diff options
Diffstat (limited to 'arch/x86/entry/vdso')
22 files changed, 2106 insertions, 0 deletions
diff --git a/arch/x86/entry/vdso/.gitignore b/arch/x86/entry/vdso/.gitignore new file mode 100644 index 000000000..37a6129d5 --- /dev/null +++ b/arch/x86/entry/vdso/.gitignore @@ -0,0 +1,8 @@ +# SPDX-License-Identifier: GPL-2.0-only +vdso.lds +vdsox32.lds +vdso32-syscall-syms.lds +vdso32-sysenter-syms.lds +vdso32-int80-syms.lds +vdso-image-*.c +vdso2c diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile new file mode 100644 index 000000000..3e88b9df8 --- /dev/null +++ b/arch/x86/entry/vdso/Makefile @@ -0,0 +1,220 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Building vDSO images for x86. +# + +# Absolute relocation type $(ARCH_REL_TYPE_ABS) needs to be defined before +# the inclusion of generic Makefile. +ARCH_REL_TYPE_ABS := R_X86_64_JUMP_SLOT|R_X86_64_GLOB_DAT|R_X86_64_RELATIVE| +ARCH_REL_TYPE_ABS += R_386_GLOB_DAT|R_386_JMP_SLOT|R_386_RELATIVE +include $(srctree)/lib/vdso/Makefile + +# Sanitizer runtimes are unavailable and cannot be linked here. +KASAN_SANITIZE := n +KMSAN_SANITIZE_vclock_gettime.o := n +KMSAN_SANITIZE_vgetcpu.o := n + +UBSAN_SANITIZE := n +KCSAN_SANITIZE := n +OBJECT_FILES_NON_STANDARD := y + +# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in. +KCOV_INSTRUMENT := n + +VDSO64-$(CONFIG_X86_64) := y +VDSOX32-$(CONFIG_X86_X32_ABI) := y +VDSO32-$(CONFIG_X86_32) := y +VDSO32-$(CONFIG_IA32_EMULATION) := y + +# files to link into the vdso +vobjs-y := vdso-note.o vclock_gettime.o vgetcpu.o +vobjs32-y := vdso32/note.o vdso32/system_call.o vdso32/sigreturn.o +vobjs32-y += vdso32/vclock_gettime.o +vobjs-$(CONFIG_X86_SGX) += vsgx.o + +# files to link into kernel +obj-y += vma.o extable.o +KASAN_SANITIZE_vma.o := y +UBSAN_SANITIZE_vma.o := y +KCSAN_SANITIZE_vma.o := y +OBJECT_FILES_NON_STANDARD_vma.o := n + +# vDSO images to build +vdso_img-$(VDSO64-y) += 64 +vdso_img-$(VDSOX32-y) += x32 +vdso_img-$(VDSO32-y) += 32 + +obj-$(VDSO32-y) += vdso32-setup.o + +vobjs := $(foreach F,$(vobjs-y),$(obj)/$F) +vobjs32 := $(foreach F,$(vobjs32-y),$(obj)/$F) + +$(obj)/vdso.o: $(obj)/vdso.so + +targets += vdso.lds $(vobjs-y) +targets += vdso32/vdso32.lds $(vobjs32-y) + +# Build the vDSO image C files and link them in. +vdso_img_objs := $(vdso_img-y:%=vdso-image-%.o) +vdso_img_cfiles := $(vdso_img-y:%=vdso-image-%.c) +vdso_img_sodbg := $(vdso_img-y:%=vdso%.so.dbg) +obj-y += $(vdso_img_objs) +targets += $(vdso_img_cfiles) +targets += $(vdso_img_sodbg) $(vdso_img-y:%=vdso%.so) + +CPPFLAGS_vdso.lds += -P -C + +VDSO_LDFLAGS_vdso.lds = -m elf_x86_64 -soname linux-vdso.so.1 --no-undefined \ + -z max-page-size=4096 + +$(obj)/vdso64.so.dbg: $(obj)/vdso.lds $(vobjs) FORCE + $(call if_changed,vdso_and_check) + +HOST_EXTRACFLAGS += -I$(srctree)/tools/include -I$(srctree)/include/uapi -I$(srctree)/arch/$(SUBARCH)/include/uapi +hostprogs += vdso2c + +quiet_cmd_vdso2c = VDSO2C $@ + cmd_vdso2c = $(obj)/vdso2c $< $(<:%.dbg=%) $@ + +$(obj)/vdso-image-%.c: $(obj)/vdso%.so.dbg $(obj)/vdso%.so $(obj)/vdso2c FORCE + $(call if_changed,vdso2c) + +# +# Don't omit frame pointers for ease of userspace debugging, but do +# optimize sibling calls. +# +CFL := $(PROFILING) -mcmodel=small -fPIC -O2 -fasynchronous-unwind-tables -m64 \ + $(filter -g%,$(KBUILD_CFLAGS)) -fno-stack-protector \ + -fno-omit-frame-pointer -foptimize-sibling-calls \ + -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO + +ifdef CONFIG_RETPOLINE +ifneq ($(RETPOLINE_VDSO_CFLAGS),) + CFL += $(RETPOLINE_VDSO_CFLAGS) +endif +endif + +$(vobjs): KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_LTO) $(CC_FLAGS_CFI) $(RANDSTRUCT_CFLAGS) $(GCC_PLUGINS_CFLAGS) $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS)) $(CFL) +$(vobjs): KBUILD_AFLAGS += -DBUILD_VDSO + +# +# vDSO code runs in userspace and -pg doesn't help with profiling anyway. +# +CFLAGS_REMOVE_vclock_gettime.o = -pg +CFLAGS_REMOVE_vdso32/vclock_gettime.o = -pg +CFLAGS_REMOVE_vgetcpu.o = -pg +CFLAGS_REMOVE_vsgx.o = -pg + +# +# X32 processes use x32 vDSO to access 64bit kernel data. +# +# Build x32 vDSO image: +# 1. Compile x32 vDSO as 64bit. +# 2. Convert object files to x32. +# 3. Build x32 VDSO image with x32 objects, which contains 64bit codes +# so that it can reach 64bit address space with 64bit pointers. +# + +CPPFLAGS_vdsox32.lds = $(CPPFLAGS_vdso.lds) +VDSO_LDFLAGS_vdsox32.lds = -m elf32_x86_64 -soname linux-vdso.so.1 \ + -z max-page-size=4096 + +# x32-rebranded versions +vobjx32s-y := $(vobjs-y:.o=-x32.o) + +# same thing, but in the output directory +vobjx32s := $(foreach F,$(vobjx32s-y),$(obj)/$F) + +# Convert 64bit object file to x32 for x32 vDSO. +quiet_cmd_x32 = X32 $@ + cmd_x32 = $(OBJCOPY) -O elf32-x86-64 $< $@ + +$(obj)/%-x32.o: $(obj)/%.o FORCE + $(call if_changed,x32) + +targets += vdsox32.lds $(vobjx32s-y) + +$(obj)/%.so: OBJCOPYFLAGS := -S --remove-section __ex_table +$(obj)/%.so: $(obj)/%.so.dbg FORCE + $(call if_changed,objcopy) + +$(obj)/vdsox32.so.dbg: $(obj)/vdsox32.lds $(vobjx32s) FORCE + $(call if_changed,vdso_and_check) + +CPPFLAGS_vdso32/vdso32.lds = $(CPPFLAGS_vdso.lds) +VDSO_LDFLAGS_vdso32.lds = -m elf_i386 -soname linux-gate.so.1 + +KBUILD_AFLAGS_32 := $(filter-out -m64,$(KBUILD_AFLAGS)) -DBUILD_VDSO +$(obj)/vdso32.so.dbg: KBUILD_AFLAGS = $(KBUILD_AFLAGS_32) +$(obj)/vdso32.so.dbg: asflags-$(CONFIG_X86_64) += -m32 + +KBUILD_CFLAGS_32 := $(filter-out -m64,$(KBUILD_CFLAGS)) +KBUILD_CFLAGS_32 := $(filter-out -mcmodel=kernel,$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out -fno-pic,$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out -mfentry,$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(RANDSTRUCT_CFLAGS),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(GCC_PLUGINS_CFLAGS),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(RETPOLINE_CFLAGS),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_LTO),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 := $(filter-out $(CC_FLAGS_CFI),$(KBUILD_CFLAGS_32)) +KBUILD_CFLAGS_32 += -m32 -msoft-float -mregparm=0 -fpic +KBUILD_CFLAGS_32 += -fno-stack-protector +KBUILD_CFLAGS_32 += $(call cc-option, -foptimize-sibling-calls) +KBUILD_CFLAGS_32 += -fno-omit-frame-pointer +KBUILD_CFLAGS_32 += -DDISABLE_BRANCH_PROFILING + +ifdef CONFIG_RETPOLINE +ifneq ($(RETPOLINE_VDSO_CFLAGS),) + KBUILD_CFLAGS_32 += $(RETPOLINE_VDSO_CFLAGS) +endif +endif + +$(obj)/vdso32.so.dbg: KBUILD_CFLAGS = $(KBUILD_CFLAGS_32) + +$(obj)/vdso32.so.dbg: $(obj)/vdso32/vdso32.lds $(vobjs32) FORCE + $(call if_changed,vdso_and_check) + +# +# The DSO images are built using a special linker script. +# +quiet_cmd_vdso = VDSO $@ + cmd_vdso = $(LD) -o $@ \ + $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \ + -T $(filter %.lds,$^) $(filter %.o,$^) && \ + sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@' + +VDSO_LDFLAGS = -shared --hash-style=both --build-id=sha1 \ + $(call ld-option, --eh-frame-hdr) -Bsymbolic -z noexecstack +GCOV_PROFILE := n + +quiet_cmd_vdso_and_check = VDSO $@ + cmd_vdso_and_check = $(cmd_vdso); $(cmd_vdso_check) + +# +# Install the unstripped copies of vdso*.so. If our toolchain supports +# build-id, install .build-id links as well. +# +quiet_cmd_vdso_install = INSTALL $(@:install_%=%) +define cmd_vdso_install + cp $< "$(MODLIB)/vdso/$(@:install_%=%)"; \ + if readelf -n $< |grep -q 'Build ID'; then \ + buildid=`readelf -n $< |grep 'Build ID' |sed -e 's/^.*Build ID: \(.