (malloc_type >= nr_malloc_types)
+			malloc_type = (random()%nr_malloc_types);
+
+		/* try again if the malloc_type we tried is unsupported */
+		if (ret == PTR_ERR_ENOTSUP)
+			continue;
+
+		break;
+	}
+
+	dprintf3("%s(%ld, prot=%x, pkey=%x) returning: %p\n", __func__,
+			size, prot, pkey, ret);
+	return ret;
+}
+
+int last_pkru_faults;
+#define UNKNOWN_PKEY -2
+void expected_pk_fault(int pkey)
+{
+	dprintf2("%s(): last_pkru_faults: %d pkru_faults: %d\n",
+			__func__, last_pkru_faults, pkru_faults);
+	dprintf2("%s(%d): last_si_pkey: %d\n", __func__, pkey, last_si_pkey);
+	pkey_assert(last_pkru_faults + 1 == pkru_faults);
+
+       /*
+	* For exec-only memory, we do not know the pkey in
+	* advance, so skip this check.
+	*/
+	if (pkey != UNKNOWN_PKEY)
+		pkey_assert(last_si_pkey == pkey);
+
+	/*
+	 * The signal handler shold have cleared out PKRU to let the
+	 * test program continue.  We now have to restore it.
+	 */
+	if (__rdpkru() != 0)
+		pkey_assert(0);
+
+	__wrpkru(shadow_pkru);
+	dprintf1("%s() set PKRU=%x to restore state after signal nuked it\n",
+			__func__, shadow_pkru);
+	last_pkru_faults = pkru_faults;
+	last_si_pkey = -1;
+}
+
+#define do_not_expect_pk_fault(msg)	do {			\
+	if (last_pkru_faults != pkru_faults)			\
+		dprintf0("unexpected PK fault: %s\n", msg);	\
+	pkey_assert(last_pkru_faults == pkru_faults);		\
+} while (0)
+
+int test_fds[10] = { -1 };
+int nr_test_fds;
+void __save_test_fd(int fd)
+{
+	pkey_assert(fd >= 0);
+	pkey_assert(nr_test_fds < ARRAY_SIZE(test_fds));
+	test_fds[nr_test_fds] = fd;
+	nr_test_fds++;
+}
+
+int get_test_read_fd(void)
+{
+	int test_fd = open("/etc/passwd", O_RDONLY);
+	__save_test_fd(test_fd);
+	return test_fd;
+}
+
+void close_test_fds(void)
+{
+	int i;
+
+	for (i = 0; i < nr_test_fds; i++) {
+		if (test_fds[i] < 0)
+			continue;
+		close(test_fds[i]);
+		test_fds[i] = -1;
+	}
+	nr_test_fds = 0;
+}
+
+#define barrier() __asm__ __volatile__("": : :"memory")
+__attribute__((noinline)) int read_ptr(int *ptr)
+{
+	/*
+	 * Keep GCC from optimizing this away somehow
+	 */
+	barrier();
+	return *ptr;
+}
+
+void test_read_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling write access to PKEY[1], doing read\n");
+	pkey_write_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	dprintf1("\n");
+}
+void test_read_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int ptr_contents;
+
+	dprintf1("disabling access to PKEY[%02d], doing read @ %p\n", pkey, ptr);
+	rdpkru();
+	pkey_access_deny(pkey);
+	ptr_contents = read_ptr(ptr);
+	dprintf1("*ptr: %d\n", ptr_contents);
+	expected_pk_fault(pkey);
+}
+void test_write_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	dprintf1("disabling write access to PKEY[%02d], doing write\n", pkey);
+	pkey_write_deny(pkey);
+	*ptr = __LINE__;
+	expected_pk_fault(pkey);
+}
+void test_write_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	dprintf1("disabling access to PKEY[%02d], doing write\n", pkey);
+	pkey_access_deny(pkey);
+	*ptr = __LINE__;
+	expected_pk_fault(pkey);
+}
+void test_kernel_write_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int ret;
+	int test_fd = get_test_read_fd();
+
+	dprintf1("disabling access to PKEY[%02d], "
+		 "having kernel read() to buffer\n", pkey);
+	pkey_access_deny(pkey);
+	ret = read(test_fd, ptr, 1);
+	dprintf1("read ret: %d\n", ret);
+	pkey_assert(ret);
+}
+void test_kernel_write_of_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ret;
+	int test_fd = get_test_read_fd();
+
+	pkey_write_deny(pkey);
+	ret = read(test_fd, ptr, 100);
+	dprintf1("read ret: %d\n", ret);
+	if (ret < 0 && (DEBUG_LEVEL > 0))
+		perror("verbose read result (OK for this to be bad)");
+	pkey_assert(ret);
+}
+
+void test_kernel_gup_of_access_disabled_region(int *ptr, u16 pkey)
+{
+	int pipe_ret, vmsplice_ret;
+	struct iovec iov;
+	int pipe_fds[2];
+
+	pipe_ret = pipe(pipe_fds);
+
+	pkey_assert(pipe_ret == 0);
+	dprintf1("disabling access to PKEY[%02d], "
+		 "having kernel vmsplice from buffer\n", pkey);
+	pkey_access_deny(pkey);
+	iov.iov_base = ptr;
+	iov.iov_len = PAGE_SIZE;
+	vmsplice_ret = vmsplice(pipe_fds[1], &iov, 1, SPLICE_F_GIFT);
+	dprintf1("vmsplice() ret: %d\n", vmsplice_ret);
+	pkey_assert(vmsplice_ret == -1);
+
+	close(pipe_fds[0]);
+	close(pipe_fds[1]);
+}
+
+void test_kernel_gup_write_to_write_disabled_region(int *ptr, u16 pkey)
+{
+	int ignored = 0xdada;
+	int futex_ret;
+	int some_int = __LINE__;
+
+	dprintf1("disabling write to PKEY[%02d], "
+		 "doing futex gunk in buffer\n", pkey);
+	*ptr = some_int;
+	pkey_write_deny(pkey);
+	futex_ret = syscall(SYS_futex, ptr, FUTEX_WAIT, some_int-1, NULL,
+			&ignored, ignored);
+	if (DEBUG_LEVEL > 0)
+		perror("futex");
+	dprintf1("futex() ret: %d\n", futex_ret);
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_syscalls_on_non_allocated_pkey(int *ptr, u16 pkey)
+{
+	int err;
+	int i;
+
+	/* Note: 0 is the default pkey, so don't mess with it */
+	for (i = 1; i < NR_PKEYS; i++) {
+		if (pkey == i)
+			continue;
+
+		dprintf1("trying get/set/free to non-allocated pkey: %2d\n", i);
+		err = sys_pkey_free(i);
+		pkey_assert(err);
+
+		err = sys_pkey_free(i);
+		pkey_assert(err);
+
+		err = sys_mprotect_pkey(ptr, PAGE_SIZE, PROT_READ, i);
+		pkey_assert(err);
+	}
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_syscalls_bad_args(int *ptr, u16 pkey)
+{
+	int err;
+	int bad_pkey = NR_PKEYS+99;
+
+	/* pass a known-invalid pkey in: */
+	err = sys_mprotect_pkey(ptr, PAGE_SIZE, PROT_READ, bad_pkey);
+	pkey_assert(err);
+}
+
+void become_child(void)
+{
+	pid_t forkret;
+
+	forkret = fork();
+	pkey_assert(forkret >= 0);
+	dprintf3("[%d] fork() ret: %d\n", getpid(), forkret);
+
+	if (!forkret) {
+		/* in the child */
+		return;
+	}
+	exit(0);
+}
+
+/* Assumes that all pkeys other than 'pkey' are unallocated */
+void test_pkey_alloc_exhaust(int *ptr, u16 pkey)
+{
+	int err;
+	int allocated_pkeys[NR_PKEYS] = {0};
+	int nr_allocated_pkeys = 0;
+	int i;
+
+	for (i = 0; i < NR_PKEYS*3; i++) {
+		int new_pkey;
+		dprintf1("%s() alloc loop: %d\n", __func__, i);
+		new_pkey = alloc_pkey();
+		dprintf4("%s()::%d, err: %d pkru: 0x%x shadow: 0x%x\n", __func__,
+				__LINE__, err, __rdpkru(), shadow_pkru);
+		rdpkru(); /* for shadow checking */
+		dprintf2("%s() errno: %d ENOSPC: %d\n", __func__, errno, ENOSPC);
+		if ((new_pkey == -1) && (errno == ENOSPC)) {
+			dprintf2("%s() failed to allocate pkey after %d tries\n",
+				__func__, nr_allocated_pkeys);
+		} else {
+			/*
+			 * Ensure the number of successes never
+			 * exceeds the number of keys supported
+			 * in the hardware.
+			 */
+			pkey_assert(nr_allocated_pkeys < NR_PKEYS);
+			allocated_pkeys[nr_allocated_pkeys++] = new_pkey;
+		}
+
+		/*
+		 * Make sure that allocation state is properly
+		 * preserved across fork().
+		 */
+		if (i == NR_PKEYS*2)
+			become_child();
+	}
+
+	dprintf3("%s()::%d\n", __func__, __LINE__);
+
+	/*
+	 * There are 16 pkeys supported in hardware.  Three are
+	 * allocated by the time we get here:
+	 *   1. The default key (0)
+	 *   2. One possibly consumed by an execute-only mapping.
+	 *   3. One allocated by the test code and passed in via
+	 *      'pkey' to this function.
+	 * Ensure that we can allocate at least another 13 (16-3).
+	 */
+	pkey_assert(i >= NR_PKEYS-3);
+
+	for (i = 0; i < nr_allocated_pkeys; i++) {
+		err = sys_pkey_free(allocated_pkeys[i]);
+		pkey_assert(!err);
+		rdpkru(); /* for shadow checking */
+	}
+}
+
+/*
+ * pkey 0 is special.  It is allocated by default, so you do not
+ * have to call pkey_alloc() to use it first.  Make sure that it
+ * is usable.
+ */
+void test_mprotect_with_pkey_0(int *ptr, u16 pkey)
+{
+	long size;
+	int prot;
+
+	assert(pkey_last_malloc_record);
+	size = pkey_last_malloc_record->size;
+	/*
+	 * This is a bit of a hack.  But mprotect() requires
+	 * huge-page-aligned sizes when operating on hugetlbfs.
+	 * So, make sure that we use something that's a multiple
+	 * of a huge page when we can.
+	 */
+	if (size >= HPAGE_SIZE)
+		size = HPAGE_SIZE;
+	prot = pkey_last_malloc_record->prot;
+
+	/* Use pkey 0 */
+	mprotect_pkey(ptr, size, prot, 0);
+
+	/* Make sure that we can set it back to the original pkey. */
+	mprotect_pkey(ptr, size, prot, pkey);
+}
+
+void test_ptrace_of_child(int *ptr, u16 pkey)
+{
+	__attribute__((__unused__)) int peek_result;
+	pid_t child_pid;
+	void *ignored = 0;
+	long ret;
+	int status;
+	/*
+	 * This is the "control" for our little expermient.  Make sure
+	 * we can always access it when ptracing.
+	 */
+	int *plain_ptr_unaligned = malloc(HPAGE_SIZE);
+	int *plain_ptr = ALIGN_PTR_UP(plain_ptr_unaligned, PAGE_SIZE);
+
+	/*
+	 * Fork a child which is an exact copy of this process, of course.
+	 * That means we can do all of our tests via ptrace() and then plain
+	 * memory access and ensure they work differently.
+	 */
+	child_pid = fork_lazy_child();
+	dprintf1("[%d] child pid: %d\n", getpid(), child_pid);
+
+	ret = ptrace(PTRACE_ATTACH, child_pid, ignored, ignored);
+	if (ret)
+		perror("attach");
+	dprintf1("[%d] attach ret: %ld %d\n", getpid(), ret, __LINE__);
+	pkey_assert(ret != -1);
+	ret = waitpid(child_pid, &status, WUNTRACED);
+	if ((ret != child_pid) || !(WIFSTOPPED(status))) {
+		fprintf(stderr, "weird waitpid result %ld stat %x\n",
+				ret, status);
+		pkey_assert(0);
+	}
+	dprintf2("waitpid ret: %ld\n", ret);
+	dprintf2("waitpid status: %d\n", status);
+
+	pkey_access_deny(pkey);
+	pkey_write_deny(pkey);
+
+	/* Write access, untested for now:
+	ret = ptrace(PTRACE_POKEDATA, child_pid, peek_at, data);
+	pkey_assert(ret != -1);
+	dprintf1("poke at %p: %ld\n", peek_at, ret);
+	*/
+
+	/*
+	 * Try to access the pkey-protected "ptr" via ptrace:
+	 */
+	ret = ptrace(PTRACE_PEEKDATA, child_pid, ptr, ignored);
+	/* expect it to work, without an error: */
+	pkey_assert(ret != -1);
+	/* Now access from the current task, and expect an exception: */
+	peek_result = read_ptr(ptr);
+	expected_pk_fault(pkey);
+
+	/*
+	 * Try to access the NON-pkey-protected "plain_ptr" via ptrace:
+	 */
+	ret = ptrace(PTRACE_PEEKDATA, child_pid, plain_ptr, ignored);
+	/* expect it to work, without an error: */
+	pkey_assert(ret != -1);
+	/* Now access from the current task, and expect NO exception: */
+	peek_result = read_ptr(plain_ptr);
+	do_not_expect_pk_fault("read plain pointer after ptrace");
+
+	ret = ptrace(PTRACE_DETACH, child_pid, ignored, 0);
+	pkey_assert(ret != -1);
+
+	ret = kill(child_pid, SIGKILL);
+	pkey_assert(ret != -1);
+
+	wait(&status);
+
+	free(plain_ptr_unaligned);
+}
+
+void *get_pointer_to_instructions(void)
+{
+	void *p1;
+
+	p1 = ALIGN_PTR_UP(&lots_o_noops_around_write, PAGE_SIZE);
+	dprintf3("&lots_o_noops: %p\n", &lots_o_noops_around_write);
+	/* lots_o_noops_around_write should be page-aligned already */
+	assert(p1 == &lots_o_noops_around_write);
+
+	/* Point 'p1' at the *second* page of the function: */
+	p1 += PAGE_SIZE;
+
+	/*
+	 * Try to ensure we fault this in on next touch to ensure
+	 * we get an instruction fault as opposed to a data one
+	 */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+
+	return p1;
+}
+
+void test_executing_on_unreadable_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	p1 = get_pointer_to_instructions();
+	lots_o_noops_around_write(&scratch);
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+
+	ret = mprotect_pkey(p1, PAGE_SIZE, PROT_EXEC, (u64)pkey);
+	pkey_assert(!ret);
+	pkey_access_deny(pkey);
+
+	dprintf2("pkru: %x\n", rdpkru());
+
+	/*
+	 * Make sure this is an *instruction* fault
+	 */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+	lots_o_noops_around_write(&scratch);
+	do_not_expect_pk_fault("executing on PROT_EXEC memory");
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+	expected_pk_fault(pkey);
+}
+
+void test_implicit_mprotect_exec_only_memory(int *ptr, u16 pkey)
+{
+	void *p1;
+	int scratch;
+	int ptr_contents;
+	int ret;
+
+	dprintf1("%s() start\n", __func__);
+
+	p1 = get_pointer_to_instructions();
+	lots_o_noops_around_write(&scratch);
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+
+	/* Use a *normal* mprotect(), not mprotect_pkey(): */
+	ret = mprotect(p1, PAGE_SIZE, PROT_EXEC);
+	pkey_assert(!ret);
+
+	dprintf2("pkru: %x\n", rdpkru());
+
+	/* Make sure this is an *instruction* fault */
+	madvise(p1, PAGE_SIZE, MADV_DONTNEED);
+	lots_o_noops_around_write(&scratch);
+	do_not_expect_pk_fault("executing on PROT_EXEC memory");
+	ptr_contents = read_ptr(p1);
+	dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
+	expected_pk_fault(UNKNOWN_PKEY);
+
+	/*
+	 * Put the memory back to non-PROT_EXEC.  Should clear the
+	 * exec-only pkey off the VMA and allow it to be readable
+	 * again.  Go to PROT_NONE first to check for a kernel bug
+	 * that did not clear the pkey when doing PROT_NONE.
+	 */
+	ret = mprotect(p1, PAGE_SIZE, PROT_NONE);
+	pkey_assert(!ret);
+
+	ret = mprotect(p1, PAGE_SIZE, PROT_READ|PROT_EXEC);
+	pkey_assert(!ret);
+	ptr_contents = read_ptr(p1);
+	do_not_expect_pk_fault("plain read on recently PROT_EXEC area");
+}
+
+void test_mprotect_pkey_on_unsupported_cpu(int *ptr, u16 pkey)
+{
+	int size = PAGE_SIZE;
+	int sret;
+
+	if (cpu_has_pku()) {
+		dprintf1("SKIP: %s: no CPU support\n", __func__);
+		return;
+	}
+
+	sret = syscall(SYS_mprotect_key, ptr, size, PROT_READ, pkey);
+	pkey_assert(sret < 0);
+}
+
+void (*pkey_tests[])(int *ptr, u16 pkey) = {
+	test_read_of_write_disabled_region,
+	test_read_of_access_disabled_region,
+	test_write_of_write_disabled_region,
+	test_write_of_access_disabled_region,
+	test_kernel_write_of_access_disabled_region,
+	test_kernel_write_of_write_disabled_region,
+	test_kernel_gup_of_access_disabled_region,
+	test_kernel_gup_write_to_write_disabled_region,
+	test_executing_on_unreadable_memory,
+	test_implicit_mprotect_exec_only_memory,
+	test_mprotect_with_pkey_0,
+	test_ptrace_of_child,
+	test_pkey_syscalls_on_non_allocated_pkey,
+	test_pkey_syscalls_bad_args,
+	test_pkey_alloc_exhaust,
+};
+
+void run_tests_once(void)
+{
+	int *ptr;
+	int prot = PROT_READ|PROT_WRITE;
+
+	for (test_nr = 0; test_nr < ARRAY_SIZE(pkey_tests); test_nr++) {
+		int pkey;
+		int orig_pkru_faults = pkru_faults;
+
+		dprintf1("======================\n");
+		dprintf1("test %d preparing...\n", test_nr);
+
+		tracing_on();
+		pkey = alloc_random_pkey();
+		dprintf1("test %d starting with pkey: %d\n", test_nr, pkey);
+		ptr = malloc_pkey(PAGE_SIZE, prot, pkey);
+		dprintf1("test %d starting...\n", test_nr);
+		pkey_tests[test_nr](ptr, pkey);
+		dprintf1("freeing test memory: %p\n", ptr);
+		free_pkey_malloc(ptr);
+		sys_pkey_free(pkey);
+
+		dprintf1("pkru_faults: %d\n", pkru_faults);
+		dprintf1("orig_pkru_faults: %d\n", orig_pkru_faults);
+
+		tracing_off();
+		close_test_fds();
+
+		printf("test %2d PASSED (iteration %d)\n", test_nr, iteration_nr);
+		dprintf1("======================\n\n");
+	}
+	iteration_nr++;
+}
+
+void pkey_setup_shadow(void)
+{
+	shadow_pkru = __rdpkru();
+}
+
+int main(void)
+{
+	int nr_iterations = 22;
+
+	srand((unsigned int)time(NULL));
+
+	setup_handlers();
+
+	printf("has pku: %d\n", cpu_has_pku());
+
+	if (!cpu_has_pku()) {
+		int size = PAGE_SIZE;
+		int *ptr;
+
+		printf("running PKEY tests for unsupported CPU/OS\n");
+
+		ptr  = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+		assert(ptr != (void *)-1);
+		test_mprotect_pkey_on_unsupported_cpu(ptr, 1);
+		exit(0);
+	}
+
+	pkey_setup_shadow();
+	printf("startup pkru: %x\n", rdpkru());
+	setup_hugetlbfs();
+
+	while (nr_iterations-- > 0)
+		run_tests_once();
+
+	printf("done (all tests OK)\n");
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/ptrace_syscall.c b/tools/testing/selftests/x86/ptrace_syscall.c
new file mode 100644
index 000000000..12aaa0631
--- /dev/null
+++ b/tools/testing/selftests/x86/ptrace_syscall.c
@@ -0,0 +1,430 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE
+
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/syscall.h>
+#include <sys/user.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <err.h>
+#include <string.h>
+#include <asm/ptrace-abi.h>
+#include <sys/auxv.h>
+
+/* Bitness-agnostic defines for user_regs_struct fields. */
+#ifdef __x86_64__
+# define user_syscall_nr	orig_rax
+# define user_arg0		rdi
+# define user_arg1		rsi
+# define user_arg2		rdx
+# define user_arg3		r10
+# define user_arg4		r8
+# define user_arg5		r9
+# define user_ip		rip
+# define user_ax		rax
+#else
+# define user_syscall_nr	orig_eax
+# define user_arg0		ebx
+# define user_arg1		ecx
+# define user_arg2		edx
+# define user_arg3		esi
+# define user_arg4		edi
+# define user_arg5		ebp
+# define user_ip		eip
+# define user_ax		eax
+#endif
+
+static int nerrs = 0;
+
+struct syscall_args32 {
+	uint32_t nr, arg0, arg1, arg2, arg3, arg4, arg5;
+};
+
+#ifdef __i386__
+extern void sys32_helper(struct syscall_args32 *, void *);
+extern void int80_and_ret(void);
+#endif
+
+/*
+ * Helper to invoke int80 with controlled regs and capture the final regs.
