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9cee5585 | 1 | /* Set up the data structures for the system-supplied DSO. |
d4697bc9 | 2 | Copyright (C) 2012-2014 Free Software Foundation, Inc. |
9cee5585 L |
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 | static inline void __attribute__ ((always_inline)) | |
20 | setup_vdso (struct link_map *main_map __attribute__ ((unused)), | |
21 | struct link_map ***first_preload __attribute__ ((unused))) | |
22 | { | |
7775448e | 23 | #ifdef NEED_DL_SYSINFO_DSO |
9cee5585 L |
24 | if (GLRO(dl_sysinfo_dso) == NULL) |
25 | return; | |
26 | ||
27 | /* Do an abridged version of the work _dl_map_object_from_fd would do | |
28 | to map in the object. It's already mapped and prelinked (and | |
29 | better be, since it's read-only and so we couldn't relocate it). | |
30 | We just want our data structures to describe it as if we had just | |
31 | mapped and relocated it normally. */ | |
32 | struct link_map *l = _dl_new_object ((char *) "", "", lt_library, NULL, | |
33 | 0, LM_ID_BASE); | |
a1ffb40e | 34 | if (__glibc_likely (l != NULL)) |
9cee5585 L |
35 | { |
36 | static ElfW(Dyn) dyn_temp[DL_RO_DYN_TEMP_CNT] attribute_relro; | |
37 | ||
38 | l->l_phdr = ((const void *) GLRO(dl_sysinfo_dso) | |
39 | + GLRO(dl_sysinfo_dso)->e_phoff); | |
40 | l->l_phnum = GLRO(dl_sysinfo_dso)->e_phnum; | |
41 | for (uint_fast16_t i = 0; i < l->l_phnum; ++i) | |
42 | { | |
43 | const ElfW(Phdr) *const ph = &l->l_phdr[i]; | |
44 | if (ph->p_type == PT_DYNAMIC) | |
45 | { | |
46 | l->l_ld = (void *) ph->p_vaddr; | |
47 | l->l_ldnum = ph->p_memsz / sizeof (ElfW(Dyn)); | |
48 | } | |
49 | else if (ph->p_type == PT_LOAD) | |
50 | { | |
51 | if (! l->l_addr) | |
52 | l->l_addr = ph->p_vaddr; | |
53 | if (ph->p_vaddr + ph->p_memsz >= l->l_map_end) | |
54 | l->l_map_end = ph->p_vaddr + ph->p_memsz; | |
55 | if ((ph->p_flags & PF_X) | |
56 | && ph->p_vaddr + ph->p_memsz >= l->l_text_end) | |
57 | l->l_text_end = ph->p_vaddr + ph->p_memsz; | |
58 | } | |
59 | else | |
60 | /* There must be no TLS segment. */ | |
61 | assert (ph->p_type != PT_TLS); | |
62 | } | |
63 | l->l_map_start = (ElfW(Addr)) GLRO(dl_sysinfo_dso); | |
64 | l->l_addr = l->l_map_start - l->l_addr; | |
65 | l->l_map_end += l->l_addr; | |
66 | l->l_text_end += l->l_addr; | |
67 | l->l_ld = (void *) ((ElfW(Addr)) l->l_ld + l->l_addr); | |
68 | elf_get_dynamic_info (l, dyn_temp); | |
69 | _dl_setup_hash (l); | |
70 | l->l_relocated = 1; | |
71 | ||
72 | /* The vDSO is always used. */ | |
73 | l->l_used = 1; | |
74 | ||
75 | /* Initialize l_local_scope to contain just this map. This allows | |
76 | the use of dl_lookup_symbol_x to resolve symbols within the vdso. | |
77 | So we create a single entry list pointing to l_real as its only | |
78 | element */ | |
79 | l->l_local_scope[0]->r_nlist = 1; | |
80 | l->l_local_scope[0]->r_list = &l->l_real; | |
81 | ||
82 | /* Now that we have the info handy, use the DSO image's soname | |
83 | so this object can be looked up by name. Note that we do not | |
84 | set l_name here. That field gives the file name of the DSO, | |
85 | and this DSO is not associated with any file. */ | |
86 | if (l->l_info[DT_SONAME] != NULL) | |
87 | { | |
88 | /* Work around a kernel problem. The kernel cannot handle | |
89 | addresses in the vsyscall DSO pages in writev() calls. */ | |
90 | const char *dsoname = ((char *) D_PTR (l, l_info[DT_STRTAB]) | |
91 | + l->l_info[DT_SONAME]->d_un.d_val); | |
f315524e | 92 | size_t len = strlen (dsoname) + 1; |
9cee5585 L |
93 | char *copy = malloc (len); |
94 | if (copy == NULL) | |
95 | _dl_fatal_printf ("out of memory\n"); | |
96 | l->l_libname->name = l->l_name = memcpy (copy, dsoname, len); | |
97 | } | |
98 | ||
99 | /* Add the vDSO to the object list. */ | |
100 | _dl_add_to_namespace_list (l, LM_ID_BASE); | |
101 | ||
a3848485 | 102 | # if IS_IN (rtld) |
9cee5585 L |
103 | /* Rearrange the list so this DSO appears after rtld_map. */ |
104 | assert (l->l_next == NULL); | |
105 | assert (l->l_prev == main_map); | |
106 | GL(dl_rtld_map).l_next = l; | |
107 | l->l_prev = &GL(dl_rtld_map); | |
108 | *first_preload = &l->l_next; | |
bb859b06 L |
109 | # else |
110 | GL(dl_nns) = 1; | |
9cee5585 L |
111 | # endif |
112 | ||
113 | /* We have a prelinked DSO preloaded by the system. */ | |
114 | GLRO(dl_sysinfo_map) = l; | |
115 | # ifdef NEED_DL_SYSINFO | |
116 | if (GLRO(dl_sysinfo) == DL_SYSINFO_DEFAULT) | |
117 | GLRO(dl_sysinfo) = GLRO(dl_sysinfo_dso)->e_entry + l->l_addr; | |
118 | # endif | |
119 | } | |
120 | #endif | |
121 | } |