*\)$$/\1/'`; \ + first=`echo $$buildid | cut -b-2`; \ + last=`echo $$buildid | cut -b3-`; \ + mkdir -p "$(MODLIB)/vdso/.build-id/$$first"; \ + ln -sf "../../$(@:install_%=%)" "$(MODLIB)/vdso/.build-id/$$first/$$last.debug"; \ + fi +endef + +vdso_img_insttargets := $(vdso_img_sodbg:%.dbg=install_%) + +$(MODLIB)/vdso: FORCE + @mkdir -p $(MODLIB)/vdso + +$(vdso_img_insttargets): install_%: $(obj)/%.dbg $(MODLIB)/vdso + $(call cmd,vdso_install) + +PHONY += vdso_install $(vdso_img_insttargets) +vdso_install: $(vdso_img_insttargets) + +clean-files := vdso32.so vdso32.so.dbg vdso64* vdso-image-*.c vdsox32.so* diff --git a/arch/x86/entry/vdso/checkundef.sh b/arch/x86/entry/vdso/checkundef.sh new file mode 100755 index 000000000..7ee90a9b5 --- /dev/null +++ b/arch/x86/entry/vdso/checkundef.sh @@ -0,0 +1,10 @@ +#!/bin/sh +nm="$1" +file="$2" +$nm "$file" | grep '^ *U' > /dev/null 2>&1 +if [ $? -eq 1 ]; then + exit 0 +else + echo "$file: undefined symbols found" >&2 + exit 1 +fi diff --git a/arch/x86/entry/vdso/extable.c b/arch/x86/entry/vdso/extable.c new file mode 100644 index 000000000..afcf5b65b --- /dev/null +++ b/arch/x86/entry/vdso/extable.c @@ -0,0 +1,46 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/err.h> +#include <linux/mm.h> +#include <asm/current.h> +#include <asm/traps.h> +#include <asm/vdso.h> + +struct vdso_exception_table_entry { + int insn, fixup; +}; + +bool fixup_vdso_exception(struct pt_regs *regs, int trapnr, + unsigned long error_code, unsigned long fault_addr) +{ + const struct vdso_image *image = current->mm->context.vdso_image; + const struct vdso_exception_table_entry *extable; + unsigned int nr_entries, i; + unsigned long base; + + /* + * Do not attempt to fixup #DB or #BP. It's impossible to identify + * whether or not a #DB/#BP originated from within an SGX enclave and + * SGX enclaves are currently the only use case for vDSO fixup. + */ + if (trapnr == X86_TRAP_DB || trapnr == X86_TRAP_BP) + return false; + + if (!current->mm->context.vdso) + return false; + + base = (unsigned long)current->mm->context.vdso + image->extable_base; + nr_entries = image->extable_len / (sizeof(*extable)); + extable = image->extable; + + for (i = 0; i < nr_entries; i++) { + if (regs->ip == base + extable[i].insn) { + regs->ip = base + extable[i].fixup; + regs->di = trapnr; + regs->si = error_code; + regs->dx = fault_addr; + return true; + } + } + + return false; +} diff --git a/arch/x86/entry/vdso/extable.h b/arch/x86/entry/vdso/extable.h new file mode 100644 index 000000000..b56f6b012 --- /dev/null +++ b/arch/x86/entry/vdso/extable.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef __VDSO_EXTABLE_H +#define __VDSO_EXTABLE_H + +/* + * Inject exception fixup for vDSO code. Unlike normal exception fixup, + * vDSO uses a dedicated handler the addresses are relative to the overall + * exception table, not each individual entry. + */ +#ifdef __ASSEMBLY__ +#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \ + ASM_VDSO_EXTABLE_HANDLE from to + +.macro ASM_VDSO_EXTABLE_HANDLE from:req to:req + .pushsection __ex_table, "a" + .long (\from) - __ex_table + .long (\to) - __ex_table + .popsection +.endm +#else +#define _ASM_VDSO_EXTABLE_HANDLE(from, to) \ + ".pushsection __ex_table, \"a\"\n" \ + ".long (" #from ") - __ex_table\n" \ + ".long (" #to ") - __ex_table\n" \ + ".popsection\n" +#endif + +#endif /* __VDSO_EXTABLE_H */ diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c new file mode 100644 index 000000000..7d70935b6 --- /dev/null +++ b/arch/x86/entry/vdso/vclock_gettime.c @@ -0,0 +1,85 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Fast user context implementation of clock_gettime, gettimeofday, and time. + * + * Copyright 2006 Andi Kleen, SUSE Labs. + * Copyright 2019 ARM Limited + * + * 32 Bit compat layer by Stefani Seibold <stefani@seibold.net> + * sponsored by Rohde & Schwarz GmbH & Co. KG Munich/Germany + */ +#include <linux/time.h> +#include <linux/kernel.h> +#include <linux/types.h> + +#include "../../../../lib/vdso/gettimeofday.c" + +extern int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz); +extern __kernel_old_time_t __vdso_time(__kernel_old_time_t *t); + +int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) +{ + return __cvdso_gettimeofday(tv, tz); +} + +int gettimeofday(struct __kernel_old_timeval *, struct timezone *) + __attribute__((weak, alias("__vdso_gettimeofday"))); + +__kernel_old_time_t __vdso_time(__kernel_old_time_t *t) +{ + return __cvdso_time(t); +} + +__kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time"))); + + +#if defined(CONFIG_X86_64) && !defined(BUILD_VDSO32_64) +/* both 64-bit and x32 use these */ +extern int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts); +extern int __vdso_clock_getres(clockid_t clock, struct __kernel_timespec *res); + +int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts) +{ + return __cvdso_clock_gettime(clock, ts); +} + +int clock_gettime(clockid_t, struct __kernel_timespec *) + __attribute__((weak, alias("__vdso_clock_gettime"))); + +int __vdso_clock_getres(clockid_t clock, + struct __kernel_timespec *res) +{ + return __cvdso_clock_getres(clock, res); +} +int clock_getres(clockid_t, struct __kernel_timespec *) + __attribute__((weak, alias("__vdso_clock_getres"))); + +#else +/* i386 only */ +extern int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts); +extern int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res); + +int __vdso_clock_gettime(clockid_t clock, struct old_timespec32 *ts) +{ + return __cvdso_clock_gettime32(clock, ts); +} + +int clock_gettime(clockid_t, struct old_timespec32 *) + __attribute__((weak, alias("__vdso_clock_gettime"))); + +int __vdso_clock_gettime64(clockid_t clock, struct __kernel_timespec *ts) +{ + return __cvdso_clock_gettime(clock, ts); +} + +int clock_gettime64(clockid_t, struct __kernel_timespec *) + __attribute__((weak, alias("__vdso_clock_gettime64"))); + +int __vdso_clock_getres(clockid_t clock, struct old_timespec32 *res) +{ + return __cvdso_clock_getres_time32(clock, res); +} + +int clock_getres(clockid_t, struct old_timespec32 *) + __attribute__((weak, alias("__vdso_clock_getres"))); +#endif diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S new file mode 100644 index 000000000..bafa73f09 --- /dev/null +++ b/arch/x86/entry/vdso/vdso-layout.lds.S @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <asm/vdso.h> + +/* + * Linker script for vDSO. This is an ELF shared object prelinked to + * its virtual address, and with only one read-only segment. + * This script controls its layout. + */ + +SECTIONS +{ + /* + * User/kernel shared data is before the vDSO. This may be a little + * uglier than putting it after the vDSO, but it avoids issues with + * non-allocatable things that dangle past the end of the PT_LOAD + * segment. + */ + + vvar_start = . - 4 * PAGE_SIZE; + vvar_page = vvar_start; + + /* Place all vvars at the offsets in asm/vvar.h. */ +#define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset; +#include <asm/vvar.h> +#undef EMIT_VVAR + + pvclock_page = vvar_start + PAGE_SIZE; + hvclock_page = vvar_start + 2 * PAGE_SIZE; + timens_page = vvar_start + 3 * PAGE_SIZE; + +#undef _ASM_X86_VVAR_H + /* Place all vvars in timens too at the offsets in asm/vvar.h. */ +#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset; +#include <asm/vvar.h> +#undef EMIT_VVAR + + . = SIZEOF_HEADERS; + + .hash : { *(.hash) } :text + .gnu.hash : { *(.gnu.hash) } + .dynsym : { *(.dynsym) } + .dynstr : { *(.dynstr) } + .gnu.version : { *(.gnu.version) } + .gnu.version_d : { *(.gnu.version_d) } + .gnu.version_r : { *(.gnu.version_r) } + + .dynamic : { *(.dynamic) } :text :dynamic + + .rodata : { + *(.rodata*) + *(.data*) + *(.sdata*) + *(.got.plt) *(.got) + *(.gnu.linkonce.d.*) + *(.bss*) + *(.dynbss*) + *(.gnu.linkonce.b.*) + } :text + + /* + * Discard .note.gnu.property sections which are unused and have + * different alignment requirement from vDSO note sections. + */ + /DISCARD/ : { + *(.note.gnu.property) + } + .note : { *(.note.*) } :text :note + + .