diff options
Diffstat (limited to 'elf/do-lookup.h')
| -rw-r--r-- | elf/do-lookup.h | 280 |
1 files changed, 167 insertions, 113 deletions
diff --git a/elf/do-lookup.h b/elf/do-lookup.h index e57d9df26d..ab9a510ba1 100644 --- a/elf/do-lookup.h +++ b/elf/do-lookup.h @@ -1,5 +1,5 @@ /* Look up a symbol in the loaded objects. - Copyright (C) 1995-2002, 2003, 2004 Free Software Foundation, Inc. + Copyright (C) 1995-2004, 2005, 2006, 2007 Free Software Foundation, Inc. This file is part of the GNU C Library. The GNU C Library is free software; you can redistribute it and/or @@ -17,150 +17,208 @@ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA. */ + /* Inner part of the lookup functions. We return a value > 0 if we found the symbol, the value 0 if nothing is found and < 0 if something bad happened. */ static int __attribute_noinline__ -do_lookup_x (const char *undef_name, unsigned long int hash, - const ElfW(Sym) *ref, struct sym_val *result, - struct r_scope_elem *scope, size_t i, +do_lookup_x (const char *undef_name, uint_fast32_t new_hash, + unsigned long int *old_hash, const ElfW(Sym) *ref, + struct sym_val *result, struct r_scope_elem *scope, size_t i, const struct r_found_version *const version, int flags, struct link_map *skip, int type_class) { - struct link_map **list = scope->r_list; size_t n = scope->r_nlist; - struct link_map *map; + /* Make sure we read the value before proceeding. Otherwise we + might use r_list pointing to the initial scope and r_nlist being + the value after a resize. That is the only path in dl-open.c not + protected by GSCOPE. A read barrier here might be to expensive. */ + __asm volatile ("" : "+r" (n), "+m" (scope->r_list)); + struct link_map **list = scope->r_list; do { - const ElfW(Sym) *symtab; - const char *strtab; - const ElfW(Half) *verstab; + /* These variables are used in the nested function. */ Elf_Symndx symidx; - const ElfW(Sym) *sym; int num_versions = 0; const ElfW(Sym) *versioned_sym = NULL; - map = list[i]->l_real; + const struct link_map *map = list[i]->l_real; /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */ - if (skip != NULL && map == skip) + if (map == skip) continue; /* Don't search the executable when resolving a copy reloc. */ if ((type_class & ELF_RTYPE_CLASS_COPY) && map->l_type == lt_executable) continue; + /* Do not look into objects which are going to be removed. */ + if (map->l_removed) + continue; + /* Print some debugging info if wanted. */ if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SYMBOLS, 0)) - _dl_debug_printf ("symbol=%s; lookup in file=%s\n", + _dl_debug_printf ("symbol=%s; lookup in file=%s [%lu]\n", undef_name, - map->l_name[0] ? map->l_name : rtld_progname); + map->l_name[0] ? map->l_name : rtld_progname, + map->l_ns); - symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); - strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); - verstab = map->l_versyms; + /* If the hash table is empty there is nothing to do here. */ + if (map->l_nbuckets == 0) + continue; - /* Search the appropriate hash bucket in this object's symbol table - for a definition for the same symbol name. */ - for (symidx = map->l_buckets[hash % map->l_nbuckets]; - symidx != STN_UNDEF; - symidx = map->l_chain[symidx]) - { - sym = &symtab[symidx]; - - assert (ELF_RTYPE_CLASS_PLT == 1); - if ((sym->st_value == 0 /* No value. */ -#ifdef USE_TLS - && ELFW(ST_TYPE) (sym->st_info) != STT_TLS -#endif - ) - || (type_class & (sym->st_shndx == SHN_UNDEF))) - continue; - - if (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC -#ifdef USE_TLS - && ELFW(ST_TYPE) (sym->st_info) != STT_TLS -#endif - ) - /* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC - entries (and STT_TLS if TLS is supported) since these - are no code/data definitions. */ - continue; - - if (sym != ref && strcmp (strtab + sym->st_name, undef_name)) - /* Not the symbol we are looking for. */ - continue; - - if (version != NULL) - { - if (__builtin_expect (verstab == NULL, 0)) - { - /* We need a versioned symbol but haven't found any. If - this is the object which is referenced in the verneed - entry it is a bug in the library since a symbol must - not simply disappear. - - It would also be a bug in the object since it means that - the list of required versions is incomplete and so the - tests in dl-version.c haven't found a problem.*/ - assert (version->filename == NULL - || ! _dl_name_match_p (version->filename, map)); - - /* Otherwise we accept the symbol. */ - } - else - { - /* We can match the version information or use the - default one if it is not hidden. */ - ElfW(Half) ndx = verstab[symidx] & 0x7fff; - if ((map->l_versions[ndx].hash != version->hash - || strcmp (map->l_versions[ndx].name, version->name)) - && (version->hidden || map->l_versions[ndx].hash - || (verstab[symidx] & 0x8000))) - /* It's not the version we want. */ - continue; - } - } - else - { - /* No specific version is selected. There are two ways we - can got here: + /* The tables for this map. */ + const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); + const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); + + + /* Nested routine to check whether the symbol matches. */ + const ElfW(Sym) * + __attribute_noinline__ + check_match (const ElfW(Sym) *sym) + { + assert (ELF_RTYPE_CLASS_PLT == 1); + if (__builtin_expect ((sym->st_value == 0 /* No value. */ + && ELFW(ST_TYPE) (sym->st_info) != STT_TLS) + || (type_class & (sym->st_shndx == SHN_UNDEF)), + 