[AArch64][libunwind] Unwinding support for return address signing with B Key

- Support for the case where the return address has been signed with the B key
- When the B key is used, a 'B' character is present in the augmentation string
  of CIE associated with the FDE for the function.

Differential Revision: https://reviews.llvm.org/D55704

llvm-svn: 349339

1 files changed, 11 insertions, 0 deletions

diff --git a/libunwind/src/DwarfParser.hpp b/libunwind/src/DwarfParser.hpp
index 68506a35053..9de2898c075 100644
--- a/libunwind/src/DwarfParser.hpp
+++ b/libunwind/src/DwarfParser.hpp
@@ -49,6 +49,9 @@ public:
     bool      isSignalFrame;
     bool      fdesHaveAugmentationData;
     uint8_t   returnAddressRegister;
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+    bool      addressesSignedWithBKey;
+#endif
   };
 
   /// Information about an FDE (Frame Description Entry)
@@ -263,6 +266,9 @@ const char *CFI_Parser<A>::parseCIE(A &addressSpace, pint_t cie,
   cieInfo->dataAlignFactor = 0;
   cieInfo->isSignalFrame = false;
   cieInfo->fdesHaveAugmentationData = false;
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+  cieInfo->addressesSignedWithBKey = false;
+#endif
   cieInfo->cieStart = cie;
   pint_t p = cie;
   pint_t cieLength = (pint_t)addressSpace.get32(p);
@@ -326,6 +332,11 @@ const char *CFI_Parser<A>::parseCIE(A &addressSpace, pint_t cie,
       case 'S':
         cieInfo->isSignalFrame = true;
         break;
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+      case 'B':
+        cieInfo->addressesSignedWithBKey = true;
+        break;
+#endif
       default:
         // ignore unknown letters
         break;