Bug 863475 - integrate ARM EXIDX unwind parsing into Breakpad. r=glandium,ted
authorJulian Seward <jseward@acm.org>
Fri, 14 Jun 2013 08:09:20 +0200
changeset 146557 8277fd16758cd48ee93171f5a72a6ba9997c8fbe
parent 146556 73a46cde2185d1221b19870c4291e858835b558d
child 146558 9ec58d112f8841d0f14e39244285ea2436eed6be
push id2697
push userbbajaj@mozilla.com
push dateMon, 05 Aug 2013 18:49:53 +0000
treeherdermozilla-beta@dfec938c7b63 [default view] [failures only]
perfherder[talos] [build metrics] [platform microbench] (compared to previous push)
reviewersglandium, ted
bugs863475
milestone24.0a1
first release with
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
last release without
nightly linux32
nightly linux64
nightly mac
nightly win32
nightly win64
Bug 863475 - integrate ARM EXIDX unwind parsing into Breakpad. r=glandium,ted
toolkit/crashreporter/google-breakpad/Makefile.am
toolkit/crashreporter/google-breakpad/src/common/Makefile.in
toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc
toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.h
toolkit/crashreporter/google-breakpad/src/common/arm_ex_to_module.cc
toolkit/crashreporter/google-breakpad/src/common/arm_ex_to_module.h
toolkit/crashreporter/google-breakpad/src/common/linux/dump_symbols.cc
toolkit/crashreporter/google-breakpad/src/common/module.cc
toolkit/crashreporter/google-breakpad/src/common/module.h
toolkit/crashreporter/google-breakpad/src/common/moz.build
toolkit/crashreporter/google-breakpad/src/common/unique_string.h
toolkit/crashreporter/google-breakpad/src/processor/cfi_frame_info.cc
--- a/toolkit/crashreporter/google-breakpad/Makefile.am
+++ b/toolkit/crashreporter/google-breakpad/Makefile.am
@@ -428,16 +428,18 @@ src_tools_linux_dump_syms_dump_syms_SOUR
 	src/common/dwarf_line_to_module.cc \
 	src/common/language.cc \
 	src/common/module.cc \
 	src/common/stabs_reader.cc \
 	src/common/stabs_to_module.cc \
 	src/common/dwarf/bytereader.cc \
 	src/common/dwarf/dwarf2diehandler.cc \
 	src/common/dwarf/dwarf2reader.cc \
+        src/common/arm_ex_reader.cc \
+        src/common/arm_ex_to_module.cc \
 	src/common/linux/dump_symbols.cc \
 	src/common/linux/elf_symbols_to_module.cc \
 	src/common/linux/elfutils.cc \
 	src/common/linux/file_id.cc \
 	src/common/linux/linux_libc_support.cc \
 	src/common/linux/memory_mapped_file.cc \
 	src/common/linux/safe_readlink.cc \
 	src/tools/linux/dump_syms/dump_syms.cc
@@ -1010,16 +1012,20 @@ EXTRA_DIST = \
 	src/client/windows/handler/exception_handler.vcproj \
 	src/client/windows/sender/crash_report_sender.cc \
 	src/client/windows/sender/crash_report_sender.h \
 	src/client/windows/sender/crash_report_sender.vcproj \
 	src/common/convert_UTF.c \
 	src/common/convert_UTF.h \
 	src/common/linux/dump_symbols.cc \
 	src/common/linux/dump_symbols.h \
+        src/common/arm_ex_reader.cc \
+        src/common/arm_ex_reader.h \
+        src/common/arm_ex_to_module.cc \
+        src/common/arm_ex_to_module.h \
 	src/common/linux/elf_symbols_to_module.cc \
 	src/common/linux/elf_symbols_to_module.h \
 	src/common/linux/elfutils.cc \
 	src/common/linux/elfutils.h \
 	src/common/linux/file_id.cc \
 	src/common/linux/file_id.h \
 	src/common/linux/guid_creator.cc \
 	src/common/linux/guid_creator.h \
--- a/toolkit/crashreporter/google-breakpad/src/common/Makefile.in
+++ b/toolkit/crashreporter/google-breakpad/src/common/Makefile.in
@@ -27,16 +27,18 @@ HOST_CPPSRCS = \
   unique_string.cc \
   md5.cc \
   dwarf_cfi_to_module.cc \
   dwarf_cu_to_module.cc \
   language.cc \
   stabs_to_module.cc \
   stabs_reader.cc \
   dwarf_line_to_module.cc \
+  arm_ex_reader.cc \
+  arm_ex_to_module.cc \
   pathname_stripper.cc \
   logging.cc \
   $(NULL)
 endif
 endif
 