+ */
+static void do_full_int80(struct syscall_args32 *args)
+{
+#ifdef __x86_64__
+	register unsigned long bp asm("bp") = args->arg5;
+	asm volatile ("int $0x80"
+		      : "+a" (args->nr),
+			"+b" (args->arg0), "+c" (args->arg1), "+d" (args->arg2),
+			"+S" (args->arg3), "+D" (args->arg4), "+r" (bp)
+			: : "r8", "r9", "r10", "r11");
+	args->arg5 = bp;
+#else
+	sys32_helper(args, int80_and_ret);
+#endif
+}
+
+#ifdef __i386__
+static void (*vsyscall32)(void);
+
+/*
+ * Nasty helper to invoke AT_SYSINFO (i.e. __kernel_vsyscall) with
+ * controlled regs and capture the final regs.  This is so nasty that it
+ * crashes my copy of gdb :)
+ */
+static void do_full_vsyscall32(struct syscall_args32 *args)
+{
+	sys32_helper(args, vsyscall32);
+}
+#endif
+
+static siginfo_t wait_trap(pid_t chld)
+{
+	siginfo_t si;
+	if (waitid(P_PID, chld, &si, WEXITED|WSTOPPED) != 0)
+		err(1, "waitid");
+	if (si.si_pid != chld)
+		errx(1, "got unexpected pid in event\n");
+	if (si.si_code != CLD_TRAPPED)
+		errx(1, "got unexpected event type %d\n", si.si_code);
+	return si;
+}
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void setsigign(int sig, int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = (void *)SIG_IGN;
+	sa.sa_flags = flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+#ifdef __x86_64__
+# define REG_BP REG_RBP
+#else
+# define REG_BP REG_EBP
+#endif
+
+static void empty_handler(int sig, siginfo_t *si, void *ctx_void)
+{
+}
+
+static void test_sys32_regs(void (*do_syscall)(struct syscall_args32 *))
+{
+	struct syscall_args32 args = {
+		.nr = 224,	/* gettid */
+		.arg0 = 10, .arg1 = 11, .arg2 = 12,
+		.arg3 = 13, .arg4 = 14, .arg5 = 15,
+	};
+
+	do_syscall(&args);
+
+	if (args.nr != getpid() ||
+	    args.arg0 != 10 || args.arg1 != 11 || args.arg2 != 12 ||
+	    args.arg3 != 13 || args.arg4 != 14 || args.arg5 != 15) {
+		printf("[FAIL]\tgetpid() failed to preserve regs\n");
+		nerrs++;
+	} else {
+		printf("[OK]\tgetpid() preserves regs\n");
+	}
+
+	sethandler(SIGUSR1, empty_handler, 0);
+
+	args.nr = 37;	/* kill */
+	args.arg0 = getpid();
+	args.arg1 = SIGUSR1;
+	do_syscall(&args);
+	if (args.nr != 0 ||
+	    args.arg0 != getpid() || args.arg1 != SIGUSR1 || args.arg2 != 12 ||
+	    args.arg3 != 13 || args.arg4 != 14 || args.arg5 != 15) {
+		printf("[FAIL]\tkill(getpid(), SIGUSR1) failed to preserve regs\n");
+		nerrs++;
+	} else {
+		printf("[OK]\tkill(getpid(), SIGUSR1) preserves regs\n");
+	}
+	clearhandler(SIGUSR1);
+}
+
+static void test_ptrace_syscall_restart(void)
+{
+	printf("[RUN]\tptrace-induced syscall restart\n");
+	pid_t chld = fork();
+	if (chld < 0)
+		err(1, "fork");
+
+	if (chld == 0) {
+		if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
+			err(1, "PTRACE_TRACEME");
+
+		pid_t pid = getpid(), tid = syscall(SYS_gettid);
+
+		printf("\tChild will make one syscall\n");
+		syscall(SYS_tgkill, pid, tid, SIGSTOP);
+
+		syscall(SYS_gettid, 10, 11, 12, 13, 14, 15);
+		_exit(0);
+	}
+
+	int status;
+
+	/* Wait for SIGSTOP. */
+	if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
+		err(1, "waitpid");
+
+	struct user_regs_struct regs;
+
+	printf("[RUN]\tSYSEMU\n");
+	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSEMU");
+	wait_trap(chld);
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_gettid ||
+	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
+	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
+	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
+		printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tInitial nr and args are correct\n");
+	}
+
+	printf("[RUN]\tRestart the syscall (ip = 0x%lx)\n",
+	       (unsigned long)regs.user_ip);
+
+	/*
+	 * This does exactly what it appears to do if syscall is int80 or
+	 * SYSCALL64.  For SYSCALL32 or SYSENTER, though, this is highly
+	 * magical.  It needs to work so that ptrace and syscall restart
+	 * work as expected.
+	 */
+	regs.user_ax = regs.user_syscall_nr;
+	regs.user_ip -= 2;
+	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_SETREGS");
+
+	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSEMU");
+	wait_trap(chld);
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_gettid ||
+	    regs.user_arg0 != 10 || regs.user_arg1 != 11 ||
+	    regs.user_arg2 != 12 || regs.user_arg3 != 13 ||
+	    regs.user_arg4 != 14 || regs.user_arg5 != 15) {
+		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tRestarted nr and args are correct\n");
+	}
+
+	printf("[RUN]\tChange nr and args and restart the syscall (ip = 0x%lx)\n",
+	       (unsigned long)regs.user_ip);
+
+	regs.user_ax = SYS_getpid;
+	regs.user_arg0 = 20;
+	regs.user_arg1 = 21;
+	regs.user_arg2 = 22;
+	regs.user_arg3 = 23;
+	regs.user_arg4 = 24;
+	regs.user_arg5 = 25;
+	regs.user_ip -= 2;
+
+	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_SETREGS");
+
+	if (ptrace(PTRACE_SYSEMU, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSEMU");
+	wait_trap(chld);
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_getpid ||
+	    regs.user_arg0 != 20 || regs.user_arg1 != 21 || regs.user_arg2 != 22 ||
+	    regs.user_arg3 != 23 || regs.user_arg4 != 24 || regs.user_arg5 != 25) {
+		printf("[FAIL]\tRestart nr or args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tReplacement nr and args are correct\n");
+	}
+
+	if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
+		err(1, "PTRACE_CONT");
+	if (waitpid(chld, &status, 0) != chld)
+		err(1, "waitpid");
+	if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
+		printf("[FAIL]\tChild failed\n");
+		nerrs++;
+	} else {
+		printf("[OK]\tChild exited cleanly\n");
+	}
+}
+
+static void test_restart_under_ptrace(void)
+{
+	printf("[RUN]\tkernel syscall restart under ptrace\n");
+	pid_t chld = fork();
+	if (chld < 0)
+		err(1, "fork");
+
+	if (chld == 0) {
+		if (ptrace(PTRACE_TRACEME, 0, 0, 0) != 0)
+			err(1, "PTRACE_TRACEME");
+
+		pid_t pid = getpid(), tid = syscall(SYS_gettid);
+
+		printf("\tChild will take a nap until signaled\n");
+		setsigign(SIGUSR1, SA_RESTART);
+		syscall(SYS_tgkill, pid, tid, SIGSTOP);
+
+		syscall(SYS_pause, 0, 0, 0, 0, 0, 0);
+		_exit(0);
+	}
+
+	int status;
+
+	/* Wait for SIGSTOP. */
+	if (waitpid(chld, &status, 0) != chld || !WIFSTOPPED(status))
+		err(1, "waitpid");
+
+	struct user_regs_struct regs;
+
+	printf("[RUN]\tSYSCALL\n");
+	if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSCALL");
+	wait_trap(chld);
+
+	/* We should be stopped at pause(2) entry. */
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_pause ||
+	    regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+	    regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+	    regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+		printf("[FAIL]\tInitial args are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tInitial nr and args are correct\n");
+	}
+
+	/* Interrupt it. */
+	kill(chld, SIGUSR1);
+
+	/* Advance.  We should be stopped at exit. */
+	printf("[RUN]\tSYSCALL\n");
+	if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSCALL");
+	wait_trap(chld);
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_pause ||
+	    regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+	    regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+	    regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+		printf("[FAIL]\tArgs after SIGUSR1 are wrong (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tArgs after SIGUSR1 are correct (ax = %ld)\n",
+		       (long)regs.user_ax);
+	}
+
+	/* Poke the regs back in.  This must not break anything. */
+	if (ptrace(PTRACE_SETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_SETREGS");
+
+	/* Catch the (ignored) SIGUSR1. */
+	if (ptrace(PTRACE_CONT, chld, 0, 0) != 0)
+		err(1, "PTRACE_CONT");
+	if (waitpid(chld, &status, 0) != chld)
+		err(1, "waitpid");
+	if (!WIFSTOPPED(status)) {
+		printf("[FAIL]\tChild was stopped for SIGUSR1 (status = 0x%x)\n", status);
+		nerrs++;
+	} else {
+		printf("[OK]\tChild got SIGUSR1\n");
+	}
+
+	/* The next event should be pause(2) again. */
+	printf("[RUN]\tStep again\n");
+	if (ptrace(PTRACE_SYSCALL, chld, 0, 0) != 0)
+		err(1, "PTRACE_SYSCALL");
+	wait_trap(chld);
+
+	/* We should be stopped at pause(2) entry. */
+
+	if (ptrace(PTRACE_GETREGS, chld, 0, &regs) != 0)
+		err(1, "PTRACE_GETREGS");
+
+	if (regs.user_syscall_nr != SYS_pause ||
+	    regs.user_arg0 != 0 || regs.user_arg1 != 0 ||
+	    regs.user_arg2 != 0 || regs.user_arg3 != 0 ||
+	    regs.user_arg4 != 0 || regs.user_arg5 != 0) {
+		printf("[FAIL]\tpause did not restart (nr=%lu, args=%lu %lu %lu %lu %lu %lu)\n", (unsigned long)regs.user_syscall_nr, (unsigned long)regs.user_arg0, (unsigned long)regs.user_arg1, (unsigned long)regs.user_arg2, (unsigned long)regs.user_arg3, (unsigned long)regs.user_arg4, (unsigned long)regs.user_arg5);
+		nerrs++;
+	} else {
+		printf("[OK]\tpause(2) restarted correctly\n");
+	}
+
+	/* Kill it. */
+	kill(chld, SIGKILL);
+	if (waitpid(chld, &status, 0) != chld)
+		err(1, "waitpid");
+}
+
+int main()
+{
+	printf("[RUN]\tCheck int80 return regs\n");
+	test_sys32_regs(do_full_int80);
+
+#if defined(__i386__) && (!defined(__GLIBC__) || __GLIBC__ > 2 || __GLIBC_MINOR__ >= 16)
+	vsyscall32 = (void *)getauxval(AT_SYSINFO);
+	if (vsyscall32) {
+		printf("[RUN]\tCheck AT_SYSINFO return regs\n");
+		test_sys32_regs(do_full_vsyscall32);
+	} else {
+		printf("[SKIP]\tAT_SYSINFO is not available\n");
+	}
+#endif
+
+	test_ptrace_syscall_restart();
+
+	test_restart_under_ptrace();
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/raw_syscall_helper_32.S b/tools/testing/selftests/x86/raw_syscall_helper_32.S
new file mode 100644
index 000000000..94410fa2b
--- /dev/null
+++ b/tools/testing/selftests/x86/raw_syscall_helper_32.S
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+.global sys32_helper
+sys32_helper:
+	/* Args: syscall_args_32*, function pointer */
+	pushl	%ebp
+	pushl	%ebx
+	pushl	%esi
+	pushl	%edi
+	movl	5*4(%esp), %eax	/* pointer to args struct */
+
+	movl	1*4(%eax), %ebx
+	movl	2*4(%eax), %ecx
+	movl	3*4(%eax), %edx
+	movl	4*4(%eax), %esi
+	movl	5*4(%eax), %edi
+	movl	6*4(%eax), %ebp
+	movl	0*4(%eax), %eax
+
+	call	*(6*4)(%esp)	/* Do the syscall */
+
+	/* Now we need to recover without losing any reg values */
+	pushl	%eax
+	movl	6*4(%esp), %eax
+	popl	0*4(%eax)
+	movl	%ebx, 1*4(%eax)
+	movl	%ecx, 2*4(%eax)
+	movl	%edx, 3*4(%eax)
+	movl	%esi, 4*4(%eax)
+	movl	%edi, 5*4(%eax)
+	movl	%ebp, 6*4(%eax)
+
+	popl	%edi
+	popl	%esi
+	popl	%ebx
+	popl	%ebp
+	ret
+
+	.type sys32_helper, @function
+	.size sys32_helper, .-sys32_helper
+
+.global int80_and_ret
+int80_and_ret:
+	int	$0x80
+	ret
+
+	.type int80_and_ret, @function
+	.size int80_and_ret, .-int80_and_ret
diff --git a/tools/testing/selftests/x86/sigreturn.c b/tools/testing/selftests/x86/sigreturn.c
new file mode 100644
index 000000000..4d9dc3f2f
--- /dev/null
+++ b/tools/testing/selftests/x86/sigreturn.c
@@ -0,0 +1,871 @@
+/*
+ * sigreturn.c - tests for x86 sigreturn(2) and exit-to-userspace
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * This is a series of tests that exercises the sigreturn(2) syscall and
+ * the IRET / SYSRET paths in the kernel.
+ *
+ * For now, this focuses on the effects of unusual CS and SS values,
+ * and it has a bunch of tests to make sure that ESP/RSP is restored
+ * properly.
+ *
+ * The basic idea behind these tests is to raise(SIGUSR1) to create a
+ * sigcontext frame, plug in the values to be tested, and then return,
+ * which implicitly invokes sigreturn(2) and programs the user context
+ * as desired.
+ *
+ * For tests for which we expect sigreturn and the subsequent return to
+ * user mode to succeed, we return to a short trampoline that generates
+ * SIGTRAP so that the meat of the tests can be ordinary C code in a
+ * SIGTRAP handler.
+ *
+ * The inner workings of each test is documented below.
+ *
+ * Do not run on outdated, unpatched kernels at risk of nasty crashes.
+ */
+
+#define _GNU_SOURCE
+
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+#include <sys/signal.h>
+#include <sys/ucontext.h>
+#include <asm/ldt.h>
+#include <err.h>
+#include <setjmp.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <sys/ptrace.h>
+#include <sys/user.h>
+
+/* Pull in AR_xyz defines. */
+typedef unsigned int u32;
+typedef unsigned short u16;
+#include "../../../../arch/x86/include/asm/desc_defs.h"
+
+/*
+ * Copied from asm/ucontext.h, as asm/ucontext.h conflicts badly with the glibc
+ * headers.
+ */
+#ifdef __x86_64__
+/*
+ * UC_SIGCONTEXT_SS will be set when delivering 64-bit or x32 signals on
+ * kernels that save SS in the sigcontext.  All kernels that set
+ * UC_SIGCONTEXT_SS will correctly restore at least the low 32 bits of esp
+ * regardless of SS (i.e. they implement espfix).
+ *
+ * Kernels that set UC_SIGCONTEXT_SS will also set UC_STRICT_RESTORE_SS
+ * when delivering a signal that came from 64-bit code.
+ *
+ * Sigreturn restores SS as follows:
+ *
+ * if (saved SS is valid || UC_STRICT_RESTORE_SS is set ||
+ *     saved CS is not 64-bit)
+ *         new SS = saved SS  (will fail IRET and signal if invalid)
+ * else
+ *         new SS = a flat 32-bit data segment
+ */
+#define UC_SIGCONTEXT_SS       0x2
+#define UC_STRICT_RESTORE_SS   0x4
+#endif
+
+/*
+ * In principle, this test can run on Linux emulation layers (e.g.
+ * Illumos "LX branded zones").  Solaris-based kernels reserve LDT
+ * entries 0-5 for their own internal purposes, so start our LDT
+ * allocations above that reservation.  (The tests don't pass on LX
+ * branded zones, but at least this lets them run.)
+ */
+#define LDT_OFFSET 6
+
+/* An aligned stack accessible through some of our segments. */
+static unsigned char stack16[65536] __attribute__((aligned(4096)));
+
+/*
+ * An aligned int3 instruction used as a trampoline.  Some of the tests
+ * want to fish out their ss values, so this trampoline copies ss to eax
+ * before the int3.
+ */
+asm (".pushsection .text\n\t"
+     ".type int3, @function\n\t"
+     ".align 4096\n\t"
+     "int3:\n\t"
+     "mov %ss,%ecx\n\t"
+     "int3\n\t"
+     ".size int3, . - int3\n\t"
+     ".align 4096, 0xcc\n\t"
+     ".popsection");
+extern char int3[4096];
+
+/*
+ * At startup, we prepapre:
+ *
+ * - ldt_nonexistent_sel: An LDT entry that doesn't exist (all-zero
+ *   descriptor or out of bounds).
+ * - code16_sel: A 16-bit LDT code segment pointing to int3.
+ * - data16_sel: A 16-bit LDT data segment pointing to stack16.
+ * - npcode32_sel: A 32-bit not-present LDT code segment pointing to int3.
+ * - npdata32_sel: A 32-bit not-present LDT data segment pointing to stack16.
+ * - gdt_data16_idx: A 16-bit GDT data segment pointing to stack16.
+ * - gdt_npdata32_idx: A 32-bit not-present GDT data segment pointing to
+ *   stack16.
+ *
+ * For no particularly good reason, xyz_sel is a selector value with the
+ * RPL and LDT bits filled in, whereas xyz_idx is just an index into the
+ * descriptor table.  These variables will be zero if their respective
+ * segments could not be allocated.
