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