summaryrefslogtreecommitdiffstats
path: root/arch/x86/um/vdso
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/um/vdso')
-rw-r--r--arch/x86/um/vdso/.gitignore2
-rw-r--r--arch/x86/um/vdso/Makefile81
-rw-r--r--arch/x86/um/vdso/checkundef.sh11
-rw-r--r--arch/x86/um/vdso/um_vdso.c72
-rw-r--r--arch/x86/um/vdso/vdso-layout.lds.S65
-rw-r--r--arch/x86/um/vdso/vdso-note.S12
-rw-r--r--arch/x86/um/vdso/vdso.S11
-rw-r--r--arch/x86/um/vdso/vdso.lds.S33
-rw-r--r--arch/x86/um/vdso/vma.c72
9 files changed, 359 insertions, 0 deletions
diff --git a/arch/x86/um/vdso/.gitignore b/arch/x86/um/vdso/.gitignore
new file mode 100644
index 000000000..652e31d82
--- /dev/null
+++ b/arch/x86/um/vdso/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+vdso.lds
diff --git a/arch/x86/um/vdso/Makefile b/arch/x86/um/vdso/Makefile
new file mode 100644
index 000000000..6fbe97c52
--- /dev/null
+++ b/arch/x86/um/vdso/Makefile
@@ -0,0 +1,81 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Building vDSO images for x86.
+#
+
+# do not instrument on vdso because KASAN is not compatible with user mode
+KASAN_SANITIZE := n
+
+# Prevents link failures: __sanitizer_cov_trace_pc() is not linked in.
+KCOV_INSTRUMENT := n
+
+VDSO64-y := y
+
+vdso-install-$(VDSO64-y) += vdso.so
+
+
+# files to link into the vdso
+vobjs-y := vdso-note.o um_vdso.o
+
+# files to link into kernel
+obj-$(VDSO64-y) += vdso.o vma.o
+
+vobjs := $(foreach F,$(vobjs-y),$(obj)/$F)
+
+$(obj)/vdso.o: $(obj)/vdso.so
+
+targets += vdso.so vdso.so.dbg vdso.lds $(vobjs-y)
+
+CPPFLAGS_vdso.lds += -P -C
+
+VDSO_LDFLAGS_vdso.lds = -m64 -Wl,-soname=linux-vdso.so.1 \
+ -Wl,-z,max-page-size=4096
+
+$(obj)/vdso.o: $(src)/vdso.S $(obj)/vdso.so
+
+$(obj)/vdso.so.dbg: $(obj)/vdso.lds $(vobjs) FORCE
+ $(call if_changed,vdso)
+
+$(obj)/%.so: OBJCOPYFLAGS := -S
+$(obj)/%.so: $(obj)/%.so.dbg FORCE
+ $(call if_changed,objcopy)
+
+#
+# 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
+
+$(vobjs): KBUILD_CFLAGS += $(CFL)
+
+#
+# vDSO code runs in userspace and -pg doesn't help with profiling anyway.
+#
+CFLAGS_REMOVE_vdso-note.o = -pg -fprofile-arcs -ftest-coverage
+CFLAGS_REMOVE_um_vdso.o = -pg -fprofile-arcs -ftest-coverage
+
+#
+# The DSO images are built using a special linker script.
+#
+quiet_cmd_vdso = VDSO $@
+ cmd_vdso = $(CC) -nostdlib -o $@ \
+ $(VDSO_LDFLAGS) $(VDSO_LDFLAGS_$(filter %.lds,$(^F))) \
+ -Wl,-T,$(filter %.lds,$^) $(filter %.o,$^) && \
+ sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
+
+VDSO_LDFLAGS = -fPIC -shared -Wl,--hash-style=sysv -z noexecstack
+GCOV_PROFILE := n
+
+#
+# Install the unstripped copy of vdso*.so listed in $(vdso-install-y).
+#
+quiet_cmd_vdso_install = INSTALL $@
+ cmd_vdso_install = cp $(obj)/$@.dbg $(MODLIB)/vdso/$@
+$(vdso-install-y): %.so: $(obj)/%.so.dbg FORCE
+ @mkdir -p $(MODLIB)/vdso
+ $(call cmd,vdso_install)
+
+PHONY += vdso_install $(vdso-install-y)
+vdso_install: $(vdso-install-y)
diff --git a/arch/x86/um/vdso/checkundef.sh b/arch/x86/um/vdso/checkundef.sh
new file mode 100644
index 000000000..8e3ea6bb9
--- /dev/null
+++ b/arch/x86/um/vdso/checkundef.sh
@@ -0,0 +1,11 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+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/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
new file mode 100644
index 000000000..ff0f3b4b6
--- /dev/null
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
+ *
+ * This vDSO turns all calls into a syscall so that UML can trap them.