+ */
+static unsigned short ldt_nonexistent_sel;
+static unsigned short code16_sel, data16_sel, npcode32_sel, npdata32_sel;
+
+static unsigned short gdt_data16_idx, gdt_npdata32_idx;
+
+static unsigned short GDT3(int idx)
+{
+	return (idx << 3) | 3;
+}
+
+static unsigned short LDT3(int idx)
+{
+	return (idx << 3) | 7;
+}
+
+/* Our sigaltstack scratch space. */
+static char altstack_data[SIGSTKSZ];
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void add_ldt(const struct user_desc *desc, unsigned short *var,
+		    const char *name)
+{
+	if (syscall(SYS_modify_ldt, 1, desc, sizeof(*desc)) == 0) {
+		*var = LDT3(desc->entry_number);
+	} else {
+		printf("[NOTE]\tFailed to create %s segment\n", name);
+		*var = 0;
+	}
+}
+
+static void setup_ldt(void)
+{
+	if ((unsigned long)stack16 > (1ULL << 32) - sizeof(stack16))
+		errx(1, "stack16 is too high\n");
+	if ((unsigned long)int3 > (1ULL << 32) - sizeof(int3))
+		errx(1, "int3 is too high\n");
+
+	ldt_nonexistent_sel = LDT3(LDT_OFFSET + 2);
+
+	const struct user_desc code16_desc = {
+		.entry_number    = LDT_OFFSET + 0,
+		.base_addr       = (unsigned long)int3,
+		.limit           = 4095,
+		.seg_32bit       = 0,
+		.contents        = 2, /* Code, not conforming */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+	add_ldt(&code16_desc, &code16_sel, "code16");
+
+	const struct user_desc data16_desc = {
+		.entry_number    = LDT_OFFSET + 1,
+		.base_addr       = (unsigned long)stack16,
+		.limit           = 0xffff,
+		.seg_32bit       = 0,
+		.contents        = 0, /* Data, grow-up */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+	add_ldt(&data16_desc, &data16_sel, "data16");
+
+	const struct user_desc npcode32_desc = {
+		.entry_number    = LDT_OFFSET + 3,
+		.base_addr       = (unsigned long)int3,
+		.limit           = 4095,
+		.seg_32bit       = 1,
+		.contents        = 2, /* Code, not conforming */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 1,
+		.useable         = 0
+	};
+	add_ldt(&npcode32_desc, &npcode32_sel, "npcode32");
+
+	const struct user_desc npdata32_desc = {
+		.entry_number    = LDT_OFFSET + 4,
+		.base_addr       = (unsigned long)stack16,
+		.limit           = 0xffff,
+		.seg_32bit       = 1,
+		.contents        = 0, /* Data, grow-up */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 1,
+		.useable         = 0
+	};
+	add_ldt(&npdata32_desc, &npdata32_sel, "npdata32");
+
+	struct user_desc gdt_data16_desc = {
+		.entry_number    = -1,
+		.base_addr       = (unsigned long)stack16,
+		.limit           = 0xffff,
+		.seg_32bit       = 0,
+		.contents        = 0, /* Data, grow-up */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 0,
+		.useable         = 0
+	};
+
+	if (syscall(SYS_set_thread_area, &gdt_data16_desc) == 0) {
+		/*
+		 * This probably indicates vulnerability to CVE-2014-8133.
+		 * Merely getting here isn't definitive, though, and we'll
+		 * diagnose the problem for real later on.
+		 */
+		printf("[WARN]\tset_thread_area allocated data16 at index %d\n",
+		       gdt_data16_desc.entry_number);
+		gdt_data16_idx = gdt_data16_desc.entry_number;
+	} else {
+		printf("[OK]\tset_thread_area refused 16-bit data\n");
+	}
+
+	struct user_desc gdt_npdata32_desc = {
+		.entry_number    = -1,
+		.base_addr       = (unsigned long)stack16,
+		.limit           = 0xffff,
+		.seg_32bit       = 1,
+		.contents        = 0, /* Data, grow-up */
+		.read_exec_only  = 0,
+		.limit_in_pages  = 0,
+		.seg_not_present = 1,
+		.useable         = 0
+	};
+
+	if (syscall(SYS_set_thread_area, &gdt_npdata32_desc) == 0) {
+		/*
+		 * As a hardening measure, newer kernels don't allow this.
+		 */
+		printf("[WARN]\tset_thread_area allocated npdata32 at index %d\n",
+		       gdt_npdata32_desc.entry_number);
+		gdt_npdata32_idx = gdt_npdata32_desc.entry_number;
+	} else {
+		printf("[OK]\tset_thread_area refused 16-bit data\n");
+	}
+}
+
+/* State used by our signal handlers. */
+static gregset_t initial_regs, requested_regs, resulting_regs;
+
+/* Instructions for the SIGUSR1 handler. */
+static volatile unsigned short sig_cs, sig_ss;
+static volatile sig_atomic_t sig_trapped, sig_err, sig_trapno;
+#ifdef __x86_64__
+static volatile sig_atomic_t sig_corrupt_final_ss;
+#endif
+
+/* Abstractions for some 32-bit vs 64-bit differences. */
+#ifdef __x86_64__
+# define REG_IP REG_RIP
+# define REG_SP REG_RSP
+# define REG_CX REG_RCX
+
+struct selectors {
+	unsigned short cs, gs, fs, ss;
+};
+
+static unsigned short *ssptr(ucontext_t *ctx)
+{
+	struct selectors *sels = (void *)&ctx->uc_mcontext.gregs[REG_CSGSFS];
+	return &sels->ss;
+}
+
+static unsigned short *csptr(ucontext_t *ctx)
+{
+	struct selectors *sels = (void *)&ctx->uc_mcontext.gregs[REG_CSGSFS];
+	return &sels->cs;
+}
+#else
+# define REG_IP REG_EIP
+# define REG_SP REG_ESP
+# define REG_CX REG_ECX
+
+static greg_t *ssptr(ucontext_t *ctx)
+{
+	return &ctx->uc_mcontext.gregs[REG_SS];
+}
+
+static greg_t *csptr(ucontext_t *ctx)
+{
+	return &ctx->uc_mcontext.gregs[REG_CS];
+}
+#endif
+
+/*
+ * Checks a given selector for its code bitness or returns -1 if it's not
+ * a usable code segment selector.
+ */
+int cs_bitness(unsigned short cs)
+{
+	uint32_t valid = 0, ar;
+	asm ("lar %[cs], %[ar]\n\t"
+	     "jnz 1f\n\t"
+	     "mov $1, %[valid]\n\t"
+	     "1:"
+	     : [ar] "=r" (ar), [valid] "+rm" (valid)
+	     : [cs] "r" (cs));
+
+	if (!valid)
+		return -1;
+
+	bool db = (ar & (1 << 22));
+	bool l = (ar & (1 << 21));
+
+	if (!(ar & (1<<11)))
+	    return -1;	/* Not code. */
+
+	if (l && !db)
+		return 64;
+	else if (!l && db)
+		return 32;
+	else if (!l && !db)
+		return 16;
+	else
+		return -1;	/* Unknown bitness. */
+}
+
+/*
+ * Checks a given selector for its code bitness or returns -1 if it's not
+ * a usable code segment selector.
+ */
+bool is_valid_ss(unsigned short cs)
+{
+	uint32_t valid = 0, ar;
+	asm ("lar %[cs], %[ar]\n\t"
+	     "jnz 1f\n\t"
+	     "mov $1, %[valid]\n\t"
+	     "1:"
+	     : [ar] "=r" (ar), [valid] "+rm" (valid)
+	     : [cs] "r" (cs));
+
+	if (!valid)
+		return false;
+
+	if ((ar & AR_TYPE_MASK) != AR_TYPE_RWDATA &&
+	    (ar & AR_TYPE_MASK) != AR_TYPE_RWDATA_EXPDOWN)
+		return false;
+
+	return (ar & AR_P);
+}
+
+/* Number of errors in the current test case. */
+static volatile sig_atomic_t nerrs;
+
+static void validate_signal_ss(int sig, ucontext_t *ctx)
+{
+#ifdef __x86_64__
+	bool was_64bit = (cs_bitness(*csptr(ctx)) == 64);
+
+	if (!(ctx->uc_flags & UC_SIGCONTEXT_SS)) {
+		printf("[FAIL]\tUC_SIGCONTEXT_SS was not set\n");
+		nerrs++;
+
+		/*
+		 * This happens on Linux 4.1.  The rest will fail, too, so
+		 * return now to reduce the noise.
+		 */
+		return;
+	}
+
+	/* UC_STRICT_RESTORE_SS is set iff we came from 64-bit mode. */
+	if (!!(ctx->uc_flags & UC_STRICT_RESTORE_SS) != was_64bit) {
+		printf("[FAIL]\tUC_STRICT_RESTORE_SS was wrong in signal %d\n",
+		       sig);
+		nerrs++;
+	}
+
+	if (is_valid_ss(*ssptr(ctx))) {
+		/*
+		 * DOSEMU was written before 64-bit sigcontext had SS, and
+		 * it tries to figure out the signal source SS by looking at
+		 * the physical register.  Make sure that keeps working.
+		 */
+		unsigned short hw_ss;
+		asm ("mov %%ss, %0" : "=rm" (hw_ss));
+		if (hw_ss != *ssptr(ctx)) {
+			printf("[FAIL]\tHW SS didn't match saved SS\n");
+			nerrs++;
+		}
+	}
+#endif
+}
+
+/*
+ * SIGUSR1 handler.  Sets CS and SS as requested and points IP to the
+ * int3 trampoline.  Sets SP to a large known value so that we can see
+ * whether the value round-trips back to user mode correctly.
+ */
+static void sigusr1(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	validate_signal_ss(sig, ctx);
+
+	memcpy(&initial_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
+
+	*csptr(ctx) = sig_cs;
+	*ssptr(ctx) = sig_ss;
+
+	ctx->uc_mcontext.gregs[REG_IP] =
+		sig_cs == code16_sel ? 0 : (unsigned long)&int3;
+	ctx->uc_mcontext.gregs[REG_SP] = (unsigned long)0x8badf00d5aadc0deULL;
+	ctx->uc_mcontext.gregs[REG_CX] = 0;
+
+	memcpy(&requested_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
+	requested_regs[REG_CX] = *ssptr(ctx);	/* The asm code does this. */
+
+	return;
+}
+
+/*
+ * Called after a successful sigreturn (via int3) or from a failed
+ * sigreturn (directly by kernel).  Restores our state so that the
+ * original raise(SIGUSR1) returns.
+ */
+static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	validate_signal_ss(sig, ctx);
+
+	sig_err = ctx->uc_mcontext.gregs[REG_ERR];
+	sig_trapno = ctx->uc_mcontext.gregs[REG_TRAPNO];
+
+	unsigned short ss;
+	asm ("mov %%ss,%0" : "=r" (ss));
+
+	greg_t asm_ss = ctx->uc_mcontext.gregs[REG_CX];
+	if (asm_ss != sig_ss && sig == SIGTRAP) {
+		/* Sanity check failure. */
+		printf("[FAIL]\tSIGTRAP: ss = %hx, frame ss = %hx, ax = %llx\n",
+		       ss, *ssptr(ctx), (unsigned long long)asm_ss);
+		nerrs++;
+	}
+
+	memcpy(&resulting_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
+	memcpy(&ctx->uc_mcontext.gregs, &initial_regs, sizeof(gregset_t));
+
+#ifdef __x86_64__
+	if (sig_corrupt_final_ss) {
+		if (ctx->uc_flags & UC_STRICT_RESTORE_SS) {
+			printf("[FAIL]\tUC_STRICT_RESTORE_SS was set inappropriately\n");
+			nerrs++;
+		} else {
+			/*
+			 * DOSEMU transitions from 32-bit to 64-bit mode by
+			 * adjusting sigcontext, and it requires that this work
+			 * even if the saved SS is bogus.
+			 */
+			printf("\tCorrupting SS on return to 64-bit mode\n");
+			*ssptr(ctx) = 0;
+		}
+	}
+#endif
+
+	sig_trapped = sig;
+}
+
+#ifdef __x86_64__
+/* Tests recovery if !UC_STRICT_RESTORE_SS */
+static void sigusr2(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (!(ctx->uc_flags & UC_STRICT_RESTORE_SS)) {
+		printf("[FAIL]\traise(2) didn't set UC_STRICT_RESTORE_SS\n");
+		nerrs++;
+		return;  /* We can't do the rest. */
+	}
+
+	ctx->uc_flags &= ~UC_STRICT_RESTORE_SS;
+	*ssptr(ctx) = 0;
+
+	/* Return.  The kernel should recover without sending another signal. */
+}
+
+static int test_nonstrict_ss(void)
+{
+	clearhandler(SIGUSR1);
+	clearhandler(SIGTRAP);
+	clearhandler(SIGSEGV);
+	clearhandler(SIGILL);
+	sethandler(SIGUSR2, sigusr2, 0);
+
+	nerrs = 0;
+
+	printf("[RUN]\tClear UC_STRICT_RESTORE_SS and corrupt SS\n");
+	raise(SIGUSR2);
+	if (!nerrs)
+		printf("[OK]\tIt worked\n");
+
+	return nerrs;
+}
+#endif
+
+/* Finds a usable code segment of the requested bitness. */
+int find_cs(int bitness)
+{
+	unsigned short my_cs;
+
+	asm ("mov %%cs,%0" :  "=r" (my_cs));
+
+	if (cs_bitness(my_cs) == bitness)
+		return my_cs;
+	if (cs_bitness(my_cs + (2 << 3)) == bitness)
+		return my_cs + (2 << 3);
+	if (my_cs > (2<<3) && cs_bitness(my_cs - (2 << 3)) == bitness)
+	    return my_cs - (2 << 3);
+	if (cs_bitness(code16_sel) == bitness)
+		return code16_sel;
+
+	printf("[WARN]\tCould not find %d-bit CS\n", bitness);
+	return -1;
+}
+
+static int test_valid_sigreturn(int cs_bits, bool use_16bit_ss, int force_ss)
+{
+	int cs = find_cs(cs_bits);
+	if (cs == -1) {
+		printf("[SKIP]\tCode segment unavailable for %d-bit CS, %d-bit SS\n",
+		       cs_bits, use_16bit_ss ? 16 : 32);
+		return 0;
+	}
+
+	if (force_ss != -1) {
+		sig_ss = force_ss;
+	} else {
+		if (use_16bit_ss) {
+			if (!data16_sel) {
+				printf("[SKIP]\tData segment unavailable for %d-bit CS, 16-bit SS\n",
+				       cs_bits);
+				return 0;
+			}
+			sig_ss = data16_sel;
+		} else {
+			asm volatile ("mov %%ss,%0" : "=r" (sig_ss));
+		}
+	}
+
+	sig_cs = cs;
+
+	printf("[RUN]\tValid sigreturn: %d-bit CS (%hx), %d-bit SS (%hx%s)\n",
+	       cs_bits, sig_cs, use_16bit_ss ? 16 : 32, sig_ss,
+	       (sig_ss & 4) ? "" : ", GDT");
+
+	raise(SIGUSR1);
+
+	nerrs = 0;
+
+	/*
+	 * Check that each register had an acceptable value when the
+	 * int3 trampoline was invoked.
+	 */
+	for (int i = 0; i < NGREG; i++) {
+		greg_t req = requested_regs[i], res = resulting_regs[i];
+
+		if (i == REG_TRAPNO || i == REG_IP)
+			continue;	/* don't care */
+
+		if (i == REG_SP) {
+			/*
+			 * If we were using a 16-bit stack segment, then
+			 * the kernel is a bit stuck: IRET only restores
+			 * the low 16 bits of ESP/RSP if SS is 16-bit.
+			 * The kernel uses a hack to restore bits 31:16,
+			 * but that hack doesn't help with bits 63:32.
+			 * On Intel CPUs, bits 63:32 end up zeroed, and, on
+			 * AMD CPUs, they leak the high bits of the kernel
+			 * espfix64 stack pointer.  There's very little that
+			 * the kernel can do about it.
+			 *
+			 * Similarly, if we are returning to a 32-bit context,
+			 * the CPU will often lose the high 32 bits of RSP.
+			 */
+
+			if (res == req)
+				continue;
+
+			if (cs_bits != 64 && ((res ^ req) & 0xFFFFFFFF) == 0) {
+				printf("[NOTE]\tSP: %llx -> %llx\n",
+				       (unsigned long long)req,
+				       (unsigned long long)res);
+				continue;
+			}
+
+			printf("[FAIL]\tSP mismatch: requested 0x%llx; got 0x%llx\n",
+			       (unsigned long long)requested_regs[i],
+			       (unsigned long long)resulting_regs[i]);
+			nerrs++;
+			continue;
+		}
+
+		bool ignore_reg = false;
+#if __i386__
+		if (i == REG_UESP)
+			ignore_reg = true;
+#else
+		if (i == REG_CSGSFS) {
+			struct selectors *req_sels =
+				(void *)&requested_regs[REG_CSGSFS];
+			struct selectors *res_sels =
+				(void *)&resulting_regs[REG_CSGSFS];
+			if (req_sels->cs != res_sels->cs) {
+				printf("[FAIL]\tCS mismatch: requested 0x%hx; got 0x%hx\n",
+				       req_sels->cs, res_sels->cs);
+				nerrs++;
+			}
+
+			if (req_sels->ss != res_sels->ss) {
+				printf("[FAIL]\tSS mismatch: requested 0x%hx; got 0x%hx\n",
+				       req_sels->ss, res_sels->ss);
+				nerrs++;
+			}
+
+			continue;
+		}
+#endif
+
+		/* Sanity check on the kernel */
+		if (i == REG_CX && req != res) {
+			printf("[FAIL]\tCX (saved SP) mismatch: requested 0x%llx; got 0x%llx\n",
+			       (unsigned long long)req,
+			       (unsigned long long)res);
+			nerrs++;
+			continue;
+		}
+
+		if (req != res && !ignore_reg) {
+			printf("[FAIL]\tReg %d mismatch: requested 0x%llx; got 0x%llx\n",
+			       i, (unsigned long long)req,
+			       (unsigned long long)res);
+			nerrs++;
+		}
+	}
+
+	if (nerrs == 0)
+		printf("[OK]\tall registers okay\n");
+
+	return nerrs;
+}
+
+static int test_bad_iret(int cs_bits, unsigned short ss, int force_cs)
+{
+	int cs = force_cs == -1 ? find_cs(cs_bits) : force_cs;
+	if (cs == -1)
+		return 0;
+
+	sig_cs = cs;
+	sig_ss = ss;
+
+	printf("[RUN]\t%d-bit CS (%hx), bogus SS (%hx)\n",
+	       cs_bits, sig_cs, sig_ss);
+
+	sig_trapped = 0;
+	raise(SIGUSR1);
+	if (sig_trapped) {
+		char errdesc[32] = "";
+		if (sig_err) {
+			const char *src = (sig_err & 1) ? " EXT" : "";
+			const char *table;
+			if ((sig_err & 0x6) == 0x0)
+				table = "GDT";
+			else if ((sig_err & 0x6) == 0x4)
+				table = "LDT";
+			else if ((sig_err & 0x6) == 0x2)
+				table = "IDT";
+			else
+				table = "???";
+
+			sprintf(errdesc, "%s%s index %d, ",
+				table, src, sig_err >> 3);
+		}
+
+		char trapname[32];
+		if (sig_trapno == 13)
+			strcpy(trapname, "GP");
+		else if (sig_trapno == 11)
+			strcpy(trapname, "NP");
+		else if (sig_trapno == 12)
+			strcpy(trapname, "SS");
+		else if (sig_trapno == 32)
+			strcpy(trapname, "IRET");  /* X86_TRAP_IRET */
+		else
+			sprintf(trapname, "%d", sig_trapno);
+
+		printf("[OK]\tGot #%s(0x%lx) (i.e. %s%s)\n",
+		       trapname, (unsigned long)sig_err,
+		       errdesc, strsignal(sig_trapped));
+		return 0;
+	} else {
+		/*
+		 * This also implicitly tests UC_STRICT_RESTORE_SS:
+		 * We check that these signals set UC_STRICT_RESTORE_SS and,
+		 * if UC_STRICT_RESTORE_SS doesn't cause strict behavior,
+		 * then we won't get SIGSEGV.
