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NPL: Fix one more bug in the single step workaround

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In the case we are stepping over the thread creation instruction, we
will end up calling Thread::SingleStep back-to-back twice (because of
the intermediate PTRACE_EVENT_CLONE stop). This will cause the cpu mask
to be set inappropriately (because the old SingleStepCheck object will
be destroyed after we create the new one), and the single-step will
fail.

Before the refactor the code was still incorrect in this case, but in a
different way (the thread was left with the incorrect mask after the
stepping was complete), so this was not easy to spot.

This fixes TestCreateDuringInstructionStep on the affected devices.

llvm-svn: 295440
This commit is contained in:
Pavel Labath 2017-02-17 11:48:34 +00:00
parent 7cab0786bd
commit a37bbbd432
3 changed files with 10 additions and 6 deletions
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5
lldb/packages/Python/lldbsuite/test/linux/thread/create_during_instruction_step/TestCreateDuringInstructionStep.py
View File

@ -16,10 +16,7 @@ from lldbsuite.test import lldbutil
class CreateDuringInstructionStepTestCase(TestBase):
mydir = TestBase.compute_mydir(__file__)
def setUp(self):
# Call super's setUp().
TestBase.setUp(self)
NO_DEBUG_INFO_TESTCASE = True
@skipUnlessPlatform(['linux'])
@expectedFailureAndroid('llvm.org/pr24737', archs=['arm'])

8
lldb/source/Plugins/Process/Linux/NativeThreadLinux.cpp
View File

@ -225,7 +225,13 @@ Error NativeThreadLinux::SingleStep(uint32_t signo) {
MaybeLogStateChange(new_state);
m_state = new_state;
m_stop_info.reason = StopReason::eStopReasonNone;
m_step_workaround = SingleStepWorkaround::Get(m_tid);
if(!m_step_workaround) {
// If we already hava a workaround inplace, don't reset it. Otherwise, the
// destructor of the existing instance will run after the new instance has
// fetched the cpu mask, and the thread will end up with the wrong mask.
m_step_workaround = SingleStepWorkaround::Get(m_tid);
}
intptr_t data = 0;
if (signo != LLDB_INVALID_SIGNAL_NUMBER)

3
lldb/source/Plugins/Process/Linux/SingleStepCheck.cpp
View File

@ -172,8 +172,9 @@ std::unique_ptr<SingleStepWorkaround> SingleStepWorkaround::Get(::pid_t tid) {
}
SingleStepWorkaround::~SingleStepWorkaround() {
Log *log = ProcessPOSIXLog::GetLogIfAllCategoriesSet(POSIX_LOG_THREAD);
LLDB_LOG(log, "Removing workaround");
if (sched_setaffinity(m_tid, sizeof m_original_set, &m_original_set) != 0) {
Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_THREAD));
LLDB_LOG(log, "Unable to reset cpu affinity for thread {0}: {1}", m_tid,
Error(errno, eErrorTypePOSIX));
}