[PATCH 8/9] selftests: move vDSO tests from Documentation/vDSO

From: Shuah Khan
Date: Fri Sep 09 2016 - 18:23:23 EST

Move vDSO tests from Documentation/vDSO to selftests/vDSO.

Signed-off-by: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
---
Documentation/vDSO/.gitignore | 2 -
Documentation/vDSO/Makefile | 17 --
Documentation/vDSO/parse_vdso.c | 269 ---------------------
Documentation/vDSO/vdso_standalone_test_x86.c | 128 ----------
Documentation/vDSO/vdso_test.c | 52 ----
tools/testing/selftests/vDSO/.gitignore | 2 +
tools/testing/selftests/vDSO/Makefile | 17 ++
tools/testing/selftests/vDSO/parse_vdso.c | 269 +++++++++++++++++++++
.../selftests/vDSO/vdso_standalone_test_x86.c | 128 ++++++++++
tools/testing/selftests/vDSO/vdso_test.c | 52 ++++
10 files changed, 468 insertions(+), 468 deletions(-)
delete mode 100644 Documentation/vDSO/.gitignore
delete mode 100644 Documentation/vDSO/Makefile
delete mode 100644 Documentation/vDSO/parse_vdso.c
delete mode 100644 Documentation/vDSO/vdso_standalone_test_x86.c
delete mode 100644 Documentation/vDSO/vdso_test.c
create mode 100644 tools/testing/selftests/vDSO/.gitignore
create mode 100644 tools/testing/selftests/vDSO/Makefile
create mode 100644 tools/testing/selftests/vDSO/parse_vdso.c
create mode 100644 tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
create mode 100644 tools/testing/selftests/vDSO/vdso_test.c

diff --git a/Documentation/vDSO/.gitignore b/Documentation/vDSO/.gitignore
deleted file mode 100644
index 133bf9e..0000000
--- a/Documentation/vDSO/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-vdso_test
-vdso_standalone_test_x86
diff --git a/Documentation/vDSO/Makefile b/Documentation/vDSO/Makefile
deleted file mode 100644
index b12e987..0000000
--- a/Documentation/vDSO/Makefile
+++ /dev/null
@@ -1,17 +0,0 @@
-ifndef CROSS_COMPILE
-# vdso_test won't build for glibc < 2.16, so disable it
-# hostprogs-y := vdso_test
-hostprogs-$(CONFIG_X86) := vdso_standalone_test_x86
-vdso_standalone_test_x86-objs := vdso_standalone_test_x86.o parse_vdso.o
-vdso_test-objs := parse_vdso.o vdso_test.o
-
-# Tell kbuild to always build the programs
-always := $(hostprogs-y)
-
-HOSTCFLAGS := -I$(objtree)/usr/include -std=gnu99
-HOSTCFLAGS_vdso_standalone_test_x86.o := -fno-asynchronous-unwind-tables -fno-stack-protector
-HOSTLOADLIBES_vdso_standalone_test_x86 := -nostdlib
-ifeq ($(CONFIG_X86_32),y)
-HOSTLOADLIBES_vdso_standalone_test_x86 += -lgcc_s
-endif
-endif
diff --git a/Documentation/vDSO/parse_vdso.c b/Documentation/vDSO/parse_vdso.c
deleted file mode 100644
index 1dbb4b8..0000000
--- a/Documentation/vDSO/parse_vdso.c
+++ /dev/null
@@ -1,269 +0,0 @@
-/*
- * parse_vdso.c: Linux reference vDSO parser
- * Written by Andrew Lutomirski, 2011-2014.
- *
- * This code is meant to be linked in to various programs that run on Linux.
- * As such, it is available with as few restrictions as possible. This file
- * is licensed under the Creative Commons Zero License, version 1.0,
- * available at http://creativecommons.org/publicdomain/zero/1.0/legalcode
- *
- * The vDSO is a regular ELF DSO that the kernel maps into user space when
- * it starts a program. It works equally well in statically and dynamically
- * linked binaries.
- *
- * This code is tested on x86. In principle it should work on any
- * architecture that has a vDSO.
- */
-
-#include <stdbool.h>
-#include <stdint.h>
-#include <string.h>
-#include <limits.h>
-#include <elf.h>
-
-/*
- * To use this vDSO parser, first call one of the vdso_init_* functions.
