1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,502 @@
1.4 +
1.5 +/* libunwind - a platform-independent unwind library
1.6 + Copyright 2011 Linaro Limited
1.7 +
1.8 +This file is part of libunwind.
1.9 +
1.10 +Permission is hereby granted, free of charge, to any person obtaining
1.11 +a copy of this software and associated documentation files (the
1.12 +"Software"), to deal in the Software without restriction, including
1.13 +without limitation the rights to use, copy, modify, merge, publish,
1.14 +distribute, sublicense, and/or sell copies of the Software, and to
1.15 +permit persons to whom the Software is furnished to do so, subject to
1.16 +the following conditions:
1.17 +
1.18 +The above copyright notice and this permission notice shall be
1.19 +included in all copies or substantial portions of the Software.
1.20 +
1.21 +THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
1.22 +EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
1.23 +MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
1.24 +NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
1.25 +LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
1.26 +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
1.27 +WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */
1.28 +
1.29 +// Copyright (c) 2010 Google Inc.
1.30 +// All rights reserved.
1.31 +//
1.32 +// Redistribution and use in source and binary forms, with or without
1.33 +// modification, are permitted provided that the following conditions are
1.34 +// met:
1.35 +//
1.36 +// * Redistributions of source code must retain the above copyright
1.37 +// notice, this list of conditions and the following disclaimer.
1.38 +// * Redistributions in binary form must reproduce the above
1.39 +// copyright notice, this list of conditions and the following disclaimer
1.40 +// in the documentation and/or other materials provided with the
1.41 +// distribution.
1.42 +// * Neither the name of Google Inc. nor the names of its
1.43 +// contributors may be used to endorse or promote products derived from
1.44 +// this software without specific prior written permission.
1.45 +//
1.46 +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
1.47 +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
1.48 +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
1.49 +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
1.50 +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
1.51 +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
1.52 +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
1.53 +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
1.54 +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
1.55 +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
1.56 +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.57 +
1.58 +
1.59 +// Derived from libunwind, with extensive modifications.
1.60 +
1.61 +
1.62 +#include "common/arm_ex_reader.h"
1.63 +#include "common/logging.h"
1.64 +
1.65 +#include <assert.h>
1.66 +
1.67 +// This file, in conjunction with arm_ex_to_module.cc, translates
1.68 +// EXIDX unwind information into the same format that Breakpad uses
1.69 +// for CFI information. Hence Breakpad's CFI unwinding abilities
1.70 +// also become usable for EXIDX.
1.71 +//
1.72 +// See: "Exception Handling ABI for the ARM Architecture", ARM IHI 0038A
1.73 +// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
1.74 +
1.75 +// EXIDX data is presented in two parts:
1.76 +//
1.77 +// * an index table. This contains two words per routine,
1.78 +// the first of which identifies the routine, and the second
1.79 +// of which is a reference to the unwind bytecode. If the
1.80 +// bytecode is very compact -- 3 bytes or less -- it can be
1.81 +// stored directly in the second word.
1.82 +//
1.83 +// * an area containing the unwind bytecodes.
1.84 +
1.85 +// General flow is: ExceptionTableInfo::Start iterates over all
1.86 +// of the index table entries (pairs). For each entry, it:
1.87 +//
1.88 +// * calls ExceptionTableInfo::ExtabEntryExtract to copy the bytecode
1.89 +// out into an intermediate buffer.
1.90 +
1.91 +// * uses ExceptionTableInfo::ExtabEntryDecode to parse the intermediate
1.92 +// buffer. Each bytecode instruction is bundled into a
1.93 +// arm_ex_to_module::extab_data structure, and handed to ..
1.94 +//
1.95 +// * .. ARMExToModule::ImproveStackFrame, which in turn hands it to
1.96 +// ARMExToModule::TranslateCmd, and that generates the pseudo-CFI
1.97 +// records that Breakpad stores.