 ifeq ($(OS_ARCH),Darwin)
 DISABLED_CMMSRCS += \
new file mode 100644
--- /dev/null
+++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.cc
@@ -0,0 +1,502 @@
+
+/* libunwind - a platform-independent unwind library
+   Copyright 2011 Linaro Limited
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
+
+// Copyright (c) 2010 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Derived from libunwind, with extensive modifications.
+
+
+#include "common/arm_ex_reader.h"
+#include "common/logging.h"
+
+#include <assert.h>
+
+// This file, in conjunction with arm_ex_to_module.cc, translates
+// EXIDX unwind information into the same format that Breakpad uses
+// for CFI information.  Hence Breakpad's CFI unwinding abilities
+// also become usable for EXIDX.
+//
+// See: "Exception Handling ABI for the ARM Architecture", ARM IHI 0038A
+// http://infocenter.arm.com/help/topic/com.arm.doc.ihi0038a/IHI0038A_ehabi.pdf
+
+// EXIDX data is presented in two parts:
+//
+// * an index table.  This contains two words per routine,
+//   the first of which identifies the routine, and the second
+//   of which is a reference to the unwind bytecode.  If the
+//   bytecode is very compact -- 3 bytes or less -- it can be
+//   stored directly in the second word.
+//
+// * an area containing the unwind bytecodes.
+
+// General flow is: ExceptionTableInfo::Start iterates over all
+// of the index table entries (pairs).  For each entry, it:
+//
+// * calls ExceptionTableInfo::ExtabEntryExtract to copy the bytecode
+//   out into an intermediate buffer.
+
+// * uses ExceptionTableInfo::ExtabEntryDecode to parse the intermediate
+//   buffer.  Each bytecode instruction is bundled into a
+//   arm_ex_to_module::extab_data structure, and handed to ..
+//
+// * .. ARMExToModule::ImproveStackFrame, which in turn hands it to
+//   ARMExToModule::TranslateCmd, and that generates the pseudo-CFI
+//   records that Breakpad stores.
+
+#define ARM_EXIDX_CANT_UNWIND 0x00000001
+#define ARM_EXIDX_COMPACT     0x80000000
+#define ARM_EXTBL_OP_FINISH   0xb0
+#define ARM_EXIDX_TABLE_LIMIT (255*4)
+
+namespace arm_ex_reader {
+
+using arm_ex_to_module::ARM_EXIDX_CMD_FINISH;
+using arm_ex_to_module::ARM_EXIDX_CMD_SUB_FROM_VSP;
+using arm_ex_to_module::ARM_EXIDX_CMD_ADD_TO_VSP;
+using arm_ex_to_module::ARM_EXIDX_CMD_REG_POP;
+using arm_ex_to_module::ARM_EXIDX_CMD_REG_TO_SP;
+using arm_ex_to_module::ARM_EXIDX_CMD_VFP_POP;
+using arm_ex_to_module::ARM_EXIDX_CMD_WREG_POP;
+using arm_ex_to_module::ARM_EXIDX_CMD_WCGR_POP;
+using arm_ex_to_module::ARM_EXIDX_CMD_RESERVED;
+using arm_ex_to_module::ARM_EXIDX_CMD_REFUSED;
+using arm_ex_to_module::exidx_entry;
+using arm_ex_to_module::ARM_EXIDX_VFP_SHIFT_16;
+using arm_ex_to_module::ARM_EXIDX_VFP_FSTMD;
+using google_breakpad::MemoryRange;
+
+
+static void* Prel31ToAddr(const void* addr) 
+{
+  uint32_t offset32 = *reinterpret_cast<const uint32_t*>(addr);
+  // sign extend offset32[30:0] to 64 bits -- copy bit 30 to positions
+  // 63:31 inclusive.
+  uint64_t offset64 = offset32;
+  if (offset64 & (1ULL << 30))
+    offset64 |= 0xFFFFFFFF80000000ULL;
+  else
+    offset64 &= 0x000000007FFFFFFFULL;
+  return ((char*)addr) + (uintptr_t)offset64;
+}
+
+
+// Extract unwind bytecode for the function denoted by |entry| into |buf|,
+// and return the number of bytes of |buf| written, along with a code
+// indicating the outcome.
+
+ExceptionTableInfo::ExExtractResult
+ExceptionTableInfo::ExtabEntryExtract(const struct exidx_entry* entry,
+                                      uint8_t* buf, size_t buf_size,
+                                      /*OUT*/size_t* buf_used)
+{
+  MemoryRange mr_out(buf, buf_size);
+
+  *buf_used = 0;
+
+# define PUT_BUF_U8(_byte) \
+  do { if (!mr_out.Covers(*buf_used, 1)) return ExOutBufOverflow; \
+       buf[(*buf_used)++] = (_byte); } while (0)
+
+# define GET_EX_U32(_lval, _addr, _sec_mr) \
+  do { if (!(_sec_mr).Covers(reinterpret_cast<const uint8_t*>(_addr) \
+                             - (_sec_mr).data(), 4)) \
+         return ExInBufOverflow; \
+       (_lval) = *(reinterpret_cast<const uint32_t*>(_addr)); } while (0)
+
+# define GET_EXIDX_U32(_lval, _addr) \
+            GET_EX_U32(_lval, _addr, mr_exidx_)
+# define GET_EXTAB_U32(_lval, _addr) \
+            GET_EX_U32(_lval, _addr, mr_extab_)
+
+  uint32_t data;
+  GET_EXIDX_U32(data, &entry->data);
+
+  // A function can be marked CANT_UNWIND if (eg) it is known to be
+  // at the bottom of the stack.
+  if (data == ARM_EXIDX_CANT_UNWIND)
+    return ExCantUnwind;
+
+  uint32_t  pers;          // personality number
+  uint32_t  extra;         // number of extra data words required
+  uint32_t  extra_allowed; // number of extra data words allowed
+  uint32_t* extbl_data;    // the handler entry, if not inlined
+
+  if (data & ARM_EXIDX_COMPACT) {
+    // The handler table entry has been inlined into the index table entry.
+    // In this case it can only be an ARM-defined compact model, since
+    // bit 31 is 1.  Only personalities 0, 1 and 2 are defined for the
+    // ARM compact model, but 1 and 2 are "Long format" and may require
+    // extra data words.  Hence the allowable personalities here are:
+    //   personality 0, in which case 'extra' has no meaning
+    //   personality 1, with zero extra words
+    //   personality 2, with zero extra words
+    extbl_data = NULL;
+    pers  = (data >> 24) & 0x0F;
+    extra = (data >> 16) & 0xFF;
