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 1.1 2005/03/08 13:04:38 davidxu 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 <stdlib.h> 37 #include <string.h> 38 #include <elf.h> 39 #include <assert.h> 40 #include "libc_private.h" 41 42 /* XXX not sure what variants to use for arm. */ 43 44 #if defined(__ia64__) || defined(__powerpc__) 45 #define TLS_VARIANT_I 46 #endif 47 #if defined(__i386__) || defined(__amd64__) || defined(__sparc64__) || \ 48 defined(__arm__) 49 #define TLS_VARIANT_II 50 #endif 51 52 #ifndef PIC 53 54 #define round(size, align) \ 55 (((size) + (align) - 1) & ~((align) - 1)) 56 57 static size_t tls_static_space; 58 static size_t tls_init_size; 59 #ifdef TLS_VARIANT_I 60 static size_t tls_init_offset; 61 #endif 62 static void *tls_init; 63 #endif 64 65 void *_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign); 66 void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign); 67 void *__tls_get_addr(void *); 68 69 #ifdef __i386__ 70 71 extern void *___tls_get_addr(void *ti) __attribute__((__regparm__(1))); 72 73 #pragma weak ___tls_get_addr 74 __attribute__((__regparm__(1))) 75 void * 76 ___tls_get_addr(void *ti __unused) 77 { 78 return (0); 79 } 80 81 #endif 82 83 #pragma weak __tls_get_addr 84 void * 85 __tls_get_addr(void *ti __unused) 86 { 87 return (0); 88 } 89 90 #ifdef TLS_VARIANT_I 91 92 #pragma weak _rtld_free_tls 93 /* 94 * Free Static TLS using the Variant I method. 95 */ 96 void 97 _rtld_free_tls(void *tls, size_t tcbsize, size_t tcbalign) 98 { 99 #ifndef PIC 100 Elf_Addr* dtv; 101 102 dtv = ((Elf_Addr**)tls)[0]; 103 free(tls); 104 free(dtv); 105 #endif 106 } 107 108 #pragma weak _rtld_allocate_tls 109 /* 110 * Allocate Static TLS using the Variant I method. 111 */ 112 void * 113 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 114 { 115 #ifndef PIC 116 size_t size; 117 char *tls; 118 Elf_Addr *dtv; 119 120 size = tls_static_space; 121 if (size < tcbsize) 122 size = tcbsize; 123 124 tls = malloc(size); 125 dtv = malloc(3 * sizeof(Elf_Addr)); 126 127 *(Elf_Addr**) tls = dtv; 128 129 dtv[0] = 1; 130 dtv[1] = 1; 131 dtv[2] = (Elf_Addr)(tls + tls_init_offset); 132 if (oldtls) { 133 /* 134 * Copy the static TLS block over whole. 135 */ 136 memcpy(tls + tls_init_offset, 137 (char*) oldtls + tls_init_offset, 138 tls_static_space - tls_init_offset); 139 140 /* 141 * We assume that this block was the one we created with 142 * allocate_initial_tls(). 143 */ 144 _rtld_free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr)); 145 } else { 146 memcpy(tls + tls_init_offset, tls_init, tls_init_size); 147 memset(tls + tls_init_offset + tls_init_size, 148 0, tls_static_space - tls_init_size); 149 } 150 151 return tls; 152 #else 153 return (0); 154 #endif 155 } 156 157 #endif 158 159 #ifdef TLS_VARIANT_II 160 161 /* 162 * Free Static TLS using the Variant II method. 163 */ 164 #pragma weak _rtld_free_tls 165 void 166 _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) 167 { 168 #ifndef PIC 169 size_t size; 170 Elf_Addr* dtv; 171 Elf_Addr tlsstart, tlsend; 172 173 /* 174 * Figure out the size of the initial TLS block so that we can 175 * find stuff which ___tls_get_addr() allocated dynamically. 