1 /* Initialization code for TLS in statically linked application.
2 Copyright (C) 2002, 2003, 2004, 2005 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/>. */
24 #include <sys/param.h>
32 #error makefile bug, this file is for static only
36 extern ElfW(Phdr) *_dl_phdr;
37 extern size_t _dl_phnum;
40 static dtv_t static_dtv[2 + TLS_SLOTINFO_SURPLUS];
45 struct dtv_slotinfo_list si;
46 /* The dtv_slotinfo_list data structure does not include the actual
47 information since it is defined as an array of size zero. We define
48 here the necessary entries. Note that it is not important whether
49 there is padding or not since we will always access the information
50 through the 'si' element. */
51 struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
54 /* Fake link map for the application. */
55 static struct link_map static_map;
58 /* Highest dtv index currently needed. */
59 size_t _dl_tls_max_dtv_idx;
60 /* Flag signalling whether there are gaps in the module ID allocation. */
61 bool _dl_tls_dtv_gaps;
62 /* Information about the dtv slots. */
63 struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
64 /* Number of modules in the static TLS block. */
65 size_t _dl_tls_static_nelem;
66 /* Size of the static TLS block. */
67 size_t _dl_tls_static_size;
68 /* Size actually allocated in the static TLS block. */
69 size_t _dl_tls_static_used;
70 /* Alignment requirement of the static TLS block. */
71 size_t _dl_tls_static_align;
73 /* Generation counter for the dtv. */
74 size_t _dl_tls_generation;
77 /* Additional definitions needed by TLS initialization. */
78 #ifdef TLS_INIT_HELPER
85 /* Create the slotinfo list. */
86 static_slotinfo.si.len = (((char *) (&static_slotinfo + 1)
87 - (char *) &static_slotinfo.si.slotinfo[0])
88 / sizeof static_slotinfo.si.slotinfo[0]);
89 // static_slotinfo.si.next = NULL; already zero
91 /* The slotinfo list. Will be extended by the code doing dynamic
93 GL(dl_tls_max_dtv_idx) = 1;
94 GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
98 init_static_tls (size_t memsz, size_t align)
100 /* That is the size of the TLS memory for this object. The initialized
101 value of _dl_tls_static_size is provided by dl-open.c to request some
102 surplus that permits dynamic loading of modules with IE-model TLS. */
103 GL(dl_tls_static_size) = roundup (memsz + GL(dl_tls_static_size),
105 GL(dl_tls_static_used) = memsz;
106 /* The alignment requirement for the static TLS block. */
107 GL(dl_tls_static_align) = align;
108 /* Number of elements in the static TLS block. */
109 GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
112 void __libc_setup_tls (size_t tcbsize, size_t tcbalign);
114 __libc_setup_tls (size_t tcbsize, size_t tcbalign)
119 void *initimage = NULL;
121 size_t max_align = tcbalign;
125 /* Look through the TLS segment if there is any. */
126 if (_dl_phdr != NULL)
127 for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
128 if (phdr->p_type == PT_TLS)
130 /* Remember the values we need. */
131 memsz = phdr->p_memsz;
132 filesz = phdr->p_filesz;
133 initimage = (void *) phdr->p_vaddr;
134 align = phdr->p_align;
135 if (phdr->p_align > max_align)
136 max_align = phdr->p_align;
140 /* We have to set up the TCB block which also (possibly) contains
141 'errno'. Therefore we avoid 'malloc' which might touch 'errno'.
142 Instead we use 'sbrk' which would only uses 'errno' if it fails.
143 In this case we are right away out of memory and the user gets
144 what she/he deserves.
146 The initialized value of _dl_tls_static_size is provided by dl-open.c
147 to request some surplus that permits dynamic loading of modules with
149 # if defined(TLS_TCB_AT_TP)
150 tcb_offset = roundup (memsz + GL(dl_tls_static_size), tcbalign);
151 tlsblock = sbrk (tcb_offset + tcbsize + max_align);
152 # elif defined(TLS_DTV_AT_TP)
153 tcb_offset = roundup (tcbsize, align ?: 1);
154 tlsblock = sbrk (tcb_offset + memsz + max_align
155 + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
156 tlsblock += TLS_PRE_TCB_SIZE;
158 /* In case a model with a different layout for the TCB and DTV
159 is defined add another #elif here and in the following #ifs. */
160 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
163 /* Align the TLS block. */
164 tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
167 /* Initialize the dtv. [0] is the length, [1] the generation counter. */
168 static_dtv[0].counter = (sizeof (static_dtv) / sizeof (static_dtv[0])) - 2;
169 // static_dtv[1].counter = 0; would be needed if not already done
171 /* Initialize the TLS block. */
172 # if defined(TLS_TCB_AT_TP)
173 static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset
174 - roundup (memsz, align ?: 1));
175 static_map.l_tls_offset = roundup (memsz, align ?: 1);
176 # elif defined(TLS_DTV_AT_TP)
177 static_dtv[2].pointer.val = (char *) tlsblock + tcb_offset;
178 static_map.l_tls_offset = tcb_offset;
180 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
182 static_dtv[2].pointer.is_static = true;
183 /* sbrk gives us zero'd memory, so we don't need to clear the remainder. */
184 memcpy (static_dtv[2].pointer.val, initimage, filesz);
186 /* Install the pointer to the dtv. */
188 /* Initialize the thread pointer. */
189 # if defined(TLS_TCB_AT_TP)
190 INSTALL_DTV ((char *) tlsblock + tcb_offset, static_dtv);
192 const char *lossage = TLS_INIT_TP ((char *) tlsblock + tcb_offset, 0);
193 # elif defined(TLS_DTV_AT_TP)
194 INSTALL_DTV (tlsblock, static_dtv);
195 const char *lossage = (char *)TLS_INIT_TP (tlsblock, 0);
197 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
199 if (__builtin_expect (lossage != NULL, 0))
202 /* We have to create a fake link map which normally would be created
203 by the dynamic linker. It just has to have enough information to
204 make the TLS routines happy. */
205 static_map.l_tls_align = align;
206 static_map.l_tls_blocksize = memsz;
207 static_map.l_tls_initimage = initimage;
208 static_map.l_tls_initimage_size = filesz;
209 static_map.l_tls_modid = 1;
212 // static_slotinfo.si.slotinfo[1].gen = 0; already zero
213 static_slotinfo.si.slotinfo[1].map = &static_map;
215 memsz = roundup (memsz, align ?: 1);
217 # if defined(TLS_TCB_AT_TP)
219 # elif defined(TLS_DTV_AT_TP)
223 init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align));
226 /* This is called only when the data structure setup was skipped at startup,
227 when there was no need for it then. Now we have dynamically loaded
228 something needing TLS, or libpthread needs it. */
235 # if defined(TLS_TCB_AT_TP)
244 extern void __pthread_initialize_minimal(void) __attribute__((weak));
246 /* This is the minimal initialization function used when libpthread is
249 __attribute__ ((weak))
250 __pthread_initialize_minimal (void)
252 __libc_setup_tls (TLS_INIT_TCB_SIZE, TLS_INIT_TCB_ALIGN);
255 #elif defined NONTLS_INIT_TP
257 /* This is the minimal initialization function used when libpthread is
260 __attribute__ ((weak))
261 __pthread_initialize_minimal (void)