Roland McGrath | 3c84db3 | 2009-06-24 17:41:40 -0700 | [diff] [blame] | 1 | /* Get CFI from ELF file's exception-handling info. |
Roland McGrath | f95760a | 2010-01-07 20:24:34 -0800 | [diff] [blame] | 2 | Copyright (C) 2009-2010 Red Hat, Inc. |
Roland McGrath | 3c84db3 | 2009-06-24 17:41:40 -0700 | [diff] [blame] | 3 | This file is part of Red Hat elfutils. |
| 4 | |
| 5 | Red Hat elfutils is free software; you can redistribute it and/or modify |
| 6 | it under the terms of the GNU General Public License as published by the |
| 7 | Free Software Foundation; version 2 of the License. |
| 8 | |
| 9 | Red Hat elfutils is distributed in the hope that it will be useful, but |
| 10 | WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU General Public License along |
| 15 | with Red Hat elfutils; if not, write to the Free Software Foundation, |
| 16 | Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA. |
| 17 | |
| 18 | In addition, as a special exception, Red Hat, Inc. gives You the |
| 19 | additional right to link the code of Red Hat elfutils with code licensed |
| 20 | under any Open Source Initiative certified open source license |
| 21 | (http://www.opensource.org/licenses/index.php) which requires the |
| 22 | distribution of source code with any binary distribution and to |
| 23 | distribute linked combinations of the two. Non-GPL Code permitted under |
| 24 | this exception must only link to the code of Red Hat elfutils through |
| 25 | those well defined interfaces identified in the file named EXCEPTION |
| 26 | found in the source code files (the "Approved Interfaces"). The files |
| 27 | of Non-GPL Code may instantiate templates or use macros or inline |
| 28 | functions from the Approved Interfaces without causing the resulting |
| 29 | work to be covered by the GNU General Public License. Only Red Hat, |
| 30 | Inc. may make changes or additions to the list of Approved Interfaces. |
| 31 | Red Hat's grant of this exception is conditioned upon your not adding |
| 32 | any new exceptions. If you wish to add a new Approved Interface or |
| 33 | exception, please contact Red Hat. You must obey the GNU General Public |
| 34 | License in all respects for all of the Red Hat elfutils code and other |
| 35 | code used in conjunction with Red Hat elfutils except the Non-GPL Code |
| 36 | covered by this exception. If you modify this file, you may extend this |
| 37 | exception to your version of the file, but you are not obligated to do |
| 38 | so. If you do not wish to provide this exception without modification, |
| 39 | you must delete this exception statement from your version and license |
| 40 | this file solely under the GPL without exception. |
| 41 | |
| 42 | Red Hat elfutils is an included package of the Open Invention Network. |
| 43 | An included package of the Open Invention Network is a package for which |
| 44 | Open Invention Network licensees cross-license their patents. No patent |
| 45 | license is granted, either expressly or impliedly, by designation as an |
| 46 | included package. Should you wish to participate in the Open Invention |
| 47 | Network licensing program, please visit www.openinventionnetwork.com |
