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 1.5 2005/03/29 19:26:19 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, size_t tcbsize,
  56                                     int flags);
  57 void __libc_free_tls(struct tls_tcb *tcb, size_t tcb_size);
  58
  59 #if !defined(RTLD_STATIC_TLS_VARIANT_II)
  60 #error "Unsupported TLS layout"
  61 #endif
  62
  63 #ifndef PIC
  64
  65 #define round(size, align) \
  66         (((size) + (align) - 1) & ~((align) - 1))
  67
  68 static size_t tls_static_space;
  69 static size_t tls_init_size;
  70 static void *tls_init;
  71 #endif
  72
  73 #ifdef __i386__
  74
  75 /* GNU ABI */
  76
  77 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1)));
  78
  79 __attribute__((__regparm__(1)))
  80 void *
  81 ___libc_tls_get_addr(void *ti __unused)
  82 {
  83         return (0);
  84 }
  85
  86 #endif
  87
  88 void *__libc_tls_get_addr(void *ti);
  89
  90 void *
  91 __libc_tls_get_addr(void *ti __unused)
  92 {
  93         return (0);
  94 }
  95
  96 #ifndef PIC
  97
  98 /*
  99  * Free Static TLS
 100  */
 101 void
 102 __libc_free_tls(struct tls_tcb *tcb, size_t tcb_size __unused)
 103 {
 104         size_t data_size;
 105
 106         if (tcb->tcb_dtv)
 107                 free(tcb->tcb_dtv);
 108         data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
 109                     ~RTLD_STATIC_TLS_ALIGN_MASK;
 110         free((char *)tcb - data_size);
 111 }
 112
 113 /*
 114  * Allocate Static TLS.
 115  */
 116 struct tls_tcb *
 117 __libc_allocate_tls(struct tls_tcb *old_tcb, size_t tcb_size, int flags)
 118 {
 119         size_t data_size;
 120         struct tls_tcb *tcb;
 121         Elf_Addr *dtv;
 122
 123         data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) &
 124                     ~RTLD_STATIC_TLS_ALIGN_MASK;
 125         tcb = malloc(data_size + tcb_size);
 126         tcb = (struct tls_tcb *)((char *)tcb + data_size);
 127         dtv = malloc(3 * sizeof(Elf_Addr));
 128
 129 #ifdef RTLD_TCB_HAS_SELF_POINTER
 130         tcb->tcb_self = tcb;
 131 #endif
 132         tcb->tcb_dtv = dtv;
 133         tcb->tcb_pthread = NULL;
 134
 135         dtv[0] = 1;
 136         dtv[1] = 1;
 137         dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space);
 138
 139         if (old_tcb) {
 140                 /*
 141                  * Copy the static TLS block over whole.
 142                  */
 143                 memcpy((char *)tcb - tls_static_space,
 144                         (char *)old_tcb - tls_static_space,
 145                         tls_static_space);
 146
 147                 /*
 148                  * We assume that this block was the one we created with
 149                  * allocate_initial_tls().
 150                  */
 151                 _rtld_free_tls(old_tcb, sizeof(struct tls_tcb));
 152         } else {
 153                 memcpy((char *)tcb - tls_static_space,
 154                         tls_init, tls_init_size);
 155                 memset((char *)tcb - tls_static_space + tls_init_size,
 156                         0, tls_static_space - tls_init_size);
 157         }
 158         return (tcb);
 159 }
 160
 161 #else
 162
 163 struct tls_tcb *
 164 __libc_allocate_tls(struct tls_tcb *old_tls __unused, size_t tcb_size __unused,
 165                         int flags __unused)
 166 {
 167         return (0);
 168 }
 169
 170 void
 171 __libc_free_tls(struct tls_tcb *tcb __unused, size_t tcb_size __unused)
 172 {
 173 }
 174
 175 #endif /* PIC */
 176
 177 extern char **environ;
 178
 179 void
 180 _init_tls()
 181 {
 182 #ifndef PIC
 183         Elf_Addr *sp;
 184         Elf_Auxinfo *aux, *auxp;
 185         Elf_Phdr *phdr;
 186         size_t phent, phnum;
 187         int i;
 188         struct tls_tcb *tcb;
 189
 190         sp = (Elf_Addr *) environ;
 191         while (*sp++ != 0)
 192                 ;
 193         aux = (Elf_Auxinfo *) sp;
 194         phdr = 0;
 195         phent = phnum = 0;
 196         for (auxp = aux; auxp->a_type != AT_NULL; auxp++) {
 197                 switch (auxp->a_type) {
 198                 case AT_PHDR:
 199                         phdr = auxp->a_un.a_ptr;
 200                         break;
 201
 202                 case AT_PHENT:
 203                         phent = auxp->a_un.a_val;
 204                         break;
 205
 206                 case AT_PHNUM:
 207                         phnum = auxp->a_un.a_val;
 208                         break;
 209                 }
 210         }
 211         if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0)
 212                 return;
 213
 214         for (i = 0; (unsigned)i < phnum; i++) {
 215                 if (phdr[i].p_type == PT_TLS) {
 216                         tls_static_space = round(phdr[i].p_memsz,
 217                             phdr[i].p_align);
 218                         tls_init_size = phdr[i].p_filesz;
 219                         tls_init = (void*) phdr[i].p_vaddr;
 220                 }
 221         }
 222
 223         if (tls_static_space) {
 224                 tcb = _rtld_allocate_tls(NULL, sizeof(struct tls_tcb), 0);
 225                 tls_set_tcb(tcb);
 226         }
 227 #endif
 228 }