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 53 #if !defined(RTLD_STATIC_TLS_VARIANT_II) 54 #error "Unsupported TLS layout" 55 #endif 56 57 #ifndef PIC 58 59 static size_t tls_static_space; 60 static size_t tls_init_size; 61 static void *tls_init; 62 static struct tls_tcb *initial_tcb; 63 #endif 64 65 void *__libc_tls_get_addr(void *ti); 66 void *__libc_tls_get_addr_tcb(struct tls_tcb *, void *); 67 68 void * 69 __libc_tls_get_addr(void *ti __unused) 70 { 71 return (NULL); 72 } 73 74 void * 75 __libc_tls_get_addr_tcb(struct tls_tcb *tcb __unused, void *got_ptr __unused) 76 { 77 return (NULL); 78 } 79 80 #ifndef PIC 81 82 /* 83 * Free Static TLS, weakly bound to _rtld_free_tls() 84 */ 85 void 86 __libc_free_tls(struct tls_tcb *tcb) 87 { 88 size_t data_size; 89 90 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 91 ~RTLD_STATIC_TLS_ALIGN_MASK; 92 93 if (tcb == initial_tcb) { 94 /* initial_tcb was allocated with mmap(), cannot call free() */ 95 } else { 96 free((char *)tcb - data_size); 97 } 98 } 99 100 /* 101 * Allocate Static TLS, weakly bound to _rtld_allocate_tls() 102 * 103 * NOTE! There is a chicken-and-egg problem here because no TLS exists 104 * on the first call into this function. 105 */ 106 struct tls_tcb * 107 __libc_allocate_tls(void) 108 { 109 size_t data_size; 110 struct tls_tcb *tcb; 111 Elf_Addr *dtv; 112 113 data_size = (tls_static_space + RTLD_STATIC_TLS_ALIGN_MASK) & 114 ~RTLD_STATIC_TLS_ALIGN_MASK; 115 116 /* 117 * Allocate space. malloc() may require a working TLS segment 118 * so we use sbrk() for main's TLS. Oops, but in order to be 119 * compatible with older kernels we cannot use sbrk() because it 120 * will generate an errno (which needs the TLS), so use mmap(). 121 */ 122 if (initial_tcb == NULL) { 123 size_t bytes; 124 125 bytes = data_size + sizeof(*tcb) + 3 * sizeof(*dtv); 126 bytes = (bytes + PAGE_MASK) & ~(size_t)PAGE_MASK; 127 tcb = mmap((void *)1, bytes, 128 PROT_READ | PROT_WRITE, 129 MAP_PRIVATE | MAP_ANON, 130 -1, 0); 131 } else { 132 tcb = malloc(data_size + sizeof(*tcb) + 3 * sizeof(*dtv)); 133 } 134 135 tcb = (struct tls_tcb *)((char *)tcb + data_size); 136 dtv = (Elf_Addr *)(tcb + 1); 137 138 memset(tcb, 0, sizeof(*tcb)); 139 #ifdef RTLD_TCB_HAS_SELF_POINTER 140 tcb->tcb_self = tcb; 141 #endif 142 tcb->tcb_dtv = dtv; 143 144 /* 145 * Dummy-up the module array. A static binary has only one. This 146 * allows us to support the generic __tls_get_addr compiler ABI 147 * function. However, if there is no RTLD linked in, nothing in 148 * the program should ever call __tls_get_addr (and our version 149 * of it doesn't do anything). 