+    extra_allowed = 0;
+  }
+  else {
+    // The index table entry is a pointer to the handler entry.  Note
+    // that Prel31ToAddr will read the given address, but we already
+    // range-checked above.
+    extbl_data = reinterpret_cast<uint32_t*>(Prel31ToAddr(&entry->data));
+    GET_EXTAB_U32(data, extbl_data);
+    if (!(data & ARM_EXIDX_COMPACT)) {
+      // This denotes a "generic model" handler.  That will involve
+      // executing arbitary machine code, which is something we
+      // can't represent here; hence reject it.
+      return ExCantRepresent;
+    }
+    // So we have a compact model representation.  Again, 3 possible
+    // personalities, but this time up to 255 allowable extra words.
+    pers  = (data >> 24) & 0x0F;
+    extra = (data >> 16) & 0xFF;
+    extra_allowed = 255;
+    extbl_data++;
+  }
+
+  // Now look at the the handler table entry.  The first word is
+  // |data| and subsequent words start at |*extbl_data|.  The number
+  // of extra words to use is |extra|, provided that the personality
+  // allows extra words.  Even if it does, none may be available --
+  // extra_allowed is the maximum number of extra words allowed. */
+  if (pers == 0) {
+    // "Su16" in the documentation -- 3 unwinding insn bytes
+    // |extra| has no meaning here; instead that byte is an unwind-info byte
+    PUT_BUF_U8(data >> 16);
+    PUT_BUF_U8(data >> 8);
+    PUT_BUF_U8(data);
+  }
+  else if ((pers == 1 || pers == 2) && extra <= extra_allowed) {
+    // "Lu16" or "Lu32" respectively -- 2 unwinding insn bytes,
+    // and up to 255 extra words.
+    PUT_BUF_U8(data >> 8);
+    PUT_BUF_U8(data);
+    for (uint32_t j = 0; j < extra; j++) {
+      GET_EXTAB_U32(data, extbl_data);
+      extbl_data++;
+      PUT_BUF_U8(data >> 24);
+      PUT_BUF_U8(data >> 16);
+      PUT_BUF_U8(data >> 8);
+      PUT_BUF_U8(data >> 0);
+    }
+  }
+  else {
+    // The entry is invalid.
+    return ExInvalid;
+  }
+
+  // Make sure the entry is terminated with "FINISH"
+  if (*buf_used > 0 && buf[(*buf_used) - 1] != ARM_EXTBL_OP_FINISH)
+    PUT_BUF_U8(ARM_EXTBL_OP_FINISH);
+
+  return ExSuccess;
+
+# undef GET_EXTAB_U32
+# undef GET_EXIDX_U32
+# undef GET_U32
+# undef PUT_BUF_U8
+}
+
+
+// Take the unwind information extracted by ExtabEntryExtract
+// and parse it into frame-unwind instructions.  These are as
+// specified in "Table 4, ARM-defined frame-unwinding instructions"
+// in the specification document detailed in comments at the top
+// of this file.
+//
+// This reads from |buf[0, +data_size)|.  It checks for overruns of
+// the input buffer and returns a negative value if that happens, or
+// for any other failure cases.  It returns zero in case of success.
+int ExceptionTableInfo::ExtabEntryDecode(const uint8_t* buf, size_t buf_size)
+{
+  if (buf == NULL || buf_size == 0)
+    return -1;
+
+  MemoryRange mr_in(buf, buf_size);
+  const uint8_t* buf_initially = buf;
+
+# define GET_BUF_U8(_lval) \
+  do { if (!mr_in.Covers(buf - buf_initially, 1)) return -1; \
+       (_lval) = *(buf++); } while (0)
+
+  const uint8_t* end = buf + buf_size;
+
+  while (buf < end) {
+    struct arm_ex_to_module::extab_data edata;
+    memset(&edata, 0, sizeof(edata));
+
+    uint8_t op;
+    GET_BUF_U8(op);
+    if ((op & 0xc0) == 0x00) {
+      // vsp = vsp + (xxxxxx << 2) + 4
+      edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP;
+      edata.data = (((int)op & 0x3f) << 2) + 4;
+    }
+    else if ((op & 0xc0) == 0x40) {
+      // vsp = vsp - (xxxxxx << 2) - 4
+      edata.cmd = ARM_EXIDX_CMD_SUB_FROM_VSP;
+      edata.data = (((int)op & 0x3f) << 2) + 4;
+    }
+    else if ((op & 0xf0) == 0x80) {
+      uint8_t op2;
+      GET_BUF_U8(op2);
+      if (op == 0x80 && op2 == 0x00) {
+        // Refuse to unwind
+        edata.cmd = ARM_EXIDX_CMD_REFUSED;
+      } else {
+        // Pop up to 12 integer registers under masks {r15-r12},{r11-r4}
+        edata.cmd = ARM_EXIDX_CMD_REG_POP;
+        edata.data = ((op & 0xf) << 8) | op2;
+        edata.data = edata.data << 4;
+      }
+    }
+    else if ((op & 0xf0) == 0x90) {
+      if (op == 0x9d || op == 0x9f) {
+        // 9d: Reserved as prefix for ARM register to register moves
+        // 9f: Reserved as perfix for Intel Wireless MMX reg to reg moves
+        edata.cmd = ARM_EXIDX_CMD_RESERVED;
+      } else {
+        // Set vsp = r[nnnn]
+        edata.cmd = ARM_EXIDX_CMD_REG_TO_SP;
+        edata.data = op & 0x0f;
+      }
+    }
+    else if ((op & 0xf0) == 0xa0) {
+      // Pop r4 to r[4+nnn],          or
+      // Pop r4 to r[4+nnn] and r14   or
+      unsigned end = (op & 0x07);
+      edata.data = (1 << (end + 1)) - 1;
+      edata.data = edata.data << 4;
+      if (op & 0x08) edata.data |= 1 << 14;
+      edata.cmd = ARM_EXIDX_CMD_REG_POP;
+    }
+    else if (op == ARM_EXTBL_OP_FINISH) {
+      // Finish
+      edata.cmd = ARM_EXIDX_CMD_FINISH;
+      buf = end;
+    }
+    else if (op == 0xb1) {
+      uint8_t op2;
+      GET_BUF_U8(op2);
+      if (op2 == 0 || (op2 & 0xf0)) {
+        // Spare
+        edata.cmd = ARM_EXIDX_CMD_RESERVED;
+      } else {
+        // Pop integer registers under mask {r3,r2,r1,r0}
+        edata.cmd = ARM_EXIDX_CMD_REG_POP;
+        edata.data = op2 & 0x0f;
+      }
+    }
+    else if (op == 0xb2) {
+      // vsp = vsp + 0x204 + (uleb128 << 2)
+      uint64_t offset = 0;
+      uint8_t byte, shift = 0;