- * If you've already parsed auxv, then pass the value of AT_SYSINFO_EHDR
- * to vdso_init_from_sysinfo_ehdr. Otherwise pass auxv to vdso_init_from_auxv.
- * Then call vdso_sym for each symbol you want. For example, to look up
- * gettimeofday on x86_64, use:
- *
- * <some pointer> = vdso_sym("LINUX_2.6", "gettimeofday");
- * or
- * <some pointer> = vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
- *
- * vdso_sym will return 0 if the symbol doesn't exist or if the init function
- * failed or was not called. vdso_sym is a little slow, so its return value
- * should be cached.
- *
- * vdso_sym is threadsafe; the init functions are not.
- *
- * These are the prototypes:
- */
-extern void vdso_init_from_auxv(void *auxv);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void *vdso_sym(const char *version, const char *name);
-
-
-/* And here's the code. */
-#ifndef ELF_BITS
-# if ULONG_MAX > 0xffffffffUL
-# define ELF_BITS 64
-# else
-# define ELF_BITS 32
-# endif
-#endif
-
-#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)
-
-static struct vdso_info
-{
- bool valid;
-
- /* Load information */
- uintptr_t load_addr;
- uintptr_t load_offset; /* load_addr - recorded vaddr */
-
- /* Symbol table */
- ELF(Sym) *symtab;
- const char *symstrings;
- ELF(Word) *bucket, *chain;
- ELF(Word) nbucket, nchain;
-
- /* Version table */
- ELF(Versym) *versym;
- ELF(Verdef) *verdef;
-} vdso_info;
-
-/* Straight from the ELF specification. */
-static unsigned long elf_hash(const unsigned char *name)
-{
- unsigned long h = 0, g;
- while (*name)
- {
- h = (h << 4) + *name++;
- if (g = h & 0xf0000000)
- h ^= g >> 24;
- h &= ~g;
- }
- return h;
-}
-
-void vdso_init_from_sysinfo_ehdr(uintptr_t base)
-{
- size_t i;
- bool found_vaddr = false;
-
- vdso_info.valid = false;
-
- vdso_info.load_addr = base;
-
- ELF(Ehdr) *hdr = (ELF(Ehdr)*)base;
- if (hdr->e_ident[EI_CLASS] !=
- (ELF_BITS == 32 ? ELFCLASS32 : ELFCLASS64)) {
- return; /* Wrong ELF class -- check ELF_BITS */
- }
-
- ELF(Phdr) *pt = (ELF(Phdr)*)(vdso_info.load_addr + hdr->e_phoff);
- ELF(Dyn) *dyn = 0;
-
- /*
- * We need two things from the segment table: the load offset
- * and the dynamic table.
- */
- for (i = 0; i < hdr->e_phnum; i++)
- {
- if (pt[i].p_type == PT_LOAD && !found_vaddr) {
- found_vaddr = true;
- vdso_info.load_offset = base
- + (uintptr_t)pt[i].p_offset
- - (uintptr_t)pt[i].p_vaddr;
- } else if (pt[i].p_type == PT_DYNAMIC) {
- dyn = (ELF(Dyn)*)(base + pt[i].p_offset);
- }
- }
-
- if (!found_vaddr || !dyn)
- return; /* Failed */
-
- /*
- * Fish out the useful bits of the dynamic table.
