[compiler-rt] d179627 - Fix sanitizer stack traces on aarch64.

[Roy Sundahl via llvm-commits]

Author: Roy Sundahl
Date: 2022-04-21T14:27:59-07:00
New Revision: d179627ef012f061a9186c9f026a3f0ec771c3e9

URL: https://github.com/llvm/llvm-project/commit/d179627ef012f061a9186c9f026a3f0ec771c3e9
DIFF: https://github.com/llvm/llvm-project/commit/d179627ef012f061a9186c9f026a3f0ec771c3e9.diff

LOG: Fix sanitizer stack traces on aarch64.

Fixes llvm-project/compiler-rt/test/asan/TestCases/null_deref.cpp on
macOS/aarch64.

The bp (base pointer) variable was being loaded from register LR and
not FP on aarch64 (except for this narrow case):
defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_8_0

Without a valid bp from the FP register, it is not possible to traverse
previous frames for a complete stack trace. The rationale for fetching
the LR as the bp for all cases except above is not clear but since the
FP register is the canonical register for use as the frame pointer, this
commit removes the restriction above for unconditional use all aarch64.

rdar://91587039

Differential Revision: https://reviews.llvm.org/D124140

Added: 
    

Modified: 
    compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
index 41b90b9f35802..05512a576ad13 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp
@@ -903,11 +903,7 @@ static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   ucontext_t *ucontext = (ucontext_t*)context;
 # if defined(__aarch64__)
   *pc = AARCH64_GET_REG(pc);
-#   if defined(__IPHONE_8_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_8_0
   *bp = AARCH64_GET_REG(fp);
-#   else
-  *bp = AARCH64_GET_REG(lr);
-#   endif
   *sp = AARCH64_GET_REG(sp);
 # elif defined(__x86_64__)
   *pc = ucontext->uc_mcontext->__ss.__rip;