unwind-dw2-fde-glibc.c revision 96489
1/* Copyright (C) 2001, 2002 Free Software Foundation, Inc. 2 Contributed by Jakub Jelinek <jakub@redhat.com>. 3 4 This file is part of GNU CC. 5 6 GNU CC is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU CC is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 GNU General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU CC; see the file COPYING. If not, write to 18 the Free Software Foundation, 59 Temple Place - Suite 330, 19 Boston, MA 02111-1307, USA. */ 20 21/* As a special exception, if you link this library with other files, 22 some of which are compiled with GCC, to produce an executable, 23 this library does not by itself cause the resulting executable 24 to be covered by the GNU General Public License. 25 This exception does not however invalidate any other reasons why 26 the executable file might be covered by the GNU General Public License. */ 27 28/* Locate the FDE entry for a given address, using PT_GNU_EH_FRAME ELF 29 segment and dl_iterate_phdr to avoid register/deregister calls at 30 DSO load/unload. */ 31 32#ifndef _GNU_SOURCE 33#define _GNU_SOURCE 1 34#endif 35 36#include "auto-host.h" /* For HAVE_LD_EH_FRAME_HDR. */ 37#include "tconfig.h" 38#ifndef inhibit_libc 39#include <stddef.h> 40#include <stdlib.h> 41#include <link.h> 42#endif 43#include "tsystem.h" 44#include "dwarf2.h" 45#include "unwind.h" 46#define NO_BASE_OF_ENCODED_VALUE 47#include "unwind-pe.h" 48#include "unwind-dw2-fde.h" 49#include "gthr.h" 50 51#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ 52 && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \ 53 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG))) 54 55static fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases); 56 57#define _Unwind_Find_FDE _Unwind_Find_registered_FDE 58#include "unwind-dw2-fde.c" 59#undef _Unwind_Find_FDE 60 61#ifndef PT_GNU_EH_FRAME 62#define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550) 63#endif 64 65struct unw_eh_callback_data 66{ 67 _Unwind_Ptr pc; 68 void *tbase; 69 void *dbase; 70 void *func; 71 fde *ret; 72}; 73 74struct unw_eh_frame_hdr 75{ 76 unsigned char version; 77 unsigned char eh_frame_ptr_enc; 78 unsigned char fde_count_enc; 79 unsigned char table_enc; 80}; 81 82/* Like base_of_encoded_value, but take the base from a struct object 83 instead of an _Unwind_Context. */ 84 85static _Unwind_Ptr 86base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data) 87{ 88 if (encoding == DW_EH_PE_omit) 89 return 0; 90 91 switch (encoding & 0x70) 92 { 93 case DW_EH_PE_absptr: 94 case DW_EH_PE_pcrel: 95 case DW_EH_PE_aligned: 96 return 0; 97 98 case DW_EH_PE_textrel: 99 return (_Unwind_Ptr) data->tbase; 100 case DW_EH_PE_datarel: 101 return (_Unwind_Ptr) data->dbase; 102 } 103 abort (); 104} 105 106static int 107_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr) 108{ 109 struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr; 110 const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic; 111 long n, match; 112 _Unwind_Ptr load_base; 113 const unsigned char *p; 114 const struct unw_eh_frame_hdr *hdr; 115 _Unwind_Ptr eh_frame; 116 struct object ob; 117 118 /* Make sure struct dl_phdr_info is at least as big as we need. */ 119 if (size < offsetof (struct dl_phdr_info, dlpi_phnum) 120 + sizeof (info->dlpi_phnum)) 121 return -1; 122 123 match = 0; 124 phdr = info->dlpi_phdr; 125 load_base = info->dlpi_addr; 126 p_eh_frame_hdr = NULL; 127 p_dynamic = NULL; 128 129 /* See if PC falls into one of the loaded segments. Find the eh_frame 130 segment at the same time. */ 131 for (n = info->dlpi_phnum; --n >= 0; phdr++) 132 { 133 if (phdr->p_type == PT_LOAD) 134 { 135 _Unwind_Ptr vaddr = phdr->p_vaddr + load_base; 136 if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz) 137 match = 1; 138 } 139 else if (phdr->p_type == PT_GNU_EH_FRAME) 140 p_eh_frame_hdr = phdr; 141 else if (phdr->p_type == PT_DYNAMIC) 142 p_dynamic = phdr; 143 } 144 if (!match || !p_eh_frame_hdr) 145 return 0; 146 147 /* Read .eh_frame_hdr header. */ 148 hdr = (const struct unw_eh_frame_hdr *) 149 (p_eh_frame_hdr->p_vaddr + load_base); 150 if (hdr->version != 1) 151 return 1; 152 153#ifdef CRT_GET_RFIB_DATA 154# ifdef __i386__ 155 data->dbase = NULL; 156 if (p_dynamic) 157 { 158 /* For dynamicly linked executables and shared libraries, 159 DT_PLTGOT is the gp value for that object. */ 160 ElfW(Dyn) *dyn = (ElfW(Dyn) *) (p_dynamic->p_vaddr + load_base); 161 for (; dyn->d_tag != DT_NULL ; dyn++) 162 if (dyn->d_tag == DT_PLTGOT) 163 { 164 /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */ 165 data->dbase = (void *) dyn->d_un.d_ptr; 166 break; 167 } 168 } 169# else 170# error What is DW_EH_PE_datarel base on this platform? 