lib/libc/gen/tls.c

   1 /*-
   2  * Copyright (c) 2004 Doug Rabson
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  *      $FreeBSD: src/lib/libc/gen/tls.c,v 1.7 2005/03/01 23:42:00 davidxu Exp $
  27  *      $DragonFly: src/lib/libc/gen/tls.c,v 1.8 2005/04/29 22:00:20 joerg Exp $
  28  */
  29
  30 /*
  31  * Define stubs for TLS internals so that programs and libraries can
  32  * link. These functions will be replaced by functional versions at
  33  * runtime from ld-elf.so.1.
  34  */
  35
  36 #include <sys/cdefs.h>
  37 #include <sys/tls.h>
  38
  39 #include <machine/tls.h>
  40
  41 #include <stdlib.h>
  42 #include <string.h>
  43 #include <elf.h>
  44 #include <assert.h>
  45
  46 #include "libc_private.h"
  47
  48 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls);
  49 __weak_reference(__libc_free_tls, _rtld_free_tls);
  50 #ifdef __i386__
  51 __weak_reference(___libc_tls_get_addr, ___tls_get_addr);
  52 #endif
  53 __weak_reference(__libc_tls_get_addr, __tls_get_addr);
  54
  55 struct tls_tcb *__libc_allocate_tls(struct tls_tcb *old_tcb);
  56 void __libc_free_tls(struct tls_tcb *tcb);
  57
  58 #if !defined(RTLD_STATIC_TLS_VARIANT_II)
  59 #error "Unsupported TLS layout"
  60 #endif
  61
  62 #ifndef PIC
  63
  64 #define round(size, align) \
  65         (((size) + (align) - 1) & ~((align) - 1))
  66
  67 static size_t tls_static_space;
  68 static size_t tls_init_size;
  69 static void *tls_init;
  70 #endif
  71
  72 #ifdef __i386__
  73
  74 /* GNU ABI */
  75
  76 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1)));
  77
  78 __attribute__((__regparm__(1)))
  79 void *
  80 ___libc_tls_get_addr(void *ti __unused)
  81 {
  82         return (0);
  83 }
  84
  85 #endif
  86
  87 void *__libc_tls_get_addr(void *ti);
  88
  89 void *
  90 __libc_tls_get_addr(void *ti __unused)
  91 {
  92         return (0);
  93 }
  94
  95 #ifndef PIC
  96
  97 /*
  98  * Free Static TLS
  99  */
 100 void
 101 __libc_free_tls(struct tls_tcb *tcb)
 102 {
 103         size_t data_size;
 104
 105         if (tcb->tcb_dtv)
 106                 free(tcb->tcb_dtv);
 107         data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
 108                     ~RTLD_STATIC_TLS_ALIGN_MASK;
 109         free((char *)tcb - data_size);
 110 }
 111
 112 /*
 113  * Allocate Static TLS.
 114  *
 115  * !!!WARNING!!! The first run for a static binary is done without valid
 116  * TLS storage.  It must not call any system calls which want to change
 117  * errno.
 118  */
 119 struct tls_tcb *
 120 __libc_allocate_tls(struct tls_tcb *old_tcb)
 121 {
 122         static int first_run = 0;
 123         size_t data_size;
 124         struct tls_tcb *tcb;
 125         Elf_Addr *dtv;
 126
 127 retry:
 128         data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
 129                     ~RTLD_STATIC_TLS_ALIGN_MASK;
 130
 131         if (first_run)
 132                 tcb = malloc(data_size + sizeof(*tcb));
 133         else
 134                 tcb = alloca(data_size + sizeof(*tcb));
 135         tcb = (struct tls_tcb *)((char *)tcb + data_size);
 136         if (first_run)
 137                 dtv = malloc(3 * sizeof(Elf_Addr));
 138         else
 139                 dtv = alloca(3 * sizeof(Elf_Addr));
 140
 141 #ifdef RTLD_TCB_HAS_SELF_POINTER
 142         tcb->tcb_self = tcb;
 143 #endif
 144         tcb->tcb_dtv = dtv;
 145         tcb->tcb_pthread = NULL;
 146
 147         dtv[0] = 1;
 148         dtv[1] = 1;
 149         dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space);
 150
 151         if (old_tcb) {
 152                 /*
 153                  * Copy the static TLS block over whole.
 154                  */
 155                 memcpy((char *)tcb - tls_static_space,
 156                         (char *)old_tcb - tls_static_space,
 157                         tls_static_space);
 158
 159                 /*
 160                  * We assume that this block was the one we created with
 161                  * allocate_initial_tls().
 162                  */
 163                 _rtld_free_tls(old_tcb);
 164         } else {
 165                 memcpy((char *)tcb - tls_static_space,
 166                         tls_init, tls_init_size);
 167                 memset((char *)tcb - tls_static_space + tls_init_size,
 168                         0, tls_static_space - tls_init_size);
 169         }
 170
 171         if (first_run)
 172                 return (tcb);
 173
 174         tls_set_tcb(tcb);
 175         first_run = 1;
 176         goto retry;
 177 }
 178
 179 #else
 180
 181 struct tls_tcb *
 182 __libc_allocate_tls(struct tls_tcb *old_tls __unused)
 183 {
 184         return (0);
 185 }
 186
 187 void
 188 __libc_free_tls(struct tls_tcb *tcb __unused)
 189 {
 190 }
 191
 192 #endif /* PIC */
 193
 194 extern char **environ;
 195
 196 void
 197 _init_tls()
 198 {
 199 #ifndef PIC
 200         Elf_Addr *sp;
 201         Elf_Auxinfo *aux, *auxp;
 202         Elf_Phdr *phdr;
 203         size_t phent, phnum;
 204         int i;
 205         struct tls_tcb *tcb;
 206
 207         sp = (Elf_Addr *) environ;
 208         while (*sp++ != 0)
 209                 ;
 210         aux = (Elf_Auxinfo *) sp;
 211         phdr = 0;
 212         phent = phnum = 0;
 213         for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
 214                 switch (auxp->a_type) {
 215                 case AT_PHDR:
 216                         phdr = auxp->a_un.a_ptr;
 217                         break;
 218
 219                 case AT_PHENT:
 220                         phent = auxp->a_un.a_val;
 221                         break;
 222
 223                 case AT_PHNUM:
 224                         phnum = auxp->a_un.a_val;
 225                         break;
 226                 }
 227         }
 228         if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0)
 229                 return;
 230
 231         for (i = 0; (unsigned)i < phnum; i++) {
 232                 if (phdr[i].p_type == PT_TLS) {
 233                         tls_static_space = round(phdr[i].p_memsz,
 234                             phdr[i].p_align);
 235                         tls_init_size = phdr[i].p_filesz;
 236                         tls_init = (void*) phdr[i].p_vaddr;
 237                 }
 238         }
 239
 240         tcb = _rtld_allocate_tls(NULL);
 241         tls_set_tcb(tcb);
 242 #endif
 243 }