1/* Initialization code for TLS in statically linked application.
2 Copyright (C) 2002-2016 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 <errno.h>
20#include <ldsodefs.h>
21#include <tls.h>
22#include <unistd.h>
23#include <stdio.h>
24#include <sys/param.h>
25
26
27#ifdef SHARED
28 #error makefile bug, this file is for static only
29#endif
30
31dtv_t _dl_static_dtv[2 + TLS_SLOTINFO_SURPLUS];
32
33
34static struct
35{
36 struct dtv_slotinfo_list si;
37 /* The dtv_slotinfo_list data structure does not include the actual
38 information since it is defined as an array of size zero. We define
39 here the necessary entries. Note that it is not important whether
40 there is padding or not since we will always access the information
41 through the 'si' element. */
42 struct dtv_slotinfo info[2 + TLS_SLOTINFO_SURPLUS];
43} static_slotinfo;
44
45
46/* Highest dtv index currently needed. */
47size_t _dl_tls_max_dtv_idx;
48/* Flag signalling whether there are gaps in the module ID allocation. */
49bool _dl_tls_dtv_gaps;
50/* Information about the dtv slots. */
51struct dtv_slotinfo_list *_dl_tls_dtv_slotinfo_list;
52/* Number of modules in the static TLS block. */
53size_t _dl_tls_static_nelem;
54/* Size of the static TLS block. Giving this initialized value
55 preallocates some surplus bytes in the static TLS area. */
56size_t _dl_tls_static_size = 2048;
57/* Size actually allocated in the static TLS block. */
58size_t _dl_tls_static_used;
59/* Alignment requirement of the static TLS block. */
60size_t _dl_tls_static_align;
61
62/* Generation counter for the dtv. */
63size_t _dl_tls_generation;
64
65
66/* Additional definitions needed by TLS initialization. */
67#ifdef TLS_INIT_HELPER
68TLS_INIT_HELPER
69#endif
70
71static void
72init_slotinfo (void)
73{
74 /* Create the slotinfo list. */
75 static_slotinfo.si.len = (((char *) (&static_slotinfo + 1)
76 - (char *) &static_slotinfo.si.slotinfo[0])
77 / sizeof static_slotinfo.si.slotinfo[0]);
78 // static_slotinfo.si.next = NULL; already zero
79
80 /* The slotinfo list. Will be extended by the code doing dynamic
81 linking. */
82 GL(dl_tls_max_dtv_idx) = 1;
83 GL(dl_tls_dtv_slotinfo_list) = &static_slotinfo.si;
84}
85
86static void
87init_static_tls (size_t memsz, size_t align)
88{
89 /* That is the size of the TLS memory for this object. The initialized
90 value of _dl_tls_static_size is provided by dl-open.c to request some
91 surplus that permits dynamic loading of modules with IE-model TLS. */
92 GL(dl_tls_static_size) = roundup (memsz + GL(dl_tls_static_size),
93 TLS_TCB_ALIGN);
94#if TLS_TCB_AT_TP
95 GL(dl_tls_static_size) += TLS_TCB_SIZE;
96#endif
97 GL(dl_tls_static_used) = memsz;
98 /* The alignment requirement for the static TLS block. */
99 GL(dl_tls_static_align) = align;
100 /* Number of elements in the static TLS block. */
101 GL(dl_tls_static_nelem) = GL(dl_tls_max_dtv_idx);
102}
103
104void
105__libc_setup_tls (size_t tcbsize, size_t tcbalign)
106{
107 void *tlsblock;
108 size_t memsz = 0;
109 size_t filesz = 0;
110 void *initimage = NULL;
111 size_t align = 0;
112 size_t max_align = tcbalign;
113 size_t tcb_offset;
114 const ElfW(Phdr) *phdr;
115
116 /* Look through the TLS segment if there is any. */
117 if (_dl_phdr != NULL)
118 for (phdr = _dl_phdr; phdr < &_dl_phdr[_dl_phnum]; ++phdr)
119 if (phdr->p_type == PT_TLS)
120 {
121 /* Remember the values we need. */
122 memsz = phdr->p_memsz;
123 filesz = phdr->p_filesz;
124 initimage = (void *) phdr->p_vaddr;
125 align = phdr->p_align;
126 if (phdr->p_align > max_align)
127 max_align = phdr->p_align;
128 break;
129 }
130
131 /* We have to set up the TCB block which also (possibly) contains
132 'errno'. Therefore we avoid 'malloc' which might touch 'errno'.
133 Instead we use 'sbrk' which would only uses 'errno' if it fails.
134 In this case we are right away out of memory and the user gets
135 what she/he deserves.