171# endif 172#endif 173#ifdef CRT_GET_RFIB_TEXT 174# error What is DW_EH_PE_textrel base on this platform? 175#endif 176 177 p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc, 178 base_from_cb_data (hdr->eh_frame_ptr_enc, 179 data), 180 (const unsigned char *) (hdr + 1), 181 &eh_frame); 182 183 /* We require here specific table encoding to speed things up. 184 Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start 185 as base, not the processor specific DW_EH_PE_datarel. */ 186 if (hdr->fde_count_enc != DW_EH_PE_omit 187 && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4)) 188 { 189 _Unwind_Ptr fde_count; 190 191 p = read_encoded_value_with_base (hdr->fde_count_enc, 192 base_from_cb_data (hdr->fde_count_enc, 193 data), 194 p, &fde_count); 195 /* Shouldn't happen. */ 196 if (fde_count == 0) 197 return 1; 198 if ((((_Unwind_Ptr) p) & 3) == 0) 199 { 200 struct fde_table { 201 signed initial_loc __attribute__ ((mode (SI))); 202 signed fde __attribute__ ((mode (SI))); 203 }; 204 const struct fde_table *table = (const struct fde_table *) p; 205 size_t lo, hi, mid; 206 _Unwind_Ptr data_base = (_Unwind_Ptr) hdr; 207 fde *f; 208 unsigned int f_enc, f_enc_size; 209 _Unwind_Ptr range; 210 211 mid = fde_count - 1; 212 if (data->pc < table[0].initial_loc + data_base) 213 return 1; 214 else if (data->pc < table[mid].initial_loc + data_base) 215 { 216 lo = 0; 217 hi = mid; 218 219 while (lo < hi) 220 { 221 mid = (lo + hi) / 2; 222 if (data->pc < table[mid].initial_loc + data_base) 223 hi = mid; 224 else if (data->pc >= table[mid + 1].initial_loc + data_base) 225 lo = mid + 1; 226 else 227 break; 228 } 229 230 if (lo >= hi) 231 __gxx_abort (); 232 } 233 234 f = (fde *) (table[mid].fde + data_base); 235 f_enc = get_fde_encoding (f); 236 f_enc_size = size_of_encoded_value (f_enc); 237 read_encoded_value_with_base (f_enc & 0x0f, 0, 238 &f->pc_begin[f_enc_size], &range); 239 if (data->pc < table[mid].initial_loc + data_base + range) 240 data->ret = f; 241 data->func = (void *) (table[mid].initial_loc + data_base); 242 return 1; 243 } 244 } 245 246 /* We have no sorted search table, so need to go the slow way. 247 As soon as GLIBC will provide API so to notify that a library has been 248 removed, we could cache this (and thus use search_object). */ 249 ob.pc_begin = NULL; 250 ob.tbase = data->tbase; 251 ob.dbase = data->dbase; 252 ob.u.single = (fde *) eh_frame; 253 ob.s.i = 0; 254 ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */ 255 data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc); 256 if (data->ret != NULL) 257 { 258 unsigned int encoding = get_fde_encoding (data->ret); 259 read_encoded_value_with_base (encoding, 260 base_from_cb_data (encoding, data), 261 data->ret->pc_begin, 262 (_Unwind_Ptr *)&data->func); 263 } 264 return 1; 265} 266 267fde * 268_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases) 269{ 270 struct unw_eh_callback_data data; 271 fde *ret; 272 273 ret = _Unwind_Find_registered_FDE (pc, bases); 274 if (ret != NULL) 275 return ret; 276 277 data.pc = (_Unwind_Ptr) pc; 278 data.tbase = NULL; 279 data.dbase = NULL; 280 data.func = NULL; 281 data.ret = NULL; 282 283 if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0) 284 return NULL; 285 286 if (data.ret) 287 { 288 bases->tbase = data.tbase; 289 bases->dbase = data.dbase; 290 bases->func = data.func; 291 } 292 return data.ret; 293} 294 295#else 296/* Prevent multiple include of header files. */ 297#define _Unwind_Find_FDE _Unwind_Find_FDE 298#include "unwind-dw2-fde.c" 299#endif 300