1 /* libunwind - a platform-independent unwind library 2 Copyright (c) 2003-2005 Hewlett-Packard Development Company, L.P. 3 Contributed by David Mosberger-Tang <davidm (at) hpl.hp.com> 4 5 This file is part of libunwind. 6 7 Permission is hereby granted, free of charge, to any person obtaining 8 a copy of this software and associated documentation files (the 9 "Software"), to deal in the Software without restriction, including 10 without limitation the rights to use, copy, modify, merge, publish, 11 distribute, sublicense, and/or sell copies of the Software, and to 12 permit persons to whom the Software is furnished to do so, subject to 13 the following conditions: 14 15 The above copyright notice and this permission notice shall be 16 included in all copies or substantial portions of the Software. 17 18 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 19 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 20 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 21 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 22 LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 24 WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ 25 26 #include "dwarf_i.h" 27 28 static inline int 29 is_cie_id (unw_word_t val, int is_debug_frame) 30 { 31 /* The CIE ID is normally 0xffffffff (for 32-bit ELF) or 32 0xffffffffffffffff (for 64-bit ELF). However, .eh_frame 33 uses 0. */ 34 if (is_debug_frame) 35 /* ANDROID support update. */ 36 return (val == (uint32_t) -1 || val == (unw_word_t) (uint64_t) -1); 37 /* End of ANDROID update. */ 38 else 39 return (val == 0); 40 } 41 42 /* Note: we don't need to keep track of more than the first four 43 characters of the augmentation string, because we (a) ignore any 44 augmentation string contents once we find an unrecognized character 45 and (b) those characters that we do recognize, can't be 46 repeated. */ 47 static inline int 48 parse_cie (unw_addr_space_t as, unw_accessors_t *a, unw_word_t addr, 49 const unw_proc_info_t *pi, struct dwarf_cie_info *dci, 50 unw_word_t base, void *arg) 51 { 52 uint8_t version, ch, augstr[5], fde_encoding, handler_encoding; 53 unw_word_t len, cie_end_addr, aug_size; 54 uint32_t u32val; 55 uint64_t u64val; 56 size_t i; 57 int ret; 58 # define STR2(x) #x 59 # define STR(x) STR2(x) 60 61 /* Pick appropriate default for FDE-encoding. DWARF spec says 62 start-IP (initial_location) and the code-size (address_range) are 63 "address-unit sized constants". The `R' augmentation can be used 64 to override this, but by default, we pick an address-sized unit 65 for fde_encoding. */ 66 switch (dwarf_addr_size (as)) 67 { 68 case 4: fde_encoding = DW_EH_PE_udata4; break; 69 case 8: fde_encoding = DW_EH_PE_udata8; break; 70 default: fde_encoding = DW_EH_PE_omit; break; 71 } 72 73 dci->lsda_encoding = DW_EH_PE_omit; 74 dci->handler = 0; 75 76 if ((ret = dwarf_readu32 (as, a, &addr, &u32val, arg)) < 0) 77 return ret; 78 79 if (u32val != 0xffffffff) 80 { 81 /* the CIE is in the 32-bit DWARF format */ 82 uint32_t cie_id; 83 /* DWARF says CIE id should be 0xffffffff, but in .eh_frame, it's 0 */ 84 const uint32_t expected_id = (base) ? 0xffffffff : 0; 85 86 len = u32val; 87 cie_end_addr = addr + len; 88 if ((ret = dwarf_readu32 (as, a, &addr, &cie_id, arg)) < 0) 89 return ret; 90 if (cie_id != expected_id) 91 { 92 Debug (1, "Unexpected CIE id %x\n", cie_id); 93 return -UNW_EINVAL; 94 } 95 } 96 else 97 { 98 /* the CIE is in the 64-bit DWARF format */ 99 uint64_t cie_id; 100 /* DWARF says CIE id should be 0xffffffffffffffff, but in 101 .eh_frame, it's 0 */ 102 const uint64_t expected_id = (base) ? 