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.
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.
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.
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/>. */
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
)
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
;
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];
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
]);
42 ElfW(Word
) strtabsize
= match
->l_info
[DT_STRSZ
]->d_un
.d_val
;
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
)
48 /* We look at all symbol table entries referenced by the hash
50 for (Elf_Symndx bucket
= 0; bucket
< match
->l_nbuckets
; ++bucket
)
52 Elf32_Word symndx
= match
->l_gnu_buckets
[bucket
];
55 const Elf32_Word
*hasharr
= &match
->l_gnu_chain_zero
[symndx
];
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
],
66 && symtab
[symndx
].st_name
< strtabsize
)
67 matchsym
= (ElfW(Sym
) *) &symtab
[symndx
];
71 while ((*hasharr
++ & 1u) == 0);
77 const ElfW(Sym
) *symtabend
;
78 if (match
->l_info
[DT_HASH
] != NULL
)
80 + ((Elf_Symndx
*) D_PTR (match
, l_info
[DT_HASH
]))[1]);
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
;
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 && __glibc_likely (!dl_symbol_visibility_binds_local_p (symtab
))
92 && ELFW(ST_TYPE
) (symtab
->st_info
) != STT_TLS
93 && (symtab
->st_shndx
!= SHN_UNDEF
94 || symtab
->st_value
!= 0)
95 && DL_ADDR_SYM_MATCH (match
, symtab
, matchsym
, addr
)
96 && symtab
->st_name
< strtabsize
)
97 matchsym
= (ElfW(Sym
) *) symtab
;
107 /* We found a symbol close by. Fill in its name and exact
109 lookup_t matchl
= LOOKUP_VALUE (match
);
111 info
->dli_sname
= strtab
+ matchsym
->st_name
;
112 info
->dli_saddr
= DL_SYMBOL_ADDRESS (matchl
, matchsym
);
116 /* No symbol matches. We return only the containing object. */
117 info
->dli_sname
= NULL
;
118 info
->dli_saddr
= NULL
;
125 _dl_addr (const void *address
, Dl_info
*info
,
126 struct link_map
**mapp
, const ElfW(Sym
) **symbolp
)
128 const ElfW(Addr
) addr
= DL_LOOKUP_ADDRESS (address
);
131 /* Protect against concurrent loads and unloads. */
132 __rtld_lock_lock_recursive (GL(dl_load_lock
));
134 struct link_map
*l
= _dl_find_dso_for_object (addr
);
138 determine_info (addr
, l
, info
, mapp
, symbolp
);
142 __rtld_lock_unlock_recursive (GL(dl_load_lock
));
146 libc_hidden_def (_dl_addr
)
148 /* Return non-zero if ADDR lies within one of L's segments. */
151 _dl_addr_inside_object (struct link_map
*l
, const ElfW(Addr
) addr
)
154 const ElfW(Addr
) reladdr
= addr
- l
->l_addr
;
157 if (l
->l_phdr
[n
].p_type
== PT_LOAD
158 && reladdr
- l
->l_phdr
[n
].p_vaddr
>= 0
159 && reladdr
- l
->l_phdr
[n
].p_vaddr
< l
->l_phdr
[n
].p_memsz
)