1.98 +
1.99 +#define ARM_EXIDX_CANT_UNWIND 0x00000001
1.100 +#define ARM_EXIDX_COMPACT 0x80000000
1.101 +#define ARM_EXTBL_OP_FINISH 0xb0
1.102 +#define ARM_EXIDX_TABLE_LIMIT (255*4)
1.103 +
1.104 +namespace arm_ex_reader {
1.105 +
1.106 +using arm_ex_to_module::ARM_EXIDX_CMD_FINISH;
1.107 +using arm_ex_to_module::ARM_EXIDX_CMD_SUB_FROM_VSP;
1.108 +using arm_ex_to_module::ARM_EXIDX_CMD_ADD_TO_VSP;
1.109 +using arm_ex_to_module::ARM_EXIDX_CMD_REG_POP;
1.110 +using arm_ex_to_module::ARM_EXIDX_CMD_REG_TO_SP;
1.111 +using arm_ex_to_module::ARM_EXIDX_CMD_VFP_POP;
1.112 +using arm_ex_to_module::ARM_EXIDX_CMD_WREG_POP;
1.113 +using arm_ex_to_module::ARM_EXIDX_CMD_WCGR_POP;
1.114 +using arm_ex_to_module::ARM_EXIDX_CMD_RESERVED;
1.115 +using arm_ex_to_module::ARM_EXIDX_CMD_REFUSED;
1.116 +using arm_ex_to_module::exidx_entry;
1.117 +using arm_ex_to_module::ARM_EXIDX_VFP_SHIFT_16;
1.118 +using arm_ex_to_module::ARM_EXIDX_VFP_FSTMD;
1.119 +using google_breakpad::MemoryRange;
1.120 +
1.121 +
1.122 +static void* Prel31ToAddr(const void* addr)
1.123 +{
1.124 + uint32_t offset32 = *reinterpret_cast<const uint32_t*>(addr);
1.125 + // sign extend offset32[30:0] to 64 bits -- copy bit 30 to positions
1.126 + // 63:31 inclusive.
1.127 + uint64_t offset64 = offset32;
1.128 + if (offset64 & (1ULL << 30))
1.129 + offset64 |= 0xFFFFFFFF80000000ULL;
1.130 + else
1.131 + offset64 &= 0x000000007FFFFFFFULL;
1.132 + return ((char*)addr) + (uintptr_t)offset64;
1.133 +}
1.134 +
1.135 +
1.136 +// Extract unwind bytecode for the function denoted by |entry| into |buf|,
1.137 +// and return the number of bytes of |buf| written, along with a code
1.138 +// indicating the outcome.
1.139 +
1.140 +ExceptionTableInfo::ExExtractResult
1.141 +ExceptionTableInfo::ExtabEntryExtract(const struct exidx_entry* entry,
1.142 + uint8_t* buf, size_t buf_size,
1.143 + /*OUT*/size_t* buf_used)
1.144 +{
1.145 + MemoryRange mr_out(buf, buf_size);
1.146 +
1.147 + *buf_used = 0;
1.148 +
1.149 +# define PUT_BUF_U8(_byte) \
1.150 + do { if (!mr_out.Covers(*buf_used, 1)) return ExOutBufOverflow; \
1.151 + buf[(*buf_used)++] = (_byte); } while (0)
1.152 +
1.153 +# define GET_EX_U32(_lval, _addr, _sec_mr) \
1.154 + do { if (!(_sec_mr).Covers(reinterpret_cast<const uint8_t*>(_addr) \
1.155 + - (_sec_mr).data(), 4)) \
1.156 + return ExInBufOverflow; \
1.157 + (_lval) = *(reinterpret_cast<const uint32_t*>(_addr)); } while (0)
1.158 +
1.159 +# define GET_EXIDX_U32(_lval, _addr) \
1.160 + GET_EX_U32(_lval, _addr, mr_exidx_)
1.161 +# define GET_EXTAB_U32(_lval, _addr) \
1.162 + GET_EX_U32(_lval, _addr, mr_extab_)
1.163 +
1.164 + uint32_t data;
1.165 + GET_EXIDX_U32(data, &entry->data);
1.166 +
1.167 + // A function can be marked CANT_UNWIND if (eg) it is known to be
1.168 + // at the bottom of the stack.
1.169 + if (data == ARM_EXIDX_CANT_UNWIND)
1.170 + return ExCantUnwind;
1.171 +
1.172 + uint32_t pers; // personality number
1.173 + uint32_t extra; // number of extra data words required
1.174 + uint32_t extra_allowed; // number of extra data words allowed
1.175 + uint32_t* extbl_data; // the handler entry, if not inlined
1.176 +
1.177 + if (data & ARM_EXIDX_COMPACT) {
1.178 + // The handler table entry has been inlined into the index table entry.
