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 #include <sys/mman.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 struct tls_tcb *__libc_allocate_tls(void); 51 void __libc_free_tls(struct tls_tcb *tcb); 52 void __libc_call_init(void); 53 54 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 55 #error "Unsupported TLS layout" 56 #endif 57 58 #ifndef PIC 59 60 static size_t tls_static_space; 61 static size_t tls_init_size; 62 static void *tls_init; 63 static struct tls_tcb *initial_tcb; 64 #endif 65 66 void *__libc_tls_get_addr(void *ti); 67 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 68 69 void * 70 __libc_tls_get_addr(void *ti __unused) 71 { 72 return (NULL); 73 } 74 75 void * 76 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 77 { 78 return (NULL); 79 } 80 81 #ifndef PIC 82 83 /* 84 * Free Static TLS, weakly bound to _rtld_free_tls() 85 */ 86 void 87 __libc_free_tls(struct tls_tcb *tcb) 88 { 89 size_t data_size; 90 91 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 92 ~RTLD_STATIC_TLS_ALIGN_MASK; 93 94 if (tcb == initial_tcb) { 95 /* initial_tcb was allocated with mmap(), cannot call free() */ 96 } else { 97 free((char *)tcb - data_size); 98 } 99 } 100 101 /* 102 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 103 * 104 * NOTE! There is a chicken-and-egg problem here because no TLS exists 105 * on the first call into this function. 106 */ 107 struct tls_tcb * 108 __libc_allocate_tls(void) 109 { 110 size_t data_size; 111 struct tls_tcb *tcb; 112 Elf_Addr *dtv; 113 114 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 115 ~RTLD_STATIC_TLS_ALIGN_MASK; 116 117 /* 118 * Allocate space. malloc() may require a working TLS segment 119 * so we use sbrk() for main's TLS. Oops, but in order to be 120 * compatible with older kernels we cannot use sbrk() because it 121 * will generate an errno (which needs the TLS), so use mmap(). 122 */ 123 if (initial_tcb == NULL) { 124 size_t bytes; 125 126 bytes = data_size + sizeof(*tcb) + 3 * sizeof(*dtv); 127 bytes = (bytes + PAGE_MASK) & ~(size_t)PAGE_MASK; 128 tcb = mmap((void *)1, bytes, 129 PROT_READ | PROT_WRITE, 130 MAP_PRIVATE | MAP_ANON, 131 -1, 0); 132 } else { 133 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 134 } 135 136 tcb = (struct tls_tcb *)((char *)tcb + data_size); 137 dtv = (Elf_Addr *)(tcb + 1); 138 139 memset(tcb, 0, sizeof(*tcb)); 140 #ifdef RTLD_TCB_HAS_SELF_POINTER 141 tcb->tcb_self = tcb; 142 #endif 143 tcb->tcb_dtv = dtv; 144 145 /* 146 * Dummy-up the module array. A static binary has only one. This 147 * allows us to support the generic __tls_get_addr compiler ABI 148 * function. However, if there is no RTLD linked in, nothing in 149 * the program should ever call __tls_get_addr (and our version 150 * of it doesn't do anything). 151 */ 152 dtv[0] = 1; 153 dtv[1] = 1; 154 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 155 156 memcpy((char *)tcb - tls_static_space, 157 tls_init, tls_init_size); 158 memset((char *)tcb - tls_static_space + tls_init_size, 159 0, tls_static_space - tls_init_size); 160 161 /* 162 * Activate the initial TCB 163 */ 164 if (initial_tcb == NULL) { 165 initial_tcb = tcb; 166 tls_set_tcb(tcb); 167 } 168 return (tcb); 169 } 170 171 #else 172 173 struct tls_tcb * 174 __libc_allocate_tls(void) 175 { 176 return (NULL); 177 } 178 179 void 180 __libc_free_tls(struct tls_tcb *tcb __unused) 181 { 182 } 183 184 #endif /* PIC */ 185 186 void 187 __libc_call_init(void) 188 { 189 } 190 191 extern char **environ; 192 193 struct tls_tcb * 194 _libc_init_tls(void) 195 { 196 struct tls_tcb *tcb; 197 198 #ifndef PIC 199 /* 200 * If this is a static binary there is no RTLD and so we have not 201 * yet calculated the static space requirement. Do so now. 202 */ 203 Elf_Addr *sp; 204 Elf_Auxinfo *aux, *auxp; 205 Elf_Phdr *phdr; 206 size_t phent, phnum; 207 int i; 208 209 sp = (Elf_Addr *) environ; 210 while (*sp++ != 0) 211 ; 212 aux = (Elf_Auxinfo *) sp; 213 phdr = NULL; 214 phent = phnum = 0; 215 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 216 switch (auxp->a_type) { 217 case AT_PHDR: 218 phdr = auxp->a_un.a_ptr; 219 break; 220 221 case AT_PHENT: 222 phent = auxp->a_un.a_val; 223 break; 224 225 case AT_PHNUM: 226 phnum = auxp->a_un.a_val; 227 break; 228 } 229 } 230 if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0) 231 return(NULL); 232 233 for (i = 0; (unsigned)i < phnum; i++) { 234 if (phdr[i].p_type == PT_TLS) { 235 tls_static_space = roundup2(phdr[i].p_memsz, 236 phdr[i].p_align); 237 tls_init_size = phdr[i].p_filesz; 238 tls_init = (void*) phdr[i].p_vaddr; 239 } 240 } 241 #endif 242 243 /* 244 * Allocate the initial TLS segment. The TLS has not been set up 245 * yet for either the static or dynamic linked case (RTLD no longer 246 * sets up an initial TLS segment for us). 247 */ 248 tcb = _libc_allocate_tls(); 249 tls_set_tcb(tcb); 250 return(tcb); 251 } 252 253 /* 254 * Allocate a standard TLS. This function is called by libc and by 255 * thread libraries to create a new TCB with libc-related fields properly 256 * initialized (whereas _rtld_allocate_tls() is unable to completely set 257 * up the TCB). 258 * 259 * Note that this is different from __libc_allocate_tls which is the 260 * weakly bound symbol that handles the case where _rtld_allocate_tls 261 * does not exist. 262 */ 263 struct tls_tcb * 264 _libc_allocate_tls(void) 265 { 266 struct tls_tcb *tcb; 267 268 tcb = _rtld_allocate_tls(); 269 return(tcb); 270 } 271 272 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls); 273 __weak_reference(__libc_free_tls, _rtld_free_tls); 274 __weak_reference(__libc_call_init, _rtld_call_init); 275 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 276 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 277 __weak_reference(_libc_init_tls, _init_tls); 278