+		 */
+		printf("[FAIL]\tDid not get SIGSEGV\n");
+		return 1;
+	}
+}
+
+int main()
+{
+	int total_nerrs = 0;
+	unsigned short my_cs, my_ss;
+
+	asm volatile ("mov %%cs,%0" : "=r" (my_cs));
+	asm volatile ("mov %%ss,%0" : "=r" (my_ss));
+	setup_ldt();
+
+	stack_t stack = {
+		.ss_sp = altstack_data,
+		.ss_size = SIGSTKSZ,
+	};
+	if (sigaltstack(&stack, NULL) != 0)
+		err(1, "sigaltstack");
+
+	sethandler(SIGUSR1, sigusr1, 0);
+	sethandler(SIGTRAP, sigtrap, SA_ONSTACK);
+
+	/* Easy cases: return to a 32-bit SS in each possible CS bitness. */
+	total_nerrs += test_valid_sigreturn(64, false, -1);
+	total_nerrs += test_valid_sigreturn(32, false, -1);
+	total_nerrs += test_valid_sigreturn(16, false, -1);
+
+	/*
+	 * Test easy espfix cases: return to a 16-bit LDT SS in each possible
+	 * CS bitness.  NB: with a long mode CS, the SS bitness is irrelevant.
+	 *
+	 * This catches the original missing-espfix-on-64-bit-kernels issue
+	 * as well as CVE-2014-8134.
+	 */
+	total_nerrs += test_valid_sigreturn(64, true, -1);
+	total_nerrs += test_valid_sigreturn(32, true, -1);
+	total_nerrs += test_valid_sigreturn(16, true, -1);
+
+	if (gdt_data16_idx) {
+		/*
+		 * For performance reasons, Linux skips espfix if SS points
+		 * to the GDT.  If we were able to allocate a 16-bit SS in
+		 * the GDT, see if it leaks parts of the kernel stack pointer.
+		 *
+		 * This tests for CVE-2014-8133.
+		 */
+		total_nerrs += test_valid_sigreturn(64, true,
+						    GDT3(gdt_data16_idx));
+		total_nerrs += test_valid_sigreturn(32, true,
+						    GDT3(gdt_data16_idx));
+		total_nerrs += test_valid_sigreturn(16, true,
+						    GDT3(gdt_data16_idx));
+	}
+
+#ifdef __x86_64__
+	/* Nasty ABI case: check SS corruption handling. */
+	sig_corrupt_final_ss = 1;
+	total_nerrs += test_valid_sigreturn(32, false, -1);
+	total_nerrs += test_valid_sigreturn(32, true, -1);
+	sig_corrupt_final_ss = 0;
+#endif
+
+	/*
+	 * We're done testing valid sigreturn cases.  Now we test states
+	 * for which sigreturn itself will succeed but the subsequent
+	 * entry to user mode will fail.
+	 *
+	 * Depending on the failure mode and the kernel bitness, these
+	 * entry failures can generate SIGSEGV, SIGBUS, or SIGILL.
+	 */
+	clearhandler(SIGTRAP);
+	sethandler(SIGSEGV, sigtrap, SA_ONSTACK);
+	sethandler(SIGBUS, sigtrap, SA_ONSTACK);
+	sethandler(SIGILL, sigtrap, SA_ONSTACK);  /* 32-bit kernels do this */
+
+	/* Easy failures: invalid SS, resulting in #GP(0) */
+	test_bad_iret(64, ldt_nonexistent_sel, -1);
+	test_bad_iret(32, ldt_nonexistent_sel, -1);
+	test_bad_iret(16, ldt_nonexistent_sel, -1);
+
+	/* These fail because SS isn't a data segment, resulting in #GP(SS) */
+	test_bad_iret(64, my_cs, -1);
+	test_bad_iret(32, my_cs, -1);
+	test_bad_iret(16, my_cs, -1);
+
+	/* Try to return to a not-present code segment, triggering #NP(SS). */
+	test_bad_iret(32, my_ss, npcode32_sel);
+
+	/*
+	 * Try to return to a not-present but otherwise valid data segment.
+	 * This will cause IRET to fail with #SS on the espfix stack.  This
+	 * exercises CVE-2014-9322.
+	 *
+	 * Note that, if espfix is enabled, 64-bit Linux will lose track
+	 * of the actual cause of failure and report #GP(0) instead.
+	 * This would be very difficult for Linux to avoid, because
+	 * espfix64 causes IRET failures to be promoted to #DF, so the
+	 * original exception frame is never pushed onto the stack.
+	 */
+	test_bad_iret(32, npdata32_sel, -1);
+
+	/*
+	 * Try to return to a not-present but otherwise valid data
+	 * segment without invoking espfix.  Newer kernels don't allow
+	 * this to happen in the first place.  On older kernels, though,
+	 * this can trigger CVE-2014-9322.
+	 */
+	if (gdt_npdata32_idx)
+		test_bad_iret(32, GDT3(gdt_npdata32_idx), -1);
+
+#ifdef __x86_64__
+	total_nerrs += test_nonstrict_ss();
+#endif
+
+	return total_nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/single_step_syscall.c b/tools/testing/selftests/x86/single_step_syscall.c
new file mode 100644
index 000000000..ddfdd635d
--- /dev/null
+++ b/tools/testing/selftests/x86/single_step_syscall.c
@@ -0,0 +1,187 @@
+/*
+ * single_step_syscall.c - single-steps various x86 syscalls
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * This is a very simple series of tests that makes system calls with
+ * the TF flag set.  This exercises some nasty kernel code in the
+ * SYSENTER case: SYSENTER does not clear TF, so SYSENTER with TF set
+ * immediately issues #DB from CPL 0.  This requires special handling in
+ * the kernel.
+ */
+
+#define _GNU_SOURCE
+
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+#include <sys/signal.h>
+#include <sys/ucontext.h>
+#include <asm/ldt.h>
+#include <err.h>
+#include <setjmp.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <sys/ptrace.h>
+#include <sys/user.h>
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static volatile sig_atomic_t sig_traps;
+
+#ifdef __x86_64__
+# define REG_IP REG_RIP
+# define WIDTH "q"
+# define INT80_CLOBBERS "r8", "r9", "r10", "r11"
+#else
+# define REG_IP REG_EIP
+# define WIDTH "l"
+# define INT80_CLOBBERS
+#endif
+
+static unsigned long get_eflags(void)
+{
+	unsigned long eflags;
+	asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags));
+	return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+	asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH
+		      : : "rm" (eflags) : "flags");
+}
+
+#define X86_EFLAGS_TF (1UL << 8)
+
+static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (get_eflags() & X86_EFLAGS_TF) {
+		set_eflags(get_eflags() & ~X86_EFLAGS_TF);
+		printf("[WARN]\tSIGTRAP handler had TF set\n");
+		_exit(1);
+	}
+
+	sig_traps++;
+
+	if (sig_traps == 10000 || sig_traps == 10001) {
+		printf("[WARN]\tHit %d SIGTRAPs with si_addr 0x%lx, ip 0x%lx\n",
+		       (int)sig_traps,
+		       (unsigned long)info->si_addr,
+		       (unsigned long)ctx->uc_mcontext.gregs[REG_IP]);
+	}
+}
+
+static void check_result(void)
+{
+	unsigned long new_eflags = get_eflags();
+	set_eflags(new_eflags & ~X86_EFLAGS_TF);
+
+	if (!sig_traps) {
+		printf("[FAIL]\tNo SIGTRAP\n");
+		exit(1);
+	}
+
+	if (!(new_eflags & X86_EFLAGS_TF)) {
+		printf("[FAIL]\tTF was cleared\n");
+		exit(1);
+	}
+
+	printf("[OK]\tSurvived with TF set and %d traps\n", (int)sig_traps);
+	sig_traps = 0;
+}
+
+int main()
+{
+#ifdef CAN_BUILD_32
+	int tmp;
+#endif
+
+	sethandler(SIGTRAP, sigtrap, 0);
+
+	printf("[RUN]\tSet TF and check nop\n");
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	asm volatile ("nop");
+	check_result();
+
+#ifdef __x86_64__
+	printf("[RUN]\tSet TF and check syscall-less opportunistic sysret\n");
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	extern unsigned char post_nop[];
+	asm volatile ("pushf" WIDTH "\n\t"
+		      "pop" WIDTH " %%r11\n\t"
+		      "nop\n\t"
+		      "post_nop:"
+		      : : "c" (post_nop) : "r11");
+	check_result();
+#endif
+#ifdef CAN_BUILD_32
+	printf("[RUN]\tSet TF and check int80\n");
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	asm volatile ("int $0x80" : "=a" (tmp) : "a" (SYS_getpid)
+			: INT80_CLOBBERS);
+	check_result();
+#endif
+
+	/*
+	 * This test is particularly interesting if fast syscalls use
+	 * SYSENTER: it triggers a nasty design flaw in SYSENTER.
+	 * Specifically, SYSENTER does not clear TF, so either SYSENTER
+	 * or the next instruction traps at CPL0.  (Of course, Intel
+	 * mostly forgot to document exactly what happens here.)  So we
+	 * get a CPL0 fault with usergs (on 64-bit kernels) and possibly
+	 * no stack.  The only sane way the kernel can possibly handle
+	 * it is to clear TF on return from the #DB handler, but this
+	 * happens way too early to set TF in the saved pt_regs, so the
+	 * kernel has to do something clever to avoid losing track of
+	 * the TF bit.
+	 *
+	 * Needless to say, we've had bugs in this area.
+	 */
+	syscall(SYS_getpid);  /* Force symbol binding without TF set. */
+	printf("[RUN]\tSet TF and check a fast syscall\n");
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	syscall(SYS_getpid);
+	check_result();
+
+	/* Now make sure that another fast syscall doesn't set TF again. */
+	printf("[RUN]\tFast syscall with TF cleared\n");
+	fflush(stdout);  /* Force a syscall */
+	if (get_eflags() & X86_EFLAGS_TF) {
+		printf("[FAIL]\tTF is now set\n");
+		exit(1);
+	}
+	if (sig_traps) {
+		printf("[FAIL]\tGot SIGTRAP\n");
+		exit(1);
+	}
+	printf("[OK]\tNothing unexpected happened\n");
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/syscall_arg_fault.c b/tools/testing/selftests/x86/syscall_arg_fault.c
new file mode 100644
index 000000000..7db4fc9fa
--- /dev/null
+++ b/tools/testing/selftests/x86/syscall_arg_fault.c
@@ -0,0 +1,130 @@
+/*
+ * syscall_arg_fault.c - tests faults 32-bit fast syscall stack args
+ * Copyright (c) 2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/signal.h>
+#include <sys/ucontext.h>
+#include <err.h>
+#include <setjmp.h>
+#include <errno.h>
+
+/* Our sigaltstack scratch space. */
+static unsigned char altstack_data[SIGSTKSZ];
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static volatile sig_atomic_t sig_traps;
+static sigjmp_buf jmpbuf;
+
+static volatile sig_atomic_t n_errs;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (ctx->uc_mcontext.gregs[REG_EAX] != -EFAULT) {
+		printf("[FAIL]\tAX had the wrong value: 0x%x\n",
+		       ctx->uc_mcontext.gregs[REG_EAX]);
+		n_errs++;
+	} else {
+		printf("[OK]\tSeems okay\n");
+	}
+
+	siglongjmp(jmpbuf, 1);
+}
+
+static void sigill(int sig, siginfo_t *info, void *ctx_void)
+{
+	printf("[SKIP]\tIllegal instruction\n");
+	siglongjmp(jmpbuf, 1);
+}
+
+int main()
+{
+	stack_t stack = {
+		.ss_sp = altstack_data,
+		.ss_size = SIGSTKSZ,
+	};
+	if (sigaltstack(&stack, NULL) != 0)
+		err(1, "sigaltstack");
+
+	sethandler(SIGSEGV, sigsegv, SA_ONSTACK);
+	sethandler(SIGILL, sigill, SA_ONSTACK);
+
+	/*
+	 * Exercise another nasty special case.  The 32-bit SYSCALL
+	 * and SYSENTER instructions (even in compat mode) each
+	 * clobber one register.  A Linux system call has a syscall
+	 * number and six arguments, and the user stack pointer
+	 * needs to live in some register on return.  That means
+	 * that we need eight registers, but SYSCALL and SYSENTER
+	 * only preserve seven registers.  As a result, one argument
+	 * ends up on the stack.  The stack is user memory, which
+	 * means that the kernel can fail to read it.
+	 *
+	 * The 32-bit fast system calls don't have a defined ABI:
+	 * we're supposed to invoke them through the vDSO.  So we'll
+	 * fudge it: we set all regs to invalid pointer values and
+	 * invoke the entry instruction.  The return will fail no
+	 * matter what, and we completely lose our program state,
+	 * but we can fix it up with a signal handler.
+	 */
+
+	printf("[RUN]\tSYSENTER with invalid state\n");
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		asm volatile (
+			"movl $-1, %%eax\n\t"
+			"movl $-1, %%ebx\n\t"
+			"movl $-1, %%ecx\n\t"
+			"movl $-1, %%edx\n\t"
+			"movl $-1, %%esi\n\t"
+			"movl $-1, %%edi\n\t"
+			"movl $-1, %%ebp\n\t"
+			"movl $-1, %%esp\n\t"
+			"sysenter"
+			: : : "memory", "flags");
+	}
+
+	printf("[RUN]\tSYSCALL with invalid state\n");
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		asm volatile (
+			"movl $-1, %%eax\n\t"
+			"movl $-1, %%ebx\n\t"
+			"movl $-1, %%ecx\n\t"
+			"movl $-1, %%edx\n\t"
+			"movl $-1, %%esi\n\t"
+			"movl $-1, %%edi\n\t"
+			"movl $-1, %%ebp\n\t"
+			"movl $-1, %%esp\n\t"
+			"syscall\n\t"
+			"pushl $0"	/* make sure we segfault cleanly */
+			: : : "memory", "flags");
+	}
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/syscall_nt.c b/tools/testing/selftests/x86/syscall_nt.c
new file mode 100644
index 000000000..74e6b3fc2
--- /dev/null
+++ b/tools/testing/selftests/x86/syscall_nt.c
@@ -0,0 +1,96 @@
+/*
+ * syscall_nt.c - checks syscalls with NT set
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * Some obscure user-space code requires the ability to make system calls
+ * with FLAGS.NT set.  Make sure it works.
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <signal.h>
+#include <err.h>
+#include <sys/syscall.h>
+#include <asm/processor-flags.h>
+
+#ifdef __x86_64__
+# define WIDTH "q"
+#else
+# define WIDTH "l"
+#endif
+
+static unsigned int nerrs;
+
+static unsigned long get_eflags(void)
+{
+	unsigned long eflags;
+	asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags));
+	return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+	asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH
+		      : : "rm" (eflags) : "flags");
+}
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void sigtrap(int sig, siginfo_t *si, void *ctx_void)
+{
+}
+
+static void do_it(unsigned long extraflags)
+{
+	unsigned long flags;
+
+	set_eflags(get_eflags() | extraflags);
+	syscall(SYS_getpid);
+	flags = get_eflags();
+	set_eflags(X86_EFLAGS_IF | X86_EFLAGS_FIXED);
+	if ((flags & extraflags) == extraflags) {
+		printf("[OK]\tThe syscall worked and flags are still set\n");
+	} else {
+		printf("[FAIL]\tThe syscall worked but flags were cleared (flags = 0x%lx but expected 0x%lx set)\n",
+		       flags, extraflags);
+		nerrs++;
+	}
+}
+
+int main(void)
+{
+	printf("[RUN]\tSet NT and issue a syscall\n");
+	do_it(X86_EFLAGS_NT);
+
+	/*
+	 * Now try it again with TF set -- TF forces returns via IRET in all
+	 * cases except non-ptregs-using 64-bit full fast path syscalls.
+	 */
+
+	sethandler(SIGTRAP, sigtrap, 0);
+
+	printf("[RUN]\tSet NT|TF and issue a syscall\n");
+	do_it(X86_EFLAGS_NT | X86_EFLAGS_TF);
+
+	return nerrs == 0 ? 0 : 1;
+}
diff --git a/tools/testing/selftests/x86/sysret_rip.c b/tools/testing/selftests/x86/sysret_rip.c
new file mode 100644
index 000000000..d85ec5b36
--- /dev/null
+++ b/tools/testing/selftests/x86/sysret_rip.c
@@ -0,0 +1,195 @@
+/*
+ * sigreturn.c - tests that x86 avoids Intel SYSRET pitfalls
+ * Copyright (c) 2014-2016 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/signal.h>
+#include <sys/ucontext.h>
+#include <sys/syscall.h>
+#include <err.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <setjmp.h>
+#include <sys/user.h>
+#include <sys/mman.h>
+#include <assert.h>
+
+
+asm (
+	".pushsection \".text\", \"ax\"\n\t"
+	".balign 4096\n\t"
+	"test_page: .globl test_page\n\t"
+	".fill 4094,1,0xcc\n\t"
+	"test_syscall_insn:\n\t"
+	"syscall\n\t"
+	".ifne . - test_page - 4096\n\t"
+	".error \"test page is not one page long\"\n\t"
+	".endif\n\t"
+	".popsection"
+    );
+
+extern const char test_page[];
+static void const *current_test_page_addr = test_page;
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+static void clearhandler(int sig)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_handler = SIG_DFL;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+/* State used by our signal handlers. */
+static gregset_t initial_regs;
+
+static volatile unsigned long rip;
+
+static void sigsegv_for_sigreturn_test(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (rip != ctx->uc_mcontext.gregs[REG_RIP]) {
+		printf("[FAIL]\tRequested RIP=0x%lx but got RIP=0x%lx\n",
+		       rip, (unsigned long)ctx->uc_mcontext.gregs[REG_RIP]);
+		fflush(stdout);
+		_exit(1);
+	}
+
+	memcpy(&ctx->uc_mcontext.gregs, &initial_regs, sizeof(gregset_t));
+
+	printf("[OK]\tGot SIGSEGV at RIP=0x%lx\n", rip);
+}
+
+static void sigusr1(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	memcpy(&initial_regs, &ctx->uc_mcontext.gregs, sizeof(gregset_t));
+
+	/* Set IP and CX to match so that SYSRET can happen. */
+	ctx->uc_mcontext.gregs[REG_RIP] = rip;
+	ctx->uc_mcontext.gregs[REG_RCX] = rip;
+
+	/* R11 and EFLAGS should already match. */
+	assert(ctx->uc_mcontext.gregs[REG_EFL] ==
+	       ctx->uc_mcontext.gregs[REG_R11]);
+
+	sethandler(SIGSEGV, sigsegv_for_sigreturn_test, SA_RESETHAND);
+
+	return;
+}
+
+static void test_sigreturn_to(unsigned long ip)
+{
+	rip = ip;
+	printf("[RUN]\tsigreturn to 0x%lx\n", ip);
+	raise(SIGUSR1);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv_for_fallthrough(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t*)ctx_void;
+
+	if (rip != ctx->uc_mcontext.gregs[REG_RIP]) {
+		printf("[FAIL]\tExpected SIGSEGV at 0x%lx but got RIP=0x%lx\n",
+		       rip, (unsigned long)ctx->uc_mcontext.gregs[REG_RIP]);
+		fflush(stdout);
+		_exit(1);
+	}
+
+	siglongjmp(jmpbuf, 1);
+}
+
+static void test_syscall_fallthrough_to(unsigned long ip)
+{
+	void *new_address = (void *)(ip - 4096);
+	void *ret;
+
+	printf("[RUN]\tTrying a SYSCALL that falls through to 0x%lx\n", ip);
+
+	ret = mremap((void *)current_test_page_addr, 4096, 4096,
+		     MREMAP_MAYMOVE | MREMAP_FIXED, new_address);
+	if (ret == MAP_FAILED) {
+		if (ip <= (1UL << 47) - PAGE_SIZE) {
+			err(1, "mremap to %p", new_address);
+		} else {
+			printf("[OK]\tmremap to %p failed\n", new_address);
+			return;
+		}
+	}
+
+	if (ret != new_address)
+		errx(1, "mremap malfunctioned: asked for %p but got %p\n",
+		     new_address, ret);
+
+	current_test_page_addr = new_address;
+	rip = ip;
+
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		asm volatile ("call *%[syscall_insn]" :: "a" (SYS_getpid),
+			      [syscall_insn] "rm" (ip - 2));
+		errx(1, "[FAIL]\tSyscall trampoline returned");
+	}
+
+	printf("[OK]\tWe survived\n");
+}
+
+int main()
+{
+	/*
+	 * When the kernel returns from a slow-path syscall, it will
+	 * detect whether SYSRET is appropriate.  If it incorrectly
+	 * thinks that SYSRET is appropriate when RIP is noncanonical,
+	 * it'll crash on Intel CPUs.