1.179 + // In this case it can only be an ARM-defined compact model, since
1.180 + // bit 31 is 1. Only personalities 0, 1 and 2 are defined for the
1.181 + // ARM compact model, but 1 and 2 are "Long format" and may require
1.182 + // extra data words. Hence the allowable personalities here are:
1.183 + // personality 0, in which case 'extra' has no meaning
1.184 + // personality 1, with zero extra words
1.185 + // personality 2, with zero extra words
1.186 + extbl_data = NULL;
1.187 + pers = (data >> 24) & 0x0F;
1.188 + extra = (data >> 16) & 0xFF;
1.189 + extra_allowed = 0;
1.190 + }
1.191 + else {
1.192 + // The index table entry is a pointer to the handler entry. Note
1.193 + // that Prel31ToAddr will read the given address, but we already
1.194 + // range-checked above.
1.195 + extbl_data = reinterpret_cast<uint32_t*>(Prel31ToAddr(&entry->data));
1.196 + GET_EXTAB_U32(data, extbl_data);
1.197 + if (!(data & ARM_EXIDX_COMPACT)) {
1.198 + // This denotes a "generic model" handler. That will involve
1.199 + // executing arbitary machine code, which is something we
1.200 + // can't represent here; hence reject it.
1.201 + return ExCantRepresent;
1.202 + }
1.203 + // So we have a compact model representation. Again, 3 possible
1.204 + // personalities, but this time up to 255 allowable extra words.
1.205 + pers = (data >> 24) & 0x0F;
1.206 + extra = (data >> 16) & 0xFF;
1.207 + extra_allowed = 255;
1.208 + extbl_data++;
1.209 + }
1.210 +
1.211 + // Now look at the the handler table entry. The first word is
1.212 + // |data| and subsequent words start at |*extbl_data|. The number
1.213 + // of extra words to use is |extra|, provided that the personality
1.214 + // allows extra words. Even if it does, none may be available --
1.215 + // extra_allowed is the maximum number of extra words allowed. */
1.216 + if (pers == 0) {
1.217 + // "Su16" in the documentation -- 3 unwinding insn bytes
1.218 + // |extra| has no meaning here; instead that byte is an unwind-info byte
1.219 + PUT_BUF_U8(data >> 16);
1.220 + PUT_BUF_U8(data >> 8);
1.221 + PUT_BUF_U8(data);
1.222 + }
1.223 + else if ((pers == 1 || pers == 2) && extra <= extra_allowed) {
1.224 + // "Lu16" or "Lu32" respectively -- 2 unwinding insn bytes,
1.225 + // and up to 255 extra words.
1.226 + PUT_BUF_U8(data >> 8);
1.227 + PUT_BUF_U8(data);
1.228 + for (uint32_t j = 0; j < extra; j++) {
1.229 + GET_EXTAB_U32(data, extbl_data);
1.230 + extbl_data++;
1.231 + PUT_BUF_U8(data >> 24);
1.232 + PUT_BUF_U8(data >> 16);
1.233 + PUT_BUF_U8(data >> 8);
1.234 + PUT_BUF_U8(data >> 0);
1.235 + }
1.236 + }
1.237 + else {
1.238 + // The entry is invalid.
1.239 + return ExInvalid;
1.240 + }
1.241 +
1.242 + // Make sure the entry is terminated with "FINISH"
1.243 + if (*buf_used > 0 && buf[(*buf_used) - 1] != ARM_EXTBL_OP_FINISH)
1.244 + PUT_BUF_U8(ARM_EXTBL_OP_FINISH);
1.245 +
1.246 + return ExSuccess;
1.247 +
1.248 +# undef GET_EXTAB_U32
1.249 +# undef GET_EXIDX_U32
1.250 +# undef GET_U32
1.251 +# undef PUT_BUF_U8
1.252 +}
1.253 +
1.254 +
1.255 +// Take the unwind information extracted by ExtabEntryExtract
1.256 +// and parse it into frame-unwind instructions. These are as
1.257 +// specified in "Table 4, ARM-defined frame-unwinding instructions"
1.258 +// in the specification document detailed in comments at the top
1.259 +// of this file.
1.260 +//
1.261 +// This reads from |buf[0, +data_size)|. It checks for overruns of
1.262 +// the input buffer and returns a negative value if that happens, or
1.263 +// for any other failure cases. It returns zero in case of success.