0xffffffffffffffffull : 0; 103 104 if ((ret = dwarf_readu64 (as, a, &addr, &u64val, arg)) < 0) 105 return ret; 106 len = u64val; 107 cie_end_addr = addr + len; 108 if ((ret = dwarf_readu64 (as, a, &addr, &cie_id, arg)) < 0) 109 return ret; 110 if (cie_id != expected_id) 111 { 112 Debug (1, "Unexpected CIE id %llx\n", (long long) cie_id); 113 return -UNW_EINVAL; 114 } 115 } 116 dci->cie_instr_end = cie_end_addr; 117 118 if ((ret = dwarf_readu8 (as, a, &addr, &version, arg)) < 0) 119 return ret; 120 121 if (version != 1 && version != 3 && version != 4) 122 { 123 Debug (1, "Got CIE version %u, expected version 1, 3 or 4\n", version); 124 return -UNW_EBADVERSION; 125 } 126 127 /* read and parse the augmentation string: */ 128 memset (augstr, 0, sizeof (augstr)); 129 for (i = 0;;) 130 { 131 if ((ret = dwarf_readu8 (as, a, &addr, &ch, arg)) < 0) 132 return ret; 133 134 if (!ch) 135 break; /* end of augmentation string */ 136 137 if (i < sizeof (augstr) - 1) 138 augstr[i++] = ch; 139 } 140 141 if (version == 4) { 142 uint8_t address_size; 143 if ((ret = dwarf_readu8(as, a, &addr, &address_size, arg)) < 0) { 144 return ret; 145 } 146 if (address_size != sizeof(unw_word_t)) { 147 return -UNW_EBADVERSION; 148 } 149 uint8_t segment_size; 150 if ((ret = dwarf_readu8(as, a, &addr, &segment_size, arg)) < 0) { 151 return ret; 152 } 153 // We don't support non-zero segment size. 154 if (segment_size != 0) { 155 return -UNW_EBADVERSION; 156 } 157 } 158 if ((ret = dwarf_read_uleb128 (as, a, &addr, &dci->code_align, arg)) < 0 159 || (ret = dwarf_read_sleb128 (as, a, &addr, &dci->data_align, arg)) < 0) 160 return ret; 161 162 /* Read the return-address column either as a u8 or as a uleb128. */ 163 if (version == 1) 164 { 165 if ((ret = dwarf_readu8 (as, a, &addr, &ch, arg)) < 0) 166 return ret; 167 dci->ret_addr_column = ch; 168 } 169 else if ((ret = dwarf_read_uleb128 (as, a, &addr, &dci->ret_addr_column, 170 arg)) < 0) 171 return ret; 172 173 i = 0; 174 if (augstr[0] == 'z') 175 { 176 dci->sized_augmentation = 1; 177 if ((ret = dwarf_read_uleb128 (as, a, &addr, &aug_size, arg)) < 0) 178 return ret; 179 i++; 180 } 181 182 for (; i < sizeof (augstr) && augstr[i]; ++i) 183 switch (augstr[i]) 184 { 185 case 'L': 186 /* read the LSDA pointer-encoding format. */ 187 if ((ret = dwarf_readu8 (as, a, &addr, &ch, arg)) < 0) 188 return ret; 189 dci->lsda_encoding = ch; 190 break; 191 192 case 'R': 193 /* read the FDE pointer-encoding format. */ 194 if ((ret = dwarf_readu8 (as, a, &addr, &fde_encoding, arg)) < 0) 195 return ret; 196 break; 197 198 case 'P': 199 /* read the personality-routine pointer-encoding format. */ 200 if ((ret = dwarf_readu8 (as, a, &addr, &handler_encoding, arg)) < 0) 201 return ret; 202 if ((ret = dwarf_read_encoded_pointer (as, a, &addr, handler_encoding, 203 pi, &dci->handler, arg)) < 0) 204 return ret; 205 break; 206 207 case 'S': 208 /* This is a signal frame. */ 209 dci->signal_frame = 1; 210 211 /* Temporarily set it to one so dwarf_parse_fde() knows that 212 it should fetch the actual ABI/TAG pair from the FDE. */ 213 dci->have_abi_marker = 1; 214 break; 215 216 default: 217 Debug (1, "Unexpected augmentation string `%s'\n", augstr); 218 if (dci->sized_augmentation) 219 /* If we have the size of the augmentation body, we can skip 220 over the parts that we don't understand, so we're OK. */ 221 goto done; 222 else 223 return -UNW_EINVAL; 224 } 225 done: 226 dci->fde_encoding = fde_encoding; 227 dci->cie_instr_start = addr; 228 Debug (15, "CIE parsed OK, augmentation = \"%s\", handler=0x%lx\n", 229 augstr, (long) dci->handler); 230 return 0; 231 } 232 233 /* Extract proc-info from the FDE starting at adress ADDR. 234 235 Pass BASE as zero for eh_frame behaviour, or a pointer to 236 debug_frame base for debug_frame behaviour. */ 237 238 HIDDEN int 239 dwarf_extract_proc_info_from_fde (unw_addr_space_t as, unw_accessors_t *a, 240 unw_word_t *addrp, unw_proc_info_t *pi, 241 int need_unwind_info, unw_word_t base, 242 void *arg) 243 { 244 unw_word_t fde_end_addr, cie_addr, cie_offset_addr, aug_end_addr = 0; 245 unw_word_t