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-rw-r--r--ldso/include/dl-elf.h21
-rw-r--r--ldso/include/dl-hash.h25
-rw-r--r--ldso/include/ldso.h10
-rw-r--r--ldso/ldso/dl-hash.c191
4 files changed, 215 insertions, 32 deletions
diff --git a/ldso/include/dl-elf.h b/ldso/include/dl-elf.h
index 9d8da0d13..3e418622d 100644
--- a/ldso/include/dl-elf.h
+++ b/ldso/include/dl-elf.h
@@ -84,8 +84,11 @@ extern void _dl_protect_relro (struct elf_resolve *l);
#endif
/* OS and/or GNU dynamic extensions */
-#define OS_NUM 1
-#define DT_RELCONT_IDX DT_NUM
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+# define OS_NUM 2 /* for DT_RELOCCOUNT and DT_GNU_HASH entries */
+#else
+# define OS_NUM 1 /* for DT_RELOCCOUNT entry */
+#endif
#ifndef ARCH_DYNAMIC_INFO
/* define in arch specific code, if needed */
@@ -93,6 +96,13 @@ extern void _dl_protect_relro (struct elf_resolve *l);
#endif
#define DYNAMIC_SIZE (DT_NUM+OS_NUM+ARCH_NUM)
+/* Keep ARCH specific entries into dynamic section at the end of the array */
+#define DT_RELCONT_IDX (DYNAMIC_SIZE - OS_NUM - ARCH_NUM)
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+/* GNU hash comes just after the relocation count */
+# define DT_GNU_HASH_IDX (DT_RELCONT_IDX + 1)
+#endif
extern void _dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
void *debug_addr, DL_LOADADDR_TYPE load_off);
@@ -131,6 +141,10 @@ void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
if (dpnt->d_tag == DT_FLAGS_1 &&
(dpnt->d_un.d_val & DF_1_NOW))
dynamic_info[DT_BIND_NOW] = 1;
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ if (dpnt->d_tag == DT_GNU_HASH)
+ dynamic_info[DT_GNU_HASH_IDX] = dpnt->d_un.d_ptr;
+#endif
}
#ifdef ARCH_DYNAMIC_INFO
else {
@@ -149,6 +163,9 @@ void __dl_parse_dynamic_info(ElfW(Dyn) *dpnt, unsigned long dynamic_info[],
ADJUST_DYN_INFO(DT_SYMTAB, load_off);
ADJUST_DYN_INFO(DT_RELOC_TABLE_ADDR, load_off);
ADJUST_DYN_INFO(DT_JMPREL, load_off);
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ ADJUST_DYN_INFO(DT_GNU_HASH_IDX, load_off);
+#endif
#undef ADJUST_DYN_INFO
}
diff --git a/ldso/include/dl-hash.h b/ldso/include/dl-hash.h
index c21094020..5239467c1 100644
--- a/ldso/include/dl-hash.h
+++ b/ldso/include/dl-hash.h
@@ -40,14 +40,39 @@ struct elf_resolve {
unsigned short int init_flag;
unsigned long rtld_flags; /* RTLD_GLOBAL, RTLD_NOW etc. */
Elf_Symndx nbucket;
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ /* Data needed to support GNU hash style */
+ Elf32_Word l_gnu_bitmask_idxbits;
+ Elf32_Word l_gnu_shift;
+ const ElfW(Addr) *l_gnu_bitmask;
+
+ union
+ {
+ const Elf32_Word *l_gnu_chain_zero;
+ const Elf_Symndx *elf_buckets;
+ };
+#else
Elf_Symndx *elf_buckets;
+#endif
+
struct init_fini_list *init_fini;
struct init_fini_list *rtld_local; /* keep tack of RTLD_LOCAL libs in same group */
/*
* These are only used with ELF style shared libraries
*/
Elf_Symndx nchain;
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ union
+ {
+ const Elf32_Word *l_gnu_buckets;
+ const Elf_Symndx *chains;
+ };
+#else
Elf_Symndx *chains;
+#endif
+
unsigned long dynamic_info[DYNAMIC_SIZE];
unsigned long n_phent;
diff --git a/ldso/include/ldso.h b/ldso/include/ldso.h
index 40ac12a57..d96d137e9 100644
--- a/ldso/include/ldso.h
+++ b/ldso/include/ldso.h
@@ -66,9 +66,17 @@ extern int _dl_debug_file;
_dl_dprintf(_dl_debug_file, "%s:%i: " fmt, __FUNCTION__, __LINE__, ## args);
# define _dl_if_debug_dprint(fmt, args...) \
do { if (_dl_debug) __dl_debug_dprint(fmt, ## args); } while (0)
+# define _dl_assert(expr) \
+ do { \
+ if (!(expr)) { \
+ __dl_debug_dprint("assert(%s)\n", #expr); \
+ _dl_exit(45); \
+ } \
+ } while (0)
#else
-# define _dl_debug_dprint(fmt, args...)
+# define __dl_debug_dprint(fmt, args...)