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr + .eh_frame : { KEEP (*(.eh_frame)) } :text + + + /* + * Text is well-separated from actual data: there's plenty of + * stuff that isn't used at runtime in between. + */ + + .text : { + *(.text*) + } :text =0x90909090, + + + + .altinstructions : { *(.altinstructions) } :text + .altinstr_replacement : { *(.altinstr_replacement) } :text + + __ex_table : { *(__ex_table) } :text + + /DISCARD/ : { + *(.discard) + *(.discard.*) + *(__bug_table) + } +} + +/* + * Very old versions of ld do not recognize this name token; use the constant. + */ +#define PT_GNU_EH_FRAME 0x6474e550 + +/* + * We must supply the ELF program headers explicitly to get just one + * PT_LOAD segment, and set the flags explicitly to make segments read-only. + */ +PHDRS +{ + text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */ + dynamic PT_DYNAMIC FLAGS(4); /* PF_R */ + note PT_NOTE FLAGS(4); /* PF_R */ + eh_frame_hdr PT_GNU_EH_FRAME; +} diff --git a/arch/x86/entry/vdso/vdso-note.S b/arch/x86/entry/vdso/vdso-note.S new file mode 100644 index 000000000..794231701 --- /dev/null +++ b/arch/x86/entry/vdso/vdso-note.S @@ -0,0 +1,15 @@ +/* + * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text. + * Here we can supply some information useful to userland. + */ + +#include <linux/build-salt.h> +#include <linux/uts.h> +#include <linux/version.h> +#include <linux/elfnote.h> + +ELFNOTE_START(Linux, 0, "a") + .long LINUX_VERSION_CODE +ELFNOTE_END + +BUILD_SALT diff --git a/arch/x86/entry/vdso/vdso.lds.S b/arch/x86/entry/vdso/vdso.lds.S new file mode 100644 index 000000000..e8c60ae7a --- /dev/null +++ b/arch/x86/entry/vdso/vdso.lds.S @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Linker script for 64-bit vDSO. + * We #include the file to define the layout details. + * + * This file defines the version script giving the user-exported symbols in + * the DSO. + */ + +#define BUILD_VDSO64 + +#include "vdso-layout.lds.S" + +/* + * This controls what userland symbols we export from the vDSO. + */ +VERSION { + LINUX_2.6 { + global: + clock_gettime; + __vdso_clock_gettime; + gettimeofday; + __vdso_gettimeofday; + getcpu; + __vdso_getcpu; + time; + __vdso_time; + clock_getres; + __vdso_clock_getres; +#ifdef CONFIG_X86_SGX + __vdso_sgx_enter_enclave; +#endif + local: *; + }; +} diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c new file mode 100644 index 000000000..90d15f2a7 --- /dev/null +++ b/arch/x86/entry/vdso/vdso2c.c @@ -0,0 +1,254 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * vdso2c - A vdso image preparation tool + * Copyright (c) 2014 Andy Lutomirski and others + * + * vdso2c requires stripped and unstripped input. It would be trivial + * to fully strip the input in here, but, for reasons described below, + * we need to write a section table. Doing this is more or less + * equivalent to dropping all non-allocatable sections, but it's + * easier to let objcopy handle that instead of doing it ourselves. + * If we ever need to do something fancier than what objcopy provides, + * it would be straightforward to add here. + * + * We're keep a section table for a few reasons: + * + * The Go runtime had a couple of bugs: it would read the section + * table to try to figure out how many dynamic symbols there were (it + * shouldn't have looked at the section table at all) and, if there + * were no SHT_SYNDYM section table entry, it would use an + * uninitialized value for the number of symbols. An empty DYNSYM + * table would work, but I see no reason not to write a valid one (and + * keep full performance for old Go programs). This hack is only + * needed on x86_64. + * + * The bug was introduced on 2012-08-31 by: + * https://code.google.com/p/go/source/detail?r=56ea40aac72b + * and was fixed on 2014-06-13 by: + * https://code.google.com/p/go/source/detail?r=fc1cd5e12595 + * + * Binutils has issues debugging the vDSO: it reads the section table to + * find SHT_NOTE; it won't look at PT_NOTE for the in-memory vDSO, which + * would break build-id if we removed the section table. Binutils + * also requires that shstrndx != 0. See: + * https://sourceware.org/bugzilla/show_bug.cgi?id=17064 + * + * elfutils might not look for PT_NOTE if there is a section table at + * all. I don't know whether this matters for any practical purpose. + * + * For simplicity, rather than hacking up a partial section table, we + * just write a mostly complete one. We omit non-dynamic symbols, + * though, since they're rather large. + * + * Once binutils gets fixed, we might be able to drop this for all but + * the 64-bit vdso, since build-id only works in kernel RPMs, and + * systems that update to new enough kernel RPMs will likely update + * binutils in sync. build-id has never worked for home-built kernel + * RPMs without manual symlinking, and I suspect that no one ever does + * that. + */ + +#include <inttypes.h> +#include <stdint.h> +#include <unistd.h> +#include <stdarg.h> +#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <fcntl.h> +#include <err.h> + +#include <sys/mman.h> +#include <sys/types.h> + +#include <tools/le_byteshift.h> + +#include <linux/elf.h> +#include <linux/types.h> +#include <linux/kernel.h> + +const char *outfilename; + +/* Symbols that we need in vdso2c. */ +enum { + sym_vvar_start, + sym_vvar_page, + sym_pvclock_page, + sym_hvclock_page, + sym_timens_page, +}; + +const int special_pages[] = { + sym_vvar_page, + sym_pvclock_page, + sym_hvclock_page, + sym_timens_page, +}; + +struct vdso_sym { + const char *name; + bool export; +}; + +struct vdso_sym required_syms[] = { + [sym_vvar_start] = {"vvar_start", true}, + [sym_vvar_page] = {"vvar_page", true}, + [sym_pvclock_page] = {"pvclock_page", true}, + [sym_hvclock_page] = {"hvclock_page", true}, + [sym_timens_page] = {"timens_page", true}, + {"VDSO32_NOTE_MASK", true}, + {"__kernel_vsyscall", true}, + {"__kernel_sigreturn", true}, + {"__kernel_rt_sigreturn", true}, + {"int80_landing_pad", true}, + {"vdso32_rt_sigreturn_landing_pad", true}, + {"vdso32_sigreturn_landing_pad", true}, +}; + +__attribute__((format(printf, 1, 2))) __attribute__((noreturn)) +static void fail(const char *format, ...) +{ + va_list ap; + va_start(ap, format); + fprintf(stderr, "Error: "); + vfprintf(stderr, format, ap); + if (outfilename) + unlink(outfilename); + exit(1); + va_end(ap); +} + +/* + * Evil macros for little-endian reads and writes + */ +#define GLE(x, bits, ifnot) \ + __builtin_choose_expr( \ + (sizeof(*(x)) == bits/8), \ + (__typeof__(*(x)))get_unaligned_le##bits(x), ifnot) + +extern void bad_get_le(void); +#define LAST_GLE(x) \ + __builtin_choose_expr(sizeof(*(x)) == 1, *(x), bad_get_le()) + +#define GET_LE(x) \ + GLE(x, 64, GLE(x, 32, GLE(x, 16, LAST_GLE(x)))) + +#define PLE(x, val, bits, ifnot) \ + __builtin_choose_expr( \ + (sizeof(*(x)) == bits/8), \ + put_unaligned_le##bits((val), (x)), ifnot) + +extern void bad_put_le(void); +#define LAST_PLE(x, val) \ + __builtin_choose_expr(sizeof(*(x)) == 1, *(x) = (val), bad_put_le()) + +#define PUT_LE(x, val) \ + PLE(x, val, 64, PLE(x, val, 32, PLE(x, val, 16, LAST_PLE(x, val)))) + + +#define NSYMS ARRAY_SIZE(required_syms) + +#define BITSFUNC3(name, bits, suffix) name##bits##suffix +#define BITSFUNC2(name, bits, suffix) BITSFUNC3(name, bits, suffix) +#define BITSFUNC(name) BITSFUNC2(name, ELF_BITS, ) + +#define INT_BITS BITSFUNC2(int, ELF_BITS, _t) + +#define ELF_BITS_XFORM2(bits, x) Elf##bits##_##x +#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x) +#define ELF(x) ELF_BITS_XFORM(ELF_BITS, x) + +#define ELF_BITS 64 +#include "vdso2c.h" +#undef ELF_BITS + +#define ELF_BITS 32 +#include "vdso2c.h" +#undef ELF_BITS + +static void go(void *raw_addr, size_t raw_len, + void *stripped_addr, size_t stripped_len, + FILE *outfile, const char *name) +{ + Elf64_Ehdr *hdr = (Elf64_Ehdr *)raw_addr; + + if (hdr->e_ident[EI_CLASS] == ELFCLASS64) { + go64(raw_addr, raw_len, stripped_addr, stripped_len, + outfile, name); + } else