- */
- ELF(Word) *hash = 0;
- vdso_info.symstrings = 0;
- vdso_info.symtab = 0;
- vdso_info.versym = 0;
- vdso_info.verdef = 0;
- for (i = 0; dyn[i].d_tag != DT_NULL; i++) {
- switch (dyn[i].d_tag) {
- case DT_STRTAB:
- vdso_info.symstrings = (const char *)
- ((uintptr_t)dyn[i].d_un.d_ptr
- + vdso_info.load_offset);
- break;
- case DT_SYMTAB:
- vdso_info.symtab = (ELF(Sym) *)
- ((uintptr_t)dyn[i].d_un.d_ptr
- + vdso_info.load_offset);
- break;
- case DT_HASH:
- hash = (ELF(Word) *)
- ((uintptr_t)dyn[i].d_un.d_ptr
- + vdso_info.load_offset);
- break;
- case DT_VERSYM:
- vdso_info.versym = (ELF(Versym) *)
- ((uintptr_t)dyn[i].d_un.d_ptr
- + vdso_info.load_offset);
- break;
- case DT_VERDEF:
- vdso_info.verdef = (ELF(Verdef) *)
- ((uintptr_t)dyn[i].d_un.d_ptr
- + vdso_info.load_offset);
- break;
- }
- }
- if (!vdso_info.symstrings || !vdso_info.symtab || !hash)
- return; /* Failed */
-
- if (!vdso_info.verdef)
- vdso_info.versym = 0;
-
- /* Parse the hash table header. */
- vdso_info.nbucket = hash[0];
- vdso_info.nchain = hash[1];
- vdso_info.bucket = &hash[2];
- vdso_info.chain = &hash[vdso_info.nbucket + 2];
-
- /* That's all we need. */
- vdso_info.valid = true;
-}
-
-static bool vdso_match_version(ELF(Versym) ver,
- const char *name, ELF(Word) hash)
-{
- /*
- * This is a helper function to check if the version indexed by
- * ver matches name (which hashes to hash).
- *
- * The version definition table is a mess, and I don't know how
- * to do this in better than linear time without allocating memory
- * to build an index. I also don't know why the table has
- * variable size entries in the first place.
- *
- * For added fun, I can't find a comprehensible specification of how
- * to parse all the weird flags in the table.
- *
- * So I just parse the whole table every time.
- */
-
- /* First step: find the version definition */
- ver &= 0x7fff; /* Apparently bit 15 means "hidden" */
- ELF(Verdef) *def = vdso_info.verdef;
- while(true) {
- if ((def->vd_flags & VER_FLG_BASE) == 0
- && (def->vd_ndx & 0x7fff) == ver)
- break;
-
- if (def->vd_next == 0)
- return false; /* No definition. */
-
- def = (ELF(Verdef) *)((char *)def + def->vd_next);
- }
-
- /* Now figure out whether it matches. */
- ELF(Verdaux) *aux = (ELF(Verdaux)*)((char *)def + def->vd_aux);
- return def->vd_hash == hash
- && !strcmp(name, vdso_info.symstrings + aux->vda_name);
-}
-
-void *vdso_sym(const char *version, const char *name)
-{
- unsigned long ver_hash;
- if (!vdso_info.valid)
- return 0;
-
- ver_hash = elf_hash(version);
- ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
-
- for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
- ELF(Sym) *sym = &vdso_info.symtab[chain];
-
- /* Check for a defined global or weak function w/ right name. */
- if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
- continue;
- if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
- ELF64_ST_BIND(sym->st_info) != STB_WEAK)
- continue;
- if (sym->st_shndx == SHN_UNDEF)
- continue;
- if (strcmp(name, vdso_info.symstrings + sym->st_name))
- continue;
-
- /* Check symbol version. */
- if (vdso_info.versym
- && !vdso_match_version(vdso_info.versym[chain],
- version, ver_hash))
- continue;
-
- return (void *)(vdso_info.load_offset + sym->st_value);
- }
-
- return 0;
-}
-
-void vdso_init_from_auxv(void *auxv)
-{
- ELF(auxv_t) *elf_auxv = auxv;
- for (int i = 0; elf_auxv[i].a_type != AT_NULL; i++)
- {
- if (elf_auxv[i].a_type == AT_SYSINFO_EHDR) {
- vdso_init_from_sysinfo_ehdr(elf_auxv[i].a_un.a_val);
- return;
- }
- }
-
- vdso_info.valid = false;
-}
diff --git a/Documentation/vDSO/vdso_standalone_test_x86.c b/Documentation/vDSO/vdso_standalone_test_x86.c
deleted file mode 100644
index 93b0ebf..0000000
--- a/Documentation/vDSO/vdso_standalone_test_x86.c
+++ /dev/null
@@ -1,128 +0,0 @@
-/*
- * vdso_test.c: Sample code to test parse_vdso.c on x86
- * Copyright (c) 2011-2014 Andy Lutomirski
- * Subject to the GNU General Public License, version 2
- *
- * You can amuse yourself by compiling with:
- * gcc -std=gnu99 -nostdlib
- * -Os -fno-asynchronous-unwind-tables -flto -lgcc_s
- * vdso_standalone_test_x86.c parse_vdso.c
- * to generate a small binary. On x86_64, you can omit -lgcc_s
- * if you want the binary to be completely standalone.