136
137 The initialized value of _dl_tls_static_size is provided by dl-open.c
138 to request some surplus that permits dynamic loading of modules with
139 IE-model TLS. */
140#if TLS_TCB_AT_TP
141 /* Align the TCB offset to the maximum alignment, as
142 _dl_allocate_tls_storage (in elf/dl-tls.c) does using __libc_memalign
143 and dl_tls_static_align. */
144 tcb_offset = roundup (memsz + GL(dl_tls_static_size), max_align);
145 tlsblock = __sbrk (tcb_offset + tcbsize + max_align);
146#elif TLS_DTV_AT_TP
147 tcb_offset = roundup (tcbsize, align ?: 1);
148 tlsblock = __sbrk (tcb_offset + memsz + max_align
149 + TLS_PRE_TCB_SIZE + GL(dl_tls_static_size));
150 tlsblock += TLS_PRE_TCB_SIZE;
151#else
152 /* In case a model with a different layout for the TCB and DTV
153 is defined add another #elif here and in the following #ifs. */
154# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
155#endif
156
157 /* Align the TLS block. */
158 tlsblock = (void *) (((uintptr_t) tlsblock + max_align - 1)
159 & ~(max_align - 1));
160
161 /* Initialize the dtv. [0] is the length, [1] the generation counter. */
162 _dl_static_dtv[0].counter = (sizeof (_dl_static_dtv) / sizeof (_dl_static_dtv[0])) - 2;
163 // _dl_static_dtv[1].counter = 0; would be needed if not already done
164
165 struct link_map *main_map = GL(dl_ns)[LM_ID_BASE]._ns_loaded;
166
167 /* Initialize the TLS block. */
168#if TLS_TCB_AT_TP
169 _dl_static_dtv[2].pointer.val = ((char *) tlsblock + tcb_offset
170 - roundup (memsz, align ?: 1));
171 main_map->l_tls_offset = roundup (memsz, align ?: 1);
172#elif TLS_DTV_AT_TP
173 _dl_static_dtv[2].pointer.val = (char *) tlsblock + tcb_offset;
174 main_map->l_tls_offset = tcb_offset;
175#else
176# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
177#endif
178 _dl_static_dtv[2].pointer.is_static = true;
179 /* sbrk gives us zero'd memory, so we don't need to clear the remainder. */
180 memcpy (_dl_static_dtv[2].pointer.val, initimage, filesz);
181
182 /* Install the pointer to the dtv. */
183
184 /* Initialize the thread pointer. */
185#if TLS_TCB_AT_TP
186 INSTALL_DTV ((char *) tlsblock + tcb_offset, _dl_static_dtv);
187
188 const char *lossage = TLS_INIT_TP ((char *) tlsblock + tcb_offset);
189#elif TLS_DTV_AT_TP
190 INSTALL_DTV (tlsblock, _dl_static_dtv);
191 const char *lossage = TLS_INIT_TP (tlsblock);
192#else
193# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
194#endif
195 if (__builtin_expect (lossage != NULL, 0))
196 __libc_fatal (lossage);
197
198 /* Update the executable's link map with enough information to make
199 the TLS routines happy. */
200 main_map->l_tls_align = align;
201 main_map->l_tls_blocksize = memsz;
202 main_map->l_tls_initimage = initimage;
203 main_map->l_tls_initimage_size = filesz;
204 main_map->l_tls_modid = 1;
205
206 init_slotinfo ();
207 // static_slotinfo.si.slotinfo[1].gen = 0; already zero
208 static_slotinfo.si.slotinfo[1].map = main_map;
209
210 memsz = roundup (memsz, align ?: 1);
211
212#if TLS_DTV_AT_TP
213 memsz += tcb_offset;
214#endif
215
216 init_static_tls (memsz, MAX (TLS_TCB_ALIGN, max_align));
217}
218
219/* This is called only when the data structure setup was skipped at startup,
220 when there was no need for it then. Now we have dynamically loaded
221 something needing TLS, or libpthread needs it. */
222int
223internal_function
224_dl_tls_setup (void)
225{
226 init_slotinfo ();
227 init_static_tls (
228#if TLS_TCB_AT_TP
229 TLS_TCB_SIZE,
230#else
231 0,
232#endif
233 TLS_TCB_ALIGN);
234 return 0;
235}
236
237
238/* This is the minimal initialization function used when libpthread is
239 not used. */
240void
241__attribute__ ((weak))
242__pthread_initialize_minimal (void)
243{
244 __libc_setup_tls (TLS_INIT_TCB_SIZE, TLS_INIT_TCB_ALIGN);
245}
246