+      do {
+        GET_BUF_U8(byte);
+        offset |= (byte & 0x7f) << shift;
+        shift += 7;
+      } while ((byte & 0x80) && buf < end);
+      edata.data = offset * 4 + 0x204;
+      edata.cmd = ARM_EXIDX_CMD_ADD_TO_VSP;
+    }
+    else if (op == 0xb3 || op == 0xc8 || op == 0xc9) {
+      // b3: Pop VFP regs D[ssss]    to D[ssss+cccc],    FSTMFDX-ishly
+      // c8: Pop VFP regs D[16+ssss] to D[16+ssss+cccc], FSTMFDD-ishly
+      // c9: Pop VFP regs D[ssss]    to D[ssss+cccc],    FSTMFDD-ishly
+      edata.cmd = ARM_EXIDX_CMD_VFP_POP;
+      GET_BUF_U8(edata.data);
+      if (op == 0xc8) edata.data |= ARM_EXIDX_VFP_SHIFT_16;
+      if (op != 0xb3) edata.data |= ARM_EXIDX_VFP_FSTMD;
+    }
+    else if ((op & 0xf8) == 0xb8 || (op & 0xf8) == 0xd0) {
+      // b8: Pop VFP regs D[8] to D[8+nnn], FSTMFDX-ishly
+      // d0: Pop VFP regs D[8] to D[8+nnn], FSTMFDD-ishly
+      edata.cmd = ARM_EXIDX_CMD_VFP_POP;
+      edata.data = 0x80 | (op & 0x07);
+      if ((op & 0xf8) == 0xd0) edata.data |= ARM_EXIDX_VFP_FSTMD;
+    }
+    else if (op >= 0xc0 && op <= 0xc5) {
+      // Intel Wireless MMX pop wR[10]-wr[10+nnn], nnn != 6,7
+      edata.cmd = ARM_EXIDX_CMD_WREG_POP;
+      edata.data = 0xa0 | (op & 0x07);
+    }
+    else if (op == 0xc6) {
+      // Intel Wireless MMX pop wR[ssss] to wR[ssss+cccc]
+      edata.cmd = ARM_EXIDX_CMD_WREG_POP;
+      GET_BUF_U8(edata.data);
+    }
+    else if (op == 0xc7) {
+      uint8_t op2;
+      GET_BUF_U8(op2);
+      if (op2 == 0 || (op2 & 0xf0)) {
+        // Spare
+        edata.cmd = ARM_EXIDX_CMD_RESERVED;
+      } else {
+        // Intel Wireless MMX pop wCGR registers under mask {wCGR3,2,1,0}
+        edata.cmd = ARM_EXIDX_CMD_WCGR_POP;
+        edata.data = op2 & 0x0f;
+      }
+    }
+    else {
+      // Spare
+      edata.cmd = ARM_EXIDX_CMD_RESERVED;
+    }
+
+    int ret = handler_->ImproveStackFrame(&edata);
+    if (ret < 0) return ret;
+  }
+  return 0;
+
+# undef GET_BUF_U8
+}
+
+void ExceptionTableInfo::Start()
+{
+  const struct exidx_entry* start
+    = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data());
+  const struct exidx_entry* end
+    = reinterpret_cast<const struct exidx_entry*>(mr_exidx_.data()
+                                                  + mr_exidx_.length());
+
+  // Iterate over each of the EXIDX entries (pairs of 32-bit words).
+  // These occupy the entire .exidx section.
+  for (const struct exidx_entry* entry = start; entry < end; ++entry) {
+
+    // Figure out the code address range that this table entry is
+    // associated with.
+    uint32_t addr = (reinterpret_cast<char*>(Prel31ToAddr(&entry->addr))
+                     - mapping_addr_ + loading_addr_) & 0x7fffffff;
+    uint32_t next_addr;
+    if (entry < end - 1)
+      next_addr = (reinterpret_cast<char*>(Prel31ToAddr(&((entry + 1)->addr)))
+                   - mapping_addr_ + loading_addr_) & 0x7fffffff;
+    else {
+      // This is the last EXIDX entry in the sequence, so we don't
+      // have an address for the start of the next function, to limit
+      // this one.  Instead use the address of the last byte of the
+      // text section associated with this .exidx section, that we
+      // have been given.  So as to avoid junking up the CFI unwind
+      // tables with absurdly large address ranges in the case where
+      // text_last_svma_ is wrong, only use the value if it is nonzero
+      // and within one page of |addr|.  Otherwise assume a length of 1.
+      //
+      // In some cases, gcc has been observed to finish the exidx
+      // section with an entry of length 1 marked CANT_UNWIND,
+      // presumably exactly for the purpose of giving a definite
+      // length for the last real entry, without having to look at
+      // text segment boundaries.
+      bool plausible = false;
+      next_addr = addr + 1;
+      if (text_last_svma_ != 0) {
+        uint32_t maybe_next_addr = text_last_svma_ + 1;
+        if (maybe_next_addr > addr && maybe_next_addr - addr <= 4096) {
+          next_addr = maybe_next_addr;
+          plausible = true;
+        }
+      }
+      if (!plausible)
+        BPLOG(INFO) << "ExceptionTableInfo: implausible EXIDX last entry size "
+                    << (int32_t)(text_last_svma_ - addr)
+                    << "; using 1 instead.";
+    }
+
+    // Extract the unwind info into |buf|.  This might fail for
+    // various reasons.  It involves reading both the .exidx and
+    // .extab sections.  All accesses to those sections are
+    // bounds-checked.
+    uint8_t buf[ARM_EXIDX_TABLE_LIMIT];
+    size_t buf_used = 0;
+    ExExtractResult res = ExtabEntryExtract(entry, buf, sizeof(buf), &buf_used);
+    if (res != ExSuccess) {
+      // Couldn't extract the unwind info, for some reason.  Move on.
+      switch (res) {
+        case ExInBufOverflow:
+          BPLOG(INFO) << "ExtabEntryExtract: .exidx/.extab section overrun";
+          break;
+        case ExOutBufOverflow:
+          BPLOG(INFO) << "ExtabEntryExtract: bytecode buffer overflow";
+          break;
+        case ExCantUnwind:
+          BPLOG(INFO) << "ExtabEntryExtract: function is marked CANT_UNWIND";
+          break;
+        case ExCantRepresent:
+          BPLOG(INFO) << "ExtabEntryExtract: bytecode can't be represented";
+          break;
+        case ExInvalid:
+          BPLOG(INFO) << "ExtabEntryExtract: index table entry is invalid";