- */
-
-#include <sys/syscall.h>
-#include <sys/time.h>
-#include <unistd.h>
-#include <stdint.h>
-
-extern void *vdso_sym(const char *version, const char *name);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void vdso_init_from_auxv(void *auxv);
-
-/* We need a libc functions... */
-int strcmp(const char *a, const char *b)
-{
- /* This implementation is buggy: it never returns -1. */
- while (*a || *b) {
- if (*a != *b)
- return 1;
- if (*a == 0 || *b == 0)
- return 1;
- a++;
- b++;
- }
-
- return 0;
-}
-
-/* ...and two syscalls. This is x86-specific. */
-static inline long x86_syscall3(long nr, long a0, long a1, long a2)
-{
- long ret;
-#ifdef __x86_64__
- asm volatile ("syscall" : "=a" (ret) : "a" (nr),
- "D" (a0), "S" (a1), "d" (a2) :
- "cc", "memory", "rcx",
- "r8", "r9", "r10", "r11" );
-#else
- asm volatile ("int $0x80" : "=a" (ret) : "a" (nr),
- "b" (a0), "c" (a1), "d" (a2) :
- "cc", "memory" );
-#endif
- return ret;
-}
-
-static inline long linux_write(int fd, const void *data, size_t len)
-{
- return x86_syscall3(__NR_write, fd, (long)data, (long)len);
-}
-
-static inline void linux_exit(int code)
-{
- x86_syscall3(__NR_exit, code, 0, 0);
-}
-
-void to_base10(char *lastdig, time_t n)
-{
- while (n) {
- *lastdig = (n % 10) + '0';
- n /= 10;
- lastdig--;
- }
-}
-
-__attribute__((externally_visible)) void c_main(void **stack)
-{
- /* Parse the stack */
- long argc = (long)*stack;
- stack += argc + 2;
-
- /* Now we're pointing at the environment. Skip it. */
- while(*stack)
- stack++;
- stack++;
-
- /* Now we're pointing at auxv. Initialize the vDSO parser. */
- vdso_init_from_auxv((void *)stack);
-
- /* Find gettimeofday. */
- typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
- gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
-
- if (!gtod)
- linux_exit(1);
-
- struct timeval tv;
- long ret = gtod(&tv, 0);
-
- if (ret == 0) {
- char buf[] = "The time is .000000\n";
- to_base10(buf + 31, tv.tv_sec);
- to_base10(buf + 38, tv.tv_usec);
- linux_write(1, buf, sizeof(buf) - 1);
- } else {
- linux_exit(ret);
- }
-
- linux_exit(0);
-}
-
-/*
- * This is the real entry point. It passes the initial stack into
- * the C entry point.
- */
-asm (
- ".text\n"
- ".global _start\n"
- ".type _start,@function\n"
- "_start:\n\t"
-#ifdef __x86_64__
- "mov %rsp,%rdi\n\t"
- "jmp c_main"
-#else
- "push %esp\n\t"
- "call c_main\n\t"
- "int $3"
-#endif
- );
diff --git a/Documentation/vDSO/vdso_test.c b/Documentation/vDSO/vdso_test.c
deleted file mode 100644
index 8daeb7d7..0000000
--- a/Documentation/vDSO/vdso_test.c
+++ /dev/null
@@ -1,52 +0,0 @@
-/*
- * vdso_test.c: Sample code to test parse_vdso.c
- * Copyright (c) 2014 Andy Lutomirski
- * Subject to the GNU General Public License, version 2
- *
- * Compile with:
- * gcc -std=gnu99 vdso_test.c parse_vdso.c
- *
- * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too.