1.264 +int ExceptionTableInfo::ExtabEntryDecode(const uint8_t* buf, size_t buf_size)
1.265 +{
1.266 + if (buf == NULL || buf_size == 0)
1.267 + return -1;
1.268 +
1.269 + MemoryRange mr_in(buf, buf_size);
1.270 + const uint8_t* buf_initially = buf;
1.271 +
1.272 +# define GET_BUF_U8(_lval) \
1.273 + do { if (!mr_in.Covers(buf - buf_initially, 1)) return -1; \
1.274 + (_lval) = *(buf++); } while (0)
1.275 +
1.276 + const uint8_t* end = buf + buf_size;
1.277 +
1.278 + while (buf < end) {
1.279 + struct arm_ex_to_module::extab_data edata;
1.280 + memset(&edata, 0, sizeof(edata));
1.281 +
1.282 + uint8_t op;
1.283 + GET_BUF_U8(op);
1.284 + if ((op & 0xc0) == 0x00) {
1.285 + // vsp = vsp + (xxxxxx << 2) + 4
1.286 + edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP;
1.287 + edata.data = (((int)op & 0x3f) << 2) + 4;
1.288 + }
1.289 + else if ((op & 0xc0) == 0x40) {
1.290 + // vsp = vsp - (xxxxxx << 2) - 4
1.291 + edata.cmd = ARM_EXIDX_CMD_SUB_FROM_VSP;
1.292 + edata.data = (((int)op & 0x3f) << 2) + 4;
1.293 + }
1.294 + else if ((op & 0xf0) == 0x80) {
1.295 + uint8_t op2;
1.296 + GET_BUF_U8(op2);
1.297 + if (op == 0x80 && op2 == 0x00) {
1.298 + // Refuse to unwind
1.299 + edata.cmd = ARM_EXIDX_CMD_REFUSED;
1.300 + } else {
1.301 + // Pop up to 12 integer registers under masks {r15-r12},{r11-r4}
1.302 + edata.cmd = ARM_EXIDX_CMD_REG_POP;
1.303 + edata.data = ((op & 0xf) << 8) | op2;
1.304 + edata.data = edata.data << 4;
1.305 + }
1.306 + }
1.307 + else if ((op & 0xf0) == 0x90) {
1.308 + if (op == 0x9d || op == 0x9f) {
1.309 + // 9d: Reserved as prefix for ARM register to register moves
1.310 + // 9f: Reserved as perfix for Intel Wireless MMX reg to reg moves
1.311 + edata.cmd = ARM_EXIDX_CMD_RESERVED;
1.312 + } else {
1.313 + // Set vsp = r[nnnn]
1.314 + edata.cmd = ARM_EXIDX_CMD_REG_TO_SP;
1.315 + edata.data = op & 0x0f;
1.316 + }
1.317 + }
1.318 + else if ((op & 0xf0) == 0xa0) {
1.319 + // Pop r4 to r[4+nnn], or
1.320 + // Pop r4 to r[4+nnn] and r14 or
1.321 + unsigned end = (op & 0x07);
1.322 + edata.data = (1 << (end + 1)) - 1;
1.323 + edata.data = edata.data << 4;
1.324 + if (op & 0x08) edata.data |= 1 << 14;
1.325 + edata.cmd = ARM_EXIDX_CMD_REG_POP;
1.326 + }
1.327 + else if (op == ARM_EXTBL_OP_FINISH) {
1.328 + // Finish
1.329 + edata.cmd = ARM_EXIDX_CMD_FINISH;
1.330 + buf = end;
1.331 + }
1.332 + else if (op == 0xb1) {
1.333 + uint8_t op2;
1.334 + GET_BUF_U8(op2);
1.335 + if (op2 == 0 || (op2 & 0xf0)) {
1.336 + // Spare
1.337 + edata.cmd = ARM_EXIDX_CMD_RESERVED;
1.338 + } else {
1.339 + // Pop integer registers under mask {r3,r2,r1,r0}
1.340 + edata.cmd = ARM_EXIDX_CMD_REG_POP;
1.341 + edata.data = op2 & 0x0f;
1.342 + }
1.343 + }
1.344 + else if (op == 0xb2) {
1.345 + // vsp = vsp + 0x204 + (uleb128 << 2)