start_ip, ip_range, aug_size, addr = *addrp; 246 int ret, ip_range_encoding; 247 struct dwarf_cie_info dci; 248 uint64_t u64val; 249 uint32_t u32val; 250 251 Debug (12, "FDE @ 0x%lx\n", (long) addr); 252 253 memset (&dci, 0, sizeof (dci)); 254 255 if ((ret = dwarf_readu32 (as, a, &addr, &u32val, arg)) < 0) 256 return ret; 257 258 if (u32val != 0xffffffff) 259 { 260 int32_t cie_offset; 261 262 /* In some configurations, an FDE with a 0 length indicates the 263 end of the FDE-table. */ 264 if (u32val == 0) 265 return -UNW_ENOINFO; 266 267 /* the FDE is in the 32-bit DWARF format */ 268 269 *addrp = fde_end_addr = addr + u32val; 270 cie_offset_addr = addr; 271 272 if ((ret = dwarf_reads32 (as, a, &addr, &cie_offset, arg)) < 0) 273 return ret; 274 275 if (is_cie_id (cie_offset, base != 0)) 276 /* ignore CIEs (happens during linear searches) */ 277 return 0; 278 279 if (base != 0) 280 cie_addr = base + cie_offset; 281 else 282 /* DWARF says that the CIE_pointer in the FDE is a 283 .debug_frame-relative offset, but the GCC-generated .eh_frame 284 sections instead store a "pcrelative" offset, which is just 285 as fine as it's self-contained. */ 286 cie_addr = cie_offset_addr - cie_offset; 287 } 288 else 289 { 290 int64_t cie_offset; 291 292 /* the FDE is in the 64-bit DWARF format */ 293 294 if ((ret = dwarf_readu64 (as, a, &addr, &u64val, arg)) < 0) 295 return ret; 296 297 *addrp = fde_end_addr = addr + u64val; 298 cie_offset_addr = addr; 299 300 if ((ret = dwarf_reads64 (as, a, &addr, &cie_offset, arg)) < 0) 301 return ret; 302 303 if (is_cie_id (cie_offset, base != 0)) 304 /* ignore CIEs (happens during linear searches) */ 305 return 0; 306 307 if (base != 0) 308 cie_addr = base + cie_offset; 309 else 310 /* DWARF says that the CIE_pointer in the FDE is a 311 .debug_frame-relative offset, but the GCC-generated .eh_frame 312 sections instead store a "pcrelative" offset, which is just 313 as fine as it's self-contained. */ 314 cie_addr = (unw_word_t) ((uint64_t) cie_offset_addr - cie_offset); 315 } 316 317 Debug (15, "looking for CIE at address %lx\n", (long) cie_addr); 318 319 if ((ret = parse_cie (as, a, cie_addr, pi, &dci, base, arg)) < 0) 320 return ret; 321 322 /* IP-range has same encoding as FDE pointers, except that it's 323 always an absolute value: */ 324 ip_range_encoding = dci.fde_encoding & DW_EH_PE_FORMAT_MASK; 325 326 if ((ret = dwarf_read_encoded_pointer (as, a, &addr, dci.fde_encoding, 327 pi, &start_ip, arg)) < 0 328 || (ret = dwarf_read_encoded_pointer (as, a, &addr, ip_range_encoding, 329 pi, &ip_range, arg)) < 0) 330 return ret; 331 pi->start_ip = start_ip; 332 pi->end_ip = start_ip + ip_range; 333 pi->handler = dci.handler; 334 335 if (dci.sized_augmentation) 336 { 337 if ((ret = dwarf_read_uleb128 (as, a, &addr, &aug_size, arg)) < 0) 338 return ret; 339 aug_end_addr = addr + aug_size; 340 } 341 342 if ((ret = dwarf_read_encoded_pointer (as, a, &addr, dci.lsda_encoding, 343 pi, &pi->lsda, arg)) < 0) 344 return ret; 345 346 Debug (15, "FDE covers IP 0x%lx-0x%lx, LSDA=0x%lx\n", 347 (long) pi->start_ip, (long) pi->end_ip, (long) pi->lsda); 348 349 if (need_unwind_info) 350 { 351 pi->format = UNW_INFO_FORMAT_TABLE; 352 pi->unwind_info_size = sizeof (dci); 353 pi->unwind_info = mempool_alloc (&dwarf_cie_info_pool); 354 if (!pi->unwind_info) 355 return -UNW_ENOMEM; 356 357 if (dci.have_abi_marker) 358 { 359 if ((ret = dwarf_readu16 (as, a, &addr, &dci.abi, arg)) < 0 360 || (ret = dwarf_readu16 (as, a, &addr, &dci.tag, arg)) < 0) 361 return ret; 362 Debug (13, "Found ABI marker = (abi=%u, tag=%u)\n", 363 dci.abi, dci.tag); 364 } 365 366 if (dci.sized_augmentation) 367 dci.fde_instr_start = aug_end_addr; 368 else 369 dci.fde_instr_start = addr; 370 dci.fde_instr_end = fde_end_addr; 371 372 memcpy (pi->unwind_info, &dci, sizeof (dci)); 373 } 374 return 0; 375 } 376
