xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame^] | 1 | /* Locate the shared object symbol nearest a given address. |
| 2 | Copyright (C) 1996-2016 Free Software Foundation, Inc. |
| 3 | This file is part of the GNU C Library. |
| 4 | |
| 5 | The GNU C Library is free software; you can redistribute it and/or |
| 6 | modify it under the terms of the GNU Lesser General Public |
| 7 | License as published by the Free Software Foundation; either |
| 8 | version 2.1 of the License, or (at your option) any later version. |
| 9 | |
| 10 | The GNU C Library is distributed in the hope that it will be useful, |
| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | Lesser General Public License for more details. |
| 14 | |
| 15 | You should have received a copy of the GNU Lesser General Public |
| 16 | License along with the GNU C Library; if not, see |
| 17 | <http://www.gnu.org/licenses/>. */ |
| 18 | |
| 19 | #include <dlfcn.h> |
| 20 | #include <stddef.h> |
| 21 | #include <ldsodefs.h> |
| 22 | |
| 23 | |
| 24 | static inline void |
| 25 | __attribute ((always_inline)) |
| 26 | determine_info (const ElfW(Addr) addr, struct link_map *match, Dl_info *info, |
| 27 | struct link_map **mapp, const ElfW(Sym) **symbolp) |
| 28 | { |
| 29 | /* Now we know what object the address lies in. */ |
| 30 | info->dli_fname = match->l_name; |
| 31 | info->dli_fbase = (void *) match->l_map_start; |
| 32 | |
| 33 | /* If this is the main program the information is incomplete. */ |
| 34 | if (__builtin_expect (match->l_name[0], 'a') == '\0' |
| 35 | && match->l_type == lt_executable) |
| 36 | info->dli_fname = _dl_argv[0]; |
| 37 | |
| 38 | const ElfW(Sym) *symtab |
| 39 | = (const ElfW(Sym) *) D_PTR (match, l_info[DT_SYMTAB]); |
| 40 | const char *strtab = (const char *) D_PTR (match, l_info[DT_STRTAB]); |
| 41 | |
| 42 | ElfW(Word) strtabsize = match->l_info[DT_STRSZ]->d_un.d_val; |
| 43 | |
| 44 | const ElfW(Sym) *matchsym = NULL; |
| 45 | if (match->l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM + DT_THISPROCNUM |
| 46 | + DT_VERSIONTAGNUM + DT_EXTRANUM + DT_VALNUM] != NULL) |
| 47 | { |
| 48 | /* We look at all symbol table entries referenced by the hash |
| 49 | table. */ |
| 50 | for (Elf_Symndx bucket = 0; bucket < match->l_nbuckets; ++bucket) |
| 51 | { |
| 52 | Elf32_Word symndx = match->l_gnu_buckets[bucket]; |
| 53 | if (symndx != 0) |
| 54 | { |
| 55 | const Elf32_Word *hasharr = &match->l_gnu_chain_zero[symndx]; |
| 56 | |
| 57 | do |
| 58 | { |
| 59 | /* The hash table never references local symbols so |
| 60 | we can omit that test here. */ |
| 61 | if ((symtab[symndx].st_shndx != SHN_UNDEF |
| 62 | || symtab[symndx].st_value != 0) |
| 63 | && ELFW(ST_TYPE) (symtab[symndx].st_info) != STT_TLS |
| 64 | && DL_ADDR_SYM_MATCH (match, &symtab[symndx], |
| 65 | matchsym, addr) |
| 66 | && symtab[symndx].st_name < strtabsize) |
| 67 | matchsym = (ElfW(Sym) *) &symtab[symndx]; |
| 68 | |
| 69 | ++symndx; |
| 70 | } |
| 71 | while ((*hasharr++ & 1u) == 0); |