0)) + return NULL; + + if (__builtin_expect (ELFW(ST_TYPE) (sym->st_info) > STT_FUNC + && ELFW(ST_TYPE) (sym->st_info) != STT_TLS, 0)) + /* Ignore all but STT_NOTYPE, STT_OBJECT and STT_FUNC + entries (and STT_TLS if TLS is supported) since these + are no code/data definitions. */ + return NULL; + + if (sym != ref && strcmp (strtab + sym->st_name, undef_name)) + /* Not the symbol we are looking for. */ + return NULL; - - a binary which does not include versioning information - is loaded + const ElfW(Half) *verstab = map->l_versyms; + if (version != NULL) + { + if (__builtin_expect (verstab == NULL, 0)) + { + /* We need a versioned symbol but haven't found any. If + this is the object which is referenced in the verneed + entry it is a bug in the library since a symbol must + not simply disappear. - - dlsym() instead of dlvsym() is used to get a symbol which - might exist in more than one form + It would also be a bug in the object since it means that + the list of required versions is incomplete and so the + tests in dl-version.c haven't found a problem.*/ + assert (version->filename == NULL + || ! _dl_name_match_p (version->filename, map)); - If the library does not provide symbol version - information there is no problem at at: we simply use the - symbol if it is defined. + /* Otherwise we accept the symbol. */ + } + else + { + /* We can match the version information or use the + default one if it is not hidden. */ + ElfW(Half) ndx = verstab[symidx] & 0x7fff; + if ((map->l_versions[ndx].hash != version->hash + || strcmp (map->l_versions[ndx].name, version->name)) + && (version->hidden || map->l_versions[ndx].hash + || (verstab[symidx] & 0x8000))) + /* It's not the version we want. */ + return NULL; + } + } + else + { + /* No specific version is selected. There are two ways we + can got here: - These two lookups need to be handled differently if the - library defines versions. In the case of the old - unversioned application the oldest (default) version - should be used. In case of a dlsym() call the latest and - public interface should be returned. */ - if (verstab != NULL) + - a binary which does not include versioning information + is loaded + + - dlsym() instead of dlvsym() is used to get a symbol which + might exist in more than one form + + If the library does not provide symbol version information + there is no problem at at: we simply use the symbol if it + is defined. + + These two lookups need to be handled differently if the + library defines versions. In the case of the old + unversioned application the oldest (default) version + should be used. In case of a dlsym() call the latest and + public interface should be returned. */ + if (verstab != NULL) + { + if ((verstab[symidx] & 0x7fff) + >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3)) + { + /* Don't accept hidden symbols. */ + if ((verstab[symidx] & 0x8000) == 0 + && num_versions++ == 0) + /* No version so far. */ + versioned_sym = sym; + + return NULL; + } + } + } + + /* There cannot be another entry for this symbol so stop here. */ + return sym; + } + + const ElfW(Sym) *sym; + const ElfW(Addr) *bitmask = map->l_gnu_bitmask; + if (__builtin_expect (bitmask != NULL, 1)) + { + ElfW(Addr) bitmask_word + = bitmask[(new_hash / __ELF_NATIVE_CLASS) + & map->l_gnu_bitmask_idxbits]; + + unsigned int hashbit1 = new_hash & (__ELF_NATIVE_CLASS - 1); + unsigned int hashbit2 = ((new_hash >> map->l_gnu_shift) + & (__ELF_NATIVE_CLASS - 1)); + + if (__builtin_expect ((bitmask_word >> hashbit1) + & (bitmask_word >> hashbit2) & 1, 0)) + { + Elf32_Word bucket = map->l_gnu_buckets[new_hash + % map->l_nbuckets]; + if (bucket != 0) { - if ((verstab[symidx] & 0x7fff) - >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3)) - { - /* Don't accept hidden symbols. */ - if ((verstab[symidx] & 0x8000) == 0 - && num_versions++ == 0) - /* No version so far. */ - versioned_sym = sym; + const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket]; - continue; - } + do + if ((*hasharr & ~1u) == (new_hash & ~1u)) + { + symidx = hasharr - map->l_gnu_chain_zero; + sym = check_match (&symtab[symidx]); + if (sym != NULL) + goto found_it; + } + while ((*hasharr++ & 1u) == 0); } } + /* No symbol found. */ + symidx = SHN_UNDEF; + } + else + { + if (*old_hash == 0xffffffff) + *old_hash = _dl_elf_hash (undef_name); - /* There cannot be another entry for this symbol so stop here. */ - goto found_it; + /* Use the old SysV-style hash table. Search the appropriate + hash bucket in this object's symbol table for a definition + for the same symbol name. */ + for (symidx = map->l_buckets[*old_hash % map->l_nbuckets]; + symidx != STN_UNDEF; + symidx = map->l_chain[symidx]) + { + sym = check_match (&symtab[symidx]); + if (sym != NULL) + goto found_it; + } } /* If we have seen exactly one versioned symbol while we are @@ -181,7 +239,7 @@ do_lookup_x (const char *undef_name, unsigned long int hash, if (! result->s) { result->s = sym; - result->m = map; + result->m = (struct link_map *) map; } break; } @@ -189,7 +247,7 @@ do_lookup_x (const char *undef_name, unsigned long int hash, case STB_GLOBAL: /* Global definition. Just what we need. */ result->s = sym; - result->m = map; + result->m = (struct link_map *) map; return 1; default: /* Local symbols are ignored. */ @@ -208,7 +266,3 @@ do_lookup_x (const char *undef_name, unsigned long int hash, /* We have not found anything until now. */ return 0; } - -#undef FCT -#undef ARG -#undef VERSIONED |