if (hdr->e_ident[EI_CLASS] == ELFCLASS32) { + go32(raw_addr, raw_len, stripped_addr, stripped_len, + outfile, name); + } else { + fail("unknown ELF class\n"); + } +} + +static void map_input(const char *name, void **addr, size_t *len, int prot) +{ + off_t tmp_len; + + int fd = open(name, O_RDONLY); + if (fd == -1) + err(1, "open(%s)", name); + + tmp_len = lseek(fd, 0, SEEK_END); + if (tmp_len == (off_t)-1) + err(1, "lseek"); + *len = (size_t)tmp_len; + + *addr = mmap(NULL, tmp_len, prot, MAP_PRIVATE, fd, 0); + if (*addr == MAP_FAILED) + err(1, "mmap"); + + close(fd); +} + +int main(int argc, char **argv) +{ + size_t raw_len, stripped_len; + void *raw_addr, *stripped_addr; + FILE *outfile; + char *name, *tmp; + int namelen; + + if (argc != 4) { + printf("Usage: vdso2c RAW_INPUT STRIPPED_INPUT OUTPUT\n"); + return 1; + } + + /* + * Figure out the struct name. If we're writing to a .so file, + * generate raw output instead. + */ + name = strdup(argv[3]); + namelen = strlen(name); + if (namelen >= 3 && !strcmp(name + namelen - 3, ".so")) { + name = NULL; + } else { + tmp = strrchr(name, '/'); + if (tmp) + name = tmp + 1; + tmp = strchr(name, '.'); + if (tmp) + *tmp = '\0'; + for (tmp = name; *tmp; tmp++) + if (*tmp == '-') + *tmp = '_'; + } + + map_input(argv[1], &raw_addr, &raw_len, PROT_READ); + map_input(argv[2], &stripped_addr, &stripped_len, PROT_READ); + + outfilename = argv[3]; + outfile = fopen(outfilename, "w"); + if (!outfile) + err(1, "fopen(%s)", outfilename); + + go(raw_addr, raw_len, stripped_addr, stripped_len, outfile, name); + + munmap(raw_addr, raw_len); + munmap(stripped_addr, stripped_len); + fclose(outfile); + + return 0; +} diff --git a/arch/x86/entry/vdso/vdso2c.h b/arch/x86/entry/vdso/vdso2c.h new file mode 100644 index 000000000..5264daa88 --- /dev/null +++ b/arch/x86/entry/vdso/vdso2c.h @@ -0,0 +1,222 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * This file is included twice from vdso2c.c. It generates code for 32-bit + * and 64-bit vDSOs. We need both for 64-bit builds, since 32-bit vDSOs + * are built for 32-bit userspace. + */ + +static void BITSFUNC(copy)(FILE *outfile, const unsigned char *data, size_t len) +{ + size_t i; + + for (i = 0; i < len; i++) { + if (i % 10 == 0) + fprintf(outfile, "\n\t"); + fprintf(outfile, "0x%02X, ", (int)(data)[i]); + } +} + + +/* + * Extract a section from the input data into a standalone blob. Used to + * capture kernel-only data that needs to persist indefinitely, e.g. the + * exception fixup tables, but only in the kernel, i.e. the section can + * be stripped from the final vDSO image. + */ +static void BITSFUNC(extract)(const unsigned char *data, size_t data_len, + FILE *outfile, ELF(Shdr) *sec, const char *name) +{ + unsigned long offset; + size_t len; + + offset = (unsigned long)GET_LE(&sec->sh_offset); + len = (size_t)GET_LE(&sec->sh_size); + + if (offset + len > data_len) + fail("section to extract overruns input data"); + + fprintf(outfile, "static const unsigned char %s[%zu] = {", name, len); + BITSFUNC(copy)(outfile, data + offset, len); + fprintf(outfile, "\n};\n\n"); +} + +static void BITSFUNC(go)(void *raw_addr, size_t raw_len, + void *stripped_addr, size_t stripped_len, + FILE *outfile, const char *image_name) +{ + int found_load = 0; + unsigned long load_size = -1; /* Work around bogus warning */ + unsigned long mapping_size; + ELF(Ehdr) *hdr = (ELF(Ehdr) *)raw_addr; + unsigned long i, syms_nr; + ELF(Shdr) *symtab_hdr = NULL, *strtab_hdr, *secstrings_hdr, + *alt_sec = NULL, *extable_sec = NULL; + ELF(Dyn) *dyn = 0, *dyn_end = 0; + const char *secstrings; + INT_BITS syms[NSYMS] = {}; + + ELF(Phdr) *pt = (ELF(Phdr) *)(raw_addr + GET_LE(&hdr->e_phoff)); + + if (GET_LE(&hdr->e_type) != ET_DYN) + fail("input is not a shared object\n"); + + /* Walk the segment table. */ + for (i = 0; i < GET_LE(&hdr->e_phnum); i++) { + if (GET_LE(&pt[i].p_type) == PT_LOAD) { + if (found_load) + fail("multiple PT_LOAD segs\n"); + + if (GET_LE(&pt[i].p_offset) != 0 || + GET_LE(&pt[i].p_vaddr) != 0) + fail("PT_LOAD in wrong place\n"); + + if (GET_LE(&pt[i].p_memsz) != GET_LE(&pt[i].p_filesz)) + fail("cannot handle memsz != filesz\n"); + + load_size = GET_LE(&pt[i].p_memsz); + found_load = 1; + } else if (GET_LE(&pt[i].p_type) == PT_DYNAMIC) { + dyn = raw_addr + GET_LE(&pt[i].p_offset); + dyn_end = raw_addr + GET_LE(&pt[i].p_offset) + + GET_LE(&pt[i].p_memsz); + } + } + if (!found_load) + fail("no PT_LOAD seg\n"); + + if (stripped_len < load_size) + fail("stripped input is too short\n"); + + if (!dyn) + fail("input has no PT_DYNAMIC section -- your toolchain is buggy\n"); + + /* Walk the dynamic table */ + for (i = 0; dyn + i < dyn_end && + GET_LE(&dyn[i].d_tag) != DT_NULL; i++) { + typeof(dyn[i].d_tag) tag = GET_LE(&dyn[i].d_tag); + if (tag == DT_REL || tag == DT_RELSZ || tag == DT_RELA || + tag == DT_RELENT || tag == DT_TEXTREL) + fail("vdso image contains dynamic relocations\n"); + } + + /* Walk the section table */ + secstrings_hdr = raw_addr + GET_LE(&hdr->e_shoff) + + GET_LE(&hdr->e_shentsize)*GET_LE(&hdr->e_shstrndx); + secstrings = raw_addr + GET_LE(&secstrings_hdr->sh_offset); + for (i = 0; i < GET_LE(&hdr->e_shnum); i++) { + ELF(Shdr) *sh = raw_addr + GET_LE(&hdr->e_shoff) + + GET_LE(&hdr->e_shentsize) * i; + if (GET_LE(&sh->sh_type) == SHT_SYMTAB) + symtab_hdr = sh; + + if (!strcmp(secstrings + GET_LE(&sh->sh_name), + ".altinstructions")) + alt_sec = sh; + if (!strcmp(secstrings + GET_LE(&sh->sh_name), "__ex_table")) + extable_sec = sh; + } + + if (!symtab_hdr) + fail("no symbol table\n"); + + strtab_hdr = raw_addr + GET_LE(&hdr->e_shoff) + + GET_LE(&hdr->e_shentsize) * GET_LE(&symtab_hdr->sh_link); + + syms_nr = GET_LE(&symtab_hdr->sh_size) / GET_LE(&symtab_hdr->sh_entsize); + /* Walk the symbol table */ + for (i = 0; i < syms_nr; i++) { + unsigned int k; + ELF(Sym) *sym = raw_addr + GET_LE(&symtab_hdr->sh_offset) + + GET_LE(&symtab_hdr->sh_entsize) * i; + const char *sym_name = raw_addr + + GET_LE(&strtab_hdr->sh_offset) + + GET_LE(&sym->st_name); + + for (k = 0; k < NSYMS; k++) { + if (!strcmp(sym_name, required_syms[k].name)) { + if (syms[k]) { + fail("duplicate symbol %s\n", + required_syms[k].name); + } + + /* + * Careful: we use negative addresses, but + * st_value is unsigned, so we rely + * on syms[k] being a signed type of the + * correct width. + */ + syms[k] = GET_LE(&sym->st_value); + } + } + } + + /* Validate mapping addresses. */ + for (i = 0; i < sizeof(special_pages) / sizeof(special_pages[0]); i++) { + INT_BITS symval = syms[special_pages[i]]; + + if (!symval) + continue; /* The mapping isn't used; ignore it. */ + + if (symval % 4096) + fail("%s must be a multiple of 4096\n", + required_syms[i].name); + if (symval + 4096 < syms[sym_vvar_start]) + fail("%s underruns vvar_start\n", + required_syms[i].name); + if (symval + 4096 > 0) + fail("%s is on the wrong side of the vdso text\n", + required_syms[i].name); + } + if (syms[sym_vvar_start] % 4096) + fail("vvar_begin must be a multiple of 4096\n"); + + if (!image_name) { + fwrite(stripped_addr, stripped_len, 1, outfile); + return; + } + + mapping_size = (stripped_len + 4095) / 4096 * 4096; + + fprintf(outfile, "/* AUTOMATICALLY GENERATED -- DO NOT EDIT */\n\n"); + fprintf(outfile, "#include <linux/linkage.h>\n"); + fprintf(outfile, "#include <asm/page_types.h>\n"); + fprintf(outfile, "#include <asm/vdso.h>\n"); + fprintf(outfile, "\n"); + fprintf(outfile, + "static unsigned char raw_data[%lu] __ro_after_init __aligned(PAGE_SIZE) = {", + mapping_size); + for (i = 0; i < stripped_len; i++) { + if (i % 10 == 0) + fprintf(outfile, "\n\t"); + fprintf(outfile, "0x%02X, ", + (int)((unsigned char *)stripped_addr)[i]); + } + fprintf(outfile, "\n};\n\n"); + if (extable_sec) + BITSFUNC(extract)(raw_addr, raw_len, outfile, + extable_sec, "extable"); + + fprintf(outfile, "const