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d66e34cd RM |
1 | /* Relocate a shared object and resolve its references to other loaded objects. |
2 | Copyright (C) 1995 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 Library General Public License as | |
7 | published by the Free Software Foundation; either version 2 of the | |
8 | 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 | Library General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU Library General Public | |
16 | License along with the GNU C Library; see the file COPYING.LIB. If | |
17 | not, write to the Free Software Foundation, Inc., 675 Mass Ave, | |
18 | Cambridge, MA 02139, USA. */ | |
19 | ||
20 | #include <link.h> | |
21 | #include <sys/types.h> | |
22 | #include <sys/mman.h> | |
23 | #include <unistd.h> | |
24 | #include <errno.h> | |
25 | #include "dynamic-link.h" | |
26 | ||
27 | ||
28 | void | |
29 | _dl_relocate_object (struct link_map *l, int lazy) | |
30 | { | |
31 | const size_t pagesize = getpagesize (); | |
32 | ||
33 | if (l->l_relocated) | |
34 | return; | |
35 | ||
36 | if (l->l_info[DT_TEXTREL]) | |
37 | { | |
38 | /* Bletch. We must make read-only segments writable | |
39 | long enough to relocate them. */ | |
40 | const Elf32_Phdr *ph; | |
41 | for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph) | |
42 | if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0) | |
43 | { | |
44 | caddr_t mapstart = ((caddr_t) l->l_addr + | |
45 | (ph->p_vaddr & ~(pagesize - 1))); | |
46 | caddr_t mapend = ((caddr_t) l->l_addr + | |
47 | ((ph->p_vaddr + ph->p_memsz + pagesize - 1) | |
48 | & ~(pagesize - 1))); | |
49 | if (mprotect (mapstart, mapend - mapstart, | |
50 | PROT_READ|PROT_WRITE) < 0) | |
421f82e5 | 51 | _dl_signal_error (errno, l->l_name, |
d66e34cd RM |
52 | "cannot make segment writable for relocation"); |
53 | } | |
54 | } | |
55 | ||
56 | { | |
57 | struct link_map *real_next, *scope; | |
58 | ||
59 | const char *strtab | |
60 | = ((void *) l->l_addr + l->l_info[DT_STRTAB]->d_un.d_ptr); | |
61 | ||
62 | ||
63 | Elf32_Addr resolve (const Elf32_Sym **ref) | |
64 | { | |
421f82e5 RM |
65 | return _dl_lookup_symbol (strtab + (*ref)->st_name, ref, scope, |
66 | l->l_name); | |
d66e34cd RM |
67 | } |
68 | ||
69 | real_next = l->l_next; | |
70 | if (l->l_info[DT_SYMBOLIC]) | |
71 | { | |
72 | l->l_prev->l_next = real_next; | |
73 | l->l_next = _dl_loaded; | |
74 | scope = l; | |
75 | } | |
76 | else | |
77 | scope = _dl_loaded; | |
78 | ||
421f82e5 | 79 | ELF_DYNAMIC_RELOCATE (l, lazy, resolve); |
d66e34cd RM |
80 | |
81 | /* Restore list frobnication done above for DT_SYMBOLIC. */ | |
82 | l->l_next = real_next; | |
83 | l->l_prev->l_next = l; | |
84 | } | |
85 | ||
a1a9d215 | 86 | if (l->l_info[DT_JMPREL] && lazy) |
d66e34cd RM |
87 | /* Set up the PLT so its unrelocated entries will |
88 | jump to _dl_runtime_resolve, which will relocate them. */ | |
89 | elf_machine_runtime_setup (l); | |
90 | ||
91 | l->l_relocated = 1; | |
92 | ||
93 | if (l->l_info[DT_TEXTREL]) | |
94 | { | |
95 | /* Undo the protection change we made before relocating. */ | |
96 | const Elf32_Phdr *ph; | |
97 | for (ph = l->l_phdr; ph < &l->l_phdr[l->l_phnum]; ++ph) | |
98 | if (ph->p_type == PT_LOAD && (ph->p_flags & PF_W) == 0) | |
99 | { | |
100 | caddr_t mapstart = ((caddr_t) l->l_addr + | |
101 | (ph->p_vaddr & ~(pagesize - 1))); | |
102 | caddr_t mapend = ((caddr_t) l->l_addr + | |
103 | ((ph->p_vaddr + ph->p_memsz + pagesize - 1) | |
104 | & ~(pagesize - 1))); | |
105 | int prot = 0; | |
106 | if (ph->p_flags & PF_R) | |
107 | prot |= PROT_READ; | |
108 | if (ph->p_flags & PF_X) | |
109 | prot |= PROT_EXEC; | |
110 | if (mprotect (mapstart, mapend - mapstart, prot) < 0) | |
421f82e5 | 111 | _dl_signal_error (errno, l->l_name, |
d66e34cd RM |
112 | "can't restore segment prot after reloc"); |
113 | } | |
114 | } | |
115 | ||
116 | } |