176 */ 177 size = round(tls_static_space, tcbalign); 178 179 dtv = ((Elf_Addr**)tcb)[1]; 180 tlsend = (Elf_Addr) tcb; 181 tlsstart = tlsend - size; 182 free((void*) tlsstart); 183 free(dtv); 184 #endif 185 } 186 187 #pragma weak _rtld_allocate_tls 188 /* 189 * Allocate Static TLS using the Variant II method. 190 */ 191 void * 192 _rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign) 193 { 194 #ifndef PIC 195 size_t size; 196 char *tls; 197 Elf_Addr *dtv; 198 Elf_Addr segbase, oldsegbase; 199 200 size = round(tls_static_space, tcbalign); 201 202 assert(tcbsize >= 2*sizeof(Elf_Addr)); 203 tls = malloc(size + tcbsize); 204 dtv = malloc(3 * sizeof(Elf_Addr)); 205 206 segbase = (Elf_Addr)(tls + size); 207 ((Elf_Addr*)segbase)[0] = segbase; 208 ((Elf_Addr*)segbase)[1] = (Elf_Addr) dtv; 209 210 dtv[0] = 1; 211 dtv[1] = 1; 212 dtv[2] = segbase - tls_static_space; 213 214 if (oldtls) { 215 /* 216 * Copy the static TLS block over whole. 217 */ 218 oldsegbase = (Elf_Addr) oldtls; 219 memcpy((void *)(segbase - tls_static_space), 220 (const void *)(oldsegbase - tls_static_space), 221 tls_static_space); 222 223 /* 224 * We assume that this block was the one we created with 225 * allocate_initial_tls(). 226 */ 227 _rtld_free_tls(oldtls, 2*sizeof(Elf_Addr), sizeof(Elf_Addr)); 228 } else { 229 memcpy((void *)(segbase - tls_static_space), 230 tls_init, tls_init_size); 231 memset((void *)(segbase - tls_static_space + tls_init_size), 232 0, tls_static_space - tls_init_size); 233 } 234 235 return (void*) segbase; 236 #else 237 return (0); 238 #endif 239 } 240 241 #endif /* TLS_VARIANT_II */ 242 243 extern char **environ; 244 245 void 246 _init_tls() 247 { 248 #ifndef PIC 249 Elf_Addr *sp; 250 Elf_Auxinfo *aux, *auxp; 251 Elf_Phdr *phdr; 252 size_t phent, phnum; 253 int i; 254 void *tls; 255 256 sp = (Elf_Addr *) environ; 257 while (*sp++ != 0) 258 ; 259 aux = (Elf_Auxinfo *) sp; 260 phdr = 0; 261 phent = phnum = 0; 262 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 263 switch (auxp->a_type) { 264 case AT_PHDR: 265 phdr = auxp->a_un.a_ptr; 266 break; 267 268 case AT_PHENT: 269 phent = auxp->a_un.a_val; 270 break; 271 272 case AT_PHNUM: 273 phnum = auxp->a_un.a_val; 274 break; 275 } 276 } 277 if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0) 278 return; 279 280 for (i = 0; (unsigned)i < phnum; i++) { 281 if (phdr[i].p_type == PT_TLS) { 282 #ifdef TLS_VARIANT_I 283 tls_static_space = round(2*sizeof(Elf_Addr), 284 phdr[i].p_align) + phdr[i].p_memsz; 285 tls_init_offset = round(2*sizeof(Elf_Addr), 286 phdr[i].p_align); 287 #else 288 tls_static_space = round(phdr[i].p_memsz, 289 phdr[i].p_align); 290 #endif 291 tls_init_size = phdr[i].p_filesz; 292 tls_init = (void*) phdr[i].p_vaddr; 293 } 294 } 295 296 tls = _rtld_allocate_tls(NULL, 2*sizeof(Elf_Addr), 297 sizeof(Elf_Addr)); 298 299 _set_tp(tls, 2 * sizeof(Elf_Addr)); 300 #endif 301 } 302