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/cdefs.h> 36 #include <sys/tls.h> 37 38 #include <machine/tls.h> 39 40 #include <stdlib.h> 41 #include <string.h> 42 #include <elf.h> 43 #include <assert.h> 44 #include <errno.h> 45 #include <unistd.h> 46 47 #include "libc_private.h" 48 49 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls); 50 __weak_reference(__libc_free_tls, _rtld_free_tls); 51 __weak_reference(__libc_call_init, _rtld_call_init); 52 #ifdef __i386__ 53 __weak_reference(___libc_tls_get_addr, ___tls_get_addr); 54 #endif 55 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 56 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 57 __weak_reference(_libc_init_tls, _init_tls); 58 59 struct tls_tcb *__libc_allocate_tls(void); 60 void __libc_free_tls(struct tls_tcb *tcb); 61 62 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 63 #error "Unsupported TLS layout" 64 #endif 65 66 #ifndef PIC 67 68 #define round(size, align) \ 69 (((size) + (align) - 1) & ~((align) - 1)) 70 71 static size_t tls_static_space; 72 static size_t tls_init_size; 73 static void *tls_init; 74 static struct tls_tcb *initial_tcb; 75 #endif 76 77 #ifdef __i386__ 78 79 /* GNU ABI */ 80 81 void *___libc_tls_get_addr(void *ti) __attribute__((__regparm__(1))); 82 83 __attribute__((__regparm__(1))) 84 void * 85 ___libc_tls_get_addr(void *ti __unused) 86 { 87 return (0); 88 } 89 90 #endif 91 92 void *__libc_tls_get_addr(void *ti); 93 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 94 95 void * 96 __libc_tls_get_addr(void *ti __unused) 97 { 98 return (NULL); 99 } 100 101 void * 102 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 103 { 104 return (NULL); 105 } 106 107 #ifndef PIC 108 109 /* 110 * Free Static TLS, weakly bound to _rtld_free_tls() 111 */ 112 void 113 __libc_free_tls(struct tls_tcb *tcb) 114 { 115 size_t data_size; 116 117 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 118 ~RTLD_STATIC_TLS_ALIGN_MASK; 119 120 if (tcb == initial_tcb) { 121 /* initial_tcb was allocated with sbrk(), cannot call free() */ 122 } else { 123 free((char *)tcb - data_size); 124 } 125 } 126 127 /* 128 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 129 * 130 * NOTE! There is a chicken-and-egg problem here because no TLS exists 131 * on the first call into this function. 132 */ 133 struct tls_tcb * 134 __libc_allocate_tls(void) 135 { 136 size_t data_size; 137 struct tls_tcb *tcb; 138 Elf_Addr *dtv; 139 140 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 141 ~RTLD_STATIC_TLS_ALIGN_MASK; 142 143 /* 144 * Allocate space. malloc() may require a working TLS segment 145 * so we use sbrk() for main's TLS. 146 */ 147 if (initial_tcb == NULL) 148 tcb = sbrk(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 149 else 150 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 151 152 tcb = (struct tls_tcb *)((char *)tcb + data_size); 153 dtv = (Elf_Addr *)(tcb + 1); 154 155 memset(tcb, 0, sizeof(*tcb)); 156 #ifdef RTLD_TCB_HAS_SELF_POINTER 157 tcb->tcb_self = tcb; 158 #endif 159 tcb->tcb_dtv = dtv; 160 161 /* 162 * Dummy-up the module array. A static binary has only one. This 163 * allows us to support the generic __tls_get_addr compiler ABI 164 * function. However, if there is no RTLD linked in, nothing in 165 * the program should ever call __tls_get_addr (and our version 166 * of it doesn't do anything). 167 */ 168 dtv[0] = 1; 169 dtv[1] = 1; 170 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 171 172 memcpy((char *)tcb - tls_static_space, 173 tls_init, tls_init_size); 174 memset((char *)tcb - tls_static_space + tls_init_size, 175 0, tls_static_space - tls_init_size); 176 177 /* 178 * Activate the initial TCB 179 */ 180 if (initial_tcb == NULL) { 181 initial_tcb = tcb; 182 tls_set_tcb(tcb); 183 } 184 return (tcb); 185 } 186 187 #else 188 189 struct tls_tcb * 190 __libc_allocate_tls(void) 191 { 192 return (NULL); 193 } 194 195 void 196 __libc_free_tls(struct tls_tcb *tcb __unused) 197 { 198 } 199 200 #endif /* PIC */ 201 202 void 203 __libc_call_init(void) 204 { 205 } 206 207 extern char **environ; 208 209 struct tls_tcb * 210 _libc_init_tls(void) 211 { 212 struct tls_tcb *tcb; 213 214 #ifndef PIC 215 /* 216 * If this is a static binary there is no RTLD and so we have not 217 * yet calculated the static space requirement. Do so now. 218 */ 219 Elf_Addr *sp; 220 Elf_Auxinfo *aux, *auxp; 221 Elf_Phdr *phdr; 222 size_t phent, phnum; 223 int i; 224 225 sp = (Elf_Addr *) environ; 226 while (*sp++ != 0) 227 ; 228 aux = (Elf_Auxinfo *) sp; 229 phdr = NULL; 230 phent = phnum = 0; 231 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 232 switch (auxp->a_type) { 233 case AT_PHDR: 234 phdr = auxp->a_un.a_ptr; 235 break; 236 237 case AT_PHENT: 238 phent = auxp->a_un.a_val; 239 break; 240 241 case AT_PHNUM: 242 phnum = auxp->a_un.a_val; 243 break; 244 } 245 } 246 if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0) 247 return(NULL); 248 249 for (i = 0; (unsigned)i < phnum; i++) { 250 if (phdr[i].p_type == PT_TLS) { 251 tls_static_space = round(phdr[i].p_memsz, 252 phdr[i].p_align); 253 tls_init_size = phdr[i].p_filesz; 254 tls_init = (void*) phdr[i].p_vaddr; 255 } 256 } 257 #endif 258 259 /* 260 * Allocate the initial TLS segment. The TLS has not been set up 261 * yet for either the static or dynamic linked case (RTLD no longer 262 * sets up an initial TLS segment for us). 263 */ 264 tcb = _libc_allocate_tls(); 265 tls_set_tcb(tcb); 266 return(tcb); 267 } 268 269 /* 270 * Allocate a standard TLS. This function is called by libc and by 271 * thread libraries to create a new TCB with libc-related fields properly 272 * initialized (whereas _rtld_allocate_tls() is unable to completely set 273 * up the TCB). 274 * 275 * Note that this is different from __libc_allocate_tls which is the 276 * weakly bound symbol that handles the case where _rtld_allocate_tls 277 * does not exist. 278 */ 279 struct tls_tcb * 280 _libc_allocate_tls(void) 281 { 282 struct tls_tcb *tcb; 283 284 tcb = _rtld_allocate_tls(); 285 286 #if 0 287 #if defined(__thread) 288 /* non-TLS libc */ 289 tcb->tcb_errno_p = &errno; 290 #elif defined(PIC) 291 /* TLS libc dynamically linked */ 292 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr()); 293 #else 294 /* TLS libc (threaded or unthreaded) */ 295 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset()); 296 #endif 297 #endif 298 return(tcb); 299 } 300 301