diff options
Diffstat (limited to 'elf/do-lookup.h')
| -rw-r--r-- | elf/do-lookup.h | 280 |
1 files changed, 113 insertions, 167 deletions
diff --git a/elf/do-lookup.h b/elf/do-lookup.h index ab9a510ba1..e57d9df26d 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) 1995-2004, 2005, 2006, 2007 Free Software Foundation, Inc. + Copyright (C) 1995-2002, 2003, 2004 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 @@ -17,208 +17,150 @@ 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, 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, +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, const struct r_found_version *const version, int flags, struct link_map *skip, int type_class) { - size_t n = scope->r_nlist; - /* 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; + size_t n = scope->r_nlist; + struct link_map *map; do { - /* These variables are used in the nested function. */ + const ElfW(Sym) *symtab; + const char *strtab; + const ElfW(Half) *verstab; Elf_Symndx symidx; + const ElfW(Sym) *sym; int num_versions = 0; const ElfW(Sym) *versioned_sym = NULL; - const struct link_map *map = list[i]->l_real; + map = list[i]->l_real; /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */ - if (map == skip) + if (skip != NULL && 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 [%lu]\n", + _dl_debug_printf ("symbol=%s; lookup in file=%s\n", undef_name, - map->l_name[0] ? map->l_name : rtld_progname, - map->l_ns); - - /* If the hash table is empty there is nothing to do here. */ - if (map->l_nbuckets == 0) - continue; - - /* 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; - - 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. - - 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. */ - return NULL; - } - } - else - { - /* No specific version is selected. There are two ways we - can got here: - - - 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. + map->l_name[0] ? map->l_name : rtld_progname); - 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; + symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); + strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); + verstab = map->l_versyms; - return NULL; - } - } - } + /* 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: - /* There cannot be another entry for this symbol so stop here. */ - return sym; - } + - a binary which does not include versioning information + is loaded - 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]; + - dlsym() instead of dlvsym() is used to get a symbol which + might exist in more than one form - unsigned int hashbit1 = new_hash & (__ELF_NATIVE_CLASS - 1); - unsigned int hashbit2 = ((new_hash >> map->l_gnu_shift) - & (__ELF_NATIVE_CLASS - 1)); + If the library does not provide symbol version + information there is no problem at at: we simply use the + symbol if it is defined. - 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) + 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) { - const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket]; + 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; - 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); + continue; + } } } - /* No symbol found. */ - symidx = SHN_UNDEF; - } - else - { - if (*old_hash == 0xffffffff) - *old_hash = _dl_elf_hash (undef_name); - /* 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; - } + /* There cannot be another entry for this symbol so stop here. */ + goto found_it; } /* If we have seen exactly one versioned symbol while we are @@ -239,7 +181,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, if (! result->s) { result->s = sym; - result->m = (struct link_map *) map; + result->m = map; } break; } @@ -247,7 +189,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, case STB_GLOBAL: /* Global definition. Just what we need. */ result->s = sym; - result->m = (struct link_map *) map; + result->m = map; return 1; default: /* Local symbols are ignored. */ @@ -266,3 +208,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash, /* We have not found anything until now. */ return 0; } + +#undef FCT +#undef ARG +#undef VERSIONED |