| 48 | <http://www.openinventionnetwork.com>. */ |
| 49 | |
| 50 | #ifdef HAVE_CONFIG_H |
| 51 | # include <config.h> |
| 52 | #endif |
| 53 | |
| 54 | #include <stdlib.h> |
| 55 | #include <string.h> |
| 56 | #include <assert.h> |
| 57 | |
| 58 | #include "libdwP.h" |
| 59 | #include "cfi.h" |
| 60 | #include "encoded-value.h" |
| 61 | #include <dwarf.h> |
| 62 | |
| 63 | |
| 64 | static Dwarf_CFI * |
| 65 | allocate_cfi (Elf *elf, GElf_Addr vaddr) |
| 66 | { |
| 67 | Dwarf_CFI *cfi = calloc (1, sizeof *cfi); |
| 68 | if (cfi == NULL) |
| 69 | { |
| 70 | __libdw_seterrno (DWARF_E_NOMEM); |
| 71 | return NULL; |
| 72 | } |
| 73 | |
| 74 | cfi->e_ident = (unsigned char *) elf_getident (elf, NULL); |
| 75 | if (cfi->e_ident == NULL) |
| 76 | { |
| 77 | free (cfi); |
| 78 | __libdw_seterrno (DWARF_E_GETEHDR_ERROR); |
| 79 | return NULL; |
| 80 | } |
| 81 | |
| 82 | if ((BYTE_ORDER == LITTLE_ENDIAN && cfi->e_ident[EI_DATA] == ELFDATA2MSB) |
| 83 | || (BYTE_ORDER == BIG_ENDIAN && cfi->e_ident[EI_DATA] == ELFDATA2LSB)) |
| 84 | cfi->other_byte_order = true; |
| 85 | |
| 86 | cfi->frame_vaddr = vaddr; |
| 87 | cfi->textrel = 0; /* XXX ? */ |
| 88 | cfi->datarel = 0; /* XXX ? */ |
| 89 | |
| 90 | return cfi; |
| 91 | } |
| 92 | |
| 93 | static const uint8_t * |
| 94 | parse_eh_frame_hdr (const uint8_t *hdr, size_t hdr_size, GElf_Addr hdr_vaddr, |
| 95 | const GElf_Ehdr *ehdr, GElf_Addr *eh_frame_vaddr, |
| 96 | size_t *table_entries, uint8_t *table_encoding) |
| 97 | { |
| 98 | const uint8_t *h = hdr; |
| 99 | |
| 100 | if (*h++ != 1) /* version */ |
| 101 | return (void *) -1l; |
| 102 | |
| 103 | uint8_t eh_frame_ptr_encoding = *h++; |
| 104 | uint8_t fde_count_encoding = *h++; |
| 105 | uint8_t fde_table_encoding = *h++; |
| 106 | |
| 107 | if (eh_frame_ptr_encoding == DW_EH_PE_omit) |
| 108 | return (void *) -1l; |
| 109 | |
| 110 | /* Dummy used by read_encoded_value. */ |
| 111 | Elf_Data_Scn dummy_cfi_hdr_data = |
| 112 | { |
| 113 | .d = { .d_buf = (void *) hdr, .d_size = hdr_size } |
| 114 | }; |
| 115 | Dwarf_CFI dummy_cfi = |
| 116 | { |
| 117 | .e_ident = ehdr->e_ident, |
| 118 | .datarel = hdr_vaddr, |
| 119 | .frame_vaddr = hdr_vaddr, |
| 120 | .data = &dummy_cfi_hdr_data, |
| 121 | }; |
| 122 | |
| 123 | if (unlikely (read_encoded_value (&dummy_cfi, eh_frame_ptr_encoding, &h, |
| 124 | eh_frame_vaddr))) |
| 125 | return (void *) -1l; |
| 126 | |
| 127 | if (fde_count_encoding != DW_EH_PE_omit) |
| 128 | { |
| 129 | Dwarf_Word fde_count; |
| 130 | if (unlikely (read_encoded_value (&dummy_cfi, fde_count_encoding, &h, |
| 131 | &fde_count))) |
| 132 | return (void *) -1l; |
| 133 | if (fde_count != 0 && (size_t) fde_count == fde_count |
| 134 | && fde_table_encoding != DW_EH_PE_omit |
| 135 | && (fde_table_encoding &~ DW_EH_PE_signed) != DW_EH_PE_uleb128) |
| 136 | { |
| 137 | *table_entries = fde_count; |
| 138 | *table_encoding = fde_table_encoding; |
| 139 | return h; |
| 140 | } |
| 141 | } |
| 142 | |
| 143 | return NULL; |
| 144 | } |
| 145 | |
| 146 | static Dwarf_CFI * |
| 147 | getcfi_gnu_eh_frame (Elf *elf, const GElf_Ehdr *ehdr, const GElf_Phdr *phdr) |
| 148 | { |
| 149 | if (unlikely (phdr->p_filesz < 4)) |
