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diff --git a/toolkit/crashreporter/google-breakpad/src/processor/stackwalker_arm64.cc b/toolkit/crashreporter/google-breakpad/src/processor/stackwalker_arm64.cc
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+// Copyright (c) 2013 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.
+
+// stackwalker_arm64.cc: arm64-specific stackwalker.
+//
+// See stackwalker_arm64.h for documentation.
+//
+// Author: Mark Mentovai, Ted Mielczarek, Jim Blandy, Colin Blundell
+
+#include <vector>
+
+#include "common/scoped_ptr.h"
+#include "google_breakpad/processor/call_stack.h"
+#include "google_breakpad/processor/memory_region.h"
+#include "google_breakpad/processor/source_line_resolver_interface.h"
+#include "google_breakpad/processor/stack_frame_cpu.h"
+#include "processor/cfi_frame_info.h"
+#include "processor/logging.h"
+#include "processor/stackwalker_arm64.h"
+
+namespace google_breakpad {
+
+
+StackwalkerARM64::StackwalkerARM64(const SystemInfo* system_info,
+                                   const MDRawContextARM64* context,
+                                   MemoryRegion* memory,
+                                   const CodeModules* modules,
+                                   StackFrameSymbolizer* resolver_helper)
+    : Stackwalker(system_info, memory, modules, resolver_helper),
+      context_(context),
+      context_frame_validity_(StackFrameARM64::CONTEXT_VALID_ALL),
+      address_range_mask_(0xffffffffffffffff) {
+  if (modules && modules->module_count() > 0) {
+    // ARM64 supports storing pointer authentication codes in the upper bits of
+    // a pointer. Make a best guess at the range of valid addresses based on the
+    // range of loaded modules.
+    const CodeModule *high_module =
+        modules->GetModuleAtSequence(modules->module_count() - 1);
+    uint64_t mask = high_module->base_address() + high_module->size();
+    mask |= mask >> 1;
+    mask |= mask >> 2;
+    mask |= mask >> 4;
+    mask |= mask >> 8;
+    mask |= mask >> 16;
+    mask |= mask >> 32;
+    address_range_mask_ = mask;
+  }
+}
+
+uint64_t StackwalkerARM64::PtrauthStrip(uint64_t ptr) {
+  uint64_t stripped = ptr & address_range_mask_;
+  return modules_ && modules_->GetModuleForAddress(stripped) ? stripped : ptr;
+}
+
+StackFrame* StackwalkerARM64::GetContextFrame() {
+  if (!context_) {
+    BPLOG(ERROR) << "Can't get context frame without context";
+    return NULL;
+  }
+
+  StackFrameARM64* frame = new StackFrameARM64();
+
+  // The instruction pointer is stored directly in a register (x32), so pull it
+  // straight out of the CPU context structure.
+  frame->context = *context_;
+  frame->context_validity = context_frame_validity_;
+  frame->trust = StackFrame::FRAME_TRUST_CONTEXT;
+  frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC];
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_LR] =
+      PtrauthStrip(frame->context.iregs[MD_CONTEXT_ARM64_REG_LR]);
+
+  return frame;
+}
+
+StackFrameARM64* StackwalkerARM64::GetCallerByCFIFrameInfo(
+    const vector<StackFrame*> &frames,
+    CFIFrameInfo* cfi_frame_info) {
+  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
+
+  static const char* register_names[] = {
+    "x0",  "x1",  "x2",  "x3",  "x4",  "x5",  "x6",  "x7",
+    "x8",  "x9",  "x10", "x11", "x12", "x13", "x14", "x15",
+    "x16", "x17", "x18", "x19", "x20", "x21", "x22", "x23",
+    "x24", "x25", "x26", "x27", "x28", "x29", "x30", "sp",
+    "pc",  NULL
+  };
+
+  // Populate a dictionary with the valid register values in last_frame.
+  CFIFrameInfo::RegisterValueMap<uint64_t> callee_registers;
+  for (int i = 0; register_names[i]; i++) {
+    if (last_frame->context_validity & StackFrameARM64::RegisterValidFlag(i))
+      callee_registers[register_names[i]] = last_frame->context.iregs[i];
+  }
+
+  // Use the STACK CFI data to recover the caller's register values.
+  CFIFrameInfo::RegisterValueMap<uint64_t> caller_registers;
+  if (!cfi_frame_info->FindCallerRegs(callee_registers, *memory_,
+                                      &caller_registers)) {
+    return NULL;
+  }
+  // Construct a new stack frame given the values the CFI recovered.
+  scoped_ptr<StackFrameARM64> frame(new StackFrameARM64());
+  for (int i = 0; register_names[i]; i++) {
+    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
+      caller_registers.find(register_names[i]);
+    if (entry != caller_registers.end()) {
+      // We recovered the value of this register; fill the context with the
+      // value from caller_registers.
