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/param.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 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 53 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 54 __weak_reference(_libc_init_tls, _init_tls); 55 56 struct tls_tcb *__libc_allocate_tls(void); 57 void __libc_free_tls(struct tls_tcb *tcb); 58 59 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 60 #error "Unsupported TLS layout" 61 #endif 62 63 #ifndef PIC 64 65 static size_t tls_static_space; 66 static size_t tls_init_size; 67 static void *tls_init; 68 static struct tls_tcb *initial_tcb; 69 #endif 70 71 void *__libc_tls_get_addr(void *ti); 72 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 73 74 void * 75 __libc_tls_get_addr(void *ti __unused) 76 { 77 return (NULL); 78 } 79 80 void * 81 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 82 { 83 return (NULL); 84 } 85 86 #ifndef PIC 87 88 /* 89 * Free Static TLS, weakly bound to _rtld_free_tls() 90 */ 91 void 92 __libc_free_tls(struct tls_tcb *tcb) 93 { 94 size_t data_size; 95 96 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 97 ~RTLD_STATIC_TLS_ALIGN_MASK; 98 99 if (tcb == initial_tcb) { 100 /* initial_tcb was allocated with sbrk(), cannot call free() */ 101 } else { 102 free((char *)tcb - data_size); 103 } 104 } 105 106 /* 107 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 108 * 109 * NOTE! There is a chicken-and-egg problem here because no TLS exists 110 * on the first call into this function. 111 */ 112 struct tls_tcb * 113 __libc_allocate_tls(void) 114 { 115 size_t data_size; 116 struct tls_tcb *tcb; 117 Elf_Addr *dtv; 118 119 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 120 ~RTLD_STATIC_TLS_ALIGN_MASK; 121 122 /* 123 * Allocate space. malloc() may require a working TLS segment 124 * so we use sbrk() for main's TLS. 125 */ 126 if (initial_tcb == NULL) 127 tcb = sbrk(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 128 else 129 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 130 131 tcb = (struct tls_tcb *)((char *)tcb + data_size); 132 dtv = (Elf_Addr *)(tcb + 1); 133 134 memset(tcb, 0, sizeof(*tcb)); 135 #ifdef RTLD_TCB_HAS_SELF_POINTER 136 tcb->tcb_self = tcb; 137 #endif 138 tcb->tcb_dtv = dtv; 139 140 /* 141 * Dummy-up the module array. A static binary has only one. This 142 * allows us to support the generic __tls_get_addr compiler ABI 143 * function. However, if there is no RTLD linked in, nothing in 144 * the program should ever call __tls_get_addr (and our version 145 * of it doesn't do anything). 146 */ 147 dtv[0] = 1; 148 dtv[1] = 1; 149 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 150 151 memcpy((char *)tcb - tls_static_space, 152 tls_init, tls_init_size); 153 memset((char *)tcb - tls_static_space + tls_init_size, 154 0, tls_static_space - tls_init_size); 155 156 /* 157 * Activate the initial TCB 158 */ 159 if (initial_tcb == NULL) { 160 initial_tcb = tcb; 161 tls_set_tcb(tcb); 162 } 163 return (tcb); 164 } 165 166 #else 167 168 struct tls_tcb * 169 __libc_allocate_tls(void) 170 { 171 return (NULL); 172 } 173 174 void 175 __libc_free_tls(struct tls_tcb *tcb __unused) 176 { 177 } 178 179 #endif /* PIC */ 180 181 void 182 __libc_call_init(void) 183 { 184 } 185 186 extern char **environ; 187 188 struct tls_tcb * 189 _libc_init_tls(void) 190 { 191 struct tls_tcb *tcb; 192 193 #ifndef PIC 194 /* 195 * If this is a static binary there is no RTLD and so we have not 196 * yet calculated the static space requirement. Do so now. 197 */ 198 Elf_Addr *sp; 199 Elf_Auxinfo *aux, *auxp; 200 Elf_Phdr *phdr; 201 size_t phent, phnum; 202 int i; 203 204 sp = (Elf_Addr *) environ; 205 while (*sp++ != 0) 206 ; 207 aux = (Elf_Auxinfo *) sp; 208 phdr = NULL; 209 phent = phnum = 0; 210 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 211 switch (auxp->a_type) { 212 case AT_PHDR: 213 phdr = auxp->a_un.a_ptr; 214 break; 215 216 case AT_PHENT: 217 phent = auxp->a_un.a_val; 218 break; 219 220 case AT_PHNUM: 221 phnum = auxp->a_un.a_val; 222 break; 223 } 224 } 225 if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0) 226 return(NULL); 227 228 for (i = 0; (unsigned)i < phnum; i++) { 229 if (phdr[i].p_type == PT_TLS) { 230 tls_static_space = roundup2(phdr[i].p_memsz, 231 phdr[i].p_align); 232 tls_init_size = phdr[i].p_filesz; 233 tls_init = (void*) phdr[i].p_vaddr; 234 } 235 } 236 #endif 237 238 /* 239 * Allocate the initial TLS segment. The TLS has not been set up 240 * yet for either the static or dynamic linked case (RTLD no longer 241 * sets up an initial TLS segment for us). 242 */ 243 tcb = _libc_allocate_tls(); 244 tls_set_tcb(tcb); 245 return(tcb); 246 } 247 248 /* 249 * Allocate a standard TLS. This function is called by libc and by 250 * thread libraries to create a new TCB with libc-related fields properly 251 * initialized (whereas _rtld_allocate_tls() is unable to completely set 252 * up the TCB). 253 * 254 * Note that this is different from __libc_allocate_tls which is the 255 * weakly bound symbol that handles the case where _rtld_allocate_tls 256 * does not exist. 257 */ 258 struct tls_tcb * 259 _libc_allocate_tls(void) 260 { 261 struct tls_tcb *tcb; 262 263 tcb = _rtld_allocate_tls(); 264 265 #if 0 266 #if defined(__thread) 267 /* non-TLS libc */ 268 tcb->tcb_errno_p = &errno; 269 #elif defined(PIC) 270 /* TLS libc dynamically linked */ 271 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr()); 272 #else 273 /* TLS libc (threaded or unthreaded) */ 274 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset()); 275 #endif 276 #endif 277 return(tcb); 278 } 279 280