- */
-
-#include <stdint.h>
-#include <elf.h>
-#include <stdio.h>
-#include <sys/auxv.h>
-#include <sys/time.h>
-
-extern void *vdso_sym(const char *version, const char *name);
-extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
-extern void vdso_init_from_auxv(void *auxv);
-
-int main(int argc, char **argv)
-{
- unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
- if (!sysinfo_ehdr) {
- printf("AT_SYSINFO_EHDR is not present!\n");
- return 0;
- }
-
- vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
-
- /* Find gettimeofday. */
- typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
- gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
-
- if (!gtod) {
- printf("Could not find __vdso_gettimeofday\n");
- return 1;
- }
-
- struct timeval tv;
- long ret = gtod(&tv, 0);
-
- if (ret == 0) {
- printf("The time is %lld.%06lld\n",
- (long long)tv.tv_sec, (long long)tv.tv_usec);
- } else {
- printf("__vdso_gettimeofday failed\n");
- }
-
- return 0;
-}
diff --git a/tools/testing/selftests/vDSO/.gitignore b/tools/testing/selftests/vDSO/.gitignore
new file mode 100644
index 0000000..133bf9e
--- /dev/null
+++ b/tools/testing/selftests/vDSO/.gitignore
@@ -0,0 +1,2 @@
+vdso_test
+vdso_standalone_test_x86
diff --git a/tools/testing/selftests/vDSO/Makefile b/tools/testing/selftests/vDSO/Makefile
new file mode 100644
index 0000000..b12e987
--- /dev/null
+++ b/tools/testing/selftests/vDSO/Makefile
@@ -0,0 +1,17 @@
+ifndef CROSS_COMPILE
+# vdso_test won't build for glibc < 2.16, so disable it
+# hostprogs-y := vdso_test
+hostprogs-$(CONFIG_X86) := vdso_standalone_test_x86
+vdso_standalone_test_x86-objs := vdso_standalone_test_x86.o parse_vdso.o
+vdso_test-objs := parse_vdso.o vdso_test.o
+
+# Tell kbuild to always build the programs
+always := $(hostprogs-y)
+
+HOSTCFLAGS := -I$(objtree)/usr/include -std=gnu99
+HOSTCFLAGS_vdso_standalone_test_x86.o := -fno-asynchronous-unwind-tables -fno-stack-protector
+HOSTLOADLIBES_vdso_standalone_test_x86 := -nostdlib
+ifeq ($(CONFIG_X86_32),y)
+HOSTLOADLIBES_vdso_standalone_test_x86 += -lgcc_s
+endif
+endif
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
new file mode 100644
index 0000000..1dbb4b8
--- /dev/null
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -0,0 +1,269 @@
+/*
+ * parse_vdso.c: Linux reference vDSO parser
+ * Written by Andrew Lutomirski, 2011-2014.
+ *
+ * This code is meant to be linked in to various programs that run on Linux.
+ * As such, it is available with as few restrictions as possible. This file
+ * is licensed under the Creative Commons Zero License, version 1.0,
+ * available at http://creativecommons.org/publicdomain/zero/1.0/legalcode
+ *
+ * The vDSO is a regular ELF DSO that the kernel maps into user space when
+ * it starts a program. It works equally well in statically and dynamically
+ * linked binaries.
+ *
+ * This code is tested on x86. In principle it should work on any
+ * architecture that has a vDSO.
+ */
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <string.h>
+#include <limits.h>
+#include <elf.h>
+
+/*
+ * To use this vDSO parser, first call one of the vdso_init_* functions.
+ * If you've already parsed auxv, then pass the value of AT_SYSINFO_EHDR
+ * to vdso_init_from_sysinfo_ehdr. Otherwise pass auxv to vdso_init_from_auxv.
+ * Then call vdso_sym for each symbol you want. For example, to look up
+ * gettimeofday on x86_64, use:
+ *
+ * <some pointer> = vdso_sym("LINUX_2.6", "gettimeofday");
+ * or
+ * <some pointer> = vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
+ *
+ * vdso_sym will return 0 if the symbol doesn't exist or if the init function
+ * failed or was not called. vdso_sym is a little slow, so its return value
+ * should be cached.
+ *
+ * vdso_sym is threadsafe; the init functions are not.