| 150 | goto invalid; |
| 151 | |
| 152 | Elf_Data *data = elf_getdata_rawchunk (elf, phdr->p_offset, phdr->p_filesz, |
| 153 | ELF_T_BYTE); |
| 154 | if (data == NULL) |
| 155 | { |
| 156 | invalid_hdr: |
| 157 | invalid: |
| 158 | /* XXX might be read error or corrupt phdr */ |
| 159 | __libdw_seterrno (DWARF_E_INVALID_CFI); |
| 160 | return NULL; |
| 161 | } |
| 162 | |
| 163 | Dwarf_Addr eh_frame_ptr; |
| 164 | size_t search_table_entries; |
| 165 | uint8_t search_table_encoding; |
| 166 | const uint8_t *search_table = parse_eh_frame_hdr (data->d_buf, phdr->p_filesz, |
| 167 | phdr->p_vaddr, ehdr, |
| 168 | &eh_frame_ptr, |
| 169 | &search_table_entries, |
| 170 | &search_table_encoding); |
| 171 | if (search_table == (void *) -1l) |
| 172 | goto invalid_hdr; |
| 173 | |
| 174 | Dwarf_Off eh_frame_offset = eh_frame_ptr - phdr->p_vaddr + phdr->p_offset; |
| 175 | Dwarf_Word eh_frame_size = 0; |
| 176 | |
| 177 | /* XXX we have no way without section headers to know the size |
| 178 | of the .eh_frame data. Calculate the largest it might possibly be. |
| 179 | This won't be wasteful if the file is already mmap'd, but if it isn't |
| 180 | it might be quite excessive. */ |
| 181 | size_t filesize; |
| 182 | if (elf_rawfile (elf, &filesize) != NULL) |
| 183 | eh_frame_size = filesize - eh_frame_offset; |
| 184 | |
| 185 | data = elf_getdata_rawchunk (elf, eh_frame_offset, eh_frame_size, ELF_T_BYTE); |
| 186 | if (data == NULL) |
| 187 | { |
| 188 | __libdw_seterrno (DWARF_E_INVALID_ELF); /* XXX might be read error */ |
| 189 | return NULL; |
| 190 | } |
| 191 | Dwarf_CFI *cfi = allocate_cfi (elf, eh_frame_ptr); |
| 192 | if (cfi != NULL) |
| 193 | { |
| 194 | cfi->data = (Elf_Data_Scn *) data; |
| 195 | |
| 196 | if (search_table != NULL) |
| 197 | { |
| 198 | cfi->search_table = search_table; |
| 199 | cfi->search_table_vaddr = phdr->p_vaddr; |
| 200 | cfi->search_table_encoding = search_table_encoding; |
| 201 | cfi->search_table_entries = search_table_entries; |
| 202 | } |
| 203 | } |
| 204 | return cfi; |
| 205 | } |
| 206 | |
| 207 | /* Search the phdrs for PT_GNU_EH_FRAME. */ |
| 208 | static Dwarf_CFI * |
| 209 | getcfi_phdr (Elf *elf, const GElf_Ehdr *ehdr) |
| 210 | { |
Roland McGrath | f95760a | 2010-01-07 20:24:34 -0800 | [diff] [blame] | 211 | size_t phnum; |
| 212 | if (unlikely (elf_getphdrnum (elf, &phnum) != 0)) |
| 213 | return NULL; |
Roland McGrath | 3c84db3 | 2009-06-24 17:41:40 -0700 | [diff] [blame] | 214 | |
Roland McGrath | f95760a | 2010-01-07 20:24:34 -0800 | [diff] [blame] | 215 | for (size_t i = 0; i < phnum; ++i) |
Roland McGrath | 3c84db3 | 2009-06-24 17:41:40 -0700 | [diff] [blame] | 216 | { |
| 217 | GElf_Phdr phdr_mem; |
| 218 | GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem); |
| 219 | if (unlikely (phdr == NULL)) |
| 220 | return NULL; |
| 221 | if (phdr->p_type == PT_GNU_EH_FRAME) |
| 222 | return getcfi_gnu_eh_frame (elf, ehdr, phdr); |
| 223 | } |
| 224 | |
| 225 | __libdw_seterrno (DWARF_E_NO_DWARF); |
| 226 | return NULL; |
| 227 | } |
| 228 | |
| 229 | static Dwarf_CFI * |
| 230 | getcfi_scn_eh_frame (Elf *elf, const GElf_Ehdr *ehdr, |
| 231 | Elf_Scn *scn, GElf_Shdr *shdr, |