1.346 + uint64_t offset = 0;
1.347 + uint8_t byte, shift = 0;
1.348 + do {
1.349 + GET_BUF_U8(byte);
1.350 + offset |= (byte & 0x7f) << shift;
1.351 + shift += 7;
1.352 + } while ((byte & 0x80) && buf < end);
1.353 + edata.data = offset * 4 + 0x204;
1.354 + edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP;
1.355 + }
1.356 + else if (op == 0xb3 || op == 0xc8 || op == 0xc9) {
1.357 + // b3: Pop VFP regs D[ssss] to D[ssss+cccc], FSTMFDX-ishly
1.358 + // c8: Pop VFP regs D[16+ssss] to D[16+ssss+cccc], FSTMFDD-ishly
1.359 + // c9: Pop VFP regs D[ssss] to D[ssss+cccc], FSTMFDD-ishly
1.360 + edata.cmd = ARM_EXIDX_CMD_VFP_POP;
1.361 + GET_BUF_U8(edata.data);
1.362 + if (op == 0xc8) edata.data |= ARM_EXIDX_VFP_SHIFT_16;
1.363 + if (op != 0xb3) edata.data |= ARM_EXIDX_VFP_FSTMD;
1.364 + }
1.365 + else if ((op & 0xf8) == 0xb8 || (op & 0xf8) == 0xd0) {
1.366 + // b8: Pop VFP regs D[8] to D[8+nnn], FSTMFDX-ishly
1.367 + // d0: Pop VFP regs D[8] to D[8+nnn], FSTMFDD-ishly
1.368 + edata.cmd = ARM_EXIDX_CMD_VFP_POP;
1.369 + edata.data = 0x80 | (op & 0x07);
1.370 + if ((op & 0xf8) == 0xd0) edata.data |= ARM_EXIDX_VFP_FSTMD;
1.371 + }
1.372 + else if (op >= 0xc0 && op <= 0xc5) {
1.373 + // Intel Wireless MMX pop wR[10]-wr[10+nnn], nnn != 6,7
1.374 + edata.cmd = ARM_EXIDX_CMD_WREG_POP;
1.375 + edata.data = 0xa0 | (op & 0x07);
1.376 + }
1.377 + else if (op == 0xc6) {
1.378 + // Intel Wireless MMX pop wR[ssss] to wR[ssss+cccc]
1.379 + edata.cmd = ARM_EXIDX_CMD_WREG_POP;
1.380 + GET_BUF_U8(edata.data);
1.381 + }
1.382 + else if (op == 0xc7) {
1.383 + uint8_t op2;
1.384 + GET_BUF_U8(op2);
1.385 + if (op2 == 0 || (op2 & 0xf0)) {
1.386 + // Spare
1.387 + edata.cmd = ARM_EXIDX_CMD_RESERVED;
1.388 + } else {
1.389 + // Intel Wireless MMX pop wCGR registers under mask {wCGR3,2,1,0}
1.390 + edata.cmd = ARM_EXIDX_CMD_WCGR_POP;
1.391 + edata.data = op2 & 0x0f;
1.392 + }
1.393 + }
1.394 + else {
1.395 + // Spare
1.396 + edata.cmd = ARM_EXIDX_CMD_RESERVED;
1.397 + }
1.398 +
1.399 + int ret = handler_->ImproveStackFrame(&edata);
1.400 + if (ret < 0) return ret;
1.401 + }
1.402 + return 0;
1.403 +
1.404 +# undef GET_BUF_U8
1.405 +}
1.406 +
1.407 +void ExceptionTableInfo::Start()
1.408 +{
1.409 + const struct exidx_entry* start
1.410 + = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data());
1.411 + const struct exidx_entry* end
1.412 + = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data()
1.413 + + mr_exidx_.length());
1.414 +
1.415 + // Iterate over each of the EXIDX entries (pairs of 32-bit words).
1.416 + // These occupy the entire .exidx section.
1.417 + for (const struct exidx_entry* entry = start; entry < end; ++entry) {
1.418 +
1.419 + // Figure out the code address range that this table entry is
1.420 + // associated with.
