unwind-dw2-fde-glibc.c revision 90075
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#include "auto-host.h" /* For HAVE_LD_EH_FRAME_HDR. */ 33#include "tconfig.h" 34#ifndef inhibit_libc 35#include <stddef.h> 36#include <stdlib.h> 37#include <link.h> 38#endif 39#include "tsystem.h" 40#include "dwarf2.h" 41#include "unwind.h" 42#define NO_BASE_OF_ENCODED_VALUE 43#include "unwind-pe.h" 44#include "unwind-dw2-fde.h" 45#include "gthr.h" 46 47#if !defined(inhibit_libc) && defined(HAVE_LD_EH_FRAME_HDR) \ 48 && (__GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2) \ 49 || (__GLIBC__ == 2 && __GLIBC_MINOR__ == 2 && defined(DT_CONFIG))) 50 51static fde * _Unwind_Find_registered_FDE (void *pc, struct dwarf_eh_bases *bases); 52 53#define _Unwind_Find_FDE _Unwind_Find_registered_FDE 54#include "unwind-dw2-fde.c" 55#undef _Unwind_Find_FDE 56 57#ifndef PT_GNU_EH_FRAME 58#define PT_GNU_EH_FRAME (PT_LOOS + 0x474e550) 59#endif 60 61struct unw_eh_callback_data 62{ 63 _Unwind_Ptr pc; 64 void *tbase; 65 void *dbase; 66 void *func; 67 fde *ret; 68}; 69 70struct unw_eh_frame_hdr 71{ 72 unsigned char version; 73 unsigned char eh_frame_ptr_enc; 74 unsigned char fde_count_enc; 75 unsigned char table_enc; 76}; 77 78/* Like base_of_encoded_value, but take the base from a struct object 79 instead of an _Unwind_Context. */ 80 81static _Unwind_Ptr 82base_from_cb_data (unsigned char encoding, struct unw_eh_callback_data *data) 83{ 84 if (encoding == DW_EH_PE_omit) 85 return 0; 86 87 switch (encoding & 0x70) 88 { 89 case DW_EH_PE_absptr: 90 case DW_EH_PE_pcrel: 91 case DW_EH_PE_aligned: 92 return 0; 93 94 case DW_EH_PE_textrel: 95 return (_Unwind_Ptr) data->tbase; 96 case DW_EH_PE_datarel: 97 return (_Unwind_Ptr) data->dbase; 98 } 99 abort (); 100} 101 102static int 103_Unwind_IteratePhdrCallback (struct dl_phdr_info *info, size_t size, void *ptr) 104{ 105 struct unw_eh_callback_data *data = (struct unw_eh_callback_data *) ptr; 106 const ElfW(Phdr) *phdr, *p_eh_frame_hdr, *p_dynamic; 107 long n, match; 108 _Unwind_Ptr load_base; 109 const unsigned char *p; 110 const struct unw_eh_frame_hdr *hdr; 111 _Unwind_Ptr eh_frame; 112 struct object ob; 113 114 /* Make sure struct dl_phdr_info is at least as big as we need. */ 115 if (size < offsetof (struct dl_phdr_info, dlpi_phnum) 116 + sizeof (info->dlpi_phnum)) 117 return -1; 118 119 match = 0; 120 phdr = info->dlpi_phdr; 121 load_base = info->dlpi_addr; 122 p_eh_frame_hdr = NULL; 123 p_dynamic = NULL; 124 125 /* See if PC falls into one of the loaded segments. Find the eh_frame 126 segment at the same time. */ 127 for (n = info->dlpi_phnum; --n >= 0; phdr++) 128 { 129 if (phdr->p_type == PT_LOAD) 130 { 131 _Unwind_Ptr vaddr = phdr->p_vaddr + load_base; 132 if (data->pc >= vaddr && data->pc < vaddr + phdr->p_memsz) 133 match = 1; 134 } 135 else if (phdr->p_type == PT_GNU_EH_FRAME) 136 p_eh_frame_hdr = phdr; 137 else if (phdr->p_type == PT_DYNAMIC) 138 p_dynamic = phdr; 139 } 140 if (!match || !p_eh_frame_hdr) 141 return 0; 142 143 /* Read .eh_frame_hdr header. */ 144 hdr = (const struct unw_eh_frame_hdr *) 145 (p_eh_frame_hdr->p_vaddr + load_base); 146 if (hdr->version != 1) 147 return 1; 148 149#ifdef CRT_GET_RFIB_DATA 150# ifdef __i386__ 151 data->dbase = NULL; 152 if (p_dynamic) 153 { 154 /* For dynamicly linked executables and shared libraries, 155 DT_PLTGOT is the gp value for that object. */ 156 ElfW(Dyn) *dyn = (ElfW(Dyn) *) (p_dynamic->p_vaddr + load_base); 157 for (; dyn->d_tag != DT_NULL ; dyn++) 158 if (dyn->d_tag == DT_PLTGOT) 159 { 160 /* On IA-32, _DYNAMIC is writable and GLIBC has relocated it. */ 161 data->dbase = (void *) dyn->d_un.d_ptr; 162 break; 163 } 164 } 165# else 166# error What is DW_EH_PE_datarel base on this platform? 