+          break;
+        default:
+          BPLOG(INFO) << "ExtabEntryExtract: unknown error: " << (int)res;
+          break;
+      }
+      continue;
+    }
+
+    // Finally, work through the unwind instructions in |buf| and
+    // create CFI entries that Breakpad can use.  This can also fail.
+    // First, add a new stack frame entry, into which ExtabEntryDecode
+    // will write the CFI entries.
+    handler_->AddStackFrame(addr, next_addr - addr);
+    int ret = ExtabEntryDecode(buf, buf_used);
+    if (ret < 0) {
+      handler_->DeleteStackFrame();
+      BPLOG(INFO) << "ExtabEntryDecode: failed with error code: " << ret;
+      continue;
+    }
+    handler_->SubmitStackFrame();
+
+  } /* iterating over .exidx */
+}
+
+} // arm_ex_reader
new file mode 100644
--- /dev/null
+++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_reader.h
@@ -0,0 +1,115 @@
+
+/* libunwind - a platform-independent unwind library
+   Copyright 2011 Linaro Limited
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
+
+// Copyright (c) 2010 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Derived from libunwind, with extensive modifications.
+
+#ifndef COMMON_ARM_EX_READER_H__
+#define COMMON_ARM_EX_READER_H__
+
+#include "common/arm_ex_to_module.h"
+#include "common/memory_range.h"
+
+namespace arm_ex_reader {
+
+// This class is a reader for ARM unwind information
+// from .ARM.exidx and .ARM.extab sections.
+class ExceptionTableInfo {
+ public:
+  ExceptionTableInfo(const char* exidx, size_t exidx_size,
+                     const char* extab, size_t extab_size,
+                     uint32_t text_last_svma,
+                     arm_ex_to_module::ARMExToModule* handler,
+                     const char* mapping_addr,
+                     uint32_t loading_addr)
+      : mr_exidx_(google_breakpad::MemoryRange(exidx, exidx_size)),
+        mr_extab_(google_breakpad::MemoryRange(extab, extab_size)),
+        text_last_svma_(text_last_svma),
+        handler_(handler), mapping_addr_(mapping_addr),
+        loading_addr_(loading_addr) { }
+
+  ~ExceptionTableInfo() { }
+
+  // Parses the entries in .ARM.exidx and possibly
+  // in .ARM.extab tables, reports what we find to
+  // arm_ex_to_module::ARMExToModule.
+  void Start();
+
+ private:
+  google_breakpad::MemoryRange mr_exidx_;
+  google_breakpad::MemoryRange mr_extab_;
+  uint32_t text_last_svma_;
+  arm_ex_to_module::ARMExToModule* handler_;
+  const char* mapping_addr_;
+  uint32_t loading_addr_;
+
+  enum ExExtractResult {
+    ExSuccess,        // success
+    ExInBufOverflow,  // out-of-range while reading .exidx
+    ExOutBufOverflow, // output buffer is too small
+    ExCantUnwind,     // this function is marked CANT_UNWIND
+    ExCantRepresent,  // entry valid, but we can't represent it
+    ExInvalid         // entry is invalid
+  };
+  ExExtractResult
+    ExtabEntryExtract(const struct arm_ex_to_module::exidx_entry* entry,
+                      uint8_t* buf, size_t buf_size,
+                      /*OUT*/size_t* buf_used);
+
+  int ExtabEntryDecode(const uint8_t* buf, size_t buf_size);
+};
+
+} // namespace arm_ex_reader
+
+#endif // COMMON_ARM_EX_READER_H__
new file mode 100644
--- /dev/null
+++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_to_module.cc
@@ -0,0 +1,206 @@
+
+/* libunwind - a platform-independent unwind library
+   Copyright 2011 Linaro Limited
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
+
+// Copyright (c) 2010 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Derived from libunwind, with extensive modifications.
+
+#include "common/unique_string.h"
+#include "common/arm_ex_to_module.h"
+
+#include <stdio.h>
+#include <assert.h>
+
+// For big-picture comments on how the EXIDX reader works, 
+// see arm_ex_reader.cc.
+
+#define ARM_EXBUF_START(x) (((x) >> 4) & 0x0f)
+#define ARM_EXBUF_COUNT(x) ((x) & 0x0f)
+#define ARM_EXBUF_END(x)   (ARM_EXBUF_START(x) + ARM_EXBUF_COUNT(x))
+
+using google_breakpad::ustr__pc;
+using google_breakpad::ustr__lr;
+using google_breakpad::ustr__sp;
+using google_breakpad::Module;
+using google_breakpad::ToUniqueString;
+using google_breakpad::UniqueString;
+
+namespace arm_ex_to_module {
+
+// Translate command from extab_data to command for Module.
+int ARMExToModule::TranslateCmd(const struct extab_data* edata,
+                                Module::StackFrameEntry* entry, string& vsp) {
+  int ret = 0;
+  switch (edata->cmd) {
+    case ARM_EXIDX_CMD_FINISH:
+      /* Copy LR to PC if there isn't currently a rule for PC in force. */
+      if (entry->initial_rules.find(ustr__pc())
+          == entry->initial_rules.end()) {
+        if (entry->initial_rules.find(ustr__lr())
+            == entry->initial_rules.end()) {
+          entry->initial_rules[ustr__pc()] = Module::Expr("lr");
+        } else {
+          entry->initial_rules[ustr__pc()] = entry->initial_rules[ustr__lr()];
+        }
+      }
+      break;
+    case ARM_EXIDX_CMD_SUB_FROM_VSP:
+      {
+        char c[16];
+        sprintf(c, " %d -", edata->data);
+        vsp += c;
+      }
+      break;
+    case ARM_EXIDX_CMD_ADD_TO_VSP:
+      {
+        char c[16];
+        sprintf(c, " %d +", edata->data);
+        vsp += c;
+      }
+      break;
+    case ARM_EXIDX_CMD_REG_POP:
+      for (unsigned int i = 0; i < 16; i++) {
+        if (edata->data & (1 << i)) {
+          entry->initial_rules[ToUniqueString(regnames[i])]
