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Commit bc6a7e51 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Fix flaky signal tests. 

The signal tests that send a SIGUSR1 signal to a remote process, can
lead to a case where the code winds up in a location for which the
unwind information is not 100% accurate. This happens near the
end of the atomic functions which manipulate the stack right before
returning, but do not have separate cfi instructions for those last
few instructions.

Add a new test type for the from_context test that will wait explicitly
for the global g_finish and not piggy back on the remote test type.

Bug: 122902885

Test: Ran flaky tests 1000 times without failure on a taimen.
Change-Id: I7d0c9b016e3a3a2c0c0949cf74af11d7785a008c
parent b26b07d8

libunwindstack/tests/UnwindTest.cpp

+15 −3
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ namespace unwindstack { 
enum TestTypeEnum : uint8_t {

  TEST_TYPE_LOCAL_UNWINDER = 0,

  TEST_TYPE_LOCAL_UNWINDER_FROM_PID,

  TEST_TYPE_LOCAL_WAIT_FOR_FINISH,

  TEST_TYPE_REMOTE,

  TEST_TYPE_REMOTE_WITH_INVALID_CALL,

};
@@ -79,7 +80,10 @@ static void SignalHandler(int, siginfo_t*, void* sigcontext) { 


extern "C" void SignalInnerFunction() {

  g_signal_ready_for_remote = true;

  while (!g_finish.load()) {

  // Avoid any function calls because not every instruction will be

  // unwindable.

  // This method of looping is only used when testing a remote unwind.

  while (true) {

  }

}
@@ -134,6 +138,11 @@ static void VerifyUnwind(pid_t pid, Maps* maps, Regs* regs, 
// off. If this doesn't happen, then all of the calls will be optimized

// away.

extern "C" void InnerFunction(TestTypeEnum test_type) {

  if (test_type == TEST_TYPE_LOCAL_WAIT_FOR_FINISH) {

    while (!g_finish.load()) {

    }

    return;

  }

  if (test_type == TEST_TYPE_REMOTE || test_type == TEST_TYPE_REMOTE_WITH_INVALID_CALL) {

    g_ready_for_remote = true;

    g_ready = true;
@@ -141,7 +150,10 @@ extern "C" void InnerFunction(TestTypeEnum test_type) { 
      void (*crash_func)() = nullptr;

      crash_func();

    }

    while (!g_finish.load()) {

    // Avoid any function calls because not every instruction will be

    // unwindable.

    // This method of looping is only used when testing a remote unwind.

    while (true) {

    }

    return;

  }
@@ -271,7 +283,7 @@ TEST_F(UnwindTest, from_context) { 
  std::atomic_int tid(0);

  std::thread thread([&]() {

    tid = syscall(__NR_gettid);

    OuterFunction(TEST_TYPE_REMOTE);

    OuterFunction(TEST_TYPE_LOCAL_WAIT_FOR_FINISH);

  });



  struct sigaction act, oldact;