1 | /* Initialization code for TLS in statically linked application. |
2 | Copyright (C) 2002-2018 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 <startup.h> |
20 | #include <errno.h> |
21 | #include <ldsodefs.h> |
22 | #include <tls.h> |
23 | #include <unistd.h> |
24 | #include <stdio.h> |
25 | #include <sys/param.h> |
26 | |
27 | |
28 | #ifdef SHARED |
29 | #error makefile bug, this file is for static only |
30 | #endif |
31 | |
32 | dtv_t _dl_static_dtv[2 + TLS_SLOTINFO_SURPLUS]; |
33 | |
34 | |
35 | static struct |
36 | { |
37 | struct dtv_slotinfo_list si; |
38 | /* The dtv_slotinfo_list data structure does not include the actual |
39 | information since it is defined as an array of size zero. We define |
40 | here the necessary entries. Note that it is not important whether |
41 | there is padding or not since we will always access the information |
42 | through the 'si' element. */ |
43 | struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS]; |
44 | } static_slotinfo; |
45 | |
46 | |
47 | /* Highest dtv index currently needed. */ |
48 | size_t _dl_tls_max_dtv_idx; |
49 | /* Flag signalling whether there are gaps in the module ID allocation. */ |
50 | bool _dl_tls_dtv_gaps; |
51 | /* Information about the dtv slots. */ |
52 | struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list; |
53 | /* Number of modules in the static TLS block. */ |
54 | size_t _dl_tls_static_nelem; |
55 | /* Size of the static TLS block. Giving this initialized value |
56 | preallocates some surplus bytes in the static TLS area. */ |
57 | size_t _dl_tls_static_size = 2048; |
58 | /* Size actually allocated in the static TLS block. */ |
59 | size_t _dl_tls_static_used; |
60 | /* Alignment requirement of the static TLS block. */ |
61 | size_t _dl_tls_static_align; |
62 | |
63 | /* Generation counter for the dtv. */ |
64 | size_t _dl_tls_generation; |
65 | |
66 | |
67 | /* Additional definitions needed by TLS initialization. */ |
68 | #ifdef TLS_INIT_HELPER |
69 | TLS_INIT_HELPER |
70 | #endif |
71 | |
72 | static void |
73 | init_slotinfo (void) |
74 | { |
75 | /* Create the slotinfo list. */ |
76 | static_slotinfo.si.len = (((char *) (&static_slotinfo + 1) |
77 | - (char *) &static_slotinfo.si.slotinfo[0]) |
78 | / sizeof static_slotinfo.si.slotinfo[0]); |
79 | // static_slotinfo.si.next = NULL; already zero |
80 | |
81 | /* The slotinfo list. Will be extended by the code doing dynamic |
82 | linking. */ |
83 | GL(dl_tls_max_dtv_idx) = 1; |
84 | GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si; |
85 | } |
86 | |
87 | static void |
88 | init_static_tls (size_t memsz, size_t align) |
89 | { |
90 | /* That is the size of the TLS memory for this object. The initialized |
91 | value of _dl_tls_static_size is provided by dl-open.c to request some |
92 | surplus that permits dynamic loading of modules with IE-model TLS. */ |
93 | GL(dl_tls_static_size) = roundup (memsz + GL(dl_tls_static_size), |
94 | TLS_TCB_ALIGN); |
95 | #if TLS_TCB_AT_TP |
96 | GL(dl_tls_static_size) += TLS_TCB_SIZE; |
97 | #endif |
98 | GL(dl_tls_static_used) = memsz; |
99 | /* The alignment requirement for the static TLS block. */ |
100 | GL(dl_tls_static_align) = align; |
101 | /* Number of elements in the static TLS block. */ |
102 | GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx); |
103 | } |
104 | |
105 | void |
106 | __libc_setup_tls (void) |
107 | { |
108 | void *tlsblock; |
109 | size_t memsz = 0; |
110 | size_t filesz = 0; |
111 | void *initimage = NULL; |
112 | size_t align = 0; |
113 | size_t max_align = TCB_ALIGNMENT; |
114 | size_t tcb_offset; |
115 | const ElfW(Phdr) *phdr; |
116 | |
117 | struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded; |
118 | |
119 | /* Look through the TLS segment if there is any. */ |
120 | if (_dl_phdr != NULL) |
121 | for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr) |
122 | if (phdr->p_type == PT_TLS) |
123 | { |
124 | /* Remember the values we need. */ |
125 | memsz = phdr->p_memsz; |