# define _dl_if_debug_dprint(fmt, args...)
+# define _dl_assert(expr)
# define _dl_debug_file 2
#endif /* __SUPPORT_LD_DEBUG__ */
diff --git a/ldso/ldso/dl-hash.c b/ldso/ldso/dl-hash.c
index 2d5ecddbb..c85035ba8 100644
--- a/ldso/ldso/dl-hash.c
+++ b/ldso/ldso/dl-hash.c
@@ -53,6 +53,19 @@ struct dyn_elf *_dl_symbol_tables = NULL;
*/
struct dyn_elf *_dl_handles = NULL;
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+/* This is the new hash function that is used by the ELF linker to generate the
+ * GNU hash table that each executable and library will have if --hash-style=[gnu,both]
+ * is passed to the linker. We need it to decode the GNU hash table. */
+static inline Elf_Symndx _dl_gnu_hash (const unsigned char *name)
+{
+ unsigned long h = 5381;
+ unsigned char c;
+ for (c = *name; c != '\0'; c = *++name)
+ h = h * 33 + c;
+ return h & 0xffffffff;
+}
+#endif
/* This is the hash function that is used by the ELF linker to generate the
* hash table that each executable and library is required to have. We need
@@ -108,6 +121,29 @@ struct elf_resolve *_dl_add_elf_hash_table(const char *libname,
tpnt->libname = _dl_strdup(libname);
tpnt->dynamic_addr = (ElfW(Dyn) *)dynamic_addr;
tpnt->libtype = loaded_file;
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ if (dynamic_info[DT_GNU_HASH_IDX] != 0) {
+
+ Elf32_Word *hash32 = (Elf_Symndx*)dynamic_info[DT_GNU_HASH_IDX];
+
+ tpnt->nbucket = *hash32++;
+ Elf32_Word symbias = *hash32++;
+ Elf32_Word bitmask_nwords = *hash32++;
+ /* Must be a power of two. */
+ _dl_assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0);
+ tpnt->l_gnu_bitmask_idxbits = bitmask_nwords - 1;
+ tpnt->l_gnu_shift = *hash32++;
+
+ tpnt->l_gnu_bitmask = (ElfW(Addr) *) hash32;
+ hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords;
+
+ tpnt->l_gnu_buckets = hash32;
+ hash32 += tpnt->nbucket;
+ tpnt->l_gnu_chain_zero = hash32 - symbias;
+ } else
+ /* Fall using old SysV hash table if GNU hash is not present */
+#endif
if (dynamic_info[DT_HASH] != 0) {
hash_addr = (Elf_Symndx*)dynamic_info[DT_HASH];
@@ -124,22 +160,117 @@ struct elf_resolve *_dl_add_elf_hash_table(const char *libname,
}
+/* Routine to check whether the symbol matches. */
+static __attribute_noinline__ const ElfW(Sym) *
+check_match (const ElfW(Sym) *sym, char *strtab, const char* undef_name, int type_class) {
+
+ if (type_class & (sym->st_shndx == SHN_UNDEF))
+ /* undefined symbol itself */
+ return NULL;
+
+ if (sym->st_value == 0)
+ /* No value */
+ return NULL;
+
+ if (ELF_ST_TYPE(sym->st_info) > STT_FUNC
+ && ELF_ST_TYPE(sym->st_info) != STT_COMMON)
+ /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC
+ * and STT_COMMON entries since these are no
+ * code/data definitions
+ */
+ return NULL;
+
+ if (_dl_strcmp(strtab + sym->st_name, undef_name) != 0)
+ return NULL;
+
+ /* This is the matching symbol */
+ return sym;
+}
+
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+
+static __always_inline const ElfW(Sym) *
+_dl_lookup_gnu_hash(struct elf_resolve *tpnt, ElfW(Sym) *symtab, unsigned long hash,
+ const char* undef_name, int type_class) {
+
+ Elf_Symndx symidx;
+ const ElfW(Sym) *sym;
+ char *strtab;
+
+ const ElfW(Addr) *bitmask = tpnt->l_gnu_bitmask;
+
+ ElfW(Addr) bitmask_word = bitmask[(hash / __ELF_NATIVE_CLASS) & tpnt->l_gnu_bitmask_idxbits];
+
+ unsigned int hashbit1 = hash & (__ELF_NATIVE_CLASS - 1);
+ unsigned int hashbit2 = ((hash >> tpnt->l_gnu_shift) & (__ELF_NATIVE_CLASS - 1));
+
+ _dl_assert (bitmask != NULL);
+
+ if (unlikely((bitmask_word >> hashbit1) & (bitmask_word >> hashbit2) & 1)) {
+
+ Elf32_Word bucket = tpnt->l_gnu_buckets[hash % tpnt->nbucket];
+
+ if (bucket != 0) {
+ const Elf32_Word *hasharr = &tpnt->l_gnu_chain_zero[bucket];
+ do {
+ if (((*hasharr ^ hash) >> 1) == 0) {
+ symidx = hasharr - tpnt->l_gnu_chain_zero;
+ strtab = (char *) (tpnt->dynamic_info[DT_STRTAB]);
