commit 0930d6cee2caf71685a84b648f85a2f80bc182c4
author Luke Cheeseman <luke.cheeseman@arm.com> Mon Dec 17 11:43:24 2018 +0000
committer Luke Cheeseman <luke.cheeseman@arm.com> Mon Dec 17 11:43:24 2018 +0000
tree baa94c4dd56225b4bee5da58607ae96cf3b420a9
parent 96fa50101690f48f0e7a7ffe363a5612d9ecac41

[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



git-svn-id: https://llvm.org/svn/llvm-project/libunwind/trunk@349339 91177308-0d34-0410-b5e6-96231b3b80d8

src/DwarfInstructions.hpp

diff --git a/src/DwarfInstructions.hpp b/src/DwarfInstructions.hpp
index 2bf19c5..1d35b22 100644
--- a/src/DwarfInstructions.hpp
+++ b/src/DwarfInstructions.hpp
@@ -211,9 +211,13 @@
         register unsigned long long x17 __asm("x17") = returnAddress;
         register unsigned long long x16 __asm("x16") = cfa;
 
-        // This is the autia1716 instruction. The hint instruction is used here
-        // as gcc does not assemble autia1716 for pre armv8.3a targets.
-        asm("hint 0xc": "+r"(x17): "r"(x16));
+        // These are the autia1716/autib1716 instructions. The hint instructions
+        // are used here as gcc does not assemble autia1716/autib1716 for pre
+        // armv8.3a targets.
+        if (cieInfo.addressesSignedWithBKey)
+          asm("hint 0xe" : "+r"(x17) : "r"(x16)); // autib1716
+        else
+          asm("hint 0xc" : "+r"(x17) : "r"(x16)); // autia1716
         returnAddress = x17;
 #endif
       }

src/DwarfParser.hpp

diff --git a/src/DwarfParser.hpp b/src/DwarfParser.hpp
index 68506a3..9de2898 100644
--- a/src/DwarfParser.hpp
+++ b/src/DwarfParser.hpp
@@ -49,6 +49,9 @@
     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 @@
   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 @@
       case 'S':
         cieInfo->isSignalFrame = true;
         break;
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+      case 'B':
+        cieInfo->addressesSignedWithBKey = true;
+        break;
+#endif
       default:
         // ignore unknown letters
         break;