struct vdso_image %s = {\n", image_name); + fprintf(outfile, "\t.data = raw_data,\n"); + fprintf(outfile, "\t.size = %lu,\n", mapping_size); + if (alt_sec) { + fprintf(outfile, "\t.alt = %lu,\n", + (unsigned long)GET_LE(&alt_sec->sh_offset)); + fprintf(outfile, "\t.alt_len = %lu,\n", + (unsigned long)GET_LE(&alt_sec->sh_size)); + } + if (extable_sec) { + fprintf(outfile, "\t.extable_base = %lu,\n", + (unsigned long)GET_LE(&extable_sec->sh_offset)); + fprintf(outfile, "\t.extable_len = %lu,\n", + (unsigned long)GET_LE(&extable_sec->sh_size)); + fprintf(outfile, "\t.extable = extable,\n"); + } + + for (i = 0; i < NSYMS; i++) { + if (required_syms[i].export && syms[i]) + fprintf(outfile, "\t.sym_%s = %" PRIi64 ",\n", + required_syms[i].name, (int64_t)syms[i]); + } + fprintf(outfile, "};\n"); +} diff --git a/arch/x86/entry/vdso/vdso32-setup.c b/arch/x86/entry/vdso/vdso32-setup.c new file mode 100644 index 000000000..43842fade --- /dev/null +++ b/arch/x86/entry/vdso/vdso32-setup.c @@ -0,0 +1,99 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * (C) Copyright 2002 Linus Torvalds + * Portions based on the vdso-randomization code from exec-shield: + * Copyright(C) 2005-2006, Red Hat, Inc., Ingo Molnar + * + * This file contains the needed initializations to support sysenter. + */ + +#include <linux/init.h> +#include <linux/smp.h> +#include <linux/kernel.h> +#include <linux/mm_types.h> +#include <linux/elf.h> + +#include <asm/processor.h> +#include <asm/vdso.h> + +#ifdef CONFIG_COMPAT_VDSO +#define VDSO_DEFAULT 0 +#else +#define VDSO_DEFAULT 1 +#endif + +/* + * Should the kernel map a VDSO page into processes and pass its + * address down to glibc upon exec()? + */ +unsigned int __read_mostly vdso32_enabled = VDSO_DEFAULT; + +static int __init vdso32_setup(char *s) +{ + vdso32_enabled = simple_strtoul(s, NULL, 0); + + if (vdso32_enabled > 1) { + pr_warn("vdso32 values other than 0 and 1 are no longer allowed; vdso disabled\n"); + vdso32_enabled = 0; + } + + return 1; +} + +/* + * For consistency, the argument vdso32=[012] affects the 32-bit vDSO + * behavior on both 64-bit and 32-bit kernels. + * On 32-bit kernels, vdso=[012] means the same thing. + */ +__setup("vdso32=", vdso32_setup); + +#ifdef CONFIG_X86_32 +__setup_param("vdso=", vdso_setup, vdso32_setup, 0); +#endif + +int __init sysenter_setup(void) +{ + init_vdso_image(&vdso_image_32); + + return 0; +} + +#ifdef CONFIG_X86_64 + +subsys_initcall(sysenter_setup); + +#ifdef CONFIG_SYSCTL +/* Register vsyscall32 into the ABI table */ +#include <linux/sysctl.h> + +static struct ctl_table abi_table2[] = { + { + .procname = "vsyscall32", + .data = &vdso32_enabled, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, + {} +}; + +static struct ctl_table abi_root_table2[] = { + { + .procname = "abi", + .mode = 0555, + .child = abi_table2 + }, + {} +}; + +static __init int ia32_binfmt_init(void) +{ + register_sysctl_table(abi_root_table2); + return 0; +} +__initcall(ia32_binfmt_init); +#endif /* CONFIG_SYSCTL */ + +#endif /* CONFIG_X86_64 */ diff --git a/arch/x86/entry/vdso/vdso32/.gitignore b/arch/x86/entry/vdso/vdso32/.gitignore new file mode 100644 index 000000000..516738484 --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +vdso32.lds diff --git a/arch/x86/entry/vdso/vdso32/note.S b/arch/x86/entry/vdso/vdso32/note.S new file mode 100644 index 000000000..2cbd39939 --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/note.S @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * This supplies .note.* sections to go into the PT_NOTE inside the vDSO text. + * Here we can supply some information useful to userland. + */ + +#include <linux/build-salt.h> +#include <linux/version.h> +#include <linux/elfnote.h> + +/* Ideally this would use UTS_NAME, but using a quoted string here + doesn't work. Remember to change this when changing the + kernel's name. */ +ELFNOTE_START(Linux, 0, "a") + .long LINUX_VERSION_CODE +ELFNOTE_END + +BUILD_SALT diff --git a/arch/x86/entry/vdso/vdso32/sigreturn.S b/arch/x86/entry/vdso/vdso32/sigreturn.S new file mode 100644 index 000000000..1bd068f72 --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/sigreturn.S @@ -0,0 +1,140 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#include <linux/linkage.h> +#include <asm/unistd_32.h> +#include <asm/asm-offsets.h> + +#ifndef SYSCALL_ENTER_KERNEL +#define SYSCALL_ENTER_KERNEL int $0x80 +#endif + + .text + .globl __kernel_sigreturn + .type __kernel_sigreturn,@function + nop /* this guy is needed for .LSTARTFDEDLSI1 below (watch for HACK) */ + ALIGN +__kernel_sigreturn: +.LSTART_sigreturn: + popl %eax /* XXX does this mean it needs unwind info? */ + movl $__NR_sigreturn, %eax + SYSCALL_ENTER_KERNEL +.LEND_sigreturn: +SYM_INNER_LABEL(vdso32_sigreturn_landing_pad, SYM_L_GLOBAL) + nop + .size __kernel_sigreturn,.-.LSTART_sigreturn + + .globl __kernel_rt_sigreturn + .type __kernel_rt_sigreturn,@function + ALIGN +__kernel_rt_sigreturn: +.LSTART_rt_sigreturn: + movl $__NR_rt_sigreturn, %eax + SYSCALL_ENTER_KERNEL +.LEND_rt_sigreturn: +SYM_INNER_LABEL(vdso32_rt_sigreturn_landing_pad, SYM_L_GLOBAL) + nop + .size __kernel_rt_sigreturn,.-.LSTART_rt_sigreturn + .previous + + .section .eh_frame,"a",@progbits +.LSTARTFRAMEDLSI1: + .long .LENDCIEDLSI1-.LSTARTCIEDLSI1 +.LSTARTCIEDLSI1: + .long 0 /* CIE ID */ + .byte 1 /* Version number */ + .string "zRS" /* NUL-terminated augmentation string */ + .uleb128 1 /* Code alignment factor */ + .sleb128 -4 /* Data alignment factor */ + .byte 8 /* Return address register column */ + .uleb128 1 /* Augmentation value length */ + .byte 0x1b /* DW_EH_PE_pcrel|DW_EH_PE_sdata4. */ + .byte 0 /* DW_CFA_nop */ + .align 4 +.LENDCIEDLSI1: + .long .LENDFDEDLSI1-.LSTARTFDEDLSI1 /* Length FDE */ +.LSTARTFDEDLSI1: + .long .LSTARTFDEDLSI1-.LSTARTFRAMEDLSI1 /* CIE pointer */ + /* HACK: The dwarf2 unwind routines will subtract 1 from the + return address to get an address in the middle of the + presumed call instruction. Since we didn't get here via + a call, we need to include the nop before the real start + to make up for it. */ + .long .LSTART_sigreturn-1-. /* PC-relative start address */ + .long .LEND_sigreturn-.LSTART_sigreturn+1 + .uleb128 0 /* Augmentation */ + /* What follows are the instructions for the table generation. + We record the locations of each register saved. This is + complicated by the fact that the "CFA" is always assumed to + be the value of the stack pointer in the caller. This means + that we must define the CFA of this body of code to be the + saved value of the stack pointer in the sigcontext. Which + also means that there is no fixed relation to the other + saved registers, which means that we must use DW_CFA_expression + to compute their addresses. It also means that when we + adjust the stack with the popl, we have to do it all over again. */ + +#define do_cfa_expr(offset) \ + .byte 0x0f; /* DW_CFA_def_cfa_expression */ \ + .uleb128 1f-0f; /* length */ \ +0: .byte 0x74; /* DW_OP_breg4 */ \ + .sleb128 offset; /* offset */ \ + .byte 0x06; /* DW_OP_deref */ \ +1: + +#define do_expr(regno, offset) \ + .byte 0x10; /* DW_CFA_expression */ \ + .uleb128 regno; /* regno */ \ + .uleb128 1f-0f; /* length */ \ +0: .byte 0x74; /* DW_OP_breg4 */ \ + .sleb128 offset; /* offset */ \ +1: + + do_cfa_expr(IA32_SIGCONTEXT_sp+4) + do_expr(0, IA32_SIGCONTEXT_ax+4) + do_expr(1, IA32_SIGCONTEXT_cx+4) + do_expr(2, IA32_SIGCONTEXT_dx+4) + do_expr(3, IA32_SIGCONTEXT_bx+4) + do_expr(5, IA32_SIGCONTEXT_bp+4) + do_expr(6, IA32_SIGCONTEXT_si+4) + do_expr(7, IA32_SIGCONTEXT_di+4) + do_expr(8, IA32_SIGCONTEXT_ip+4) + + .byte 0x42 /* DW_CFA_advance_loc 2 -- nop; popl eax. */ + + do_cfa_expr(IA32_SIGCONTEXT_sp) + do_expr(0, IA32_SIGCONTEXT_ax) + do_expr(1, IA32_SIGCONTEXT_cx) + do_expr(2, IA32_SIGCONTEXT_dx) + do_expr(3, IA32_SIGCONTEXT_bx) + do_expr(5, IA32_SIGCONTEXT_bp) + do_expr(6, IA32_SIGCONTEXT_si) + do_expr(7, IA32_SIGCONTEXT_di) + do_expr(8, IA32_SIGCONTEXT_ip) + + .align 4 +.LENDFDEDLSI1: + + .long .LENDFDEDLSI2-.LSTARTFDEDLSI2 /* Length FDE */ +.LSTARTFDEDLSI2: + .long .LSTARTFDEDLSI2-.LSTARTFRAMEDLSI1 /* CIE pointer */ + /* HACK: See above wrt unwind library assumptions. */ + .long .LSTART_rt_sigreturn-1-. /* PC-relative start address */ + .long .LEND_rt_sigreturn-.LSTART_rt_sigreturn+1 + .uleb128 0 /* Augmentation */ + /* What follows are the instructions for the table generation. + We record the locations of each register saved. This is + slightly less complicated than the above, since we don't + modify the stack pointer in the process. */ + + do_cfa_expr(IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_sp) + do_expr(0, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ax) + do_expr(1, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_cx) + do_expr(2, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_dx) + do_expr(3, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bx) + do_expr(5, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_bp) + do_expr(6, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_si) + do_expr(7, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_di) + do_expr(8, IA32_RT_SIGFRAME_sigcontext-4 + IA32_SIGCONTEXT_ip) + + .align 4 +.LENDFDEDLSI2: + .previous diff --git a/arch/x86/entry/vdso/vdso32/system_call.S b/arch/x86/entry/vdso/vdso32/system_call.S new file mode 100644 index 000000000..d33c6513f --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/system_call.S @@ -0,0 +1,85 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * AT_SYSINFO entry point +*/ + +#include <linux/linkage.h> +#include <asm/dwarf2.h> +#include <asm/cpufeatures.h> +#include <asm/alternative.h> + + .text + .globl __kernel_vsyscall + .type __kernel_vsyscall,@function + ALIGN +__kernel_vsyscall: + CFI_STARTPROC + /* + * Reshuffle regs so that all of any of the entry instructions + * will preserve enough state. + * + * A really nice entry sequence would be: + * pushl %edx + * pushl %ecx + * movl %esp, %ecx + * + * Unfortunately, naughty Android versions between July and December + * 2015 actually hardcode the traditional Linux SYSENTER entry + * sequence. That is severely broken for a number of reasons (ask + * anyone with an AMD CPU, for example). Nonetheless, we try to keep + * it working approximately as well as it ever worked. + * + * This link may elucidate some of the history: + * https://android-review.googlesource.com/#/q/Iac3295376d61ef83e713ac9b528f3b50aa780cd7 + * personally, I find it hard to understand what's going on there. + * + * Note to future user developers: DO NOT USE SYSENTER IN YOUR CODE. + * Execute an indirect call to the address in the AT_SYSINFO auxv + * entry. That is the ONLY correct way to make a fast 32-bit system + * call on Linux. (Open-coding int $0x80 is also fine, but it's + * slow.) + */ + pushl %ecx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ecx, 0 + pushl %edx + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET edx, 0 + pushl %ebp + CFI_ADJUST_CFA_OFFSET 4 + CFI_REL_OFFSET ebp, 0 + + #define SYSENTER_SEQUENCE "movl %esp, %ebp; sysenter" + #define SYSCALL_SEQUENCE "movl %ecx, %ebp; syscall" + +#ifdef CONFIG_X86_64 + /* If SYSENTER (Intel) or SYSCALL32 (AMD) is available, use it. */ + ALTERNATIVE_2 "", SYSENTER_SEQUENCE, X86_FEATURE_SYSENTER32, \ + SYSCALL_SEQUENCE, X86_FEATURE_SYSCALL32 +#else + ALTERNATIVE "", SYSENTER_SEQUENCE, X86_FEATURE_SEP +#endif + + /* Enter using int $0x80 */ + int $0x80 +SYM_INNER_LABEL(int80_landing_pad, SYM_L_GLOBAL) + + /* + * Restore EDX and ECX in case they were clobbered. EBP is not + * clobbered (the kernel restores it), but it's cleaner and + * probably faster to pop it than to adjust ESP using addl. + */ + popl %ebp + CFI_RESTORE ebp + CFI_ADJUST_CFA_OFFSET -4 + popl %edx + CFI_RESTORE edx + CFI_ADJUST_CFA_OFFSET -4 + popl %ecx + CFI_RESTORE ecx + CFI_ADJUST_CFA_OFFSET -4 + RET + CFI_ENDPROC + + .size __kernel_vsyscall,.-__kernel_vsyscall + .previous diff --git a/arch/x86/entry/vdso/vdso32/vclock_gettime.c b/arch/x86/entry/vdso/vdso32/vclock_gettime.c new file mode 100644 index 000000000..283ed9d00 --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/vclock_gettime.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +#define BUILD_VDSO32 + +#ifdef CONFIG_X86_64 + +/* + * in case of a 32 bit VDSO for a 64 bit kernel fake a 32 bit kernel + * configuration + */ +#undef CONFIG_64BIT +#undef CONFIG_X86_64 +#undef CONFIG_COMPAT +#undef CONFIG_PGTABLE_LEVELS +#undef CONFIG_ILLEGAL_POINTER_VALUE +#undef CONFIG_SPARSEMEM_VMEMMAP +#undef CONFIG_NR_CPUS +#undef CONFIG_PARAVIRT_XXL + +#define CONFIG_X86_32 1 +#define CONFIG_PGTABLE_LEVELS 2 +#define CONFIG_PAGE_OFFSET 0 +#define CONFIG_ILLEGAL_POINTER_VALUE 0 +#define CONFIG_NR_CPUS 1 + +#define BUILD_VDSO32_64 + +#endif + +#include "../vclock_gettime.c" diff --git a/arch/x86/entry/vdso/vdso32/vdso32.lds.S b/arch/x86/entry/vdso/vdso32/vdso32.lds.S new file mode 100644 index 000000000..c7720995a --- /dev/null +++ b/arch/x86/entry/vdso/vdso32/vdso32.lds.S @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Linker script for 32-bit vDSO. + * We #include the file to define the layout details. + * + * This file defines the version script giving the user-exported symbols in + * the DSO. + */ + +#include <asm/page.h> + +#define BUILD_VDSO32 + +#include "../vdso-layout.lds.S" + +/* The ELF entry point can be used to set the AT_SYSINFO value. */ +ENTRY(__kernel_vsyscall); + +/* + * This controls what userland symbols we export from the vDSO. + */ +VERSION +{ + LINUX_2.6 { + global: + __vdso_clock_gettime; + __vdso_gettimeofday; + __vdso_time; + __vdso_clock_getres; + __vdso_clock_gettime64; + }; + + LINUX_2.5 { + global: + __kernel_vsyscall; + __kernel_sigreturn; + __kernel_rt_sigreturn; + local: *; + }; +} diff --git a/arch/x86/entry/vdso/vdsox32.lds.S b/arch/x86/entry/vdso/vdsox32.lds.S new file mode 100644 index 000000000..16a8050a4 --- /dev/null +++ b/arch/x86/entry/vdso/vdsox32.lds.S @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Linker script for x32 vDSO. + * We #include the file to define the layout details. + * + * This file defines the version script giving the user-exported symbols in + * the DSO. + */ + +#define BUILD_VDSOX32 + +#include "vdso-layout.lds.S" + +/* + * This controls what userland symbols we export from the vDSO. + */ +VERSION { + LINUX_2.6 { + global: + __vdso_clock_gettime; + __vdso_gettimeofday; + __vdso_getcpu; + __vdso_time; + __vdso_clock_getres; + local: *; + }; +} diff --git a/arch/x86/entry/vdso/vgetcpu.c b/arch/x86/entry/vdso/vgetcpu.c new file mode 100644 index 000000000..b88a82bbc --- /dev/null +++ b/arch/x86/entry/vdso/vgetcpu.c @@ -0,0 +1,22 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2006 Andi Kleen, SUSE Labs. + * + * Fast user context implementation of getcpu() + */ + +#include <linux/kernel.h> +#include <linux/getcpu.h> +#include <linux/time.h> +#include <asm/vgtod.h> + +notrace long +__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused) +{ + vdso_read_cpunode(cpu, node); + + return 0; +} + +long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache) + __attribute__((weak, alias("__vdso_getcpu"))); diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c new file mode 100644 index 000000000..128866139 --- /dev/null +++ b/arch/x86/entry/vdso/vma.c @@ -0,0 +1,459 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2007 Andi Kleen, SUSE Labs. + * + * This contains most of the x86 vDSO kernel-side code. + */ +#include <linux/mm.h> +#include <linux/err.h> +#include <linux/sched.h> +#include <linux/sched/task_stack.h> +#include <linux/slab.h> +#include <linux/init.h> +#include <linux/random.h> +#include <linux/elf.h> +#include <linux/cpu.h> +#include <linux/ptrace.h> +#include <linux/time_namespace.h> + +#include <asm/pvclock.h> +#include <asm/vgtod.h> +#include <asm/proto.h> +#include <asm/vdso.h> +#include <asm/vvar.h> +#include <asm/tlb.h> +#include <asm/page.h> +#include <asm/desc.h> +#include <asm/cpufeature.h> +#include <clocksource/hyperv_timer.h> + +#undef _ASM_X86_VVAR_H +#define EMIT_VVAR(name, offset) \ + const size_t name ## _offset = offset; +#include <asm/vvar.h> + +struct vdso_data *arch_get_vdso_data(void *vvar_page) +{ + return (struct vdso_data *)(vvar_page + _vdso_data_offset); +} +#undef EMIT_VVAR + +unsigned int vclocks_used __read_mostly; + +#if defined(CONFIG_X86_64) +unsigned int __read_mostly vdso64_enabled = 1; +#endif + +void __init init_vdso_image(const struct vdso_image *image) +{ + BUG_ON(image->size % PAGE_SIZE != 0); + + apply_alternatives((struct alt_instr *)(image->data + image->alt), + (struct alt_instr *)(image->data + image->alt + + image->alt_len)); +} + +static const struct vm_special_mapping vvar_mapping; +struct linux_binprm; + +static vm_fault_t vdso_fault(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + const struct vdso_image *image = vma->vm_mm->context.vdso_image; + + if (!image || (vmf->pgoff << PAGE_SHIFT) >= image->size) + return VM_FAULT_SIGBUS; + + vmf->page = virt_to_page(image->data + (vmf->pgoff << PAGE_SHIFT)); + get_page(vmf->page); + return 0; +} + +static void vdso_fix_landing(const struct vdso_image *image, + struct vm_area_struct *new_vma) +{ +#if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION + if (in_ia32_syscall() && image == &vdso_image_32) { + struct pt_regs *regs = current_pt_regs(); + unsigned long vdso_land = image->sym_int80_landing_pad; + unsigned long old_land_addr = vdso_land + + (unsigned long)current->mm->context.vdso; + + /* Fixing userspace landing - look at do_fast_syscall_32 */ + if (regs->ip == old_land_addr) + regs->ip = new_vma->vm_start + vdso_land; + } +#endif +} + +static int vdso_mremap(const struct vm_special_mapping *sm, + struct vm_area_struct *new_vma) +{ + const struct vdso_image *image = current->mm->context.vdso_image; + + vdso_fix_landing(image, new_vma); + current->mm->context.vdso = (void __user *)new_vma->vm_start; + + return 0; +} + +#ifdef CONFIG_TIME_NS +static struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + if (likely(vma->vm_mm == current->mm)) + return current->nsproxy->time_ns->vvar_page; + + /* + * VM_PFNMAP | VM_IO protect .fault() handler from being called + * through interfaces like /proc/$pid/mem or + * process_vm_{readv,writev}() as long as there's no .access() + * in special_mapping_vmops(). + * For more details check_vma_flags() and __access_remote_vm() + */ + + WARN(1, "vvar_page accessed remotely"); + + return NULL; +} + +/* + * The vvar page layout depends on whether a task belongs to the root or + * non-root time namespace. Whenever a task changes its namespace, the VVAR + * page tables are cleared and then they will re-faulted with a + * corresponding layout. + * See also the comment near timens_setup_vdso_data() for details. + */ +int vdso_join_timens(struct task_struct *task, struct time_namespace *ns) +{ + struct mm_struct *mm = task->mm; + struct vm_area_struct *vma; + VMA_ITERATOR(vmi, mm, 0); + + mmap_read_lock(mm); + for_each_vma(vmi, vma) { + unsigned long size = vma->vm_end - vma->vm_start; + + if (vma_is_special_mapping(vma, &vvar_mapping)) + zap_page_range(vma, vma->vm_start, size); + } + mmap_read_unlock(mm); + + return 0; +} +#else +static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma) +{ + return NULL; +} +#endif + +static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + const struct vdso_image *image = vma->vm_mm->context.vdso_image; + unsigned long pfn; + long sym_offset; + + if (!image) + return VM_FAULT_SIGBUS; + + sym_offset = (long)(vmf->pgoff << PAGE_SHIFT) + + image->sym_vvar_start; + + /* + * Sanity check: a symbol offset of zero means that the page + * does not exist for this vdso image, not that the page is at + * offset zero relative to the text mapping. This should be + * impossible here, because sym_offset should only be zero for + * the page past the end of the vvar mapping. + */ + if (sym_offset == 0) + return VM_FAULT_SIGBUS; + + if (sym_offset == image->sym_vvar_page) { + struct page *timens_page = find_timens_vvar_page(vma); + + pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT; + + /* + * If a task belongs to a time namespace then a namespace + * specific VVAR is mapped with the sym_vvar_page offset and + * the real VVAR page is mapped with the sym_timens_page + * offset. + * See also the comment near timens_setup_vdso_data(). + */ + if (timens_page) { + unsigned long addr; + vm_fault_t err; + + /* + * Optimization: inside time namespace pre-fault + * VVAR page too. As on timens page there are only + * offsets for clocks on VVAR, it'll be faulted + * shortly by VDSO code. + */ + addr = vmf->address + (image->sym_timens_page - sym_offset); + err = vmf_insert_pfn(vma, addr, pfn); + if (unlikely(err & VM_FAULT_ERROR)) + return err; + + pfn = page_to_pfn(timens_page); + } + + return vmf_insert_pfn(vma, vmf->address, pfn); + } else if (sym_offset == image->sym_pvclock_page) { + struct pvclock_vsyscall_time_info *pvti = + pvclock_get_pvti_cpu0_va(); + if (pvti && vclock_was_used(VDSO_CLOCKMODE_PVCLOCK)) { + return vmf_insert_pfn_prot(vma, vmf->address, + __pa(pvti) >> PAGE_SHIFT, + pgprot_decrypted(vma->vm_page_prot)); + } + } else if (sym_offset == image->sym_hvclock_page) { + struct ms_hyperv_tsc_page *tsc_pg = hv_get_tsc_page(); + + if (tsc_pg && vclock_was_used(VDSO_CLOCKMODE_HVCLOCK)) + return vmf_insert_pfn(vma, vmf->address, + virt_to_phys(tsc_pg) >> PAGE_SHIFT); + } else if (sym_offset == image->sym_timens_page) { + struct page *timens_page = find_timens_vvar_page(vma); + + if (!timens_page) + return VM_FAULT_SIGBUS; + + pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT; + return vmf_insert_pfn(vma, vmf->address, pfn); + } + + return VM_FAULT_SIGBUS; +} + +static const struct vm_special_mapping vdso_mapping = { + .name = "[vdso]", + .fault = vdso_fault, + .mremap = vdso_mremap, +}; +static const struct vm_special_mapping vvar_mapping = { + .name = "[vvar]", + .fault = vvar_fault, +}; + +/* + * Add vdso and vvar mappings to current process. + * @image - blob to map + * @addr - request a specific address (zero to map at free addr) + */ +static int map_vdso(const struct vdso_image *image, unsigned long addr) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + unsigned long text_start; + int ret = 0; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + addr = get_unmapped_area(NULL, addr, + image->size - image->sym_vvar_start, 0, 0); + if (IS_ERR_VALUE(addr)) { + ret = addr; + goto up_fail; + } + + text_start = addr - image->sym_vvar_start; + + /* + * MAYWRITE to allow gdb to COW and set breakpoints + */ + vma = _install_special_mapping(mm, + text_start, + image->size, + VM_READ|VM_EXEC| + VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, + &vdso_mapping); + + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + goto up_fail; + } + + vma = _install_special_mapping(mm, + addr, + -image->sym_vvar_start, + VM_READ|VM_MAYREAD|VM_IO|VM_DONTDUMP| + VM_PFNMAP, + &vvar_mapping); + + if (IS_ERR(vma)) { + ret = PTR_ERR(vma); + do_munmap(mm, text_start, image->size, NULL); + } else { + current->mm->context.vdso = (void __user *)text_start; + current->mm->context.vdso_image = image; + } + +up_fail: + mmap_write_unlock(mm); + return ret; +} + +#ifdef CONFIG_X86_64 +/* + * Put the vdso above the (randomized) stack with another randomized + * offset. This way there is no hole in the middle of address space. + * To save memory make