+	 */
+	sethandler(SIGUSR1, sigusr1, 0);
+	for (int i = 47; i < 64; i++)
+		test_sigreturn_to(1UL<<i);
+
+	clearhandler(SIGUSR1);
+
+	sethandler(SIGSEGV, sigsegv_for_fallthrough, 0);
+
+	/* One extra test to check that we didn't screw up the mremap logic. */
+	test_syscall_fallthrough_to((1UL << 47) - 2*PAGE_SIZE);
+
+	/* These are the interesting cases. */
+	for (int i = 47; i < 64; i++) {
+		test_syscall_fallthrough_to((1UL<<i) - PAGE_SIZE);
+		test_syscall_fallthrough_to(1UL<<i);
+	}
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/sysret_ss_attrs.c b/tools/testing/selftests/x86/sysret_ss_attrs.c
new file mode 100644
index 000000000..ce42d5a64
--- /dev/null
+++ b/tools/testing/selftests/x86/sysret_ss_attrs.c
@@ -0,0 +1,112 @@
+/*
+ * sysret_ss_attrs.c - test that syscalls return valid hidden SS attributes
+ * Copyright (c) 2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * On AMD CPUs, SYSRET can return with a valid SS descriptor with with
+ * the hidden attributes set to an unusable state.  Make sure the kernel
+ * doesn't let this happen.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <err.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <pthread.h>
+
+static void *threadproc(void *ctx)
+{
+	/*
+	 * Do our best to cause sleeps on this CPU to exit the kernel and
+	 * re-enter with SS = 0.
+	 */
+	while (true)
+		;
+
+	return NULL;
+}
+
+#ifdef __x86_64__
+extern unsigned long call32_from_64(void *stack, void (*function)(void));
+
+asm (".pushsection .text\n\t"
+     ".code32\n\t"
+     "test_ss:\n\t"
+     "pushl $0\n\t"
+     "popl %eax\n\t"
+     "ret\n\t"
+     ".code64");
+extern void test_ss(void);
+#endif
+
+int main()
+{
+	/*
+	 * Start a busy-looping thread on the same CPU we're on.
+	 * For simplicity, just stick everything to CPU 0.  This will
+	 * fail in some containers, but that's probably okay.
+	 */
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(0, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+		printf("[WARN]\tsched_setaffinity failed\n");
+
+	pthread_t thread;
+	if (pthread_create(&thread, 0, threadproc, 0) != 0)
+		err(1, "pthread_create");
+
+#ifdef __x86_64__
+	unsigned char *stack32 = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
+				      MAP_32BIT | MAP_ANONYMOUS | MAP_PRIVATE,
+				      -1, 0);
+	if (stack32 == MAP_FAILED)
+		err(1, "mmap");
+#endif
+
+	printf("[RUN]\tSyscalls followed by SS validation\n");
+
+	for (int i = 0; i < 1000; i++) {
+		/*
+		 * Go to sleep and return using sysret (if we're 64-bit
+		 * or we're 32-bit on AMD on a 64-bit kernel).  On AMD CPUs,
+		 * SYSRET doesn't fix up the cached SS descriptor, so the
+		 * kernel needs some kind of workaround to make sure that we
+		 * end the system call with a valid stack segment.  This
+		 * can be a confusing failure because the SS *selector*
+		 * is the same regardless.
+		 */
+		usleep(2);
+
+#ifdef __x86_64__
+		/*
+		 * On 32-bit, just doing a syscall through glibc is enough
+		 * to cause a crash if our cached SS descriptor is invalid.
+		 * On 64-bit, it's not, so try extra hard.
+		 */
+		call32_from_64(stack32 + 4088, test_ss);
+#endif
+	}
+
+	printf("[OK]\tWe survived\n");
+
+#ifdef __x86_64__
+	munmap(stack32, 4096);
+#endif
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/test_FCMOV.c b/tools/testing/selftests/x86/test_FCMOV.c
new file mode 100644
index 000000000..6b5036fbb
--- /dev/null
+++ b/tools/testing/selftests/x86/test_FCMOV.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+#undef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#undef __USE_GNU
+#define __USE_GNU 1
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+
+#define TEST(insn) \
+long double __attribute__((noinline)) insn(long flags) \
+{						\
+	long double out;			\
+	asm ("\n"				\
+	"	push	%1""\n"			\
+	"	popf""\n"			\
+	"	fldpi""\n"			\
+	"	fld1""\n"			\
+	"	" #insn " %%st(1), %%st" "\n"	\
+	"	ffree	%%st(1)" "\n"		\
+	: "=t" (out)				\
+	: "r" (flags)				\
+	);					\
+	return out;				\
+}
+
+TEST(fcmovb)
+TEST(fcmove)
+TEST(fcmovbe)
+TEST(fcmovu)
+TEST(fcmovnb)
+TEST(fcmovne)
+TEST(fcmovnbe)
+TEST(fcmovnu)
+
+enum {
+	CF = 1 << 0,
+	PF = 1 << 2,
+	ZF = 1 << 6,
+};
+
+void sighandler(int sig)
+{
+	printf("[FAIL]\tGot signal %d, exiting\n", sig);
+	exit(1);
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	int err = 0;
+
+	/* SIGILL triggers on 32-bit kernels w/o fcomi emulation
+	 * when run with "no387 nofxsr". Other signals are caught
+	 * just in case.
+	 */
+	signal(SIGILL, sighandler);
+	signal(SIGFPE, sighandler);
+	signal(SIGSEGV, sighandler);
+
+	printf("[RUN]\tTesting fcmovCC instructions\n");
+	/* If fcmovCC() returns 1.0, the move wasn't done */
+	err |= !(fcmovb(0)   == 1.0); err |= !(fcmovnb(0)  != 1.0);
+	err |= !(fcmove(0)   == 1.0); err |= !(fcmovne(0)  != 1.0);
+	err |= !(fcmovbe(0)  == 1.0); err |= !(fcmovnbe(0) != 1.0);
+	err |= !(fcmovu(0)   == 1.0); err |= !(fcmovnu(0)  != 1.0);
+
+	err |= !(fcmovb(CF)  != 1.0); err |= !(fcmovnb(CF)  == 1.0);
+	err |= !(fcmove(CF)  == 1.0); err |= !(fcmovne(CF)  != 1.0);
+	err |= !(fcmovbe(CF) != 1.0); err |= !(fcmovnbe(CF) == 1.0);
+	err |= !(fcmovu(CF)  == 1.0); err |= !(fcmovnu(CF)  != 1.0);
+
+	err |= !(fcmovb(ZF)  == 1.0); err |= !(fcmovnb(ZF)  != 1.0);
+	err |= !(fcmove(ZF)  != 1.0); err |= !(fcmovne(ZF)  == 1.0);
+	err |= !(fcmovbe(ZF) != 1.0); err |= !(fcmovnbe(ZF) == 1.0);
+	err |= !(fcmovu(ZF)  == 1.0); err |= !(fcmovnu(ZF)  != 1.0);
+
+	err |= !(fcmovb(PF)  == 1.0); err |= !(fcmovnb(PF)  != 1.0);
+	err |= !(fcmove(PF)  == 1.0); err |= !(fcmovne(PF)  != 1.0);
+	err |= !(fcmovbe(PF) == 1.0); err |= !(fcmovnbe(PF) != 1.0);
+	err |= !(fcmovu(PF)  != 1.0); err |= !(fcmovnu(PF)  == 1.0);
+
+        if (!err)
+                printf("[OK]\tfcmovCC\n");
+	else
+		printf("[FAIL]\tfcmovCC errors: %d\n", err);
+
+	return err;
+}
diff --git a/tools/testing/selftests/x86/test_FCOMI.c b/tools/testing/selftests/x86/test_FCOMI.c
new file mode 100644
index 000000000..aec6692c6
--- /dev/null
+++ b/tools/testing/selftests/x86/test_FCOMI.c
@@ -0,0 +1,332 @@
+// SPDX-License-Identifier: GPL-2.0
+#undef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#undef __USE_GNU
+#define __USE_GNU 1
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <fenv.h>
+
+enum {
+	CF = 1 << 0,
+	PF = 1 << 2,
+	ZF = 1 << 6,
+	ARITH = CF | PF | ZF,
+};
+
+long res_fcomi_pi_1;
+long res_fcomi_1_pi;
+long res_fcomi_1_1;
+long res_fcomi_nan_1;
+/* sNaN is s|111 1111 1|1xx xxxx xxxx xxxx xxxx xxxx */
+/* qNaN is s|111 1111 1|0xx xxxx xxxx xxxx xxxx xxxx (some x must be nonzero) */
+int snan = 0x7fc11111;
+int qnan = 0x7f811111;
+unsigned short snan1[5];
+/* sNaN80 is s|111 1111 1111 1111 |10xx xx...xx (some x must be nonzero) */
+unsigned short snan80[5] = { 0x1111, 0x1111, 0x1111, 0x8111, 0x7fff };
+
+int test(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fld1""\n"
+	"	fldpi""\n"
+	"	fcomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_1_pi""\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fldpi""\n"
+	"	fld1""\n"
+	"	fcomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_pi_1""\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fld1""\n"
+	"	fld1""\n"
+	"	fcomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_1_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_1_pi & ARITH) != (0)) {
+		printf("[BAD]\tfcomi_1_pi with flags:%lx\n", flags);
+		return 1;
+	}
+	if ((res_fcomi_pi_1 & ARITH) != (CF)) {
+		printf("[BAD]\tfcomi_pi_1 with flags:%lx->%lx\n", flags, res_fcomi_pi_1 & ARITH);
+		return 1;
+	}
+	if ((res_fcomi_1_1 & ARITH) != (ZF)) {
+		printf("[BAD]\tfcomi_1_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != 0) {
+		printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int test_qnan(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+	"	push	%0""\n"
+	"	popf""\n"
+	"	flds	qnan""\n"
+	"	fld1""\n"
+	"	fnclex""\n"		// fld of a qnan raised FE_INVALID, clear it
+	"	fcomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_nan_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
+		printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != FE_INVALID) {
+		printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int testu_qnan(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+	"	push	%0""\n"
+	"	popf""\n"
+	"	flds	qnan""\n"
+	"	fld1""\n"
+	"	fnclex""\n"		// fld of a qnan raised FE_INVALID, clear it
+	"	fucomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_nan_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
+		printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != 0) {
+		printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int testu_snan(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+	"	push	%0""\n"
+	"	popf""\n"
+//	"	flds	snan""\n"	// WRONG, this will convert 32-bit fp snan to a *qnan* in 80-bit fp register!
+//	"	fstpt	snan1""\n"	// if uncommented, it prints "snan1:7fff c111 1100 0000 0000" - c111, not 8111!
+//	"	fnclex""\n"		// flds of a snan raised FE_INVALID, clear it
+	"	fldt	snan80""\n"	// fldt never raise FE_INVALID
+	"	fld1""\n"
+	"	fucomi	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	ffree	%%st(1)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_nan_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
+		printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
+		return 1;
+	}
+//	printf("snan:%x snan1:%04x %04x %04x %04x %04x\n", snan, snan1[4], snan1[3], snan1[2], snan1[1], snan1[0]);
+	if (fetestexcept(FE_INVALID) != FE_INVALID) {
+		printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int testp(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fld1""\n"
+	"	fldpi""\n"
+	"	fcomip	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_1_pi""\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fldpi""\n"
+	"	fld1""\n"
+	"	fcomip	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_pi_1""\n"
+
+	"	push	%0""\n"
+	"	popf""\n"
+	"	fld1""\n"
+	"	fld1""\n"
+	"	fcomip	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_1_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_1_pi & ARITH) != (0)) {
+		printf("[BAD]\tfcomi_1_pi with flags:%lx\n", flags);
+		return 1;
+	}
+	if ((res_fcomi_pi_1 & ARITH) != (CF)) {
+		printf("[BAD]\tfcomi_pi_1 with flags:%lx->%lx\n", flags, res_fcomi_pi_1 & ARITH);
+		return 1;
+	}
+	if ((res_fcomi_1_1 & ARITH) != (ZF)) {
+		printf("[BAD]\tfcomi_1_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != 0) {
+		printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int testp_qnan(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+	"	push	%0""\n"
+	"	popf""\n"
+	"	flds	qnan""\n"
+	"	fld1""\n"
+	"	fnclex""\n"		// fld of a qnan raised FE_INVALID, clear it
+	"	fcomip	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_nan_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
+		printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != FE_INVALID) {
+		printf("[BAD]\tFE_INVALID is not set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+int testup_qnan(long flags)
+{
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+
+	asm ("\n"
+	"	push	%0""\n"
+	"	popf""\n"
+	"	flds	qnan""\n"
+	"	fld1""\n"
+	"	fnclex""\n"		// fld of a qnan raised FE_INVALID, clear it
+	"	fucomip	%%st(1), %%st" "\n"
+	"	ffree	%%st(0)" "\n"
+	"	pushf""\n"
+	"	pop	res_fcomi_nan_1""\n"
+	:
+	: "r" (flags)
+	);
+	if ((res_fcomi_nan_1 & ARITH) != (ZF|CF|PF)) {
+		printf("[BAD]\tfcomi_qnan_1 with flags:%lx\n", flags);
+		return 1;
+	}
+	if (fetestexcept(FE_INVALID) != 0) {
+		printf("[BAD]\tFE_INVALID is set in %s\n", __func__);
+		return 1;
+	}
+	return 0;
+}
+
+void sighandler(int sig)
+{
+	printf("[FAIL]\tGot signal %d, exiting\n", sig);
+	exit(1);
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	int err = 0;
+
+	/* SIGILL triggers on 32-bit kernels w/o fcomi emulation
+	 * when run with "no387 nofxsr". Other signals are caught
+	 * just in case.
+	 */
+	signal(SIGILL, sighandler);
+	signal(SIGFPE, sighandler);
+	signal(SIGSEGV, sighandler);
+
+	printf("[RUN]\tTesting f[u]comi[p] instructions\n");
+	err |= test(0);
+	err |= test_qnan(0);
+	err |= testu_qnan(0);
+	err |= testu_snan(0);
+	err |= test(CF|ZF|PF);
+	err |= test_qnan(CF|ZF|PF);
+	err |= testu_qnan(CF|ZF|PF);
+	err |= testu_snan(CF|ZF|PF);
+	err |= testp(0);
+	err |= testp_qnan(0);
+	err |= testup_qnan(0);
+	err |= testp(CF|ZF|PF);
+	err |= testp_qnan(CF|ZF|PF);
+	err |= testup_qnan(CF|ZF|PF);
+	if (!err)
+		printf("[OK]\tf[u]comi[p]\n");
+	else
+		printf("[FAIL]\tf[u]comi[p] errors: %d\n", err);
+
+	return err;
+}
diff --git a/tools/testing/selftests/x86/test_FISTTP.c b/tools/testing/selftests/x86/test_FISTTP.c
new file mode 100644
index 000000000..09789c0ce
--- /dev/null
+++ b/tools/testing/selftests/x86/test_FISTTP.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+#undef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#undef __USE_GNU
+#define __USE_GNU 1
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <fenv.h>
+
+unsigned long long res64 = -1;
+unsigned int res32 = -1;
+unsigned short res16 = -1;
+
+int test(void)
+{
+	int ex;
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fld1""\n"
+	"	fisttp	res16""\n"
+	"	fld1""\n"
+	"	fisttpl	res32""\n"
+	"	fld1""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 1 || res32 != 1 || res64 != 1) {
+		printf("[BAD]\tfisttp 1\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != 0) {
+		printf("[BAD]\tfisttp 1: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldpi""\n"
+	"	fisttp	res16""\n"
+	"	fldpi""\n"
+	"	fisttpl	res32""\n"
+	"	fldpi""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 3 || res32 != 3 || res64 != 3) {
+		printf("[BAD]\tfisttp pi\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp pi: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttp	res16""\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttpl	res32""\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 0xfffd || res32 != 0xfffffffd || res64 != 0xfffffffffffffffdULL) {
+		printf("[BAD]\tfisttp -pi\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp -pi: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldln2""\n"
+	"	fisttp	res16""\n"
+	"	fldln2""\n"
+	"	fisttpl	res32""\n"
+	"	fldln2""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	/* Test truncation to zero (round-to-nearest would give 1 here) */
+	if (res16 != 0 || res32 != 0 || res64 != 0) {
+		printf("[BAD]\tfisttp ln2\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp ln2: wrong exception state\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+void sighandler(int sig)
+{
+	printf("[FAIL]\tGot signal %d, exiting\n", sig);
+	exit(1);
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	int err = 0;
+
+	/* SIGILL triggers on 32-bit kernels w/o fisttp emulation
+	 * when run with "no387 nofxsr". Other signals are caught
+	 * just in case.
+	 */
+	signal(SIGILL, sighandler);
+	signal(SIGFPE, sighandler);
+	signal(SIGSEGV, sighandler);
+
+	printf("[RUN]\tTesting fisttp instructions\n");
+	err |= test();
+	if (!err)
+		printf("[OK]\tfisttp\n");
+	else
+		printf("[FAIL]\tfisttp errors: %d\n", err);
+
+	return err;
+}
diff --git a/tools/testing/selftests/x86/test_mremap_vdso.c b/tools/testing/selftests/x86/test_mremap_vdso.c
new file mode 100644
index 000000000..64f11c8d9
--- /dev/null
+++ b/tools/testing/selftests/x86/test_mremap_vdso.c
@@ -0,0 +1,115 @@
+/*
+ * 32-bit test to check vDSO mremap.