+            = Module::Expr(vsp + " ^");
+          vsp += " 4 +";
+        }
+      }
+      /* Set cfa in case the SP got popped. */
+      if (edata->data & (1 << 13)) {
+        Module::Expr& vsp_expr = entry->initial_rules[ustr__sp()];
+        // It must be a postfix expression (we don't generate anything
+        // else here), so return -1 to fail out if it isn't.
+        if (!vsp_expr.isExprPostfix()) {
+          ret = -1;
+          break;
+        };
+        vsp = vsp_expr.getExprPostfix();
+      }
+      break;
+    case ARM_EXIDX_CMD_REG_TO_SP: {
+      assert (edata->data < 16);
+      const char* const regname = regnames[edata->data];
+      const UniqueString* regname_us = ToUniqueString(regname);
+      if (entry->initial_rules.find(regname_us) == entry->initial_rules.end()) {
+        entry->initial_rules[ustr__sp()] = Module::Expr(regname);
+      } else {
+        entry->initial_rules[ustr__sp()] = entry->initial_rules[regname_us];
+      }
+      Module::Expr& vsp_expr = entry->initial_rules[ustr__sp()];
+      if (!vsp_expr.isExprPostfix()) {
+        ret = -1;
+        break;
+      };
+      vsp = vsp_expr.getExprPostfix();
+      break;
+    }
+    case ARM_EXIDX_CMD_VFP_POP:
+      /* Don't recover VFP registers, but be sure to adjust the stack
+         pointer. */
+      for (unsigned int i = ARM_EXBUF_START(edata->data);
+           i <= ARM_EXBUF_END(edata->data); i++) {
+        vsp += " 8 +";
+      }
+      if (!(edata->data & ARM_EXIDX_VFP_FSTMD)) {
+        vsp += " 4 +";
+      }
+      break;
+    case ARM_EXIDX_CMD_WREG_POP:
+      for (unsigned int i = ARM_EXBUF_START(edata->data);
+           i <= ARM_EXBUF_END(edata->data); i++) {
+        vsp += " 8 +";
+      }
+      break;
+    case ARM_EXIDX_CMD_WCGR_POP:
+      // Pop wCGR registers under mask {wCGR3,2,1,0}, hence "i < 4"
+      for (unsigned int i = 0; i < 4; i++) {
+        if (edata->data & (1 << i)) {
+          vsp += " 4 +";
+        }
+      }
+      break;
+    case ARM_EXIDX_CMD_REFUSED:
+    case ARM_EXIDX_CMD_RESERVED:
+      ret = -1;
+      break;
+  }
+  return ret;
+}
+
+void ARMExToModule::AddStackFrame(uintptr_t addr, size_t size) {
+  stack_frame_entry_ = new Module::StackFrameEntry;
+  stack_frame_entry_->address = addr;
+  stack_frame_entry_->size = size;
+  stack_frame_entry_->initial_rules[ToUniqueString(kCFA)] = Module::Expr("sp");
+  vsp_ = "sp";
+}
+
+int ARMExToModule::ImproveStackFrame(const struct extab_data* edata) {
+  return TranslateCmd(edata, stack_frame_entry_, vsp_) ;
+}
+
+void ARMExToModule::DeleteStackFrame() {
+  delete stack_frame_entry_;
+}
+
+void ARMExToModule::SubmitStackFrame() {
+  // return address always winds up in pc
+  stack_frame_entry_->initial_rules[ToUniqueString(kRA)]
+    = stack_frame_entry_->initial_rules[ustr__pc()];
+  // the final value of vsp is the new value of sp
+  stack_frame_entry_->initial_rules[ustr__sp()] = vsp_;
+  module_->AddStackFrameEntry(stack_frame_entry_);
+}
+
+} // namespace arm_ex_to_module
new file mode 100644
--- /dev/null
+++ b/toolkit/crashreporter/google-breakpad/src/common/arm_ex_to_module.h
@@ -0,0 +1,129 @@
+
+/* libunwind - a platform-independent unwind library
+   Copyright 2011 Linaro Limited
+
+This file is part of libunwind.
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
+
+// Copyright (c) 2010 Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+// Derived from libunwind, with extensive modifications.
+
+#ifndef COMMON_ARM_EX_TO_MODULE__
+#define COMMON_ARM_EX_TO_MODULE__
+
+#include "common/module.h"
+
+#include <string.h>
+
+namespace arm_ex_to_module {
+
+using google_breakpad::Module;
+
+typedef enum extab_cmd {
+  ARM_EXIDX_CMD_FINISH,
+  ARM_EXIDX_CMD_SUB_FROM_VSP,
+  ARM_EXIDX_CMD_ADD_TO_VSP,
+  ARM_EXIDX_CMD_REG_POP,
+  ARM_EXIDX_CMD_REG_TO_SP,
+  ARM_EXIDX_CMD_VFP_POP,
+  ARM_EXIDX_CMD_WREG_POP,
+  ARM_EXIDX_CMD_WCGR_POP,
+  ARM_EXIDX_CMD_RESERVED,
+  ARM_EXIDX_CMD_REFUSED,
+} extab_cmd_t;
+
+struct exidx_entry {
+  uint32_t addr;
+  uint32_t data;
+};
+
+struct extab_data {
+  extab_cmd_t cmd;
+  uint32_t data;
+};
+
+enum extab_cmd_flags {
+  ARM_EXIDX_VFP_SHIFT_16 = 1 << 16,
+  ARM_EXIDX_VFP_FSTMD = 1 << 17, // distinguishes FSTMxxD from FSTMxxX
+};
+
+const string kRA = ".ra";
+const string kCFA = ".cfa";
+
+static const char* const regnames[] = {
+ "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+ "r8", "r9", "r10", "r11", "r12", "sp", "lr", "pc",
+ "f0", "f1", "f2", "f3", "f4", "f5", "f6", "f7",
+ "fps", "cpsr"
+};
+
+// Receives information from arm_ex_reader::ExceptionTableInfo
+// and adds it to the Module object
+class ARMExToModule {
+ public:
+  ARMExToModule(Module* module)
+      : module_(module) { }
+  ~ARMExToModule() { }
+  void AddStackFrame(uintptr_t addr, size_t size);
+  int ImproveStackFrame(const struct extab_data* edata);
+  void DeleteStackFrame();
+  void SubmitStackFrame();
+ private:
+  Module* module_;
+  Module::StackFrameEntry* stack_frame_entry_;
+  string vsp_;
+  int TranslateCmd(const struct extab_data* edata,
+                   Module::StackFrameEntry* entry,
+                   string& vsp);
+};
+
+} // namespace arm_ex_to_module
+
+#endif // COMMON_ARM_EX_TO_MODULE__
--- a/toolkit/crashreporter/google-breakpad/src/common/linux/dump_symbols.cc
+++ b/toolkit/crashreporter/google-breakpad/src/common/linux/dump_symbols.cc
@@ -47,16 +47,17 @@
 #include <unistd.h>
 