+ */
+
+
+/* Disable profiling for userspace code */
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/time.h>
+#include <linux/getcpu.h>
+#include <asm/unistd.h>
+
+int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
+{
+ long ret;
+
+ asm("syscall"
+ : "=a" (ret)
+ : "0" (__NR_clock_gettime), "D" (clock), "S" (ts)
+ : "rcx", "r11", "memory");
+
+ return ret;
+}
+int clock_gettime(clockid_t, struct __kernel_old_timespec *)
+ __attribute__((weak, alias("__vdso_clock_gettime")));
+
+int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+ long ret;
+
+ asm("syscall"
+ : "=a" (ret)
+ : "0" (__NR_gettimeofday), "D" (tv), "S" (tz)
+ : "rcx", "r11", "memory");
+
+ return ret;
+}
+int gettimeofday(struct __kernel_old_timeval *, struct timezone *)
+ __attribute__((weak, alias("__vdso_gettimeofday")));
+
+__kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
+{
+ long secs;
+
+ asm volatile("syscall"
+ : "=a" (secs)
+ : "0" (__NR_time), "D" (t) : "cc", "r11", "cx", "memory");
+
+ return secs;
+}
+__kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
+
+long
+__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+{
+ /*
+ * UML does not support SMP, we can cheat here. :)
+ */
+
+ if (cpu)
+ *cpu = 0;
+ if (node)
+ *node = 0;
+
+ return 0;
+}
+
+long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
+ __attribute__((weak, alias("__vdso_getcpu")));
diff --git a/arch/x86/um/vdso/vdso-layout.lds.S b/arch/x86/um/vdso/vdso-layout.lds.S
new file mode 100644
index 000000000..439b790df
--- /dev/null
+++ b/arch/x86/um/vdso/vdso-layout.lds.S
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * 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
+{
+ . = VDSO_PRELINK + 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) }
+
+ .note : { *(.note.*) } :text :note
+
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : { KEEP (*(.eh_frame)) } :text
+
+ .dynamic : { *(.dynamic) } :text :dynamic
+
+ .rodata : { *(.rodata*) } :text
+ .data : {
+ *(.data*)
+ *(.sdata*)
+ *(.got.plt) *(.got)
+ *(.gnu.linkonce.d.*)
+ *(.bss*)
+ *(.dynbss*)
+ *(.gnu.linkonce.b.*)
+ }
+
+ .altinstructions : { *(.altinstructions) }
+ .altinstr_replacement : { *(.altinstr_replacement) }
+
+ /*
+ * Align the actual code well away from the non-instruction data.
+ * This is the best thing for the I-cache.
+ */
+ . = ALIGN(0x100);
+
+ .text : { *(.text*) } :text =0x90909090
+}
+
+/*
+ * 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/um/vdso/vdso-note.S b/arch/x86/um/vdso/vdso-note.S
new file mode 100644
index 000000000..79a071e43
--- /dev/null
+++ b/arch/x86/um/vdso/vdso-note.S
@@ -0,0 +1,12 @@
+/*
+ * 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/uts.h>
+#include <linux/version.h>
+#include <linux/elfnote.h>
+
+ELFNOTE_START(Linux, 0, "a")
+ .long LINUX_VERSION_CODE
+ELFNOTE_END
diff --git a/arch/x86/um/vdso/vdso.S b/arch/x86/um/vdso/vdso.S
new file mode 100644
index 000000000..a6eaf293a
--- /dev/null
+++ b/arch/x86/um/vdso/vdso.S
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/init.h>
+#include <linux/linkage.h>
+
+__INITDATA
+
+SYM_DATA_START(vdso_start)
+ .incbin "arch/x86/um/vdso/vdso.so"
+SYM_DATA_END_LABEL(vdso_start, SYM_L_GLOBAL, vdso_end)
+
+__FINIT
diff --git a/arch/x86/um/vdso/vdso.lds.S b/arch/x86/um/vdso/vdso.lds.S
new file mode 100644
index 000000000..73c508587
--- /dev/null
+++ b/arch/x86/um/vdso/vdso.lds.S
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Linker script for 64-bit vDSO.
+ * We #include the file to define the layout details.
+ * Here we only choose the prelinked virtual address.
+ *
+ * This file defines the version script giving the user-exported symbols in
+ * the DSO. We can define local symbols here called VDSO* to make their
+ * values visible using the asm-x86/vdso.h macros from the kernel proper.
+ */
+
+#define VDSO_PRELINK 0xffffffffff700000
+#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;
+ local: *;
+ };
+}
+
+VDSO64_PRELINK = VDSO_PRELINK;
diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c
new file mode 100644
index 000000000..76d9f6ce7
--- /dev/null
+++ b/arch/x86/um/vdso/vma.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2011 Richard Weinberger <richrd@nod.at>
+ */
+
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/page.h>
+#include <asm/elf.h>
+#include <linux/init.h>
+
+static unsigned int __read_mostly vdso_enabled = 1;
+unsigned long um_vdso_addr;
+
+extern unsigned long task_size;
+extern char vdso_start[], vdso_end[];
+
+static struct page **vdsop;
+
+static int __init init_vdso(void)
+{
+ struct page *um_vdso;
+
+ BUG_ON(vdso_end - vdso_start > PAGE_SIZE);
+
+ um_vdso_addr = task_size - PAGE_SIZE;
+
+ vdsop = kmalloc(sizeof(struct page *), GFP_KERNEL);
+ if (!vdsop)
+ goto oom;
+
+ um_vdso = alloc_page(GFP_KERNEL);
+ if (!um_vdso) {
+ kfree(vdsop);
+
+ goto oom;
+ }
+
+ copy_page(page_address(um_vdso), vdso_start);
+ *vdsop = um_vdso;
+
+ return 0;
+
+oom:
+ printk(KERN_ERR "Cannot allocate vdso\n");
+ vdso_enabled = 0;
+
+ return -ENOMEM;
+}
+subsys_initcall(init_vdso);
+
+int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
+{
+ int err;
+ struct mm_struct *mm = current->mm;
+
+ if (!vdso_enabled)
+ return 0;
+
+ if (mmap_write_lock_killable(mm))
+ return -EINTR;
+
+ err = install_special_mapping(mm, um_vdso_addr, PAGE_SIZE,
+ VM_READ|VM_EXEC|
+ VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
+ vdsop);
+
+ mmap_write_unlock(mm);
+
+ return err;
+}