sure it is still in the same PTE as the stack + * top. This doesn't give that many random bits. + * + * Note that this algorithm is imperfect: the distribution of the vdso + * start address within a PMD is biased toward the end. + * + * Only used for the 64-bit and x32 vdsos. + */ +static unsigned long vdso_addr(unsigned long start, unsigned len) +{ + unsigned long addr, end; + unsigned offset; + + /* + * Round up the start address. It can start out unaligned as a result + * of stack start randomization. + */ + start = PAGE_ALIGN(start); + + /* Round the lowest possible end address up to a PMD boundary. */ + end = (start + len + PMD_SIZE - 1) & PMD_MASK; + if (end >= DEFAULT_MAP_WINDOW) + end = DEFAULT_MAP_WINDOW; + end -= len; + + if (end > start) { + offset = prandom_u32_max(((end - start) >> PAGE_SHIFT) + 1); + addr = start + (offset << PAGE_SHIFT); + } else { + addr = start; + } + + /* + * Forcibly align the final address in case we have a hardware + * issue that requires alignment for performance reasons. + */ + addr = align_vdso_addr(addr); + + return addr; +} + +static int map_vdso_randomized(const struct vdso_image *image) +{ + unsigned long addr = vdso_addr(current->mm->start_stack, image->size-image->sym_vvar_start); + + return map_vdso(image, addr); +} +#endif + +int map_vdso_once(const struct vdso_image *image, unsigned long addr) +{ + struct mm_struct *mm = current->mm; + struct vm_area_struct *vma; + VMA_ITERATOR(vmi, mm, 0); + + mmap_write_lock(mm); + /* + * Check if we have already mapped vdso blob - fail to prevent + * abusing from userspace install_special_mapping, which may + * not do accounting and rlimit right. + * We could search vma near context.vdso, but it's a slowpath, + * so let's explicitly check all VMAs to be completely sure. + */ + for_each_vma(vmi, vma) { + if (vma_is_special_mapping(vma, &vdso_mapping) || + vma_is_special_mapping(vma, &vvar_mapping)) { + mmap_write_unlock(mm); + return -EEXIST; + } + } + mmap_write_unlock(mm); + + return map_vdso(image, addr); +} + +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) +static int load_vdso32(void) +{ + if (vdso32_enabled != 1) /* Other values all mean "disabled" */ + return 0; + + return map_vdso(&vdso_image_32, 0); +} +#endif + +#ifdef CONFIG_X86_64 +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + if (!vdso64_enabled) + return 0; + + return map_vdso_randomized(&vdso_image_64); +} + +#ifdef CONFIG_COMPAT +int compat_arch_setup_additional_pages(struct linux_binprm *bprm, + int uses_interp, bool x32) +{ +#ifdef CONFIG_X86_X32_ABI + if (x32) { + if (!vdso64_enabled) + return 0; + return map_vdso_randomized(&vdso_image_x32); + } +#endif +#ifdef CONFIG_IA32_EMULATION + return load_vdso32(); +#else + return 0; +#endif +} +#endif +#else +int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) +{ + return load_vdso32(); +} +#endif + +bool arch_syscall_is_vdso_sigreturn(struct pt_regs *regs) +{ +#if defined(CONFIG_X86_32) || defined(CONFIG_IA32_EMULATION) + const struct vdso_image *image = current->mm->context.vdso_image; + unsigned long vdso = (unsigned long) current->mm->context.vdso; + + if (in_ia32_syscall() && image == &vdso_image_32) { + if (regs->ip == vdso + image->sym_vdso32_sigreturn_landing_pad || + regs->ip == vdso + image->sym_vdso32_rt_sigreturn_landing_pad) + return true; + } +#endif + return false; +} + +#ifdef CONFIG_X86_64 +static __init int vdso_setup(char *s) +{ + vdso64_enabled = simple_strtoul(s, NULL, 0); + return 1; +} +__setup("vdso=", vdso_setup); + +static int __init init_vdso(void) +{ + BUILD_BUG_ON(VDSO_CLOCKMODE_MAX >= 32); + + init_vdso_image(&vdso_image_64); + +#ifdef CONFIG_X86_X32_ABI + init_vdso_image(&vdso_image_x32); +#endif + + return 0; +} +subsys_initcall(init_vdso); +#endif /* CONFIG_X86_64 */ diff --git a/arch/x86/entry/vdso/vsgx.S b/arch/x86/entry/vdso/vsgx.S new file mode 100644 index 000000000..d77d278ee --- /dev/null +++ b/arch/x86/entry/vdso/vsgx.S @@ -0,0 +1,151 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include <linux/linkage.h> +#include <asm/export.h> +#include <asm/errno.h> +#include <asm/enclu.h> + +#include "extable.h" + +/* Relative to %rbp. */ +#define SGX_ENCLAVE_OFFSET_OF_RUN 16 + +/* The offsets relative to struct sgx_enclave_run. */ +#define SGX_ENCLAVE_RUN_TCS 0 +#define SGX_ENCLAVE_RUN_LEAF 8 +#define SGX_ENCLAVE_RUN_EXCEPTION_VECTOR 12 +#define SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE 14 +#define SGX_ENCLAVE_RUN_EXCEPTION_ADDR 16 +#define SGX_ENCLAVE_RUN_USER_HANDLER 24 +#define SGX_ENCLAVE_RUN_USER_DATA 32 /* not used */ +#define SGX_ENCLAVE_RUN_RESERVED_START 40 +#define SGX_ENCLAVE_RUN_RESERVED_END 256 + +.code64 +.section .text, "ax" + +SYM_FUNC_START(__vdso_sgx_enter_enclave) + /* Prolog */ + .cfi_startproc + push %rbp + .cfi_adjust_cfa_offset 8 + .cfi_rel_offset %rbp, 0 + mov %rsp, %rbp + .cfi_def_cfa_register %rbp + push %rbx + .cfi_rel_offset %rbx, -8 + + mov %ecx, %eax +.Lenter_enclave: + /* EENTER <= function <= ERESUME */ + cmp $EENTER, %eax + jb .Linvalid_input + cmp $ERESUME, %eax + ja .Linvalid_input + + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rcx + + /* Validate that the reserved area contains only zeros. */ + mov $SGX_ENCLAVE_RUN_RESERVED_START, %rbx +1: + cmpq $0, (%rcx, %rbx) + jne .Linvalid_input + add $8, %rbx + cmpq $SGX_ENCLAVE_RUN_RESERVED_END, %rbx + jne 1b + + /* Load TCS and AEP */ + mov SGX_ENCLAVE_RUN_TCS(%rcx), %rbx + lea .Lasync_exit_pointer(%rip), %rcx + + /* Single ENCLU serving as both EENTER and AEP (ERESUME) */ +.Lasync_exit_pointer: +.Lenclu_eenter_eresume: + enclu + + /* EEXIT jumps here unless the enclave is doing something fancy. */ + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx + + /* Set exit_reason. */ + movl $EEXIT, SGX_ENCLAVE_RUN_LEAF(%rbx) + + /* Invoke userspace's exit handler if one was provided. */ +.Lhandle_exit: + cmpq $0, SGX_ENCLAVE_RUN_USER_HANDLER(%rbx) + jne .Linvoke_userspace_handler + + /* Success, in the sense that ENCLU was attempted. */ + xor %eax, %eax + +.Lout: + pop %rbx + leave + .cfi_def_cfa %rsp, 8 + RET + + /* The out-of-line code runs with the pre-leave stack frame. */ + .cfi_def_cfa %rbp, 16 + +.Linvalid_input: + mov $(-EINVAL), %eax + jmp .Lout + +.Lhandle_exception: + mov SGX_ENCLAVE_OFFSET_OF_RUN(%rbp), %rbx + + /* Set the exception info. */ + mov %eax, (SGX_ENCLAVE_RUN_LEAF)(%rbx) + mov %di, (SGX_ENCLAVE_RUN_EXCEPTION_VECTOR)(%rbx) + mov %si, (SGX_ENCLAVE_RUN_EXCEPTION_ERROR_CODE)(%rbx) + mov %rdx, (SGX_ENCLAVE_RUN_EXCEPTION_ADDR)(%rbx) + jmp .Lhandle_exit + +.Linvoke_userspace_handler: + /* Pass the untrusted RSP (at exit) to the callback via %rcx. */ + mov %rsp, %rcx + + /* Save struct sgx_enclave_exception %rbx is about to be clobbered. */ + mov %rbx, %rax + + /* Save the untrusted RSP offset in %rbx (non-volatile register). */ + mov %rsp, %rbx + and $0xf, %rbx + + /* + * Align stack per x86_64 ABI. Note, %rsp needs to be 16-byte aligned + * _after_ pushing the parameters on the stack, hence the bonus push. + */ + and $-0x10, %rsp + push %rax + + /* Push struct sgx_enclave_exception as a param to the callback. */ + push %rax + + /* Clear RFLAGS.DF per x86_64 ABI */ + cld + + /* + * Load the callback pointer to %rax and lfence for LVI (load value + * injection) protection before making the call. + */ + mov SGX_ENCLAVE_RUN_USER_HANDLER(%rax), %rax + lfence + call *%rax + + /* Undo the post-exit %rsp adjustment. */ + lea 0x10(%rsp, %rbx), %rsp + + /* + * If the return from callback is zero or negative, return immediately, + * else re-execute ENCLU with the positive return value interpreted as + * the requested ENCLU function. + */ + cmp $0, %eax + jle .Lout + jmp .Lenter_enclave + + .cfi_endproc + +_ASM_VDSO_EXTABLE_HANDLE(.Lenclu_eenter_eresume, .Lhandle_exception) + +SYM_FUNC_END(__vdso_sgx_enter_enclave) |