[NativeProcessLinux] Fix removal of temporary breakpoints

Summary:
There was an issue in NPL, where we attempted removal of temporary breakpoints (used to implement
software single stepping), while some threads of the process were running. This is a problem
since we currently always use the main thread's ID in the removal ptrace call. Therefore, if the
main thread was still running, the ptrace call would fail, and the software breakpoint would
remain, causing all kinds of problems. This change removes the breakpoints after all threads have
stopped. This fixes TestExitDuringStep on Android arm and can also potentially help in other
situations, as previously the breakpoint would not get removed if the thread stopped for another
reason.

Test Plan: TestExitDuringStep passes, other tests remain unchanged.

Reviewers: tberghammer

Subscribers: tberghammer, aemerson, lldb-commits

Differential Revision: http://reviews.llvm.org/D9792

llvm-svn: 237448

2 files changed, 21 insertions, 19 deletions

diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
index fd88ddf6158..4cdfd6d529c 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.cpp
@@ -2601,18 +2601,8 @@ NativeProcessLinux::MonitorBreakpoint(lldb::pid_t pid, NativeThreadProtocolSP th
                 log->Printf("NativeProcessLinux::%s() pid = %" PRIu64 " fixup: %s",
                         __FUNCTION__, pid, error.AsCString());
 
-        auto it = m_threads_stepping_with_breakpoint.find(pid);
-        if (it != m_threads_stepping_with_breakpoint.end())
-        {
-            Error error = RemoveBreakpoint (it->second);
-            if (error.Fail())
-                if (log)
-                    log->Printf("NativeProcessLinux::%s() pid = %" PRIu64 " remove stepping breakpoint: %s",
-                            __FUNCTION__, pid, error.AsCString());
-
-            m_threads_stepping_with_breakpoint.erase(it);
+        if (m_threads_stepping_with_breakpoint.find(pid) != m_threads_stepping_with_breakpoint.end())
             std::static_pointer_cast<NativeThreadLinux>(thread_sp)->SetStoppedByTrace();
-        }
     }
     else
         if (log)
@@ -3023,7 +3013,6 @@ NativeProcessLinux::Resume (const ResumeActionList &resume_actions)
     if (log)
         log->Printf ("NativeProcessLinux::%s called: pid %" PRIu64, __FUNCTION__, GetID ());
 
-    bool stepping = false;
     bool software_single_step = !SupportHardwareSingleStepping();
 
     Monitor::ScopedOperationLock monitor_lock(*m_monitor_up);
@@ -3109,7 +3098,6 @@ NativeProcessLinux::Resume (const ResumeActionList &resume_actions)
                         return step_result;
                     },
                     false);
-            stepping = true;
             break;
         }
 
@@ -4081,7 +4069,7 @@ NativeProcessLinux::StopTrackingThread (lldb::tid_t thread_id)
     if (m_pending_notification_up)
     {
         m_pending_notification_up->wait_for_stop_tids.erase(thread_id);
-        SignalIfRequirementsSatisfied();
+        SignalIfAllThreadsStopped();
     }
 
     return found;
@@ -4331,10 +4319,24 @@ NativeProcessLinux::StopRunningThreads(const lldb::tid_t triggering_tid)
 }
 
 void
-NativeProcessLinux::SignalIfRequirementsSatisfied()
+NativeProcessLinux::SignalIfAllThreadsStopped()
 {
     if (m_pending_notification_up && m_pending_notification_up->wait_for_stop_tids.empty ())
     {
+        Log *log(GetLogIfAnyCategoriesSet(LIBLLDB_LOG_PROCESS | LIBLLDB_LOG_BREAKPOINTS));
+
+        // Clear any temporary breakpoints we used to implement software single stepping.
+        for (const auto &thread_info: m_threads_stepping_with_breakpoint)
+        {
+            Error error = RemoveBreakpoint (thread_info.second);
+            if (error.Fail())
+                if (log)
+                    log->Printf("NativeProcessLinux::%s() pid = %" PRIu64 " remove stepping breakpoint: %s",
+                            __FUNCTION__, thread_info.first, error.AsCString());
+        }
+        m_threads_stepping_with_breakpoint.clear();
+
+        // Notify the delegate about the stop
         SetCurrentThreadID(m_pending_notification_up->triggering_tid);
         SetState(StateType::eStateStopped, true);
         m_pending_notification_up.reset();
@@ -4386,7 +4388,7 @@ NativeProcessLinux::ThreadDidStop (lldb::tid_t tid, bool initiated_by_llgs)
     if (m_pending_notification_up)
     {
         m_pending_notification_up->wait_for_stop_tids.erase(tid);
-        SignalIfRequirementsSatisfied();
+        SignalIfAllThreadsStopped();
     }
 
     Error error;
@@ -4423,7 +4425,7 @@ NativeProcessLinux::DoStopThreads(PendingNotificationUP &&notification_up)
 
     RequestStopOnAllRunningThreads();
 
-    SignalIfRequirementsSatisfied();
+    SignalIfAllThreadsStopped();
 }
 
 void
diff --git a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
index f280b36f332..57c598ff770 100644
--- a/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
+++ b/lldb/source/Plugins/Process/Linux/NativeProcessLinux.h
@@ -385,8 +385,8 @@ namespace process_linux {
         };
         typedef std::unique_ptr<PendingNotification> PendingNotificationUP;
 
-        // Fire pending notification if no pending thread stops remain.
-        void SignalIfRequirementsSatisfied();
+        // Notify the delegate if all threads have stopped.
+        void SignalIfAllThreadsStopped();
 
         void
         RequestStopOnAllRunningThreads();