1.421 + uint32_t addr = (reinterpret_cast<char*>(Prel31ToAddr(&entry->addr))
1.422 + - mapping_addr_ + loading_addr_) & 0x7fffffff;
1.423 + uint32_t next_addr;
1.424 + if (entry < end - 1)
1.425 + next_addr = (reinterpret_cast<char*>(Prel31ToAddr(&((entry + 1)->addr)))
1.426 + - mapping_addr_ + loading_addr_) & 0x7fffffff;
1.427 + else {
1.428 + // This is the last EXIDX entry in the sequence, so we don't
1.429 + // have an address for the start of the next function, to limit
1.430 + // this one. Instead use the address of the last byte of the
1.431 + // text section associated with this .exidx section, that we
1.432 + // have been given. So as to avoid junking up the CFI unwind
1.433 + // tables with absurdly large address ranges in the case where
1.434 + // text_last_svma_ is wrong, only use the value if it is nonzero
1.435 + // and within one page of |addr|. Otherwise assume a length of 1.
1.436 + //
1.437 + // In some cases, gcc has been observed to finish the exidx
1.438 + // section with an entry of length 1 marked CANT_UNWIND,
1.439 + // presumably exactly for the purpose of giving a definite
1.440 + // length for the last real entry, without having to look at
1.441 + // text segment boundaries.
1.442 + bool plausible = false;
1.443 + next_addr = addr + 1;
1.444 + if (text_last_svma_ != 0) {
1.445 + uint32_t maybe_next_addr = text_last_svma_ + 1;
1.446 + if (maybe_next_addr > addr && maybe_next_addr - addr <= 4096) {
1.447 + next_addr = maybe_next_addr;
1.448 + plausible = true;
1.449 + }
1.450 + }
1.451 + if (!plausible)
1.452 + BPLOG(INFO) << "ExceptionTableInfo: implausible EXIDX last entry size "
1.453 + << (int32_t)(text_last_svma_ - addr)
1.454 + << "; using 1 instead.";
1.455 + }
1.456 +
1.457 + // Extract the unwind info into |buf|. This might fail for
1.458 + // various reasons. It involves reading both the .exidx and
1.459 + // .extab sections. All accesses to those sections are
1.460 + // bounds-checked.
1.461 + uint8_t buf[ARM_EXIDX_TABLE_LIMIT];
1.462 + size_t buf_used = 0;
1.463 + ExExtractResult res = ExtabEntryExtract(entry, buf, sizeof(buf), &buf_used);
1.464 + if (res != ExSuccess) {
1.465 + // Couldn't extract the unwind info, for some reason. Move on.
1.466 + switch (res) {
1.467 + case ExInBufOverflow:
1.468 + BPLOG(INFO) << "ExtabEntryExtract: .exidx/.extab section overrun";
1.469 + break;
1.470 + case ExOutBufOverflow:
1.471 + BPLOG(INFO) << "ExtabEntryExtract: bytecode buffer overflow";
1.472 + break;
1.473 + case ExCantUnwind:
1.474 + BPLOG(INFO) << "ExtabEntryExtract: function is marked CANT_UNWIND";
1.475 + break;
1.476 + case ExCantRepresent:
1.477 + BPLOG(INFO) << "ExtabEntryExtract: bytecode can't be represented";
1.478 + break;
1.479 + case ExInvalid:
1.480 + BPLOG(INFO) << "ExtabEntryExtract: index table entry is invalid";
1.481 + break;
1.482 + default:
1.483 + BPLOG(INFO) << "ExtabEntryExtract: unknown error: " << (int)res;
1.484 + break;
1.485 + }
1.486 + continue;
1.487 + }
1.488 +
1.489 + // Finally, work through the unwind instructions in |buf| and
1.490 + // create CFI entries that Breakpad can use. This can also fail.
1.491 + // First, add a new stack frame entry, into which ExtabEntryDecode
1.492 + // will write the CFI entries.
1.493 + handler_->AddStackFrame(addr, next_addr - addr);
1.494 + int ret = ExtabEntryDecode(buf, buf_used);
1.495 + if (ret < 0) {
1.496 + handler_->DeleteStackFrame();
1.497 + BPLOG(INFO) << "ExtabEntryDecode: failed with error code: " << ret;
1.498 + continue;
1.499 + }
1.500 + handler_->SubmitStackFrame();
1.501 +
1.502 + } /* iterating over .exidx */
1.503 +}
1.504 +
1.505 +} // arm_ex_reader
