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Diffstat (limited to 'tools/testing/selftests/vDSO/parse_vdso.c')
-rw-r--r--tools/testing/selftests/vDSO/parse_vdso.c159
1 files changed, 106 insertions, 53 deletions
diff --git a/tools/testing/selftests/vDSO/parse_vdso.c b/tools/testing/selftests/vDSO/parse_vdso.c
index 413f75620a35..3ff00fb624a4 100644
--- a/tools/testing/selftests/vDSO/parse_vdso.c
+++ b/tools/testing/selftests/vDSO/parse_vdso.c
@@ -19,13 +19,14 @@
#include <stdint.h>
#include <string.h>
#include <limits.h>
-#include <elf.h>
+#include <linux/auxvec.h>
+#include <linux/elf.h>
#include "parse_vdso.h"
/* And here's the code. */
#ifndef ELF_BITS
-# if ULONG_MAX > 0xffffffffUL
+# if __SIZEOF_LONG__ >= 8
# define ELF_BITS 64
# else
# define ELF_BITS 32
@@ -36,6 +37,12 @@
#define ELF_BITS_XFORM(bits, x) ELF_BITS_XFORM2(bits, x)
#define ELF(x) ELF_BITS_XFORM(ELF_BITS, x)
+#ifdef __s390x__
+#define ELF_HASH_ENTRY ELF(Xword)
+#else
+#define ELF_HASH_ENTRY ELF(Word)
+#endif
+
static struct vdso_info
{
bool valid;
@@ -47,28 +54,45 @@ static struct vdso_info
/* Symbol table */
ELF(Sym) *symtab;
const char *symstrings;
- ELF(Word) *bucket, *chain;
- ELF(Word) nbucket, nchain;
+ ELF(Word) *gnu_hash, *gnu_bucket;
+ ELF_HASH_ENTRY *bucket, *chain;
+ ELF_HASH_ENTRY 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)
+/*
+ * Straight from the ELF specification...and then tweaked slightly, in order to
+ * avoid a few clang warnings.
+ */
+static unsigned long elf_hash(const char *name)
{
unsigned long h = 0, g;
- while (*name)
+ const unsigned char *uch_name = (const unsigned char *)name;
+
+ while (*uch_name)
{
- h = (h << 4) + *name++;
- if (g = h & 0xf0000000)
+ h = (h << 4) + *uch_name++;
+ g = h & 0xf0000000;
+ if (g)
h ^= g >> 24;
h &= ~g;
}
return h;
}
+static uint32_t gnu_hash(const char *name)
+{
+ const unsigned char *s = (void *)name;
+ uint32_t h = 5381;
+
+ for (; *s; s++)
+ h += h * 32 + *s;
+ return h;
+}
+
void vdso_init_from_sysinfo_ehdr(uintptr_t base)
{
size_t i;
@@ -109,8 +133,9 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base)
/*
* Fish out the useful bits of the dynamic table.
*/
- ELF(Word) *hash = 0;
+ ELF_HASH_ENTRY *hash = 0;
vdso_info.symstrings = 0;
+ vdso_info.gnu_hash = 0;
vdso_info.symtab = 0;
vdso_info.versym = 0;
vdso_info.verdef = 0;
@@ -127,10 +152,15 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base)
+ vdso_info.load_offset);
break;
case DT_HASH:
- hash = (ELF(Word) *)
+ hash = (ELF_HASH_ENTRY *)
((uintptr_t)dyn[i].d_un.d_ptr
+ vdso_info.load_offset);
break;
+ case DT_GNU_HASH:
+ vdso_info.gnu_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
@@ -143,17 +173,27 @@ void vdso_init_from_sysinfo_ehdr(uintptr_t base)
break;
}
}
- if (!vdso_info.symstrings || !vdso_info.symtab || !hash)
+ if (!vdso_info.symstrings || !vdso_info.symtab ||
+ (!hash && !vdso_info.gnu_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];
+ if (vdso_info.gnu_hash) {
+ vdso_info.nbucket = vdso_info.gnu_hash[0];
+ /* The bucket array is located after the header (4 uint32) and the bloom
+ * filter (size_t array of gnu_hash[2] elements).
+ */
+ vdso_info.gnu_bucket = vdso_info.gnu_hash + 4 +
+ sizeof(size_t) / 4 * vdso_info.gnu_hash[2];
+ } else {
+ 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;
@@ -197,6 +237,26 @@ static bool vdso_match_version(ELF(Versym) ver,
&& !strcmp(name, vdso_info.symstrings + aux->vda_name);
}
+static bool check_sym(ELF(Sym) *sym, ELF(Word) i, const char *name,
+ const char *version, unsigned long ver_hash)
+{
+ /* Check for a defined global or weak function w/ right name. */
+ if (ELF64_ST_TYPE(sym->st_info) != STT_FUNC)
+ return false;
+ if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
+ ELF64_ST_BIND(sym->st_info) != STB_WEAK)
+ return false;
+ if (strcmp(name, vdso_info.symstrings + sym->st_name))
+ return false;
+
+ /* Check symbol version. */
+ if (vdso_info.versym &&
+ !vdso_match_version(vdso_info.versym[i], version, ver_hash))
+ return false;
+
+ return true;
+}
+
void *vdso_sym(const char *version, const char *name)
{
unsigned long ver_hash;
@@ -204,44 +264,37 @@ void *vdso_sym(const char *version, const char *name)
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;
+ ELF(Word) i;
+
+ if (vdso_info.gnu_hash) {
+ uint32_t h1 = gnu_hash(name), h2, *hashval;
+
+ i = vdso_info.gnu_bucket[h1 % vdso_info.nbucket];
+ if (i == 0)
+ return 0;
+ h1 |= 1;
+ hashval = vdso_info.gnu_bucket + vdso_info.nbucket +
+ (i - vdso_info.gnu_hash[1]);
+ for (;; i++) {
+ ELF(Sym) *sym = &vdso_info.symtab[i];
+ h2 = *hashval++;
+ if (h1 == (h2 | 1) &&
+ check_sym(sym, i, name, version, ver_hash))
+ return (void *)(vdso_info.load_offset +
+ sym->st_value);
+ if (h2 & 1)
+ break;
+ }
+ } else {
+ i = vdso_info.bucket[elf_hash(name) % vdso_info.nbucket];
+ for (; i; i = vdso_info.chain[i]) {
+ ELF(Sym) *sym = &vdso_info.symtab[i];
+ if (sym->st_shndx != SHN_UNDEF &&
+ check_sym(sym, i, name, version, ver_hash))
+ return (void *)(vdso_info.load_offset +
+ sym->st_value);
}
}
- vdso_info.valid = false;
+ return 0;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.