 #include <iostream>
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
 
+#include "common/arm_ex_reader.h"
 #include "common/dwarf/bytereader-inl.h"
 #include "common/dwarf/dwarf2diehandler.h"
 #include "common/dwarf_cfi_to_module.h"
 #include "common/dwarf_cu_to_module.h"
 #include "common/dwarf_line_to_module.h"
 #include "common/linux/elfutils.h"
 #include "common/linux/elfutils-inl.h"
 #include "common/linux/elf_symbols_to_module.h"
@@ -65,16 +66,20 @@
 #include "common/scoped_ptr.h"
 #ifndef NO_STABS_SUPPORT
 #include "common/stabs_reader.h"
 #include "common/stabs_to_module.h"
 #endif
 #include "common/using_std_string.h"
 #include "common/logging.h"
 
+#if defined(__ANDROID__) && !defined(SHT_ARM_EXIDX)
+# define SHT_ARM_EXIDX (SHT_LOPROC + 1)
+#endif
+
 // This namespace contains helper functions.
 namespace {
 
 using google_breakpad::DwarfCFIToModule;
 using google_breakpad::DwarfCUToModule;
 using google_breakpad::DwarfLineToModule;
 using google_breakpad::ElfClass;
 using google_breakpad::ElfClass32;
@@ -340,16 +345,62 @@ bool LoadDwarfCFI(const string& dwarf_fi
                                                        section_name);
   dwarf2reader::CallFrameInfo parser(cfi, cfi_size,
                                      &byte_reader, &handler, &dwarf_reporter,
                                      eh_frame);
   parser.Start();
   return true;
 }
 
+template<typename ElfClass>
+bool LoadARMexidx(const typename ElfClass::Ehdr* elf_header,
+                  const typename ElfClass::Shdr* exidx_section,
+                  const typename ElfClass::Shdr* extab_section,
+                  uint32_t loading_addr,
+                  Module* module) {
+  // To do this properly we need to know:
+  // * the bounds of the .ARM.exidx section in the mapped image
+  // * the bounds of the .ARM.extab section in the mapped image
+  // * the vma of the last byte in the text section associated with the .exidx
+  // The first two are easy.  The third is a bit tricky.  If we can't
+  // figure out what it is, just pass in zero.
+  const char *exidx_img
+    = GetOffset<ElfClass, char>(elf_header, exidx_section->sh_offset);
+  size_t exidx_size = exidx_section->sh_size;
+  const char *extab_img
+    = GetOffset<ElfClass, char>(elf_header, extab_section->sh_offset);
+  size_t extab_size = extab_section->sh_size;
+
+  // The sh_link field of the exidx section gives the section number
+  // for the associated text section.
+  uint32_t exidx_text_last_svma = 0;
+  int exidx_text_sno = exidx_section->sh_link;
+  typedef typename ElfClass::Shdr Shdr;
+  // |sections| points to the section header table
+  const Shdr* sections
+    = GetOffset<ElfClass, Shdr>(elf_header, elf_header->e_shoff);
+  const int num_sections = elf_header->e_shnum;
+  if (exidx_text_sno >= 0 && exidx_text_sno < num_sections) {
+    const Shdr* exidx_text_shdr = &sections[exidx_text_sno];
+    if (exidx_text_shdr->sh_size > 0) {
+      exidx_text_last_svma
+        = exidx_text_shdr->sh_addr + exidx_text_shdr->sh_size - 1;
+    }
+  }
+
+  arm_ex_to_module::ARMExToModule handler(module);
+  arm_ex_reader::ExceptionTableInfo
+    parser(exidx_img, exidx_size, extab_img, extab_size, exidx_text_last_svma,
+           &handler,
+           reinterpret_cast<const char*>(elf_header),
+           loading_addr);
+  parser.Start();
+  return true;
+}
+
 bool LoadELF(const string& obj_file, MmapWrapper* map_wrapper,
              void** elf_header) {
   int obj_fd = open(obj_file.c_str(), O_RDONLY);
   if (obj_fd < 0) {
     fprintf(stderr, "Failed to open ELF file '%s': %s\n",
             obj_file.c_str(), strerror(errno));
     return false;
   }
@@ -629,16 +680,39 @@ bool LoadSymbols(const string& obj_file,
                                  eh_frame_section, true,
                                  got_section, text_section, big_endian, module);
       found_usable_info = found_usable_info || result;
       if (result)
         BPLOG(INFO) << "LoadSymbols:   read CFI from .eh_frame";
     }
   }
 
+  // ARM has special unwind tables that can be used.
+  const Shdr* arm_exidx_section =
+      FindElfSectionByName<ElfClass>(".ARM.exidx", SHT_ARM_EXIDX,
+                                     sections, names, names_end,
+                                     elf_header->e_shnum);
+  const Shdr* arm_extab_section =
+      FindElfSectionByName<ElfClass>(".ARM.extab", SHT_PROGBITS,
+                                     sections, names, names_end,
+                                     elf_header->e_shnum);
+  // Only load information from this section if there isn't a .debug_info
+  // section.
+  if (!found_debug_info_section
+      && arm_exidx_section && arm_extab_section && symbol_data != NO_CFI) {
+    info->LoadedSection(".ARM.exidx");
+    info->LoadedSection(".ARM.extab");
+    bool result = LoadARMexidx<ElfClass>(elf_header,
+                                         arm_exidx_section, arm_extab_section,
+                                         loading_addr, module);
+    found_usable_info = found_usable_info || result;
+    if (result)
+      BPLOG(INFO) << "LoadSymbols:   read EXIDX from .ARM.{exidx,extab}";
+  }
+
   if (!found_debug_info_section && symbol_data != ONLY_CFI) {
     fprintf(stderr, "%s: file contains no debugging information"
             " (no \".stab\" or \".debug_info\" sections)\n",
             obj_file.c_str());
 
