2 files changed, 33 insertions, 1 deletions
diff --git a/src/processor/stackwalker_arm64.cc b/src/processor/stackwalker_arm64.cc
index f9660112..47e245ed 100644
--- a/src/processor/stackwalker_arm64.cc
+++ b/src/processor/stackwalker_arm64.cc
@@ -54,8 +54,29 @@ StackwalkerARM64::StackwalkerARM64(const SystemInfo* system_info,
                                    StackFrameSymbolizer* resolver_helper)
     : Stackwalker(system_info, memory, modules, resolver_helper),
       context_(context),
-      context_frame_validity_(StackFrameARM64::CONTEXT_VALID_ALL) { }
+      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_) {
@@ -71,6 +92,8 @@ StackFrame* StackwalkerARM64::GetContextFrame() {
   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;
 }
@@ -202,6 +225,8 @@ StackFrameARM64* StackwalkerARM64::GetCallerByFramePointer(
     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];
 
diff --git a/src/processor/stackwalker_arm64.h b/src/processor/stackwalker_arm64.h
index 121e8246..241383ea 100644
--- a/src/processor/stackwalker_arm64.h
+++ b/src/processor/stackwalker_arm64.h
@@ -68,6 +68,9 @@ class StackwalkerARM64 : public Stackwalker {
   }
 
  private:
+  // Strip pointer authentication codes from an address.
+  uint64_t PtrauthStrip(uint64_t ptr);
+
   // Implementation of Stackwalker, using arm64 context and stack conventions.
   virtual StackFrame* GetContextFrame();
   virtual StackFrame* GetCallerFrame(const CallStack* stack,
@@ -95,6 +98,10 @@ class StackwalkerARM64 : public Stackwalker {
   // CONTEXT_VALID_ALL in real use; it is only changeable for the sake of
   // unit tests.
   uint64_t context_frame_validity_;
+
+  // A mask of the valid address bits, determined from the address range of
+  // modules_.
+  uint64_t address_range_mask_;
 };