+ *
+ * These are the prototypes:
+ */
+extern void vdso_init_from_auxv(void *auxv);
+extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
+extern void *vdso_sym(const char *version, const char *name);
+
+
+/* And here's the code. */
+#ifndef ELF_BITS
+# if ULONG_MAX > 0xffffffffUL
+# define ELF_BITS 64
+# else
+# define ELF_BITS 32
+# endif
+#endif
+
+#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)
+
+static struct vdso_info
+{
+ bool valid;
+
+ /* Load information */
+ uintptr_t load_addr;
+ uintptr_t load_offset; /* load_addr - recorded vaddr */
+
+ /* Symbol table */
+ ELF(Sym) *symtab;
+ const char *symstrings;
+ ELF(Word) *bucket, *chain;
+ ELF(Word) nbucket, nchain;
+
+ /* Version table */
+ ELF(Versym) *versym;
+ ELF(Verdef) *verdef;
+} vdso_info;
+
+/* Straight from the ELF specification. */
+static unsigned long elf_hash(const unsigned char *name)
+{
+ unsigned long h = 0, g;
+ while (*name)
+ {
+ h = (h << 4) + *name++;
+ if (g = h & 0xf0000000)
+ h ^= g >> 24;
+ h &= ~g;
+ }
+ return h;
+}
+
+void vdso_init_from_sysinfo_ehdr(uintptr_t base)
+{
+ size_t i;
+ bool found_vaddr = false;
+
+ vdso_info.valid = false;
+
+ vdso_info.load_addr = base;
+
+ ELF(Ehdr) *hdr = (ELF(Ehdr)*)base;
+ if (hdr->e_ident[EI_CLASS] !=
+ (ELF_BITS == 32 ? ELFCLASS32 : ELFCLASS64)) {
+ return; /* Wrong ELF class -- check ELF_BITS */
+ }
+
+ ELF(Phdr) *pt = (ELF(Phdr)*)(vdso_info.load_addr + hdr->e_phoff);
+ ELF(Dyn) *dyn = 0;
+
+ /*
+ * We need two things from the segment table: the load offset
+ * and the dynamic table.
+ */
+ for (i = 0; i < hdr->e_phnum; i++)
+ {
+ if (pt[i].p_type == PT_LOAD && !found_vaddr) {
+ found_vaddr = true;
+ vdso_info.load_offset = base
+ + (uintptr_t)pt[i].p_offset
+ - (uintptr_t)pt[i].p_vaddr;
+ } else if (pt[i].p_type == PT_DYNAMIC) {
+ dyn = (ELF(Dyn)*)(base + pt[i].p_offset);
+ }
+ }
+
+ if (!found_vaddr || !dyn)
+ return; /* Failed */
+
+ /*
+ * Fish out the useful bits of the dynamic table.
+ */
+ ELF(Word) *hash = 0;
+ vdso_info.symstrings = 0;
+ vdso_info.symtab = 0;
+ vdso_info.versym = 0;
+ vdso_info.verdef = 0;
+ for (i = 0; dyn[i].d_tag != DT_NULL; i++) {
+ switch (dyn[i].d_tag) {
+ case DT_STRTAB:
+ vdso_info.symstrings = (const char *)
+ ((uintptr_t)dyn[i].d_un.d_ptr
+ + vdso_info.load_offset);
+ break;
+ case DT_SYMTAB:
+ vdso_info.symtab = (ELF(Sym) *)
+ ((uintptr_t)dyn[i].d_un.d_ptr
+ + vdso_info.load_offset);
+ break;
+ case DT_HASH:
+ hash = (ELF(Word) *)
+ ((uintptr_t)dyn[i].d_un.d_ptr
+ + vdso_info.load_offset);
+ break;
+ case DT_VERSYM:
+ vdso_info.versym = (ELF(Versym) *)
+ ((uintptr_t)dyn[i].d_un.d_ptr
+ + vdso_info.load_offset);
+ break;
+ case DT_VERDEF:
+ vdso_info.verdef = (ELF(Verdef) *)
+ ((uintptr_t)dyn[i].d_un.d_ptr
+ + vdso_info.load_offset);
+ break;
+ }
+ }
+ if (!vdso_info.symstrings || !vdso_info.symtab || !hash)
+ return; /* Failed */
+
+ if (!vdso_info.verdef)
+ vdso_info.versym = 0;
+
+ /* Parse the hash table header. */
+ vdso_info.nbucket = hash[0];
+ vdso_info.nchain = hash[1];
+ vdso_info.bucket = &hash[2];
+ vdso_info.chain = &hash[vdso_info.nbucket + 2];
+
+ /* That's all we need. */
+ vdso_info.valid = true;
+}
+
+static bool vdso_match_version(ELF(Versym) ver,
+ const char *name, ELF(Word) hash)
+{
+ /*
+ * This is a helper function to check if the version indexed by
+ * ver matches name (which hashes to hash).