+ *
+ * Copyright (c) 2016 Dmitry Safonov
+ * Suggested-by: Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+/*
+ * Can be built statically:
+ * gcc -Os -Wall -static -m32 test_mremap_vdso.c
+ */
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <errno.h>
+#include <unistd.h>
+#include <string.h>
+
+#include <sys/mman.h>
+#include <sys/auxv.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+
+#define PAGE_SIZE	4096
+
+static int try_to_remap(void *vdso_addr, unsigned long size)
+{
+	void *dest_addr, *new_addr;
+
+	/* Searching for memory location where to remap */
+	dest_addr = mmap(0, size, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+	if (dest_addr == MAP_FAILED) {
+		printf("[WARN]\tmmap failed (%d): %m\n", errno);
+		return 0;
+	}
+
+	printf("[NOTE]\tMoving vDSO: [%p, %#lx] -> [%p, %#lx]\n",
+		vdso_addr, (unsigned long)vdso_addr + size,
+		dest_addr, (unsigned long)dest_addr + size);
+	fflush(stdout);
+
+	new_addr = mremap(vdso_addr, size, size,
+			MREMAP_FIXED|MREMAP_MAYMOVE, dest_addr);
+	if ((unsigned long)new_addr == (unsigned long)-1) {
+		munmap(dest_addr, size);
+		if (errno == EINVAL) {
+			printf("[NOTE]\tvDSO partial move failed, will try with bigger size\n");
+			return -1; /* Retry with larger */
+		}
+		printf("[FAIL]\tmremap failed (%d): %m\n", errno);
+		return 1;
+	}
+
+	return 0;
+
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	pid_t child;
+
+	child = fork();
+	if (child == -1) {
+		printf("[WARN]\tfailed to fork (%d): %m\n", errno);
+		return 1;
+	}
+
+	if (child == 0) {
+		unsigned long vdso_size = PAGE_SIZE;
+		unsigned long auxval;
+		int ret = -1;
+
+		auxval = getauxval(AT_SYSINFO_EHDR);
+		printf("\tAT_SYSINFO_EHDR is %#lx\n", auxval);
+		if (!auxval || auxval == -ENOENT) {
+			printf("[WARN]\tgetauxval failed\n");
+			return 0;
+		}
+
+		/* Simpler than parsing ELF header */
+		while (ret < 0) {
+			ret = try_to_remap((void *)auxval, vdso_size);
+			vdso_size += PAGE_SIZE;
+		}
+
+#ifdef __i386__
+		/* Glibc is likely to explode now - exit with raw syscall */
+		asm volatile ("int $0x80" : : "a" (__NR_exit), "b" (!!ret));
+#else /* __x86_64__ */
+		syscall(SYS_exit, ret);
+#endif
+	} else {
+		int status;
+
+		if (waitpid(child, &status, 0) != child ||
+			!WIFEXITED(status)) {
+			printf("[FAIL]\tmremap() of the vDSO does not work on this kernel!\n");
+			return 1;
+		} else if (WEXITSTATUS(status) != 0) {
+			printf("[FAIL]\tChild failed with %d\n",
+					WEXITSTATUS(status));
+			return 1;
+		}
+		printf("[OK]\n");
+	}
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/test_syscall_vdso.c b/tools/testing/selftests/x86/test_syscall_vdso.c
new file mode 100644
index 000000000..c9c328107
--- /dev/null
+++ b/tools/testing/selftests/x86/test_syscall_vdso.c
@@ -0,0 +1,408 @@
+/*
+ * 32-bit syscall ABI conformance test.
+ *
+ * Copyright (c) 2015 Denys Vlasenko
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+/*
+ * Can be built statically:
+ * gcc -Os -Wall -static -m32 test_syscall_vdso.c thunks_32.S
+ */
+#undef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#undef __USE_GNU
+#define __USE_GNU 1
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <elf.h>
+#include <sys/ptrace.h>
+#include <sys/wait.h>
+
+#if !defined(__i386__)
+int main(int argc, char **argv, char **envp)
+{
+	printf("[SKIP]\tNot a 32-bit x86 userspace\n");
+	return 0;
+}
+#else
+
+long syscall_addr;
+long get_syscall(char **envp)
+{
+	Elf32_auxv_t *auxv;
+	while (*envp++ != NULL)
+		continue;
+	for (auxv = (void *)envp; auxv->a_type != AT_NULL; auxv++)
+		if (auxv->a_type == AT_SYSINFO)
+			return auxv->a_un.a_val;
+	printf("[WARN]\tAT_SYSINFO not supplied\n");
+	return 0;
+}
+
+asm (
+	"	.pushsection .text\n"
+	"	.global	int80\n"
+	"int80:\n"
+	"	int	$0x80\n"
+	"	ret\n"
+	"	.popsection\n"
+);
+extern char int80;
+
+struct regs64 {
+	uint64_t rax, rbx, rcx, rdx;
+	uint64_t rsi, rdi, rbp, rsp;
+	uint64_t r8,  r9,  r10, r11;
+	uint64_t r12, r13, r14, r15;
+};
+struct regs64 regs64;
+int kernel_is_64bit;
+
+asm (
+	"	.pushsection .text\n"
+	"	.code64\n"
+	"get_regs64:\n"
+	"	push	%rax\n"
+	"	mov	$regs64, %eax\n"
+	"	pop	0*8(%rax)\n"
+	"	movq	%rbx, 1*8(%rax)\n"
+	"	movq	%rcx, 2*8(%rax)\n"
+	"	movq	%rdx, 3*8(%rax)\n"
+	"	movq	%rsi, 4*8(%rax)\n"
+	"	movq	%rdi, 5*8(%rax)\n"
+	"	movq	%rbp, 6*8(%rax)\n"
+	"	movq	%rsp, 7*8(%rax)\n"
+	"	movq	%r8,  8*8(%rax)\n"
+	"	movq	%r9,  9*8(%rax)\n"
+	"	movq	%r10, 10*8(%rax)\n"
+	"	movq	%r11, 11*8(%rax)\n"
+	"	movq	%r12, 12*8(%rax)\n"
+	"	movq	%r13, 13*8(%rax)\n"
+	"	movq	%r14, 14*8(%rax)\n"
+	"	movq	%r15, 15*8(%rax)\n"
+	"	ret\n"
+	"poison_regs64:\n"
+	"	movq	$0x7f7f7f7f, %r8\n"
+	"	shl	$32, %r8\n"
+	"	orq	$0x7f7f7f7f, %r8\n"
+	"	movq	%r8, %r9\n"
+	"	incq	%r9\n"
+	"	movq	%r9, %r10\n"
+	"	incq	%r10\n"
+	"	movq	%r10, %r11\n"
+	"	incq	%r11\n"
+	"	movq	%r11, %r12\n"
+	"	incq	%r12\n"
+	"	movq	%r12, %r13\n"
+	"	incq	%r13\n"
+	"	movq	%r13, %r14\n"
+	"	incq	%r14\n"
+	"	movq	%r14, %r15\n"
+	"	incq	%r15\n"
+	"	ret\n"
+	"	.code32\n"
+	"	.popsection\n"
+);
+extern void get_regs64(void);
+extern void poison_regs64(void);
+extern unsigned long call64_from_32(void (*function)(void));
+void print_regs64(void)
+{
+	if (!kernel_is_64bit)
+		return;
+	printf("ax:%016llx bx:%016llx cx:%016llx dx:%016llx\n", regs64.rax,  regs64.rbx,  regs64.rcx,  regs64.rdx);
+	printf("si:%016llx di:%016llx bp:%016llx sp:%016llx\n", regs64.rsi,  regs64.rdi,  regs64.rbp,  regs64.rsp);
+	printf(" 8:%016llx  9:%016llx 10:%016llx 11:%016llx\n", regs64.r8 ,  regs64.r9 ,  regs64.r10,  regs64.r11);
+	printf("12:%016llx 13:%016llx 14:%016llx 15:%016llx\n", regs64.r12,  regs64.r13,  regs64.r14,  regs64.r15);
+}
+
+int check_regs64(void)
+{
+	int err = 0;
+	int num = 8;
+	uint64_t *r64 = &regs64.r8;
+	uint64_t expected = 0x7f7f7f7f7f7f7f7fULL;
+
+	if (!kernel_is_64bit)
+		return 0;
+
+	do {
+		if (*r64 == expected++)
+			continue; /* register did not change */
+		if (syscall_addr != (long)&int80) {
+			/*
+			 * Non-INT80 syscall entrypoints are allowed to clobber R8+ regs:
+			 * either clear them to 0, or for R11, load EFLAGS.
+			 */
+			if (*r64 == 0)
+				continue;
+			if (num == 11) {
+				printf("[NOTE]\tR11 has changed:%016llx - assuming clobbered by SYSRET insn\n", *r64);
+				continue;
+			}
+		} else {
+			/*
+			 * INT80 syscall entrypoint can be used by
+			 * 64-bit programs too, unlike SYSCALL/SYSENTER.
+			 * Therefore it must preserve R12+
+			 * (they are callee-saved registers in 64-bit C ABI).
+			 *
+			 * Starting in Linux 4.17 (and any kernel that
+			 * backports the change), R8..11 are preserved.
+			 * Historically (and probably unintentionally), they
+			 * were clobbered or zeroed.
+			 */
+		}
+		printf("[FAIL]\tR%d has changed:%016llx\n", num, *r64);
+		err++;
+	} while (r64++, ++num < 16);
+
+	if (!err)
+		printf("[OK]\tR8..R15 did not leak kernel data\n");
+	return err;
+}
+
+int nfds;
+fd_set rfds;
+fd_set wfds;
+fd_set efds;
+struct timespec timeout;
+sigset_t sigmask;
+struct {
+	sigset_t *sp;
+	int sz;
+} sigmask_desc;
+
+void prep_args()
+{
+	nfds = 42;
+	FD_ZERO(&rfds);
+	FD_ZERO(&wfds);
+	FD_ZERO(&efds);
+	FD_SET(0, &rfds);
+	FD_SET(1, &wfds);
+	FD_SET(2, &efds);
+	timeout.tv_sec = 0;
+	timeout.tv_nsec = 123;
+	sigemptyset(&sigmask);
+	sigaddset(&sigmask, SIGINT);
+	sigaddset(&sigmask, SIGUSR2);
+	sigaddset(&sigmask, SIGRTMAX);
+	sigmask_desc.sp = &sigmask;
+	sigmask_desc.sz = 8; /* bytes */
+}
+
+static void print_flags(const char *name, unsigned long r)
+{
+	static const char *bitarray[] = {
+	"\n" ,"c\n" ,/* Carry Flag */
+	"0 " ,"1 "  ,/* Bit 1 - always on */
+	""   ,"p "  ,/* Parity Flag */
+	"0 " ,"3? " ,
+	""   ,"a "  ,/* Auxiliary carry Flag */
+	"0 " ,"5? " ,
+	""   ,"z "  ,/* Zero Flag */
+	""   ,"s "  ,/* Sign Flag */
+	""   ,"t "  ,/* Trap Flag */
+	""   ,"i "  ,/* Interrupt Flag */
+	""   ,"d "  ,/* Direction Flag */
+	""   ,"o "  ,/* Overflow Flag */
+	"0 " ,"1 "  ,/* I/O Privilege Level (2 bits) */
+	"0"  ,"1"   ,/* I/O Privilege Level (2 bits) */
+	""   ,"n "  ,/* Nested Task */
+	"0 " ,"15? ",
+	""   ,"r "  ,/* Resume Flag */
+	""   ,"v "  ,/* Virtual Mode */
+	""   ,"ac " ,/* Alignment Check/Access Control */
+	""   ,"vif ",/* Virtual Interrupt Flag */
+	""   ,"vip ",/* Virtual Interrupt Pending */
+	""   ,"id " ,/* CPUID detection */
+	NULL
+	};
+	const char **bitstr;
+	int bit;
+
+	printf("%s=%016lx ", name, r);
+	bitstr = bitarray + 42;
+	bit = 21;
+	if ((r >> 22) != 0)
+		printf("(extra bits are set) ");
+	do {
+		if (bitstr[(r >> bit) & 1][0])
+			fputs(bitstr[(r >> bit) & 1], stdout);
+		bitstr -= 2;
+		bit--;
+	} while (bit >= 0);
+}
+
+int run_syscall(void)
+{
+	long flags, bad_arg;
+
+	prep_args();
+
+	if (kernel_is_64bit)
+		call64_from_32(poison_regs64);
+	/*print_regs64();*/
+
+	asm("\n"
+	/* Try 6-arg syscall: pselect. It should return quickly */
+	"	push	%%ebp\n"
+	"	mov	$308, %%eax\n"     /* PSELECT */
+	"	mov	nfds, %%ebx\n"     /* ebx  arg1 */
+	"	mov	$rfds, %%ecx\n"    /* ecx  arg2 */
+	"	mov	$wfds, %%edx\n"    /* edx  arg3 */
+	"	mov	$efds, %%esi\n"    /* esi  arg4 */
+	"	mov	$timeout, %%edi\n" /* edi  arg5 */
+	"	mov	$sigmask_desc, %%ebp\n" /* %ebp arg6 */
+	"	push	$0x200ed7\n"      /* set almost all flags */
+	"	popf\n"		/* except TF, IOPL, NT, RF, VM, AC, VIF, VIP */
+	"	call	*syscall_addr\n"
+	/* Check that registers are not clobbered */
+	"	pushf\n"
+	"	pop	%%eax\n"
+	"	cld\n"
+	"	cmp	nfds, %%ebx\n"     /* ebx  arg1 */
+	"	mov	$1, %%ebx\n"
+	"	jne	1f\n"
+	"	cmp	$rfds, %%ecx\n"    /* ecx  arg2 */
+	"	mov	$2, %%ebx\n"
+	"	jne	1f\n"
+	"	cmp	$wfds, %%edx\n"    /* edx  arg3 */
+	"	mov	$3, %%ebx\n"
+	"	jne	1f\n"
+	"	cmp	$efds, %%esi\n"    /* esi  arg4 */
+	"	mov	$4, %%ebx\n"
+	"	jne	1f\n"
+	"	cmp	$timeout, %%edi\n" /* edi  arg5 */
+	"	mov	$5, %%ebx\n"
+	"	jne	1f\n"
+	"	cmpl	$sigmask_desc, %%ebp\n" /* %ebp arg6 */
+	"	mov	$6, %%ebx\n"
+	"	jne	1f\n"
+	"	mov	$0, %%ebx\n"
+	"1:\n"
+	"	pop	%%ebp\n"
+	: "=a" (flags), "=b" (bad_arg)
+	:
+	: "cx", "dx", "si", "di"
+	);
+
+	if (kernel_is_64bit) {
+		memset(&regs64, 0x77, sizeof(regs64));
+		call64_from_32(get_regs64);
+		/*print_regs64();*/
+	}
+
+	/*
+	 * On paravirt kernels, flags are not preserved across syscalls.
+	 * Thus, we do not consider it a bug if some are changed.
+	 * We just show ones which do.
+	 */
+	if ((0x200ed7 ^ flags) != 0) {
+		print_flags("[WARN]\tFlags before", 0x200ed7);
+		print_flags("[WARN]\tFlags  after", flags);
+		print_flags("[WARN]\tFlags change", (0x200ed7 ^ flags));
+	}
+
+	if (bad_arg) {
+		printf("[FAIL]\targ#%ld clobbered\n", bad_arg);
+		return 1;
+	}
+	printf("[OK]\tArguments are preserved across syscall\n");
+
+	return check_regs64();
+}
+
+int run_syscall_twice()
+{
+	int exitcode = 0;
+	long sv;
+
+	if (syscall_addr) {
+		printf("[RUN]\tExecuting 6-argument 32-bit syscall via VDSO\n");
+		exitcode = run_syscall();
+	}
+	sv = syscall_addr;
+	syscall_addr = (long)&int80;
+	printf("[RUN]\tExecuting 6-argument 32-bit syscall via INT 80\n");
+	exitcode += run_syscall();
+	syscall_addr = sv;
+	return exitcode;
+}
+
+void ptrace_me()
+{
+	pid_t pid;
+
+	fflush(NULL);
+	pid = fork();
+	if (pid < 0)
+		exit(1);
+	if (pid == 0) {
+		/* child */
+		if (ptrace(PTRACE_TRACEME, 0L, 0L, 0L) != 0)
+			exit(0);
+		raise(SIGSTOP);
+		return;
+	}
+	/* parent */
+	printf("[RUN]\tRunning tests under ptrace\n");
+	while (1) {
+		int status;
+		pid = waitpid(-1, &status, __WALL);
+		if (WIFEXITED(status))
+			exit(WEXITSTATUS(status));
+		if (WIFSIGNALED(status))
+			exit(WTERMSIG(status));
+		if (pid <= 0 || !WIFSTOPPED(status)) /* paranoia */
+			exit(255);
+		/*
+		 * Note: we do not inject sig = WSTOPSIG(status).
+		 * We probably should, but careful: do not inject SIGTRAP
+		 * generated by syscall entry/exit stops.
+		 * That kills the child.