| 72 | } |
| 73 | } |
| 74 | } |
| 75 | else |
| 76 | { |
| 77 | const ElfW(Sym) *symtabend; |
| 78 | if (match->l_info[DT_HASH] != NULL) |
| 79 | symtabend = (symtab |
| 80 | + ((Elf_Symndx *) D_PTR (match, l_info[DT_HASH]))[1]); |
| 81 | else |
| 82 | /* There is no direct way to determine the number of symbols in the |
| 83 | dynamic symbol table and no hash table is present. The ELF |
| 84 | binary is ill-formed but what shall we do? Use the beginning of |
| 85 | the string table which generally follows the symbol table. */ |
| 86 | symtabend = (const ElfW(Sym) *) strtab; |
| 87 | |
| 88 | for (; (void *) symtab < (void *) symtabend; ++symtab) |
| 89 | if ((ELFW(ST_BIND) (symtab->st_info) == STB_GLOBAL |
| 90 | || ELFW(ST_BIND) (symtab->st_info) == STB_WEAK) |
| 91 | && ELFW(ST_TYPE) (symtab->st_info) != STT_TLS |
| 92 | && (symtab->st_shndx != SHN_UNDEF |
| 93 | || symtab->st_value != 0) |
| 94 | && DL_ADDR_SYM_MATCH (match, symtab, matchsym, addr) |
| 95 | && symtab->st_name < strtabsize) |
| 96 | matchsym = (ElfW(Sym) *) symtab; |
| 97 | } |
| 98 | |
| 99 | if (mapp) |
| 100 | *mapp = match; |
| 101 | if (symbolp) |
| 102 | *symbolp = matchsym; |
| 103 | |
| 104 | if (matchsym) |
| 105 | { |
| 106 | /* We found a symbol close by. Fill in its name and exact |
| 107 | address. */ |
| 108 | lookup_t matchl = LOOKUP_VALUE (match); |
| 109 | |
| 110 | info->dli_sname = strtab + matchsym->st_name; |
| 111 | info->dli_saddr = DL_SYMBOL_ADDRESS (matchl, matchsym); |
| 112 | } |
| 113 | else |
| 114 | { |
| 115 | /* No symbol matches. We return only the containing object. */ |
| 116 | info->dli_sname = NULL; |
| 117 | info->dli_saddr = NULL; |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | |
| 122 | int |
| 123 | internal_function |
| 124 | _dl_addr (const void *address, Dl_info *info, |
| 125 | struct link_map **mapp, const ElfW(Sym) **symbolp) |
| 126 | { |
| 127 | const ElfW(Addr) addr = DL_LOOKUP_ADDRESS (address); |
| 128 | int result = 0; |
| 129 | |
| 130 | /* Protect against concurrent loads and unloads. */ |
| 131 | __rtld_lock_lock_recursive (GL(dl_load_lock)); |
| 132 | |
| 133 | struct link_map *l = _dl_find_dso_for_object (addr); |
| 134 | |
| 135 | if (l) |
| 136 | { |
| 137 | determine_info (addr, l, info, mapp, symbolp); |
| 138 | result = 1; |
| 139 | } |
| 140 | |
| 141 | __rtld_lock_unlock_recursive (GL(dl_load_lock)); |
| 142 | |
| 143 | return result; |
| 144 | } |
| 145 | libc_hidden_def (_dl_addr) |
| 146 | |
| 147 | /* Return non-zero if ADDR lies within one of L's segments. */ |
| 148 | int |
| 149 | internal_function |
| 150 | _dl_addr_inside_object (struct link_map *l, const ElfW(Addr) addr) |
| 151 | { |
| 152 | int n = l->l_phnum; |
| 153 | const ElfW(Addr) reladdr = addr - l->l_addr; |
| 154 | |
| 155 | while (--n >= 0) |
| 156 | if (l->l_phdr[n].p_type == PT_LOAD |
| 157 | && reladdr - l->l_phdr[n].p_vaddr >= 0 |
| 158 | && reladdr - l->l_phdr[n].p_vaddr < l->l_phdr[n].p_memsz) |
| 159 | return 1; |
| 160 | return 0; |
| 161 | } |