Disable return PAC in __pthread_start.

This function doesn't return, but it does appear in stack traces. Avoid
using return PAC in this function because we may end up resetting IA,
which may confuse unwinders due to mismatching keys.

Bug: 189808795
Change-Id: I953da9078acd1d43eb7a47fb11f75caa0099fa12
(cherry picked from commit 26d83ba7abcbfa725794c144411214d16f64b75a)
CRs-Fixed:2965421

1 files changed, 19 insertions, 4 deletions

diff --git a/tests/stack_unwinding_test.cpp b/tests/stack_unwinding_test.cpp
index 0ff6f30a6..2f891a6e1 100644
--- a/tests/stack_unwinding_test.cpp
+++ b/tests/stack_unwinding_test.cpp
@@ -66,13 +66,28 @@ static int noinline unwind_one_frame_deeper() {
   return count;
 }
 
-TEST(stack_unwinding, easy) {
+static void UnwindTest() {
   int count = 0;
   _Unwind_Backtrace(FrameCounter, &count);
   int deeper_count = unwind_one_frame_deeper();
   ASSERT_EQ(count + 1, deeper_count);
 }
 
+TEST(stack_unwinding, easy) {
+  UnwindTest();
+}
+
+TEST(stack_unwinding, thread) {
+  pthread_t thread;
+  ASSERT_EQ(0, pthread_create(&thread, nullptr, [](void*) -> void* {
+    UnwindTest();
+    return nullptr;
+  }, nullptr));
+  void *retval;
+  ASSERT_EQ(0, pthread_join(thread, &retval));
+  EXPECT_EQ(nullptr, retval);
+}
+
 struct UnwindData {
   volatile bool signal_handler_complete = false;
   int expected_frame_count = 0;
@@ -98,7 +113,7 @@ static void verify_unwind_data(const UnwindData& unwind_data) {
   EXPECT_EQ(unwind_data.handler_frame_count + 1, unwind_data.handler_one_deeper_frame_count);
 }
 
-static void noinline UnwindTest() {
+static void noinline SignalUnwindTest() {
   g_unwind_data = {};
 
   _Unwind_Backtrace(FrameCounter, &g_unwind_data.expected_frame_count);
@@ -114,12 +129,12 @@ static void noinline UnwindTest() {
 TEST(stack_unwinding, unwind_through_signal_frame) {
   ScopedSignalHandler ssh(SIGUSR1, UnwindSignalHandler);
 
-  UnwindTest();
+  SignalUnwindTest();
 }
 
 // On LP32, the SA_SIGINFO flag gets you __restore_rt instead of __restore.
 TEST(stack_unwinding, unwind_through_signal_frame_SA_SIGINFO) {
   ScopedSignalHandler ssh(SIGUSR1, UnwindSignalHandler, SA_SIGINFO);
 
-  UnwindTest();
+  SignalUnwindTest();
 }