+ *
+ * The version definition table is a mess, and I don't know how
+ * to do this in better than linear time without allocating memory
+ * to build an index. I also don't know why the table has
+ * variable size entries in the first place.
+ *
+ * For added fun, I can't find a comprehensible specification of how
+ * to parse all the weird flags in the table.
+ *
+ * So I just parse the whole table every time.
+ */
+
+ /* First step: find the version definition */
+ ver &= 0x7fff; /* Apparently bit 15 means "hidden" */
+ ELF(Verdef) *def = vdso_info.verdef;
+ while(true) {
+ if ((def->vd_flags & VER_FLG_BASE) == 0
+ && (def->vd_ndx & 0x7fff) == ver)
+ break;
+
+ if (def->vd_next == 0)
+ return false; /* No definition. */
+
+ def = (ELF(Verdef) *)((char *)def + def->vd_next);
+ }
+
+ /* Now figure out whether it matches. */
+ ELF(Verdaux) *aux = (ELF(Verdaux)*)((char *)def + def->vd_aux);
+ return def->vd_hash == hash
+ && !strcmp(name, vdso_info.symstrings + aux->vda_name);
+}
+
+void *vdso_sym(const char *version, const char *name)
+{
+ unsigned long ver_hash;
+ if (!vdso_info.valid)
+ return 0;
+
+ ver_hash = elf_hash(version);
+ ELF(Word) chain = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
+
+ for (; chain != STN_UNDEF; chain = vdso_info.chain[chain]) {
+ ELF(Sym) *sym = &vdso_info.symtab[chain];
+
+ /* Check for a defined global or weak function w/ right name. */
+ if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+ continue;
+ if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
+ ELF64_ST_BIND(sym->st_info) != STB_WEAK)
+ continue;
+ if (sym->st_shndx == SHN_UNDEF)
+ continue;
+ if (strcmp(name, vdso_info.symstrings + sym->st_name))
+ continue;
+
+ /* Check symbol version. */
+ if (vdso_info.versym
+ && !vdso_match_version(vdso_info.versym[chain],
+ version, ver_hash))
+ continue;
+
+ return (void *)(vdso_info.load_offset + sym->st_value);
+ }
+
+ return 0;
+}
+
+void vdso_init_from_auxv(void *auxv)
+{
+ ELF(auxv_t) *elf_auxv = auxv;
+ for (int i = 0; elf_auxv[i].a_type != AT_NULL; i++)
+ {
+ if (elf_auxv[i].a_type == AT_SYSINFO_EHDR) {
+ vdso_init_from_sysinfo_ehdr(elf_auxv[i].a_un.a_val);
+ return;
+ }
+ }
+
+ vdso_info.valid = false;
+}
diff --git a/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
new file mode 100644
index 0000000..93b0ebf
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_standalone_test_x86.c
@@ -0,0 +1,128 @@
+/*
+ * vdso_test.c: Sample code to test parse_vdso.c on x86
+ * Copyright (c) 2011-2014 Andy Lutomirski
+ * Subject to the GNU General Public License, version 2
+ *
+ * You can amuse yourself by compiling with:
+ * gcc -std=gnu99 -nostdlib
+ * -Os -fno-asynchronous-unwind-tables -flto -lgcc_s
+ * vdso_standalone_test_x86.c parse_vdso.c
+ * to generate a small binary. On x86_64, you can omit -lgcc_s
+ * if you want the binary to be completely standalone.