167# endif 168#endif 169#ifdef CRT_GET_RFIB_TEXT 170# error What is DW_EH_PE_textrel base on this platform? 171#endif 172 173 p = read_encoded_value_with_base (hdr->eh_frame_ptr_enc, 174 base_from_cb_data (hdr->eh_frame_ptr_enc, 175 data), 176 (const unsigned char *) (hdr + 1), 177 &eh_frame); 178 179 /* We require here specific table encoding to speed things up. 180 Also, DW_EH_PE_datarel here means using PT_GNU_EH_FRAME start 181 as base, not the processor specific DW_EH_PE_datarel. */ 182 if (hdr->fde_count_enc != DW_EH_PE_omit 183 && hdr->table_enc == (DW_EH_PE_datarel | DW_EH_PE_sdata4)) 184 { 185 _Unwind_Ptr fde_count; 186 187 p = read_encoded_value_with_base (hdr->fde_count_enc, 188 base_from_cb_data (hdr->fde_count_enc, 189 data), 190 p, &fde_count); 191 /* Shouldn't happen. */ 192 if (fde_count == 0) 193 return 1; 194 if ((((_Unwind_Ptr) p) & 3) == 0) 195 { 196 struct fde_table { 197 signed initial_loc __attribute__ ((mode (SI))); 198 signed fde __attribute__ ((mode (SI))); 199 }; 200 const struct fde_table *table = (const struct fde_table *) p; 201 size_t lo, hi, mid; 202 _Unwind_Ptr data_base = (_Unwind_Ptr) hdr; 203 fde *f; 204 unsigned int f_enc, f_enc_size; 205 _Unwind_Ptr range; 206 207 mid = fde_count - 1; 208 if (data->pc < table[0].initial_loc + data_base) 209 return 1; 210 else if (data->pc < table[mid].initial_loc + data_base) 211 { 212 lo = 0; 213 hi = mid; 214 215 while (lo < hi) 216 { 217 mid = (lo + hi) / 2; 218 if (data->pc < table[mid].initial_loc + data_base) 219 hi = mid; 220 else if (data->pc >= table[mid + 1].initial_loc + data_base) 221 lo = mid + 1; 222 else 223 break; 224 } 225 226 if (lo >= hi) 227 __gxx_abort (); 228 } 229 230 f = (fde *) (table[mid].fde + data_base); 231 f_enc = get_fde_encoding (f); 232 f_enc_size = size_of_encoded_value (f_enc); 233 read_encoded_value_with_base (f_enc & 0x0f, 0, 234 &f->pc_begin[f_enc_size], &range); 235 if (data->pc < table[mid].initial_loc + data_base + range) 236 data->ret = f; 237 data->func = (void *) (table[mid].initial_loc + data_base); 238 return 1; 239 } 240 } 241 242 /* We have no sorted search table, so need to go the slow way. 243 As soon as GLIBC will provide API so to notify that a library has been 244 removed, we could cache this (and thus use search_object). */ 245 ob.pc_begin = NULL; 246 ob.tbase = data->tbase; 247 ob.dbase = data->dbase; 248 ob.u.single = (fde *) eh_frame; 249 ob.s.i = 0; 250 ob.s.b.mixed_encoding = 1; /* Need to assume worst case. */ 251 data->ret = linear_search_fdes (&ob, (fde *) eh_frame, (void *) data->pc); 252 if (data->ret != NULL) 253 { 254 unsigned int encoding = get_fde_encoding (data->ret); 255 read_encoded_value_with_base (encoding, 256 base_from_cb_data (encoding, data), 257 data->ret->pc_begin, 258 (_Unwind_Ptr *)&data->func); 259 } 260 return 1; 261} 262 263fde * 264_Unwind_Find_FDE (void *pc, struct dwarf_eh_bases *bases) 265{ 266 struct unw_eh_callback_data data; 267 fde *ret; 268 269 ret = _Unwind_Find_registered_FDE (pc, bases); 270 if (ret != NULL) 271 return ret; 272 273 data.pc = (_Unwind_Ptr) pc; 274 data.tbase = NULL; 275 data.dbase = NULL; 276 data.func = NULL; 277 data.ret = NULL; 278 279 if (dl_iterate_phdr (_Unwind_IteratePhdrCallback, &data) < 0) 280 return NULL; 281 282 if (data.ret) 283 { 284 bases->tbase = data.tbase; 285 bases->dbase = data.dbase; 286 bases->func = data.func; 287 } 288 return data.ret; 289} 290 291#else 292/* Prevent multiple include of header files. */ 293#define _Unwind_Find_FDE _Unwind_Find_FDE 294#include "unwind-dw2-fde.c" 295#endif 296