126 | filesz = phdr->p_filesz; |
127 | initimage = (void *) phdr->p_vaddr + main_map->l_addr; |
128 | align = phdr->p_align; |
129 | if (phdr->p_align > max_align) |
130 | max_align = phdr->p_align; |
131 | break; |
132 | } |
133 | |
134 | /* We have to set up the TCB block which also (possibly) contains |
135 | 'errno'. Therefore we avoid 'malloc' which might touch 'errno'. |
136 | Instead we use 'sbrk' which would only uses 'errno' if it fails. |
137 | In this case we are right away out of memory and the user gets |
138 | what she/he deserves. |
139 | |
140 | The initialized value of _dl_tls_static_size is provided by dl-open.c |
141 | to request some surplus that permits dynamic loading of modules with |
142 | IE-model TLS. */ |
143 | #if TLS_TCB_AT_TP |
144 | /* Align the TCB offset to the maximum alignment, as |
145 | _dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign |
146 | and dl_tls_static_align. */ |
147 | tcb_offset = roundup (memsz + GL(dl_tls_static_size), max_align); |
148 | tlsblock = __sbrk (tcb_offset + TLS_INIT_TCB_SIZE + max_align); |
149 | #elif TLS_DTV_AT_TP |
150 | tcb_offset = roundup (TLS_INIT_TCB_SIZE, align ?: 1); |
151 | tlsblock = __sbrk (tcb_offset + memsz + max_align |
152 | + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size)); |
153 | tlsblock += TLS_PRE_TCB_SIZE; |
154 | #else |
155 | /* In case a model with a different layout for the TCB and DTV |
156 | is defined add another #elif here and in the following #ifs. */ |
157 | # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" |
158 | #endif |
159 | |
160 | /* Align the TLS block. */ |
161 | tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1) |
162 | & ~(max_align - 1)); |
163 | |
164 | /* Initialize the dtv. [0] is the length, [1] the generation counter. */ |
165 | _dl_static_dtv[0].counter = (sizeof (_dl_static_dtv) / sizeof (_dl_static_dtv[0])) - 2; |
166 | // _dl_static_dtv[1].counter = 0; would be needed if not already done |
167 | |
168 | /* Initialize the TLS block. */ |
169 | #if TLS_TCB_AT_TP |
170 | _dl_static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset |
171 | - roundup (memsz, align ?: 1)); |
172 | main_map->l_tls_offset = roundup (memsz, align ?: 1); |
173 | #elif TLS_DTV_AT_TP |
174 | _dl_static_dtv[2].pointer.val = (char *) tlsblock + tcb_offset; |
175 | main_map->l_tls_offset = tcb_offset; |
176 | #else |
177 | # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" |
178 | #endif |
179 | _dl_static_dtv[2].pointer.to_free = NULL; |
180 | /* sbrk gives us zero'd memory, so we don't need to clear the remainder. */ |
181 | memcpy (_dl_static_dtv[2].pointer.val, initimage, filesz); |
182 | |
183 | /* Install the pointer to the dtv. */ |
184 | |
185 | /* Initialize the thread pointer. */ |
186 | #if TLS_TCB_AT_TP |
187 | INSTALL_DTV ((char *) tlsblock + tcb_offset, _dl_static_dtv); |
188 | |
189 | const char *lossage = TLS_INIT_TP ((char *) tlsblock + tcb_offset); |
190 | #elif TLS_DTV_AT_TP |
191 | INSTALL_DTV (tlsblock, _dl_static_dtv); |
192 | const char *lossage = TLS_INIT_TP (tlsblock); |
193 | #else |
194 | # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined" |
195 | #endif |
196 | if (__builtin_expect (lossage != NULL, 0)) |
197 | _startup_fatal (lossage); |
198 | |
199 | /* Update the executable's link map with enough information to make |
200 | the TLS routines happy. */ |
201 | main_map->l_tls_align = align; |
202 | main_map->l_tls_blocksize = memsz; |
203 | main_map->l_tls_initimage = initimage; |
204 | main_map->l_tls_initimage_size = filesz; |
205 | main_map->l_tls_modid = 1; |
206 | |
207 | init_slotinfo (); |
208 | // static_slotinfo.si.slotinfo[1].gen = 0; already zero |
209 | static_slotinfo.si.slotinfo[1].map = main_map; |
210 | |
211 | memsz = roundup (memsz, align ?: 1); |
212 | |
213 | #if TLS_DTV_AT_TP |
214 | memsz += tcb_offset; |
215 | #endif |
216 | |
217 | init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align)); |
218 | } |
219 | |