arm64: don't interpret DW_CFA_GNU_window_save

DW_CFA_AARCH64_negate_ra_state uses the same encoding as
DW_CFA_GNU_window_save. It is meant to indicate that x30/LR
has been signed, but breakpad does not require this information.

Bug: b/239086293
Change-Id: I5a17bd5e0673a3ff80a8c6e347013d66054314e8
Reviewed-on: https://chromium-review.googlesource.com/c/breakpad/breakpad/+/3781136
Reviewed-by: Mark Mentovai <mark@chromium.org>

src/common/dwarf/dwarf2reader.cc

@@ -2721,12 +2721,20 @@ bool CallFrameInfo::State::DoInstruction() {
     case DW_CFA_nop:
       break;
 
+    // case DW_CFA_AARCH64_negate_ra_state
+    case DW_CFA_GNU_window_save: {
+      if (handler_->Architecture() == "arm64") {
+        // Indicates that the return address, x30 has been signed.
+        // Breakpad will speculatively remove pointer-authentication codes when
+        // interpreting return addresses, regardless of this bit.
+      } else if (handler_->Architecture() == "sparc" ||
+                 handler_->Architecture() == "sparcv9") {
         // A SPARC register window save: Registers 8 through 15 (%o0-%o7)
         // are saved in registers 24 through 31 (%i0-%i7), and registers
         // 16 through 31 (%l0-%l7 and %i0-%i7) are saved at CFA offsets
         // (0-15 * the register size). The register numbers must be
         // hard-coded. A GNU extension, and not a pretty one.
-    case DW_CFA_GNU_window_save: {
+
         // Save %o0-%o7 in %i0-%i7.
         for (int i = 8; i < 16; i++)
           if (!DoRule(i, new RegisterRule(i + 16)))
@@ -2738,6 +2746,7 @@ bool CallFrameInfo::State::DoInstruction() {
           if (!DoRule(i, new OffsetRule(Handler::kCFARegister,
                                         (i - 16) * reader_->AddressSize())))
             return false;
+      }
       break;
     }
 

src/common/dwarf/dwarf2reader.h

@@ -1332,6 +1332,9 @@ class CallFrameInfo::Handler {
   // should stop.
   virtual bool End() = 0;
 
+  // The target architecture for the data.
+  virtual string Architecture() = 0;
+
   // Handler functions for Linux C++ exception handling data. These are
   // only called if the data includes 'z' augmentation strings.
 

src/common/dwarf/dwarf2reader_cfi_unittest.cc

@@ -114,6 +114,7 @@ class MockCallFrameInfoHandler: public CallFrameInfo::Handler {
   MOCK_METHOD3(ValExpressionRule, bool(uint64_t address, int reg,
                                        const string& expression));
   MOCK_METHOD0(End, bool());
+  MOCK_METHOD0(Architecture, string());
   MOCK_METHOD2(PersonalityRoutine, bool(uint64_t address, bool indirect));
   MOCK_METHOD2(LanguageSpecificDataArea, bool(uint64_t address, bool indirect));
   MOCK_METHOD0(SignalHandler, bool());
@@ -1539,6 +1540,8 @@ TEST_F(CFIInsn, DW_CFA_GNU_window_save) {
       .D8(google_breakpad::DW_CFA_GNU_window_save)
       .FinishEntry();
 
+  EXPECT_CALL(handler, Architecture()).WillRepeatedly(Return("sparc"));
+
   // Don't include all the rules in any particular sequence.
 
   // The caller's %o0-%o7 have become the callee's %i0-%i7. This is

src/common/dwarf_cfi_to_module.cc

@@ -264,6 +264,10 @@ bool DwarfCFIToModule::End() {
   return true;
 }
 
+string DwarfCFIToModule::Architecture() {
+  return module_->architecture();
+}
+
 void DwarfCFIToModule::Reporter::UnnamedRegister(size_t offset, int reg) {
   fprintf(stderr, "%s, section '%s': "
           "the call frame entry at offset 0x%zx refers to register %d,"

src/common/dwarf_cfi_to_module.h

@@ -152,6 +152,8 @@ class DwarfCFIToModule: public CallFrameInfo::Handler {
                                  const string& expression);
   virtual bool End();
 
+  virtual string Architecture();
+
  private:
   // Return the name to use for register REG.
   string RegisterName(int i);