+      frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
+      frame->context.iregs[i] = entry->second;
+    } else if (19 <= i && i <= 29 && (last_frame->context_validity &
+                                      StackFrameARM64::RegisterValidFlag(i))) {
+      // If the STACK CFI data doesn't mention some callee-saves register, and
+      // it is valid in the callee, assume the callee has not yet changed it.
+      // Registers r19 through r29 are callee-saves, according to the Procedure
+      // Call Standard for the ARM AARCH64 Architecture, which the Linux ABI
+      // follows.
+      frame->context_validity |= StackFrameARM64::RegisterValidFlag(i);
+      frame->context.iregs[i] = last_frame->context.iregs[i];
+    }
+  }
+  // If the CFI doesn't recover the PC explicitly, then use .ra.
+  if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_PC)) {
+    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
+      caller_registers.find(".ra");
+    if (entry != caller_registers.end()) {
+      frame->context_validity |= StackFrameARM64::CONTEXT_VALID_PC;
+      frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = entry->second;
+    }
+  }
+  // If the CFI doesn't recover the SP explicitly, then use .cfa.
+  if (!(frame->context_validity & StackFrameARM64::CONTEXT_VALID_SP)) {
+    CFIFrameInfo::RegisterValueMap<uint64_t>::iterator entry =
+      caller_registers.find(".cfa");
+    if (entry != caller_registers.end()) {
+      frame->context_validity |= StackFrameARM64::CONTEXT_VALID_SP;
+      frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = entry->second;
+    }
+  }
+
+  // If we didn't recover the PC and the SP, then the frame isn't very useful.
+  static const uint64_t essentials = (StackFrameARM64::CONTEXT_VALID_SP
+                                     | StackFrameARM64::CONTEXT_VALID_PC);
+  if ((frame->context_validity & essentials) != essentials)
+    return NULL;
+
+  frame->trust = StackFrame::FRAME_TRUST_CFI;
+  return frame.release();
+}
+
+StackFrameARM64* StackwalkerARM64::GetCallerByStackScan(
+    const vector<StackFrame*> &frames) {
+  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
+  uint64_t last_sp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];
+  uint64_t caller_sp, caller_pc;
+
+  if (!ScanForReturnAddress(last_sp, &caller_sp, &caller_pc,
+                            frames.size() == 1 /* is_context_frame */)) {
+    // No plausible return address was found.
+    return NULL;
+  }
+
+  // ScanForReturnAddress found a reasonable return address. Advance
+  // %sp to the location above the one where the return address was
+  // found.
+  caller_sp += 8;
+
+  // Create a new stack frame (ownership will be transferred to the caller)
+  // and fill it in.
+  StackFrameARM64* frame = new StackFrameARM64();
+
+  frame->trust = StackFrame::FRAME_TRUST_SCAN;
+  frame->context = last_frame->context;
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] = caller_pc;
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
+  frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
+                            StackFrameARM64::CONTEXT_VALID_SP;
+
+  return frame;
+}
+
+StackFrameARM64* StackwalkerARM64::GetCallerByFramePointer(
+    const vector<StackFrame*> &frames) {
+  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
+  if (!(last_frame->context_validity & StackFrameARM64::CONTEXT_VALID_LR)) {
+    CorrectRegLRByFramePointer(frames, last_frame);
+  }
+
+  uint64_t last_fp = last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP];
+
+  uint64_t caller_fp = 0;
+  if (last_fp && !memory_->GetMemoryAtAddress(last_fp, &caller_fp)) {
+    BPLOG(ERROR) << "Unable to read caller_fp from last_fp: 0x"
+                 << std::hex << last_fp;
+    return NULL;
+  }
+
+  uint64_t caller_lr = 0;
+  if (last_fp && !memory_->GetMemoryAtAddress(last_fp + 8, &caller_lr)) {
+    BPLOG(ERROR) << "Unable to read caller_lr from last_fp + 8: 0x"
+                 << std::hex << (last_fp + 8);
+    return NULL;
+  }
+
+  caller_lr = PtrauthStrip(caller_lr);
+
+  uint64_t caller_sp = last_fp ? last_fp + 16 :
+      last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP];
+
+  // Create a new stack frame (ownership will be transferred to the caller)
+  // and fill it in.
