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 1.10 2005/11/19 22:32:53 swildner 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 #include <errno.h> 46 #include <unistd.h> 47 48 #include "libc_private.h" 49 50 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls); 51 __weak_reference(__libc_free_tls, _rtld_free_tls); 52 __weak_reference(__libc_call_init, _rtld_call_init); 53 #ifdef __i386__ 54 __weak_reference(___libc_tls_get_addr, ___tls_get_addr); 55 #endif 56 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 57 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 58 __weak_reference(_libc_init_tls, _init_tls); 59 60 struct tls_tcb *__libc_allocate_tls(void); 61 void __libc_free_tls(struct tls_tcb *tcb); 62 63 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 64 #error "Unsupported TLS layout" 65 #endif 66 67 #ifndef PIC 68 69 #define round(size, align) \ 70 (((size) + (align) - 1) & ~((align) - 1)) 71 72 static size_t tls_static_space; 73 static size_t tls_init_size; 74 static void *tls_init; 75 static struct tls_tcb *initial_tcb; 76 #endif 77 78 #ifdef __i386__ 79 80 /* GNU ABI */ 81 82 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1))); 83 84 __attribute__((__regparm__(1))) 85 void * 86 ___libc_tls_get_addr(void *ti __unused) 87 { 88 return (0); 89 } 90 91 #endif 92 93 void *__libc_tls_get_addr(void *ti); 94 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 95 96 void * 97 __libc_tls_get_addr(void *ti __unused) 98 { 99 return (NULL); 100 } 101 102 void * 103 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 104 { 105 return (NULL); 106 } 107 108 #ifndef PIC 109 110 /* 111 * Free Static TLS, weakly bound to _rtld_free_tls() 112 */ 113 void 114 __libc_free_tls(struct tls_tcb *tcb) 115 { 116 size_t data_size; 117 118 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 119 ~RTLD_STATIC_TLS_ALIGN_MASK; 120 121 if (tcb == initial_tcb) { 122 /* initial_tcb was allocated with sbrk(), cannot call free() */ 123 } else { 124 free((char *)tcb - data_size); 125 } 126 } 127 128 /* 129 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 130 * 131 * NOTE! There is a chicken-and-egg problem here because no TLS exists 132 * on the first call into this function. 133 */ 134 struct tls_tcb * 135 __libc_allocate_tls(void) 136 { 137 size_t data_size; 138 struct tls_tcb *tcb; 139 Elf_Addr *dtv; 140 141 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 142 ~RTLD_STATIC_TLS_ALIGN_MASK; 143 144 /* 145 * Allocate space. malloc() may require a working TLS segment 146 * so we use sbrk() for main's TLS. 147 */ 148 if (initial_tcb == NULL) 149 tcb = sbrk(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 150 else 151 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 152 153 tcb = (struct tls_tcb *)((char *)tcb + data_size); 154 dtv = (Elf_Addr *)(tcb + 1); 155 156 memset(tcb, 0, sizeof(*tcb)); 157 #ifdef RTLD_TCB_HAS_SELF_POINTER 158 tcb->tcb_self = tcb; 159 #endif 160 tcb->tcb_dtv = dtv; 161 162 /* 163 * Dummy-up the module array. A static binary has only one. This 164 * allows us to support the generic __tls_get_addr compiler ABI 165 * function. However, if there is no RTLD linked in, nothing in 166 * the program should ever call __tls_get_addr (and our version 167 * of it doesn't do anything). 168 */ 169 dtv[0] = 1; 170 dtv[1] = 1; 171 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 172 173 memcpy((char *)tcb - tls_static_space, 174 tls_init, tls_init_size); 175 memset((char *)tcb - tls_static_space + tls_init_size, 176 0, tls_static_space - tls_init_size); 177 178 /* 179 * Activate the initial TCB 180 */ 181 if (initial_tcb == NULL) { 182 initial_tcb = tcb; 183 tls_set_tcb(tcb); 184 } 185 return (tcb); 186 } 187 188 #else 189 190 struct tls_tcb * 191 __libc_allocate_tls(void) 192 { 193 return (NULL); 194 } 195 196 void 197 __libc_free_tls(struct tls_tcb *tcb __unused) 198 { 199 } 200 201 #endif /* PIC */ 202 203 void 204 __libc_call_init(void) 205 { 206 } 207 208 extern char **environ; 209 210 struct tls_tcb * 211 _libc_init_tls(void) 212 { 213 struct tls_tcb *tcb; 214 215 #ifndef PIC 216 /* 217 * If this is a static binary there is no RTLD and so we have not 218 * yet calculated the static space requirement. Do so now. 219 */ 220 Elf_Addr *sp; 221 Elf_Auxinfo *aux, *auxp; 222 Elf_Phdr *phdr; 223 size_t phent, phnum; 224 int i; 225 226 sp = (Elf_Addr *) environ; 227 while (*sp++ != 0) 228 ; 229 aux = (Elf_Auxinfo *) sp; 230 phdr = 0; 231 phent = phnum = 0; 232 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 233 switch (auxp->a_type) { 234 case AT_PHDR: 235 phdr = auxp->a_un.a_ptr; 236 break; 237 238 case AT_PHENT: 239 phent = auxp->a_un.a_val; 240 break; 241 242 case AT_PHNUM: 243 phnum = auxp->a_un.a_val; 244 break; 245 } 246 } 247 if (phdr == 0 || phent != sizeof(Elf_Phdr) || phnum == 0) 248 return(NULL); 249 250 for (i = 0; (unsigned)i < phnum; i++) { 251 if (phdr[i].p_type == PT_TLS) { 252 tls_static_space = round(phdr[i].p_memsz, 253 phdr[i].p_align); 254 tls_init_size = phdr[i].p_filesz; 255 tls_init = (void*) phdr[i].p_vaddr; 256 } 257 } 258 #endif 259 260 /* 261 * Allocate the initial TLS segment. The TLS has not been set up 262 * yet for either the static or dynamic linked case (RTLD no longer 263 * sets up an initial TLS segment for us). 264 */ 265 tcb = _libc_allocate_tls(); 266 tls_set_tcb(tcb); 267 return(tcb); 268 } 269 270 /* 271 * Allocate a standard TLS. This function is called by libc and by 272 * thread libraries to create a new TCB with libc-related fields properly 273 * initialized (whereas _rtld_allocate_tls() is unable to completely set 274 * up the TCB). 275 * 276 * Note that this is different from __libc_allocate_tls which is the 277 * weakly bound symbol that handles the case where _rtld_allocate_tls 278 * does not exist. 279 */ 280 struct tls_tcb * 281 _libc_allocate_tls(void) 282 { 283 struct tls_tcb *tcb; 284 285 tcb = _rtld_allocate_tls(); 286 287 #if 0 288 #if defined(__thread) 289 /* non-TLS libc */ 290 tcb->tcb_errno_p = &errno; 291 #elif defined(PIC) 292 /* TLS libc dynamically linked */ 293 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr()); 294 #else 295 /* TLS libc (threaded or unthreaded) */ 296 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset()); 297 #endif 298 #endif 299 return(tcb); 300 } 301 302