Use elf offset in signal step check.

The function StepIfSignalHandler assumed that the rel_pc passed
to it was actually an elf offset. A new version of clang created a libc.so
that has a load bias, so tests unwinding through a signal handler
would fail on arm. On other ABIs, there is unwind information that could
be used instead, so the unwind still worked.

The fix is to subtract the load bias from the rel_pc to get an elf
offset to pass to the Register StepIfSignalHandler functions. Change all
of the Register funtions to make it clear what the first parameter means.

Add a unit test for this new code. Also, add an offline test for
this case.

Bug: 145683525

Test: Ran unit tests using the new clang and the old clang.
Change-Id: I3e249653b79bcad6d3a56411a7911fde4888e9d6

1 files changed, 1 insertions, 1 deletions

diff --git a/libunwindstack/include/unwindstack/RegsX86_64.h b/libunwindstack/include/unwindstack/RegsX86_64.h
index dc9a220..3e919a4 100644
--- a/libunwindstack/include/unwindstack/RegsX86_64.h
+++ b/libunwindstack/include/unwindstack/RegsX86_64.h
@@ -41,7 +41,7 @@ class RegsX86_64 : public RegsImpl<uint64_t> {
 
   bool SetPcFromReturnAddress(Memory* process_memory) override;
 
-  bool StepIfSignalHandler(uint64_t rel_pc, Elf* elf, Memory* process_memory) override;
+  bool StepIfSignalHandler(uint64_t elf_offset, Elf* elf, Memory* process_memory) override;
 
   void SetFromUcontext(x86_64_ucontext_t* ucontext);