+  StackFrameARM64* frame = new StackFrameARM64();
+
+  frame->trust = StackFrame::FRAME_TRUST_FP;
+  frame->context = last_frame->context;
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_FP] = caller_fp;
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_SP] = caller_sp;
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] =
+      last_frame->context.iregs[MD_CONTEXT_ARM64_REG_LR];
+  frame->context.iregs[MD_CONTEXT_ARM64_REG_LR] = caller_lr;
+  frame->context_validity = StackFrameARM64::CONTEXT_VALID_PC |
+                            StackFrameARM64::CONTEXT_VALID_LR |
+                            StackFrameARM64::CONTEXT_VALID_FP |
+                            StackFrameARM64::CONTEXT_VALID_SP;
+  return frame;
+}
+
+void StackwalkerARM64::CorrectRegLRByFramePointer(
+    const vector<StackFrame*>& frames,
+    StackFrameARM64* last_frame) {
+  // Need at least two frames to correct and
+  // register $FP should always be greater than register $SP.
+  if (frames.size() < 2 || !last_frame ||
+      last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP] <=
+          last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP])
+    return;
+
+  StackFrameARM64* last_last_frame =
+      static_cast<StackFrameARM64*>(*(frames.end() - 2));
+  uint64_t last_last_fp =
+      last_last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP];
+
+  uint64_t last_fp = 0;
+  if (last_last_fp && !memory_->GetMemoryAtAddress(last_last_fp, &last_fp)) {
+    BPLOG(ERROR) << "Unable to read last_fp from last_last_fp: 0x"
+                 << std::hex << last_last_fp;
+    return;
+  }
+  // Give up if STACK CFI doesn't agree with frame pointer.
+  if (last_frame->context.iregs[MD_CONTEXT_ARM64_REG_FP] != last_fp)
+    return;
+
+  uint64_t last_lr = 0;
+  if (last_last_fp && !memory_->GetMemoryAtAddress(last_last_fp + 8, &last_lr)) {
+    BPLOG(ERROR) << "Unable to read last_lr from (last_last_fp + 8): 0x"
+                 << std::hex << (last_last_fp + 8);
+    return;
+  }
+  last_lr = PtrauthStrip(last_lr);
+
+  last_frame->context.iregs[MD_CONTEXT_ARM64_REG_LR] = last_lr;
+}
+
+bool StackwalkerARM64::ValidInstructionPointerInFrame(const StackFrameARM64& frame) {
+  const uint64_t ip = frame.context.iregs[MD_CONTEXT_ARM64_REG_PC];
+
+  if ((ip < 0x1000) || (ip > 0x000fffffffffffff)) {
+    // The IP points into the first page or above the user space threshold
+    return false;
+  }
+
+  return true;
+}
+
+StackFrame* StackwalkerARM64::GetCallerFrame(const CallStack* stack,
+                                             bool stack_scan_allowed) {
+  if (!memory_ || !stack) {
+    BPLOG(ERROR) << "Can't get caller frame without memory or stack";
+    return NULL;
+  }
+
+  const vector<StackFrame*> &frames = *stack->frames();
+  StackFrameARM64* last_frame = static_cast<StackFrameARM64*>(frames.back());
+  scoped_ptr<StackFrameARM64> frame;
+
+  // See if there is DWARF call frame information covering this address.
+  scoped_ptr<CFIFrameInfo> cfi_frame_info(
+      frame_symbolizer_->FindCFIFrameInfo(last_frame));
+  if (cfi_frame_info.get())
+    frame.reset(GetCallerByCFIFrameInfo(frames, cfi_frame_info.get()));
+
+  // If CFI failed, or there wasn't CFI available, fall back to frame pointer.
+  if (!frame.get() || !ValidInstructionPointerInFrame(*frame))
+    frame.reset(GetCallerByFramePointer(frames));
+
+  // If everything failed, fall back to stack scanning.
+  if (stack_scan_allowed &&
+      (!frame.get() || !ValidInstructionPointerInFrame(*frame)))
+    frame.reset(GetCallerByStackScan(frames));
+
+  // If nothing worked, tell the caller.
+  if (!frame.get())
+    return NULL;
+
+  // Should we terminate the stack walk? (end-of-stack or broken invariant)
+  if (TerminateWalk(frame->context.iregs[MD_CONTEXT_ARM64_REG_PC],
+                    frame->context.iregs[MD_CONTEXT_ARM64_REG_SP],
+                    last_frame->context.iregs[MD_CONTEXT_ARM64_REG_SP],
+                    frames.size() == 1)) {
+    return NULL;
+  }
+
+  // The new frame's context's PC is the return address, which is one
+  // instruction past the instruction that caused us to arrive at the callee.
+  // ARM64 instructions have a uniform 4-byte encoding, so subtracting 4 off
+  // the return address gets back to the beginning of the call instruction.
+  // Callers that require the exact return address value may access
+  // frame->context.iregs[MD_CONTEXT_ARM64_REG_PC].
+  frame->instruction = frame->context.iregs[MD_CONTEXT_ARM64_REG_PC] - 4;
+
+  return frame.release();
+}
+
+
+}  // namespace google_breakpad