     // Failed, but maybe there's a .gnu_debuglink section?
     if (read_gnu_debug_link) {
       const Shdr* gnu_debuglink_section
--- a/toolkit/crashreporter/google-breakpad/src/common/module.cc
+++ b/toolkit/crashreporter/google-breakpad/src/common/module.cc
@@ -253,17 +253,17 @@ void Module::AssignSourceIds() {
 
 bool Module::ReportError() {
   fprintf(stderr, "error writing symbol file: %s\n",
           strerror(errno));
   return false;
 }
 
 std::ostream& operator<<(std::ostream& stream, const Module::Expr& expr) {
-  assert(!expr.invalid());
+  assert(!expr.isExprInvalid());
   switch (expr.how_) {
     case Module::kExprSimple:
       stream << expr.ident_ << " " << expr.offset_ << " +";
       break;
     case Module::kExprSimpleMem:
       stream << expr.ident_ << " " << expr.offset_ << " + ^";
       break;
     case Module::kExprPostfix:
--- a/toolkit/crashreporter/google-breakpad/src/common/module.h
+++ b/toolkit/crashreporter/google-breakpad/src/common/module.h
@@ -160,17 +160,24 @@ class Module {
     }
     // Construct an invalid expression
     Expr() {
       postfix_ = "";
       ident_ = NULL;
       offset_ = 0;
       how_ = kExprInvalid;
     }
-    bool invalid() const { return how_ == kExprInvalid; }
+    bool isExprInvalid() const { return how_ == kExprInvalid; }
+    bool isExprPostfix() const { return how_ == kExprPostfix; }
+
+    // Return the postfix expression string.  This is only
+    // meaningful on Exprs for which isExprPostfix returns true.
+    // In all other cases it returns an empty string.
+    string getExprPostfix() const { return postfix_; }
+
     bool operator==(const Expr& other) const {
       return how_ == other.how_ &&
           ident_ == other.ident_ &&
           offset_ == other.offset_ &&
           postfix_ == other.postfix_;
     }
 
     // The identifier that gives the starting value for simple expressions.
--- a/toolkit/crashreporter/google-breakpad/src/common/moz.build
+++ b/toolkit/crashreporter/google-breakpad/src/common/moz.build
@@ -26,16 +26,18 @@ if CONFIG['OS_TARGET'] != 'WINNT':
         'md5.cc',
         'dwarf/bytereader.cc',
         'dwarf_cfi_to_module.cc',
         'dwarf/dwarf2reader.cc',
         'dwarf_cu_to_module.cc',
         'language.cc',
         'dwarf/dwarf2diehandler.cc',
         'dwarf_line_to_module.cc',
+        'arm_ex_reader.cc',
+        'arm_ex_to_module.cc',
     ]
 
 if CONFIG['OS_ARCH'] == 'Linux':
     CPP_SOURCES += [
         'linux/dump_symbols.cc',
         'linux/elf_symbols_to_module.cc',
     ]
 
--- a/toolkit/crashreporter/google-breakpad/src/common/unique_string.h
+++ b/toolkit/crashreporter/google-breakpad/src/common/unique_string.h
@@ -230,16 +230,37 @@ inline static const UniqueString* ustr__
 
 // ".ra"
 inline static const UniqueString* ustr__ZDra() {
   static const UniqueString* us = NULL;
   if (!us) us = ToUniqueString(".ra");
   return us;
 }
 
+// "pc"
+inline static const UniqueString* ustr__pc() {
+  static const UniqueString* us = NULL;
+  if (!us) us = ToUniqueString("pc");
+  return us;
+}
+
+// "lr"
+inline static const UniqueString* ustr__lr() {
+  static const UniqueString* us = NULL;
+  if (!us) us = ToUniqueString("lr");
+  return us;
+}
+
+// "sp"
+inline static const UniqueString* ustr__sp() {
+  static const UniqueString* us = NULL;
+  if (!us) us = ToUniqueString("sp");
+  return us;
+}
+
 template <typename ValueType>
 class UniqueStringMap
 {
  private:
   static const int N_FIXED = 10;
 
  public:
   UniqueStringMap() : n_fixed_(0), n_sets_(0), n_gets_(0), n_clears_(0) {};
--- a/toolkit/crashreporter/google-breakpad/src/processor/cfi_frame_info.cc
+++ b/toolkit/crashreporter/google-breakpad/src/processor/cfi_frame_info.cc
@@ -49,17 +49,17 @@ namespace google_breakpad {
 #endif
 
 template<typename V>
 bool CFIFrameInfo::FindCallerRegs(const RegisterValueMap<V> &registers,
                                   const MemoryRegion &memory,
                                   RegisterValueMap<V> *caller_registers) const {
   // If there are not rules for both .ra and .cfa in effect at this address,
   // don't use this CFI data for stack walking.
-  if (cfa_rule_.invalid() || ra_rule_.invalid())
+  if (cfa_rule_.isExprInvalid() || ra_rule_.isExprInvalid())
     return false;
 
   RegisterValueMap<V> working;
   PostfixEvaluator<V> evaluator(&working, &memory);
 
   caller_registers->clear();
 
   // First, compute the CFA.
@@ -100,20 +100,20 @@ template bool CFIFrameInfo::FindCallerRe
 template bool CFIFrameInfo::FindCallerRegs<uint64_t>(
     const RegisterValueMap<uint64_t> &registers,
     const MemoryRegion &memory,
     RegisterValueMap<uint64_t> *caller_registers) const;
 
 string CFIFrameInfo::Serialize() const {
   std::ostringstream stream;
 
-  if (!cfa_rule_.invalid()) {
+  if (!cfa_rule_.isExprInvalid()) {
     stream << ".cfa: " << cfa_rule_;
   }
-  if (!ra_rule_.invalid()) {
+  if (!ra_rule_.isExprInvalid()) {
     if (static_cast<std::streamoff>(stream.tellp()) != 0)
       stream << " ";
     stream << ".ra: " << ra_rule_;
   }
 
   // Visit the register rules in alphabetical order.  Because
   // register_rules_ has the elements in some arbitrary order,
   // get the names out into a vector, sort them, and visit in