| 232 | Elf_Scn *hdr_scn, GElf_Addr hdr_vaddr) |
| 233 | { |
| 234 | Elf_Data *data = elf_rawdata (scn, NULL); |
| 235 | if (data == NULL) |
| 236 | { |
| 237 | __libdw_seterrno (DWARF_E_INVALID_ELF); |
| 238 | return NULL; |
| 239 | } |
| 240 | Dwarf_CFI *cfi = allocate_cfi (elf, shdr->sh_addr); |
| 241 | if (cfi != NULL) |
| 242 | { |
| 243 | cfi->data = (Elf_Data_Scn *) data; |
| 244 | if (hdr_scn != NULL) |
| 245 | { |
| 246 | Elf_Data *hdr_data = elf_rawdata (hdr_scn, NULL); |
| 247 | if (hdr_data != NULL) |
| 248 | { |
| 249 | GElf_Addr eh_frame_vaddr; |
| 250 | cfi->search_table_vaddr = hdr_vaddr; |
| 251 | cfi->search_table |
| 252 | = parse_eh_frame_hdr (hdr_data->d_buf, hdr_data->d_size, |
| 253 | hdr_vaddr, ehdr, &eh_frame_vaddr, |
| 254 | &cfi->search_table_entries, |
| 255 | &cfi->search_table_encoding); |
| 256 | if (cfi->search_table == (void *) -1l) |
| 257 | { |
| 258 | free (cfi); |
| 259 | /* XXX might be read error or corrupt phdr */ |
| 260 | __libdw_seterrno (DWARF_E_INVALID_CFI); |
| 261 | return NULL; |
| 262 | } |
| 263 | |
| 264 | /* Sanity check. */ |
| 265 | if (unlikely (eh_frame_vaddr != shdr->sh_addr)) |
| 266 | cfi->search_table = NULL; |
| 267 | } |
| 268 | } |
| 269 | } |
| 270 | return cfi; |
| 271 | } |
| 272 | |
| 273 | /* Search for the sections named ".eh_frame" and ".eh_frame_hdr". */ |
| 274 | static Dwarf_CFI * |
| 275 | getcfi_shdr (Elf *elf, const GElf_Ehdr *ehdr) |
| 276 | { |
| 277 | size_t shstrndx; |
| 278 | if (elf_getshdrstrndx (elf, &shstrndx) != 0) |
| 279 | { |
| 280 | __libdw_seterrno (DWARF_E_GETEHDR_ERROR); |
| 281 | return NULL; |
| 282 | } |
| 283 | |
| 284 | if (shstrndx != 0) |
| 285 | { |
| 286 | Elf_Scn *hdr_scn = NULL; |
| 287 | GElf_Addr hdr_vaddr = 0; |
| 288 | Elf_Scn *scn = NULL; |
| 289 | while ((scn = elf_nextscn (elf, scn)) != NULL) |
| 290 | { |
| 291 | GElf_Shdr shdr_mem; |
| 292 | GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem); |
| 293 | if (shdr == NULL) |
| 294 | continue; |
| 295 | const char *name = elf_strptr (elf, shstrndx, shdr->sh_name); |
| 296 | if (name == NULL) |
| 297 | continue; |
| 298 | if (!strcmp (name, ".eh_frame_hdr")) |
| 299 | { |
| 300 | hdr_scn = scn; |
| 301 | hdr_vaddr = shdr->sh_addr; |
| 302 | } |
| 303 | else if (!strcmp (name, ".eh_frame")) |
| 304 | return getcfi_scn_eh_frame (elf, ehdr, scn, shdr, |
| 305 | hdr_scn, hdr_vaddr); |
| 306 | } |
| 307 | } |
| 308 | |
| 309 | return (void *) -1l; |
| 310 | } |
| 311 | |
| 312 | Dwarf_CFI * |
| 313 | dwarf_getcfi_elf (elf) |
| 314 | Elf *elf; |
| 315 | { |
| 316 | if (elf_kind (elf) != ELF_K_ELF) |
| 317 | { |
| 318 | __libdw_seterrno (DWARF_E_NOELF); |
| 319 | return NULL; |
| 320 | } |
| 321 | |
| 322 | GElf_Ehdr ehdr_mem; |
| 323 | GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem); |
| 324 | if (unlikely (ehdr == NULL)) |
| 325 | { |
| 326 | __libdw_seterrno (DWARF_E_INVALID_ELF); |
| 327 | return NULL; |
| 328 | } |
| 329 | |
| 330 | Dwarf_CFI *result = getcfi_shdr (elf, ehdr); |
| 331 | if (result == (void *) -1l) |
| 332 | result = getcfi_phdr (elf, ehdr); |
| 333 | |
| 334 | return result; |
| 335 | } |
| 336 | INTDEF (dwarf_getcfi_elf) |