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 */ 28 29 /* 30 * Define stubs for TLS internals so that programs and libraries can 31 * link. These functions will be replaced by functional versions at 32 * runtime from ld-elf.so.1. 33 */ 34 35 #include <sys/tls.h> 36 37 #include <machine/tls.h> 38 39 #include <stdlib.h> 40 #include <string.h> 41 #include <elf.h> 42 #include <assert.h> 43 #include <errno.h> 44 #include <unistd.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 __weak_reference(__libc_call_init, _rtld_call_init); 51 #ifdef __i386__ 52 __weak_reference(___libc_tls_get_addr, ___tls_get_addr); 53 #endif 54 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 55 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 56 __weak_reference(_libc_init_tls, _init_tls); 57 58 struct tls_tcb *__libc_allocate_tls(void); 59 void __libc_free_tls(struct tls_tcb *tcb); 60 61 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 62 #error "Unsupported TLS layout" 63 #endif 64 65 #ifndef PIC 66 67 #define round(size, align) \ 68 (((size) + (align) - 1) & ~((align) - 1)) 69 70 static size_t tls_static_space; 71 static size_t tls_init_size; 72 static void *tls_init; 73 static struct tls_tcb *initial_tcb; 74 #endif 75 76 #ifdef __i386__ 77 78 /* GNU ABI */ 79 80 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1))); 81 82 __attribute__((__regparm__(1))) 83 void * 84 ___libc_tls_get_addr(void *ti __unused) 85 { 86 return (0); 87 } 88 89 #endif 90 91 void *__libc_tls_get_addr(void *ti); 92 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 93 94 void * 95 __libc_tls_get_addr(void *ti __unused) 96 { 97 return (NULL); 98 } 99 100 void * 101 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 102 { 103 return (NULL); 104 } 105 106 #ifndef PIC 107 108 /* 109 * Free Static TLS, weakly bound to _rtld_free_tls() 110 */ 111 void 112 __libc_free_tls(struct tls_tcb *tcb) 113 { 114 size_t data_size; 115 116 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 117 ~RTLD_STATIC_TLS_ALIGN_MASK; 118 119 if (tcb == initial_tcb) { 120 /* initial_tcb was allocated with sbrk(), cannot call free() */ 121 } else { 122 free((char *)tcb - data_size); 123 } 124 } 125 126 /* 127 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 128 * 129 * NOTE! There is a chicken-and-egg problem here because no TLS exists 130 * on the first call into this function. 131 */ 132 struct tls_tcb * 133 __libc_allocate_tls(void) 134 { 135 size_t data_size; 136 struct tls_tcb *tcb; 137 Elf_Addr *dtv; 138 139 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 140 ~RTLD_STATIC_TLS_ALIGN_MASK; 141 142 /* 143 * Allocate space. malloc() may require a working TLS segment 144 * so we use sbrk() for main's TLS. 145 */ 146 if (initial_tcb == NULL) 147 tcb = sbrk(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 148 else 149 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 150 151 tcb = (struct tls_tcb *)((char *)tcb + data_size); 152 dtv = (Elf_Addr *)(tcb + 1); 153 154 memset(tcb, 0, sizeof(*tcb)); 155 #ifdef RTLD_TCB_HAS_SELF_POINTER 156 tcb->tcb_self = tcb; 157 #endif 158 tcb->tcb_dtv = dtv; 159 160 /* 161 * Dummy-up the module array. A static binary has only one. This 162 * allows us to support the generic __tls_get_addr compiler ABI 163 * function. However, if there is no RTLD linked in, nothing in 164 * the program should ever call __tls_get_addr (and our version 165 * of it doesn't do anything). 166 */ 167 dtv[0] = 1; 168 dtv[1] = 1; 169 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 170 171 memcpy((char *)tcb - tls_static_space, 172 tls_init, tls_init_size); 173 memset((char *)tcb - tls_static_space + tls_init_size, 174 0, tls_static_space - tls_init_size); 175 176 /* 177 * Activate the initial TCB 178 */ 179 if (initial_tcb == NULL) { 180 initial_tcb = tcb; 181 tls_set_tcb(tcb); 182 } 183 return (tcb); 184 } 185 186 #else 187 188 struct tls_tcb * 189 __libc_allocate_tls(void) 190 { 191 return (NULL); 192 } 193 194 void 195 __libc_free_tls(struct tls_tcb *tcb __unused) 196 { 197 } 198 199 #endif /* PIC */ 200 201 void 202 __libc_call_init(void) 203 { 204 } 205 206 extern char **environ; 207 208 struct tls_tcb * 209 _libc_init_tls(void) 210 { 211 struct tls_tcb *tcb; 212 213 #ifndef PIC 214 /* 215 * If this is a static binary there is no RTLD and so we have not 216 * yet calculated the static space requirement. Do so now. 217 */ 218 Elf_Addr *sp; 219 Elf_Auxinfo *aux, *auxp; 220 Elf_Phdr *phdr; 221 size_t phent, phnum; 222 int i; 223 224 sp = (Elf_Addr *) environ; 225 while (*sp++ != 0) 226 ; 227 aux = (Elf_Auxinfo *) sp; 228 phdr = NULL; 229 phent = phnum = 0; 230 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 231 switch (auxp->a_type) { 232 case AT_PHDR: 233 phdr = auxp->a_un.a_ptr; 234 break; 235 236 case AT_PHENT: 237 phent = auxp->a_un.a_val; 238 break; 239 240 case AT_PHNUM: 241 phnum = auxp->a_un.a_val; 242 break; 243 } 244 } 245 if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0) 246 return(NULL); 247 248 for (i = 0; (unsigned)i < phnum; i++) { 249 if (phdr[i].p_type == PT_TLS) { 250 tls_static_space = round(phdr[i].p_memsz, 251 phdr[i].p_align); 252 tls_init_size = phdr[i].p_filesz; 253 tls_init = (void*) phdr[i].p_vaddr; 254 } 255 } 256 #endif 257 258 /* 259 * Allocate the initial TLS segment. The TLS has not been set up 260 * yet for either the static or dynamic linked case (RTLD no longer 261 * sets up an initial TLS segment for us). 262 */ 263 tcb = _libc_allocate_tls(); 264 tls_set_tcb(tcb); 265 return(tcb); 266 } 267 268 /* 269 * Allocate a standard TLS. This function is called by libc and by 270 * thread libraries to create a new TCB with libc-related fields properly 271 * initialized (whereas _rtld_allocate_tls() is unable to completely set 272 * up the TCB). 273 * 274 * Note that this is different from __libc_allocate_tls which is the 275 * weakly bound symbol that handles the case where _rtld_allocate_tls 276 * does not exist. 277 */ 278 struct tls_tcb * 279 _libc_allocate_tls(void) 280 { 281 struct tls_tcb *tcb; 282 283 tcb = _rtld_allocate_tls(); 284 285 #if 0 286 #if defined(__thread) 287 /* non-TLS libc */ 288 tcb->tcb_errno_p = &errno; 289 #elif defined(PIC) 290 /* TLS libc dynamically linked */ 291 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr()); 292 #else 293 /* TLS libc (threaded or unthreaded) */ 294 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset()); 295 #endif 296 #endif 297 return(tcb); 298 } 299 300