[libunwind] r349339 - [AArch64][libunwind] Unwinding support for return address signing with B Key

[Luke Cheeseman via cfe-commits]

Author: lukecheeseman
Date: Mon Dec 17 03:43:24 2018
New Revision: 349339

URL: http://llvm.org/viewvc/llvm-project?rev=349339&view=rev
Log:
[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


Modified:
    libunwind/trunk/src/DwarfInstructions.hpp
    libunwind/trunk/src/DwarfParser.hpp

Modified: libunwind/trunk/src/DwarfInstructions.hpp
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/DwarfInstructions.hpp?rev=349339&r1=349338&r2=349339&view=diff
==============================================================================
--- libunwind/trunk/src/DwarfInstructions.hpp (original)
+++ libunwind/trunk/src/DwarfInstructions.hpp Mon Dec 17 03:43:24 2018
@@ -211,9 +211,13 @@ int DwarfInstructions<A, R>::stepWithDwa
         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
       }

Modified: libunwind/trunk/src/DwarfParser.hpp
URL: http://llvm.org/viewvc/llvm-project/libunwind/trunk/src/DwarfParser.hpp?rev=349339&r1=349338&r2=349339&view=diff
==============================================================================
--- libunwind/trunk/src/DwarfParser.hpp (original)
+++ libunwind/trunk/src/DwarfParser.hpp Mon Dec 17 03:43:24 2018
@@ -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 &a
   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 &a
       case 'S':
         cieInfo->isSignalFrame = true;
         break;
+#if defined(_LIBUNWIND_TARGET_AARCH64)
+      case 'B':
+        cieInfo->addressesSignedWithBKey = true;
+        break;
+#endif
       default:
         // ignore unknown letters
         break;