1 /* Initialization code for TLS in statically linked application.
2 Copyright (C) 2002 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, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
27 extern ElfW(Phdr) *_dl_phdr;
28 extern size_t _dl_phnum;
31 /* DTV with just one element plus overhead. */
32 static dtv_t static_dtv[3];
37 struct dtv_slotinfo_list si;
38 /* The dtv_slotinfo_list data structure does not include the actual
39 informatin since it is defined as an array of size zero. We
40 define here the necessary entries. Not that it is not important
41 whether there is padding or not since we will always access the
42 informatin through the 'si' element. */
43 struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
46 /* Fake link map for the application. */
47 static struct link_map static_map;
50 /* Additional definitions needed by TLS initialization. */
51 #ifdef TLS_INIT_HELPER
57 __libc_setup_tls (size_t tcbsize, size_t tcbalign)
64 size_t max_align = tcbalign;
65 size_t loadaddr = ~0ul;
69 /* Look through the TLS segment if there is any. */
71 for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
73 if (phdr->p_type == PT_TLS)
75 /* Remember the values we need. */
76 memsz = phdr->p_memsz;
77 filesz = phdr->p_filesz;
78 initimage = phdr->p_vaddr;
79 align = phdr->p_align;
80 if (phdr->p_align > max_align)
81 max_align = phdr->p_align;
83 else if (phdr->p_type == PT_LOAD)
85 /* We have to find the load address which is not easy.
86 Look for the load segment with the lowest address. */
87 if (phdr->p_vaddr < loadaddr)
88 loadaddr = phdr->p_vaddr;
92 if (memsz == 0 && tcbsize == 0)
93 /* We do not need a TLS block and no thread descriptor. */
96 /* We have to set up the TCB block which also (possibly) contains
97 'errno'. Therefore we avoid 'malloc' which might touch 'errno'.
98 Instead we use 'sbrk' which would only uses 'errno' if it fails.
99 In this case we are right away out of memory and the user gets
100 what she/he deserves. */
102 tlsblock = __sbrk (roundup (memsz, tcbalign) + tcbsize + max_align);
104 tlsblock = __sbrk (roundup (tcbsize, align) + memsz + max_align);
106 /* In case a model with a different layout for the TCB and DTV
107 is defined add another #elif here and in the following #ifs. */
108 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
111 /* Align the TLS block. */
112 tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
115 /* Initialize the dtv. [0] is the length, [1] the generation counter. */
116 static_dtv[0].counter = 1;
117 // static_dtv[1].counter = 0; would be needed if not already done
119 /* Initialize the TLS block. */
121 static_dtv[2].pointer = tlsblock;
123 tcb_offset = roundup (tcbsize, align);
124 static_dtv[2].pointer = (char *) tlsblock + tcb_offset;
126 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
128 memset (__mempcpy (static_dtv[2].pointer, (char *) loadaddr + initimage,
130 '\0', memsz - filesz);
132 /* Install the pointer to the dtv. */
134 /* Initialize the thread pointer. */
136 tcb_offset = roundup (memsz, tcbalign);
138 INSTALL_DTV ((char *) tlsblock + tcb_offset, static_dtv);
140 TLS_INIT_TP ((char *) tlsblock + tcb_offset);
142 INSTALL_DTV (tlsblock, static_dtv);
143 TLS_INIT_TP (tlsblock);
145 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
148 /* We have to create a fake link map which normally would be created
149 by the dynamic linker. It just has to have enough information to
150 make the TLS routines happy. */
151 static_map.l_tls_align = align;
152 static_map.l_tls_blocksize = memsz;
153 static_map.l_tls_initimage_size = filesz;
154 static_map.l_tls_offset = tcb_offset;
155 static_map.l_type = lt_executable;
156 static_map.l_tls_modid = 1;
158 /* Create the slotinfo list. */
159 static_slotinfo.si.len = 1; /* Only one element. */
160 // static_slotinfo.si.next = NULL; already zero
162 static_slotinfo.si.slotinfo[1].gen = 0;
163 static_slotinfo.si.slotinfo[1].map = &static_map;
165 /* The slotinfo list. Will be extended by the code doing dynamic
167 GL(dl_tls_max_dtv_idx) = 1;
168 GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
170 /* That is the size of the TLS memory for this object. */
171 GL(dl_tls_static_size) = (roundup (memsz, align ?: 1)
176 /* The alignment requirement for the static TLS block. */
177 GL(dl_tls_static_align) = MAX (TLS_TCB_ALIGN, max_align);
178 /* Number of elements in the static TLS block. */
179 GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
183 /* This is the minimal initialization function used when libpthread is
186 __attribute__ ((weak))
187 __pthread_initialize_minimal (void)
189 __libc_setup_tls (0, 1);