+ */
+
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <stdint.h>
+
+extern void *vdso_sym(const char *version, const char *name);
+extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
+extern void vdso_init_from_auxv(void *auxv);
+
+/* We need a libc functions... */
+int strcmp(const char *a, const char *b)
+{
+ /* This implementation is buggy: it never returns -1. */
+ while (*a || *b) {
+ if (*a != *b)
+ return 1;
+ if (*a == 0 || *b == 0)
+ return 1;
+ a++;
+ b++;
+ }
+
+ return 0;
+}
+
+/* ...and two syscalls. This is x86-specific. */
+static inline long x86_syscall3(long nr, long a0, long a1, long a2)
+{
+ long ret;
+#ifdef __x86_64__
+ asm volatile ("syscall" : "=a" (ret) : "a" (nr),
+ "D" (a0), "S" (a1), "d" (a2) :
+ "cc", "memory", "rcx",
+ "r8", "r9", "r10", "r11" );
+#else
+ asm volatile ("int $0x80" : "=a" (ret) : "a" (nr),
+ "b" (a0), "c" (a1), "d" (a2) :
+ "cc", "memory" );
+#endif
+ return ret;
+}
+
+static inline long linux_write(int fd, const void *data, size_t len)
+{
+ return x86_syscall3(__NR_write, fd, (long)data, (long)len);
+}
+
+static inline void linux_exit(int code)
+{
+ x86_syscall3(__NR_exit, code, 0, 0);
+}
+
+void to_base10(char *lastdig, time_t n)
+{
+ while (n) {
+ *lastdig = (n % 10) + '0';
+ n /= 10;
+ lastdig--;
+ }
+}
+
+__attribute__((externally_visible)) void c_main(void **stack)
+{
+ /* Parse the stack */
+ long argc = (long)*stack;
+ stack += argc + 2;
+
+ /* Now we're pointing at the environment. Skip it. */
+ while(*stack)
+ stack++;
+ stack++;
+
+ /* Now we're pointing at auxv. Initialize the vDSO parser. */
+ vdso_init_from_auxv((void *)stack);
+
+ /* Find gettimeofday. */
+ typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
+ gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
+
+ if (!gtod)
+ linux_exit(1);
+
+ struct timeval tv;
+ long ret = gtod(&tv, 0);
+
+ if (ret == 0) {
+ char buf[] = "The time is .000000\n";
+ to_base10(buf + 31, tv.tv_sec);
+ to_base10(buf + 38, tv.tv_usec);
+ linux_write(1, buf, sizeof(buf) - 1);
+ } else {
+ linux_exit(ret);
+ }
+
+ linux_exit(0);
+}
+
+/*
+ * This is the real entry point. It passes the initial stack into
+ * the C entry point.
+ */
+asm (
+ ".text\n"
+ ".global _start\n"
+ ".type _start,@function\n"
+ "_start:\n\t"
+#ifdef __x86_64__
+ "mov %rsp,%rdi\n\t"
+ "jmp c_main"
+#else
+ "push %esp\n\t"
+ "call c_main\n\t"
+ "int $3"
+#endif
+ );
diff --git a/tools/testing/selftests/vDSO/vdso_test.c b/tools/testing/selftests/vDSO/vdso_test.c
new file mode 100644
index 0000000..8daeb7d7
--- /dev/null
+++ b/tools/testing/selftests/vDSO/vdso_test.c
@@ -0,0 +1,52 @@
+/*
+ * vdso_test.c: Sample code to test parse_vdso.c
+ * Copyright (c) 2014 Andy Lutomirski
+ * Subject to the GNU General Public License, version 2
+ *
+ * Compile with:
+ * gcc -std=gnu99 vdso_test.c parse_vdso.c
+ *
+ * Tested on x86, 32-bit and 64-bit. It may work on other architectures, too.
+ */
+
+#include <stdint.h>
+#include <elf.h>
+#include <stdio.h>
+#include <sys/auxv.h>
+#include <sys/time.h>
+
+extern void *vdso_sym(const char *version, const char *name);
+extern void vdso_init_from_sysinfo_ehdr(uintptr_t base);
+extern void vdso_init_from_auxv(void *auxv);
+
+int main(int argc, char **argv)
+{
+ unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
+ if (!sysinfo_ehdr) {
+ printf("AT_SYSINFO_EHDR is not present!\n");
+ return 0;
+ }
+
+ vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
+
+ /* Find gettimeofday. */
+ typedef long (*gtod_t)(struct timeval *tv, struct timezone *tz);
+ gtod_t gtod = (gtod_t)vdso_sym("LINUX_2.6", "__vdso_gettimeofday");
+
+ if (!gtod) {
+ printf("Could not find __vdso_gettimeofday\n");
+ return 1;
+ }
+
+ struct timeval tv;
+ long ret = gtod(&tv, 0);
+
+ if (ret == 0) {
+ printf("The time is %lld.%06lld\n",
+ (long long)tv.tv_sec, (long long)tv.tv_usec);
+ } else {
+ printf("__vdso_gettimeofday failed\n");
+ }
+
+ return 0;
+}
--
2.7.4