+ sym = check_match (&symtab[symidx], strtab, undef_name, type_class);
+ if (sym != NULL)
+ return sym;
+ }
+ } while ((*hasharr++ & 1u) == 0);
+ }
+ }
+ /* No symbol found. */
+ return NULL;
+}
+#endif
+
+static __always_inline const ElfW(Sym) *
+_dl_lookup_sysv_hash(struct elf_resolve *tpnt, ElfW(Sym) *symtab, unsigned long hash, const char* undef_name, int type_class) {
+
+ unsigned long hn;
+ char *strtab;
+ const ElfW(Sym) *sym;
+ Elf_Symndx symidx;
+
+ /* Avoid calling .urem here. */
+ do_rem(hn, hash, tpnt->nbucket);
+ strtab = (char *) (tpnt->dynamic_info[DT_STRTAB]);
+
+ _dl_assert(tpnt->elf_buckets != NULL);
+
+ for (symidx = tpnt->elf_buckets[hn]; symidx != STN_UNDEF; symidx = tpnt->chains[symidx]) {
+ sym = check_match (&symtab[symidx], strtab, undef_name, type_class);
+ if (sym != NULL)
+ /* At this point the symbol is that we are looking for */
+ return sym;
+ }
+ /* No symbol found into the current module*/
+ return NULL;
+}
+
/*
* This function resolves externals, and this is either called when we process
* relocations or when we call an entry in the PLT table for the first time.
*/
char *_dl_find_hash(const char *name, struct dyn_elf *rpnt, struct elf_resolve *mytpnt, int type_class)
{
- struct elf_resolve *tpnt;
- int si;
- char *strtab;
+ struct elf_resolve *tpnt = NULL;
ElfW(Sym) *symtab;
- unsigned long elf_hash_number, hn;
- const ElfW(Sym) *sym;
- char *weak_result = NULL;
- elf_hash_number = _dl_elf_hash((const unsigned char *)name);
+ unsigned long elf_hash_number = 0xffffffff;
+ const ElfW(Sym) *sym = NULL;
+
+ char *weak_result = NULL;
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ unsigned long gnu_hash_number = _dl_gnu_hash((const unsigned char *)name);
+#endif
+
for (; rpnt; rpnt = rpnt->next) {
tpnt = rpnt->dyn;
@@ -165,29 +296,32 @@ char *_dl_find_hash(const char *name, struct dyn_elf *rpnt, struct elf_resolve *
if (tpnt->nbucket == 0)
continue;
- /* Avoid calling .urem here. */
- do_rem(hn, elf_hash_number, tpnt->nbucket);
- symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB];
- strtab = (char *) (tpnt->dynamic_info[DT_STRTAB]);
-
- for (si = tpnt->elf_buckets[hn]; si != STN_UNDEF; si = tpnt->chains[si]) {
- sym = &symtab[si];
+ symtab = (ElfW(Sym) *) (intptr_t) (tpnt->dynamic_info[DT_SYMTAB]);
+
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ /* Prefer GNU hash style, if any */
+ if(tpnt->l_gnu_bitmask) {
+ if((sym = _dl_lookup_gnu_hash(tpnt, symtab, gnu_hash_number, name, type_class)) != NULL)
+ /* If sym has been found, do not search further */
+ break;
+ } else {
+#endif
+ /* Use the old SysV-style hash table */
+
+ /* Calculate the old sysv hash number only once */
+ if(elf_hash_number == 0xffffffff)
+ elf_hash_number = _dl_elf_hash((const unsigned char *)name);
- if (type_class & (sym->st_shndx == SHN_UNDEF))
- continue;
- if (sym->st_value == 0)
- continue;
- if (ELF_ST_TYPE(sym->st_info) > STT_FUNC
- && ELF_ST_TYPE(sym->st_info) != STT_COMMON)
- /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC
- * and STT_COMMON entries since these are no
- * code/data definitions
- */
- continue;
- if (_dl_strcmp(strtab + sym->st_name, name) != 0)
- continue;
+ if((sym = _dl_lookup_sysv_hash(tpnt, symtab, elf_hash_number, name, type_class)) != NULL )
+ break;
+#ifdef __LDSO_GNU_HASH_SUPPORT__
+ }
+#endif
+ } /* end of for (; rpnt; rpnt = rpnt->next) { */
- switch (ELF_ST_BIND(sym->st_info)) {
+ if(sym) {
+ /* At this point we have found the requested symbol, do binding */
+ switch (ELF_ST_BIND(sym->st_info)) {
case STB_WEAK:
#if 0
/* Perhaps we should support old style weak symbol handling
@@ -200,7 +334,6 @@ char *_dl_find_hash(const char *name, struct dyn_elf *rpnt, struct elf_resolve *
return (char*) DL_RELOC_ADDR(tpnt->loadaddr, sym->st_value);
default: /* Local symbols not handled here */
break;
- }
}
}
return weak_result;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-06 06:12:14 +0000