150 */ 151 dtv[0] = 1; 152 dtv[1] = 1; 153 dtv[2] = (Elf_Addr)((char *)tcb - tls_static_space); 154 155 memcpy((char *)tcb - tls_static_space, 156 tls_init, tls_init_size); 157 memset((char *)tcb - tls_static_space + tls_init_size, 158 0, tls_static_space - tls_init_size); 159 160 /* 161 * Activate the initial TCB 162 */ 163 if (initial_tcb == NULL) { 164 initial_tcb = tcb; 165 tls_set_tcb(tcb); 166 } 167 return (tcb); 168 } 169 170 #else 171 172 struct tls_tcb * 173 __libc_allocate_tls(void) 174 { 175 return (NULL); 176 } 177 178 void 179 __libc_free_tls(struct tls_tcb *tcb __unused) 180 { 181 } 182 183 #endif /* PIC */ 184 185 void 186 __libc_call_init(void) 187 { 188 } 189 190 extern char **environ; 191 192 struct tls_tcb * 193 _libc_init_tls(void) 194 { 195 struct tls_tcb *tcb; 196 197 #ifndef PIC 198 /* 199 * If this is a static binary there is no RTLD and so we have not 200 * yet calculated the static space requirement. Do so now. 201 */ 202 Elf_Addr *sp; 203 Elf_Auxinfo *aux, *auxp; 204 Elf_Phdr *phdr; 205 size_t phent, phnum; 206 int i; 207 208 sp = (Elf_Addr *) environ; 209 while (*sp++ != 0) 210 ; 211 aux = (Elf_Auxinfo *) sp; 212 phdr = NULL; 213 phent = phnum = 0; 214 for (auxp = aux; auxp->a_type != AT_NULL; auxp++) { 215 switch (auxp->a_type) { 216 case AT_PHDR: 217 phdr = auxp->a_un.a_ptr; 218 break; 219 220 case AT_PHENT: 221 phent = auxp->a_un.a_val; 222 break; 223 224 case AT_PHNUM: 225 phnum = auxp->a_un.a_val; 226 break; 227 } 228 } 229 if (phdr == NULL || phent != sizeof(Elf_Phdr) || phnum == 0) 230 return(NULL); 231 232 for (i = 0; (unsigned)i < phnum; i++) { 233 if (phdr[i].p_type == PT_TLS) { 234 tls_static_space = roundup2(phdr[i].p_memsz, 235 phdr[i].p_align); 236 tls_init_size = phdr[i].p_filesz; 237 tls_init = (void*) phdr[i].p_vaddr; 238 } 239 } 240 #endif 241 242 /* 243 * Allocate the initial TLS segment. The TLS has not been set up 244 * yet for either the static or dynamic linked case (RTLD no longer 245 * sets up an initial TLS segment for us). 246 */ 247 tcb = _libc_allocate_tls(); 248 tls_set_tcb(tcb); 249 return(tcb); 250 } 251 252 /* 253 * Allocate a standard TLS. This function is called by libc and by 254 * thread libraries to create a new TCB with libc-related fields properly 255 * initialized (whereas _rtld_allocate_tls() is unable to completely set 256 * up the TCB). 257 * 258 * Note that this is different from __libc_allocate_tls which is the 259 * weakly bound symbol that handles the case where _rtld_allocate_tls 260 * does not exist. 261 */ 262 struct tls_tcb * 263 _libc_allocate_tls(void) 264 { 265 struct tls_tcb *tcb; 266 267 tcb = _rtld_allocate_tls(); 268 269 #if 0 270 #if defined(__thread) 271 /* non-TLS libc */ 272 tcb->tcb_errno_p = &errno; 273 #elif defined(PIC) 274 /* TLS libc dynamically linked */ 275 tcb->tcb_errno_p = __tls_get_addr_tcb(tcb, __get_errno_GOT_ptr()); 276 #else 277 /* TLS libc (threaded or unthreaded) */ 278 tcb->tcb_errno_p = (void *)((char *)tcb + __get_errno_GS_offset()); 279 #endif 280 #endif 281 return(tcb); 282 } 283 284 __weak_reference(__libc_allocate_tls, _rtld_allocate_tls); 285 __weak_reference(__libc_free_tls, _rtld_free_tls); 286 __weak_reference(__libc_call_init, _rtld_call_init); 287 __weak_reference(__libc_tls_get_addr, __tls_get_addr); 288 __weak_reference(__libc_tls_get_addr_tcb, __tls_get_addr_tcb); 289 __weak_reference(_libc_init_tls, _init_tls); 290