+		 */
+		ptrace(PTRACE_SYSCALL, pid, 0L, 0L /*sig*/);
+	}
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	int exitcode = 0;
+	int cs;
+
+	asm("\n"
+	"	movl	%%cs, %%eax\n"
+	: "=a" (cs)
+	);
+	kernel_is_64bit = (cs == 0x23);
+	if (!kernel_is_64bit)
+		printf("[NOTE]\tNot a 64-bit kernel, won't test R8..R15 leaks\n");
+
+	/* This only works for non-static builds:
+	 * syscall_addr = dlsym(dlopen("linux-gate.so.1", RTLD_NOW), "__kernel_vsyscall");
+	 */
+	syscall_addr = get_syscall(envp);
+
+	exitcode += run_syscall_twice();
+	ptrace_me();
+	exitcode += run_syscall_twice();
+
+	return exitcode;
+}
+#endif
diff --git a/tools/testing/selftests/x86/test_vdso.c b/tools/testing/selftests/x86/test_vdso.c
new file mode 100644
index 000000000..35edd61d1
--- /dev/null
+++ b/tools/testing/selftests/x86/test_vdso.c
@@ -0,0 +1,337 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ldt_gdt.c - Test cases for LDT and GDT access
+ * Copyright (c) 2011-2015 Andrew Lutomirski
+ */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/syscall.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <errno.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <limits.h>
+
+#ifndef SYS_getcpu
+# ifdef __x86_64__
+#  define SYS_getcpu 309
+# else
+#  define SYS_getcpu 318
+# endif
+#endif
+
+/* max length of lines in /proc/self/maps - anything longer is skipped here */
+#define MAPS_LINE_LEN 128
+
+int nerrs = 0;
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+
+vgettime_t vdso_clock_gettime;
+
+typedef long (*vgtod_t)(struct timeval *tv, struct timezone *tz);
+
+vgtod_t vdso_gettimeofday;
+
+typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
+
+getcpu_t vgetcpu;
+getcpu_t vdso_getcpu;
+
+static void *vsyscall_getcpu(void)
+{
+#ifdef __x86_64__
+	FILE *maps;
+	char line[MAPS_LINE_LEN];
+	bool found = false;
+
+	maps = fopen("/proc/self/maps", "r");
+	if (!maps) /* might still be present, but ignore it here, as we test vDSO not vsyscall */
+		return NULL;
+
+	while (fgets(line, MAPS_LINE_LEN, maps)) {
+		char r, x;
+		void *start, *end;
+		char name[MAPS_LINE_LEN];
+
+		/* sscanf() is safe here as strlen(name) >= strlen(line) */
+		if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
+			   &start, &end, &r, &x, name) != 5)
+			continue;
+
+		if (strcmp(name, "[vsyscall]"))
+			continue;
+
+		/* assume entries are OK, as we test vDSO here not vsyscall */
+		found = true;
+		break;
+	}
+
+	fclose(maps);
+
+	if (!found) {
+		printf("Warning: failed to find vsyscall getcpu\n");
+		return NULL;
+	}
+	return (void *) (0xffffffffff600800);
+#else
+	return NULL;
+#endif
+}
+
+
+static void fill_function_pointers()
+{
+	void *vdso = dlopen("linux-vdso.so.1",
+			    RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-gate.so.1",
+			      RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso) {
+		printf("[WARN]\tfailed to find vDSO\n");
+		return;
+	}
+
+	vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
+	if (!vdso_getcpu)
+		printf("Warning: failed to find getcpu in vDSO\n");
+
+	vgetcpu = (getcpu_t) vsyscall_getcpu();
+
+	vdso_clock_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+	if (!vdso_clock_gettime)
+		printf("Warning: failed to find clock_gettime in vDSO\n");
+
+	vdso_gettimeofday = (vgtod_t)dlsym(vdso, "__vdso_gettimeofday");
+	if (!vdso_gettimeofday)
+		printf("Warning: failed to find gettimeofday in vDSO\n");
+
+}
+
+static long sys_getcpu(unsigned * cpu, unsigned * node,
+		       void* cache)
+{
+	return syscall(__NR_getcpu, cpu, node, cache);
+}
+
+static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
+{
+	return syscall(__NR_clock_gettime, id, ts);
+}
+
+static inline int sys_gettimeofday(struct timeval *tv, struct timezone *tz)
+{
+	return syscall(__NR_gettimeofday, tv, tz);
+}
+
+static void test_getcpu(void)
+{
+	printf("[RUN]\tTesting getcpu...\n");
+
+	for (int cpu = 0; ; cpu++) {
+		cpu_set_t cpuset;
+		CPU_ZERO(&cpuset);
+		CPU_SET(cpu, &cpuset);
+		if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0)
+			return;
+
+		unsigned cpu_sys, cpu_vdso, cpu_vsys,
+			node_sys, node_vdso, node_vsys;
+		long ret_sys, ret_vdso = 1, ret_vsys = 1;
+		unsigned node;
+
+		ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
+		if (vdso_getcpu)
+			ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
+		if (vgetcpu)
+			ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
+
+		if (!ret_sys)
+			node = node_sys;
+		else if (!ret_vdso)
+			node = node_vdso;
+		else if (!ret_vsys)
+			node = node_vsys;
+
+		bool ok = true;
+		if (!ret_sys && (cpu_sys != cpu || node_sys != node))
+			ok = false;
+		if (!ret_vdso && (cpu_vdso != cpu || node_vdso != node))
+			ok = false;
+		if (!ret_vsys && (cpu_vsys != cpu || node_vsys != node))
+			ok = false;
+
+		printf("[%s]\tCPU %u:", ok ? "OK" : "FAIL", cpu);
+		if (!ret_sys)
+			printf(" syscall: cpu %u, node %u", cpu_sys, node_sys);
+		if (!ret_vdso)
+			printf(" vdso: cpu %u, node %u", cpu_vdso, node_vdso);
+		if (!ret_vsys)
+			printf(" vsyscall: cpu %u, node %u", cpu_vsys,
+			       node_vsys);
+		printf("\n");
+
+		if (!ok)
+			nerrs++;
+	}
+}
+
+static bool ts_leq(const struct timespec *a, const struct timespec *b)
+{
+	if (a->tv_sec != b->tv_sec)
+		return a->tv_sec < b->tv_sec;
+	else
+		return a->tv_nsec <= b->tv_nsec;
+}
+
+static bool tv_leq(const struct timeval *a, const struct timeval *b)
+{
+	if (a->tv_sec != b->tv_sec)
+		return a->tv_sec < b->tv_sec;
+	else
+		return a->tv_usec <= b->tv_usec;
+}
+
+static char const * const clocknames[] = {
+	[0] = "CLOCK_REALTIME",
+	[1] = "CLOCK_MONOTONIC",
+	[2] = "CLOCK_PROCESS_CPUTIME_ID",
+	[3] = "CLOCK_THREAD_CPUTIME_ID",
+	[4] = "CLOCK_MONOTONIC_RAW",
+	[5] = "CLOCK_REALTIME_COARSE",
+	[6] = "CLOCK_MONOTONIC_COARSE",
+	[7] = "CLOCK_BOOTTIME",
+	[8] = "CLOCK_REALTIME_ALARM",
+	[9] = "CLOCK_BOOTTIME_ALARM",
+	[10] = "CLOCK_SGI_CYCLE",
+	[11] = "CLOCK_TAI",
+};
+
+static void test_one_clock_gettime(int clock, const char *name)
+{
+	struct timespec start, vdso, end;
+	int vdso_ret, end_ret;
+
+	printf("[RUN]\tTesting clock_gettime for clock %s (%d)...\n", name, clock);
+
+	if (sys_clock_gettime(clock, &start) < 0) {
+		if (errno == EINVAL) {
+			vdso_ret = vdso_clock_gettime(clock, &vdso);
+			if (vdso_ret == -EINVAL) {
+				printf("[OK]\tNo such clock.\n");
+			} else {
+				printf("[FAIL]\tNo such clock, but __vdso_clock_gettime returned %d\n", vdso_ret);
+				nerrs++;
+			}
+		} else {
+			printf("[WARN]\t clock_gettime(%d) syscall returned error %d\n", clock, errno);
+		}
+		return;
+	}
+
+	vdso_ret = vdso_clock_gettime(clock, &vdso);
+	end_ret = sys_clock_gettime(clock, &end);
+
+	if (vdso_ret != 0 || end_ret != 0) {
+		printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
+		       vdso_ret, errno);
+		nerrs++;
+		return;
+	}
+
+	printf("\t%llu.%09ld %llu.%09ld %llu.%09ld\n",
+	       (unsigned long long)start.tv_sec, start.tv_nsec,
+	       (unsigned long long)vdso.tv_sec, vdso.tv_nsec,
+	       (unsigned long long)end.tv_sec, end.tv_nsec);
+
+	if (!ts_leq(&start, &vdso) || !ts_leq(&vdso, &end)) {
+		printf("[FAIL]\tTimes are out of sequence\n");
+		nerrs++;
+	}
+}
+
+static void test_clock_gettime(void)
+{
+	for (int clock = 0; clock < sizeof(clocknames) / sizeof(clocknames[0]);
+	     clock++) {
+		test_one_clock_gettime(clock, clocknames[clock]);
+	}
+
+	/* Also test some invalid clock ids */
+	test_one_clock_gettime(-1, "invalid");
+	test_one_clock_gettime(INT_MIN, "invalid");
+	test_one_clock_gettime(INT_MAX, "invalid");
+}
+
+static void test_gettimeofday(void)
+{
+	struct timeval start, vdso, end;
+	struct timezone sys_tz, vdso_tz;
+	int vdso_ret, end_ret;
+
+	if (!vdso_gettimeofday)
+		return;
+
+	printf("[RUN]\tTesting gettimeofday...\n");
+
+	if (sys_gettimeofday(&start, &sys_tz) < 0) {
+		printf("[FAIL]\tsys_gettimeofday failed (%d)\n", errno);
+		nerrs++;
+		return;
+	}
+
+	vdso_ret = vdso_gettimeofday(&vdso, &vdso_tz);
+	end_ret = sys_gettimeofday(&end, NULL);
+
+	if (vdso_ret != 0 || end_ret != 0) {
+		printf("[FAIL]\tvDSO returned %d, syscall errno=%d\n",
+		       vdso_ret, errno);
+		nerrs++;
+		return;
+	}
+
+	printf("\t%llu.%06ld %llu.%06ld %llu.%06ld\n",
+	       (unsigned long long)start.tv_sec, start.tv_usec,
+	       (unsigned long long)vdso.tv_sec, vdso.tv_usec,
+	       (unsigned long long)end.tv_sec, end.tv_usec);
+
+	if (!tv_leq(&start, &vdso) || !tv_leq(&vdso, &end)) {
+		printf("[FAIL]\tTimes are out of sequence\n");
+		nerrs++;
+	}
+
+	if (sys_tz.tz_minuteswest == vdso_tz.tz_minuteswest &&
+	    sys_tz.tz_dsttime == vdso_tz.tz_dsttime) {
+		printf("[OK]\ttimezones match: minuteswest=%d, dsttime=%d\n",
+		       sys_tz.tz_minuteswest, sys_tz.tz_dsttime);
+	} else {
+		printf("[FAIL]\ttimezones do not match\n");
+		nerrs++;
+	}
+
+	/* And make sure that passing NULL for tz doesn't crash. */
+	vdso_gettimeofday(&vdso, NULL);
+}
+
+int main(int argc, char **argv)
+{
+	fill_function_pointers();
+
+	test_clock_gettime();
+	test_gettimeofday();
+
+	/*
+	 * Test getcpu() last so that, if something goes wrong setting affinity,
+	 * we still run the other tests.
+	 */
+	test_getcpu();
+
+	return nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/test_vsyscall.c b/tools/testing/selftests/x86/test_vsyscall.c
new file mode 100644
index 000000000..0b4f1cc22
--- /dev/null
+++ b/tools/testing/selftests/x86/test_vsyscall.c
@@ -0,0 +1,506 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <sys/time.h>
+#include <time.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+#include <dlfcn.h>
+#include <string.h>
+#include <inttypes.h>
+#include <signal.h>
+#include <sys/ucontext.h>
+#include <errno.h>
+#include <err.h>
+#include <sched.h>
+#include <stdbool.h>
+#include <setjmp.h>
+
+#ifdef __x86_64__
+# define VSYS(x) (x)
+#else
+# define VSYS(x) 0
+#endif
+
+#ifndef SYS_getcpu
+# ifdef __x86_64__
+#  define SYS_getcpu 309
+# else
+#  define SYS_getcpu 318
+# endif
+#endif
+
+/* max length of lines in /proc/self/maps - anything longer is skipped here */
+#define MAPS_LINE_LEN 128
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+/* vsyscalls and vDSO */
+bool should_read_vsyscall = false;
+
+typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
+gtod_t vgtod = (gtod_t)VSYS(0xffffffffff600000);
+gtod_t vdso_gtod;
+
+typedef int (*vgettime_t)(clockid_t, struct timespec *);
+vgettime_t vdso_gettime;
+
+typedef long (*time_func_t)(time_t *t);
+time_func_t vtime = (time_func_t)VSYS(0xffffffffff600400);
+time_func_t vdso_time;
+
+typedef long (*getcpu_t)(unsigned *, unsigned *, void *);
+getcpu_t vgetcpu = (getcpu_t)VSYS(0xffffffffff600800);
+getcpu_t vdso_getcpu;
+
+static void init_vdso(void)
+{
+	void *vdso = dlopen("linux-vdso.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso)
+		vdso = dlopen("linux-gate.so.1", RTLD_LAZY | RTLD_LOCAL | RTLD_NOLOAD);
+	if (!vdso) {
+		printf("[WARN]\tfailed to find vDSO\n");
+		return;
+	}
+
+	vdso_gtod = (gtod_t)dlsym(vdso, "__vdso_gettimeofday");
+	if (!vdso_gtod)
+		printf("[WARN]\tfailed to find gettimeofday in vDSO\n");
+
+	vdso_gettime = (vgettime_t)dlsym(vdso, "__vdso_clock_gettime");
+	if (!vdso_gettime)
+		printf("[WARN]\tfailed to find clock_gettime in vDSO\n");
+
+	vdso_time = (time_func_t)dlsym(vdso, "__vdso_time");
+	if (!vdso_time)
+		printf("[WARN]\tfailed to find time in vDSO\n");
+
+	vdso_getcpu = (getcpu_t)dlsym(vdso, "__vdso_getcpu");
+	if (!vdso_getcpu) {
+		/* getcpu() was never wired up in the 32-bit vDSO. */
+		printf("[%s]\tfailed to find getcpu in vDSO\n",
+		       sizeof(long) == 8 ? "WARN" : "NOTE");
+	}
+}
+
+static int init_vsys(void)
+{
+#ifdef __x86_64__
+	int nerrs = 0;
+	FILE *maps;
+	char line[MAPS_LINE_LEN];
+	bool found = false;
+
+	maps = fopen("/proc/self/maps", "r");
+	if (!maps) {
+		printf("[WARN]\tCould not open /proc/self/maps -- assuming vsyscall is r-x\n");
+		should_read_vsyscall = true;
+		return 0;
+	}
+
+	while (fgets(line, MAPS_LINE_LEN, maps)) {
+		char r, x;
+		void *start, *end;
+		char name[MAPS_LINE_LEN];
+
+		/* sscanf() is safe here as strlen(name) >= strlen(line) */
+		if (sscanf(line, "%p-%p %c-%cp %*x %*x:%*x %*u %s",
+			   &start, &end, &r, &x, name) != 5)
+			continue;
+
+		if (strcmp(name, "[vsyscall]"))
+			continue;
+
+		printf("\tvsyscall map: %s", line);
+
+		if (start != (void *)0xffffffffff600000 ||
+		    end != (void *)0xffffffffff601000) {
+			printf("[FAIL]\taddress range is nonsense\n");
+			nerrs++;
+		}
+
+		printf("\tvsyscall permissions are %c-%c\n", r, x);
+		should_read_vsyscall = (r == 'r');
+		if (x != 'x') {
+			vgtod = NULL;
+			vtime = NULL;
+			vgetcpu = NULL;
+		}
+
+		found = true;
+		break;
+	}
+
+	fclose(maps);
+
+	if (!found) {
+		printf("\tno vsyscall map in /proc/self/maps\n");
+		should_read_vsyscall = false;
+		vgtod = NULL;
+		vtime = NULL;
+		vgetcpu = NULL;
+	}
+
+	return nerrs;
+#else
+	return 0;
+#endif
+}
+
+/* syscalls */
+static inline long sys_gtod(struct timeval *tv, struct timezone *tz)
+{
+	return syscall(SYS_gettimeofday, tv, tz);
+}
+
+static inline int sys_clock_gettime(clockid_t id, struct timespec *ts)
+{
+	return syscall(SYS_clock_gettime, id, ts);
+}
+
+static inline long sys_time(time_t *t)
+{
+	return syscall(SYS_time, t);
+}
+
+static inline long sys_getcpu(unsigned * cpu, unsigned * node,
+			      void* cache)
+{
+	return syscall(SYS_getcpu, cpu, node, cache);
+}
+
+static jmp_buf jmpbuf;
+
+static void sigsegv(int sig, siginfo_t *info, void *ctx_void)
+{
+	siglongjmp(jmpbuf, 1);
+}
+
+static double tv_diff(const struct timeval *a, const struct timeval *b)
+{
+	return (double)(a->tv_sec - b->tv_sec) +
+		(double)((int)a->tv_usec - (int)b->tv_usec) * 1e-6;
+}
+
+static int check_gtod(const struct timeval *tv_sys1,
+		      const struct timeval *tv_sys2,
+		      const struct timezone *tz_sys,
+		      const char *which,
+		      const struct timeval *tv_other,
+		      const struct timezone *tz_other)
+{
+	int nerrs = 0;
+	double d1, d2;
+
+	if (tz_other && (tz_sys->tz_minuteswest != tz_other->tz_minuteswest || tz_sys->tz_dsttime != tz_other->tz_dsttime)) {
+		printf("[FAIL] %s tz mismatch\n", which);
+		nerrs++;
+	}
+
+	d1 = tv_diff(tv_other, tv_sys1);
+	d2 = tv_diff(tv_sys2, tv_other); 
+	printf("\t%s time offsets: %lf %lf\n", which, d1, d2);
+
+	if (d1 < 0 || d2 < 0) {
+		printf("[FAIL]\t%s time was inconsistent with the syscall\n", which);
+		nerrs++;
+	} else {
+		printf("[OK]\t%s gettimeofday()'s timeval was okay\n", which);
+	}
+
+	return nerrs;
+}
+
+static int test_gtod(void)
+{
+	struct timeval tv_sys1, tv_sys2, tv_vdso, tv_vsys;
+	struct timezone tz_sys, tz_vdso, tz_vsys;
+	long ret_vdso = -1;
+	long ret_vsys = -1;
+	int nerrs = 0;
+
+	printf("[RUN]\ttest gettimeofday()\n");
+
+	if (sys_gtod(&tv_sys1, &tz_sys) != 0)
+		err(1, "syscall gettimeofday");
+	if (vdso_gtod)
+		ret_vdso = vdso_gtod(&tv_vdso, &tz_vdso);
+	if (vgtod)
+		ret_vsys = vgtod(&tv_vsys, &tz_vsys);
+	if (sys_gtod(&tv_sys2, &tz_sys) != 0)
+		err(1, "syscall gettimeofday");
+
+	if (vdso_gtod) {
+		if (ret_vdso == 0) {
+			nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vDSO", &tv_vdso, &tz_vdso);
+		} else {
+			printf("[FAIL]\tvDSO gettimeofday() failed: %ld\n", ret_vdso);
+			nerrs++;
+		}
+	}
+
+	if (vgtod) {
+		if (ret_vsys == 0) {
+			nerrs += check_gtod(&tv_sys1, &tv_sys2, &tz_sys, "vsyscall", &tv_vsys, &tz_vsys);
+		} else {
+			printf("[FAIL]\tvsys gettimeofday() failed: %ld\n", ret_vsys);
+			nerrs++;
+		}
+	}
+
+	return nerrs;
+}
+
+static int test_time(void) {
+	int nerrs = 0;
+
+	printf("[RUN]\ttest time()\n");
+	long t_sys1, t_sys2, t_vdso = 0, t_vsys = 0;
+	long t2_sys1 = -1, t2_sys2 = -1, t2_vdso = -1, t2_vsys = -1;
+	t_sys1 = sys_time(&t2_sys1);
+	if (vdso_time)
+		t_vdso = vdso_time(&t2_vdso);
+	if (vtime)
+		t_vsys = vtime(&t2_vsys);
+	t_sys2 = sys_time(&t2_sys2);
+	if (t_sys1 < 0 || t_sys1 != t2_sys1 || t_sys2 < 0 || t_sys2 != t2_sys2) {
+		printf("[FAIL]\tsyscall failed (ret1:%ld output1:%ld ret2:%ld output2:%ld)\n", t_sys1, t2_sys1, t_sys2, t2_sys2);
+		nerrs++;
+		return nerrs;
+	}
+
+	if (vdso_time) {
+		if (t_vdso < 0 || t_vdso != t2_vdso) {
+			printf("[FAIL]\tvDSO failed (ret:%ld output:%ld)\n", t_vdso, t2_vdso);
+			nerrs++;
+		} else if (t_vdso < t_sys1 || t_vdso > t_sys2) {
+			printf("[FAIL]\tvDSO returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vdso, t_sys2);
+			nerrs++;
+		} else {
+			printf("[OK]\tvDSO time() is okay\n");
+		}
+	}
+
+	if (vtime) {
+		if (t_vsys < 0 || t_vsys != t2_vsys) {
+			printf("[FAIL]\tvsyscall failed (ret:%ld output:%ld)\n", t_vsys, t2_vsys);
+			nerrs++;
+		} else if (t_vsys < t_sys1 || t_vsys > t_sys2) {
+			printf("[FAIL]\tvsyscall returned the wrong time (%ld %ld %ld)\n", t_sys1, t_vsys, t_sys2);
+			nerrs++;
+		} else {
+			printf("[OK]\tvsyscall time() is okay\n");
+		}
+	}
+
+	return nerrs;
+}
+
+static int test_getcpu(int cpu)
+{
+	int nerrs = 0;
+	long ret_sys, ret_vdso = -1, ret_vsys = -1;
+
+	printf("[RUN]\tgetcpu() on CPU %d\n", cpu);
+
+	cpu_set_t cpuset;
+	CPU_ZERO(&cpuset);
+	CPU_SET(cpu, &cpuset);
+	if (sched_setaffinity(0, sizeof(cpuset), &cpuset) != 0) {
+		printf("[SKIP]\tfailed to force CPU %d\n", cpu);
+		return nerrs;
+	}
+
+	unsigned cpu_sys, cpu_vdso, cpu_vsys, node_sys, node_vdso, node_vsys;
+	unsigned node = 0;
+	bool have_node = false;
+	ret_sys = sys_getcpu(&cpu_sys, &node_sys, 0);
+	if (vdso_getcpu)
+		ret_vdso = vdso_getcpu(&cpu_vdso, &node_vdso, 0);
+	if (vgetcpu)
+		ret_vsys = vgetcpu(&cpu_vsys, &node_vsys, 0);
+
+	if (ret_sys == 0) {
+		if (cpu_sys != cpu) {
+			printf("[FAIL]\tsyscall reported CPU %hu but should be %d\n", cpu_sys, cpu);
+			nerrs++;
+		}
+
+		have_node = true;
+		node = node_sys;
+	}
+
+	if (vdso_getcpu) {
+		if (ret_vdso) {
+			printf("[FAIL]\tvDSO getcpu() failed\n");
+			nerrs++;
+		} else {
+			if (!have_node) {
+				have_node = true;
+				node = node_vdso;
+			}
+
+			if (cpu_vdso != cpu) {
+				printf("[FAIL]\tvDSO reported CPU %hu but should be %d\n", cpu_vdso, cpu);
+				nerrs++;
+			} else {
+				printf("[OK]\tvDSO reported correct CPU\n");
+			}
+
+			if (node_vdso != node) {
+				printf("[FAIL]\tvDSO reported node %hu but should be %hu\n", node_vdso, node);
+				nerrs++;
+			} else {
+				printf("[OK]\tvDSO reported correct node\n");
+			}
+		}
+	}
+
+	if (vgetcpu) {
+		if (ret_vsys) {
+			printf("[FAIL]\tvsyscall getcpu() failed\n");
+			nerrs++;
+		} else {
+			if (!have_node) {
+				have_node = true;
+				node = node_vsys;
+			}
+
+			if (cpu_vsys != cpu) {
+				printf("[FAIL]\tvsyscall reported CPU %hu but should be %d\n", cpu_vsys, cpu);
+				nerrs++;
+			} else {
+				printf("[OK]\tvsyscall reported correct CPU\n");
+			}
+
+			if (node_vsys != node) {
+				printf("[FAIL]\tvsyscall reported node %hu but should be %hu\n", node_vsys, node);
+				nerrs++;
+			} else {
+				printf("[OK]\tvsyscall reported correct node\n");
+			}
+		}
+	}
+
+	return nerrs;
+}
+
+static int test_vsys_r(void)
+{
+#ifdef __x86_64__
+	printf("[RUN]\tChecking read access to the vsyscall page\n");
+	bool can_read;
+	if (sigsetjmp(jmpbuf, 1) == 0) {
+		*(volatile int *)0xffffffffff600000;
+		can_read = true;
+	} else {
+		can_read = false;
+	}
+
+	if (can_read && !should_read_vsyscall) {
+		printf("[FAIL]\tWe have read access, but we shouldn't\n");
+		return 1;
+	} else if (!can_read && should_read_vsyscall) {
+		printf("[FAIL]\tWe don't have read access, but we should\n");
+		return 1;
+	} else {
+		printf("[OK]\tgot expected result\n");
+	}
+#endif
+
+	return 0;
+}
+
+
+#ifdef __x86_64__
+#define X86_EFLAGS_TF (1UL << 8)
+static volatile sig_atomic_t num_vsyscall_traps;
+
+static unsigned long get_eflags(void)
+{
+	unsigned long eflags;
+	asm volatile ("pushfq\n\tpopq %0" : "=rm" (eflags));
+	return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+	asm volatile ("pushq %0\n\tpopfq" : : "rm" (eflags) : "flags");
+}
+
+static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t *)ctx_void;
+	unsigned long ip = ctx->uc_mcontext.gregs[REG_RIP];
+
+	if (((ip ^ 0xffffffffff600000UL) & ~0xfffUL) == 0)
+		num_vsyscall_traps++;
+}
+
+static int test_emulation(void)
+{
+	time_t tmp;
+	bool is_native;
+
+	if (!vtime)
+		return 0;
+
+	printf("[RUN]\tchecking that vsyscalls are emulated\n");
+	sethandler(SIGTRAP, sigtrap, 0);
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	vtime(&tmp);
+	set_eflags(get_eflags() & ~X86_EFLAGS_TF);
+
+	/*
+	 * If vsyscalls are emulated, we expect a single trap in the
+	 * vsyscall page -- the call instruction will trap with RIP
+	 * pointing to the entry point before emulation takes over.
+	 * In native mode, we expect two traps, since whatever code
+	 * the vsyscall page contains will be more than just a ret
+	 * instruction.
+	 */
+	is_native = (num_vsyscall_traps > 1);
+
+	printf("[%s]\tvsyscalls are %s (%d instructions in vsyscall page)\n",
+	       (is_native ? "FAIL" : "OK"),
+	       (is_native ? "native" : "emulated"),
+	       (int)num_vsyscall_traps);
+
+	return is_native;
+}
+#endif
+
+int main(int argc, char **argv)
+{
+	int nerrs = 0;
+
+	init_vdso();
+	nerrs += init_vsys();
+
+	nerrs += test_gtod();
+	nerrs += test_time();
+	nerrs += test_getcpu(0);
+	nerrs += test_getcpu(1);
+
+	sethandler(SIGSEGV, sigsegv, 0);
+	nerrs += test_vsys_r();
+
+#ifdef __x86_64__
+	nerrs += test_emulation();
+#endif
+
+	return nerrs ? 1 : 0;
+}
diff --git a/tools/testing/selftests/x86/thunks.S b/tools/testing/selftests/x86/thunks.S
new file mode 100644
index 000000000..ce8a995bb
--- /dev/null
+++ b/tools/testing/selftests/x86/thunks.S
@@ -0,0 +1,67 @@
+/*
+ * thunks.S - assembly helpers for mixed-bitness code
+ * Copyright (c) 2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * These are little helpers that make it easier to switch bitness on
+ * the fly.
+ */
+
+	.text
+
+	.global call32_from_64
+	.type call32_from_64, @function
+call32_from_64:
+	// rdi: stack to use
+	// esi: function to call
+
+	// Save registers
+	pushq %rbx
+	pushq %rbp
+	pushq %r12
+	pushq %r13
+	pushq %r14
+	pushq %r15
+	pushfq
+
+	// Switch stacks
+	mov %rsp,(%rdi)
+	mov %rdi,%rsp
+
+	// Switch to compatibility mode
+	pushq $0x23  /* USER32_CS */
+	pushq $1f
+	lretq
+
+1:
+	.code32
+	// Call the function
+	call *%esi
+	// Switch back to long mode
+	jmp $0x33,$1f
+	.code64
+
+1:
+	// Restore the stack
+	mov (%rsp),%rsp
+
+	// Restore registers
+	popfq
+	popq %r15
+	popq %r14
+	popq %r13
+	popq %r12
+	popq %rbp
+	popq %rbx
+
+	ret
+
+.size call32_from_64, .-call32_from_64
diff --git a/tools/testing/selftests/x86/thunks_32.S b/tools/testing/selftests/x86/thunks_32.S
new file mode 100644
index 000000000..29b644bb9
--- /dev/null
+++ b/tools/testing/selftests/x86/thunks_32.S
@@ -0,0 +1,55 @@
+/*
+ * thunks_32.S - assembly helpers for mixed-bitness code
+ * Copyright (c) 2015 Denys Vlasenko
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * These are little helpers that make it easier to switch bitness on
+ * the fly.
+ */
+
+	.text
+	.code32
+
+	.global call64_from_32
+	.type call32_from_64, @function
+
+	// 4(%esp): function to call
+call64_from_32:
+	// Fetch function address
+	mov	4(%esp), %eax
+
+	// Save registers which are callee-clobbered by 64-bit ABI
+	push	%ecx
+	push	%edx
+	push	%esi
+	push	%edi
+
+	// Switch to long mode
+	jmp	$0x33,$1f
+1:	.code64
+
+	// Call the function
+	call	*%rax
+
+	// Switch to compatibility mode
+	push	$0x23  /* USER32_CS */
+	.code32; push $1f; .code64 /* hack: can't have X86_64_32S relocation in 32-bit ELF */
+	lretq
+1:	.code32
+
+	pop	%edi
+	pop	%esi
+	pop	%edx
+	pop	%ecx
+
+	ret
+
+.size call64_from_32, .-call64_from_32
diff --git a/tools/testing/selftests/x86/trivial_32bit_program.c b/tools/testing/selftests/x86/trivial_32bit_program.c
new file mode 100644
index 000000000..fabdf0f51
--- /dev/null
+++ b/tools/testing/selftests/x86/trivial_32bit_program.c
@@ -0,0 +1,18 @@
+/*
+ * Trivial program to check that we have a valid 32-bit build environment.
+ * Copyright (c) 2015 Andy Lutomirski
+ * GPL v2
+ */
+
+#ifndef __i386__
+# error wrong architecture
+#endif
+
+#include <stdio.h>
+
+int main()
+{
+	printf("\n");
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/trivial_64bit_program.c b/tools/testing/selftests/x86/trivial_64bit_program.c
new file mode 100644
index 000000000..05c6a41b3
--- /dev/null
+++ b/tools/testing/selftests/x86/trivial_64bit_program.c
@@ -0,0 +1,18 @@
+/*
+ * Trivial program to check that we have a valid 64-bit build environment.
+ * Copyright (c) 2015 Andy Lutomirski
+ * GPL v2
+ */
+
+#ifndef __x86_64__
+# error wrong architecture
+#endif
+
+#include <stdio.h>
+
+int main()
+{
+	printf("\n");
+
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/trivial_program.c b/tools/testing/selftests/x86/trivial_program.c
new file mode 100644
index 000000000..46a447163
--- /dev/null
+++ b/tools/testing/selftests/x86/trivial_program.c
@@ -0,0 +1,10 @@
+/* Trivial program to check that compilation with certain flags is working. */
+
+#include <stdio.h>
+
+int
+main(void)
+{
+	puts("");
+	return 0;
+}
diff --git a/tools/testing/selftests/x86/unwind_vdso.c b/tools/testing/selftests/x86/unwind_vdso.c
new file mode 100644
index 000000000..00a26a82f
--- /dev/null
+++ b/tools/testing/selftests/x86/unwind_vdso.c
@@ -0,0 +1,211 @@
+/*
+ * unwind_vdso.c - tests unwind info for AT_SYSINFO in the vDSO
+ * Copyright (c) 2014-2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * This tests __kernel_vsyscall's unwind info.
+ */
+
+#define _GNU_SOURCE
+
+#include <features.h>
+#include <stdio.h>
+
+#if defined(__GLIBC__) && __GLIBC__ == 2 && __GLIBC_MINOR__ < 16
+
+int main()
+{
+	/* We need getauxval(). */
+	printf("[SKIP]\tGLIBC before 2.16 cannot compile this test\n");
+	return 0;
+}
+
+#else
+
+#include <sys/time.h>
+#include <stdlib.h>
+#include <syscall.h>
+#include <unistd.h>
+#include <string.h>
+#include <inttypes.h>
+#include <sys/mman.h>
+#include <signal.h>
+#include <sys/ucontext.h>
+#include <err.h>
+#include <stddef.h>
+#include <stdbool.h>
+#include <sys/ptrace.h>
+#include <sys/user.h>
+#include <sys/ucontext.h>
+#include <link.h>
+#include <sys/auxv.h>
+#include <dlfcn.h>
+#include <unwind.h>
+
+static void sethandler(int sig, void (*handler)(int, siginfo_t *, void *),
+		       int flags)
+{
+	struct sigaction sa;
+	memset(&sa, 0, sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO | flags;
+	sigemptyset(&sa.sa_mask);
+	if (sigaction(sig, &sa, 0))
+		err(1, "sigaction");
+}
+
+#ifdef __x86_64__
+# define WIDTH "q"
+#else
+# define WIDTH "l"
+#endif
+
+static unsigned long get_eflags(void)
+{
+	unsigned long eflags;
+	asm volatile ("pushf" WIDTH "\n\tpop" WIDTH " %0" : "=rm" (eflags));
+	return eflags;
+}
+
+static void set_eflags(unsigned long eflags)
+{
+	asm volatile ("push" WIDTH " %0\n\tpopf" WIDTH
+		      : : "rm" (eflags) : "flags");
+}
+
+#define X86_EFLAGS_TF (1UL << 8)
+
+static volatile sig_atomic_t nerrs;
+static unsigned long sysinfo;
+static bool got_sysinfo = false;
+static unsigned long return_address;
+
+struct unwind_state {
+	unsigned long ip;	/* trap source */
+	int depth;		/* -1 until we hit the trap source */
+};
+
+_Unwind_Reason_Code trace_fn(struct _Unwind_Context * ctx, void *opaque)
+{
+	struct unwind_state *state = opaque;
+	unsigned long ip = _Unwind_GetIP(ctx);
+
+	if (state->depth == -1) {
+		if (ip == state->ip)
+			state->depth = 0;
+		else
+			return _URC_NO_REASON;	/* Not there yet */
+	}
+	printf("\t  0x%lx\n", ip);
+
+	if (ip == return_address) {
+		/* Here we are. */
+		unsigned long eax = _Unwind_GetGR(ctx, 0);
+		unsigned long ecx = _Unwind_GetGR(ctx, 1);
+		unsigned long edx = _Unwind_GetGR(ctx, 2);
+		unsigned long ebx = _Unwind_GetGR(ctx, 3);
+		unsigned long ebp = _Unwind_GetGR(ctx, 5);
+		unsigned long esi = _Unwind_GetGR(ctx, 6);
+		unsigned long edi = _Unwind_GetGR(ctx, 7);
+		bool ok = (eax == SYS_getpid || eax == getpid()) &&
+			ebx == 1 && ecx == 2 && edx == 3 &&
+			esi == 4 && edi == 5 && ebp == 6;
+
+		if (!ok)
+			nerrs++;
+		printf("[%s]\t  NR = %ld, args = %ld, %ld, %ld, %ld, %ld, %ld\n",
+		       (ok ? "OK" : "FAIL"),
+		       eax, ebx, ecx, edx, esi, edi, ebp);
+
+		return _URC_NORMAL_STOP;
+	} else {
+		state->depth++;
+		return _URC_NO_REASON;
+	}
+}
+
+static void sigtrap(int sig, siginfo_t *info, void *ctx_void)
+{
+	ucontext_t *ctx = (ucontext_t *)ctx_void;
+	struct unwind_state state;
+	unsigned long ip = ctx->uc_mcontext.gregs[REG_EIP];
+
+	if (!got_sysinfo && ip == sysinfo) {
+		got_sysinfo = true;
+
+		/* Find the return address. */
+		return_address = *(unsigned long *)(unsigned long)ctx->uc_mcontext.gregs[REG_ESP];
+
+		printf("\tIn vsyscall at 0x%lx, returning to 0x%lx\n",
+		       ip, return_address);
+	}
+
+	if (!got_sysinfo)
+		return;		/* Not there yet */
+
+	if (ip == return_address) {
+		ctx->uc_mcontext.gregs[REG_EFL] &= ~X86_EFLAGS_TF;
+		printf("\tVsyscall is done\n");
+		return;
+	}
+
+	printf("\tSIGTRAP at 0x%lx\n", ip);
+
+	state.ip = ip;
+	state.depth = -1;
+	_Unwind_Backtrace(trace_fn, &state);
+}
+
+int main()
+{
+	sysinfo = getauxval(AT_SYSINFO);
+	printf("\tAT_SYSINFO is 0x%lx\n", sysinfo);
+
+	Dl_info info;
+	if (!dladdr((void *)sysinfo, &info)) {
+		printf("[WARN]\tdladdr failed on AT_SYSINFO\n");
+	} else {
+		printf("[OK]\tAT_SYSINFO maps to %s, loaded at 0x%p\n",
+		       info.dli_fname, info.dli_fbase);
+	}
+
+	sethandler(SIGTRAP, sigtrap, 0);
+
+	syscall(SYS_getpid);  /* Force symbol binding without TF set. */
+	printf("[RUN]\tSet TF and check a fast syscall\n");
+	set_eflags(get_eflags() | X86_EFLAGS_TF);
+	syscall(SYS_getpid, 1, 2, 3, 4, 5, 6);
+	if (!got_sysinfo) {
+		set_eflags(get_eflags() & ~X86_EFLAGS_TF);
+
+		/*
+		 * The most likely cause of this is that you're on Debian or
+		 * a Debian-based distro, you're missing libc6-i686, and you're
+		 * affected by libc/19006 (https://sourceware.org/PR19006).
+		 */
+		printf("[WARN]\tsyscall(2) didn't enter AT_SYSINFO\n");
+	}
+
+	if (get_eflags() & X86_EFLAGS_TF) {
+		printf("[FAIL]\tTF is still set\n");
+		nerrs++;
+	}
+
+	if (nerrs) {
+		printf("[FAIL]\tThere were errors\n");
+		return 1;
+	} else {
+		printf("[OK]\tAll is well\n");
+		return 0;
+	}
+}
+
+#endif	/* New enough libc */
diff --git a/tools/testing/selftests/x86/vdso_restorer.c b/tools/testing/selftests/x86/vdso_restorer.c
new file mode 100644
index 000000000..cb038424a
--- /dev/null
+++ b/tools/testing/selftests/x86/vdso_restorer.c
@@ -0,0 +1,88 @@
+/*
+ * vdso_restorer.c - tests vDSO-based signal restore
+ * Copyright (c) 2015 Andrew Lutomirski
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * This makes sure that sa_restorer == NULL keeps working on 32-bit
+ * configurations.  Modern glibc doesn't use it under any circumstances,
+ * so it's easy to overlook breakage.
+ *
+ * 64-bit userspace has never supported sa_restorer == NULL, so this is
+ * 32-bit only.
+ */
+
+#define _GNU_SOURCE
+
+#include <err.h>
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+#include <unistd.h>
+#include <syscall.h>
+#include <sys/syscall.h>
+
+/* Open-code this -- the headers are too messy to easily use them. */
+struct real_sigaction {
+	void *handler;
+	unsigned long flags;
+	void *restorer;
+	unsigned int mask[2];
+};
+
+static volatile sig_atomic_t handler_called;
+
+static void handler_with_siginfo(int sig, siginfo_t *info, void *ctx_void)
+{
+	handler_called = 1;
+}
+
+static void handler_without_siginfo(int sig)
+{
+	handler_called = 1;
+}
+
+int main()
+{
+	int nerrs = 0;
+	struct real_sigaction sa;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.handler = handler_with_siginfo;
+	sa.flags = SA_SIGINFO;
+	sa.restorer = NULL;	/* request kernel-provided restorer */
+
+	if (syscall(SYS_rt_sigaction, SIGUSR1, &sa, NULL, 8) != 0)
+		err(1, "raw rt_sigaction syscall");
+
+	raise(SIGUSR1);
+
+	if (handler_called) {
+		printf("[OK]\tSA_SIGINFO handler returned successfully\n");
+	} else {
+		printf("[FAIL]\tSA_SIGINFO handler was not called\n");
+		nerrs++;
+	}
+
+	sa.flags = 0;
+	sa.handler = handler_without_siginfo;
+	if (syscall(SYS_sigaction, SIGUSR1, &sa, 0) != 0)
+		err(1, "raw sigaction syscall");
+	handler_called = 0;
+
+	raise(SIGUSR1);
+
+	if (handler_called) {
+		printf("[OK]\t!SA_SIGINFO handler returned successfully\n");
+	} else {
+		printf("[FAIL]\t!SA_SIGINFO handler was not called\n");
+		nerrs++;
+	}
+}