[lldb] [Process/NetBSD] Fix handling concurrent watchpoint events

Fix handling concurrent watchpoint events so that they are reported
correctly in LLDB.

If multiple watchpoints are hit concurrently, the NetBSD kernel reports
them as series of SIGTRAPs with a thread specified, and the debugger
investigates DR6 in order to establish which watchpoint was hit.  This
is normally fine.

However, LLDB disables and reenables the watchpoint on all threads after
each hit, which results in the hit status from DR6 being wiped.
As a result, it can't establish which watchpoint was hit in successive
SIGTRAP processing.

In order to workaround this problem, clear DR6 only if the breakpoint
is overwritten with a new one.  More specifically, move cleaning DR6
from ClearHardwareWatchpoint() to SetHardwareWatchpointWithIndex(),
and do that only if the newly requested watchpoint is different
from the one being set previously.  This ensures that the disable-enable
logic of LLDB does not clear watchpoint hit status for the remaining
threads.

This also involves refactoring of watchpoint logic.  With the old logic,
clearing watchpoint involved wiping dr6 & dr7, and setting it setting
dr{0..3} & dr7.  With the new logic, only enable bit is cleared
from dr7, and the remaining bits are cleared/overwritten while setting
new watchpoint.

Differential Revision: https://reviews.llvm.org/D70025

6 files changed, 0 insertions, 6 deletions

diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentManyWatchpoints.py b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentManyWatchpoints.py
index cce537ac77a..55c7d3f7521 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentManyWatchpoints.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentManyWatchpoints.py
@@ -14,7 +14,6 @@ class ConcurrentManyWatchpoints(ConcurrentEventsBase):
 
     # Atomic sequences are not supported yet for MIPS in LLDB.
     @skipIf(triple='^mips')
-    @expectedFailureNetBSD
     @add_test_categories(["watchpoint"])
     @skipIfOutOfTreeDebugserver
     def test(self):
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentNWatchNBreak.py b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentNWatchNBreak.py
index 84a4ac6f7a3..b921ac04ccc 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentNWatchNBreak.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentNWatchNBreak.py
@@ -15,7 +15,6 @@ class ConcurrentNWatchNBreak(ConcurrentEventsBase):
     @skipIfFreeBSD  # timing out on buildbot
     # Atomic sequences are not supported yet for MIPS in LLDB.
     @skipIf(triple='^mips')
-    @expectedFailureNetBSD
     @add_test_categories(["watchpoint"])
     def test(self):
         """Test with 5 watchpoint and breakpoint threads."""
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointThreads.py b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointThreads.py
index 62eac557cfc..025d9116945 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointThreads.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointThreads.py
@@ -15,7 +15,6 @@ class ConcurrentTwoWatchpointThreads(ConcurrentEventsBase):
     @skipIfFreeBSD  # timing out on buildbot
     # Atomic sequences are not supported yet for MIPS in LLDB.
     @skipIf(triple='^mips')
-    @expectedFailureNetBSD
     @add_test_categories(["watchpoint"])
     def test(self):
         """Test two threads that trigger a watchpoint. """
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneBreakpoint.py b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneBreakpoint.py
index 31d6e425a62..5e95531ae09 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneBreakpoint.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneBreakpoint.py
@@ -15,7 +15,6 @@ class ConcurrentTwoWatchpointsOneBreakpoint(ConcurrentEventsBase):
     @skipIfFreeBSD  # timing out on buildbot
     # Atomic sequences are not supported yet for MIPS in LLDB.
     @skipIf(triple='^mips')
-    @expectedFailureNetBSD
     @add_test_categories(["watchpoint"])
     def test(self):
         """Test two threads that trigger a watchpoint and one breakpoint thread. """
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneDelayBreakpoint.py b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneDelayBreakpoint.py
index 16584472c97..aa57e816bb5 100644
--- a/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneDelayBreakpoint.py
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/thread/concurrent_events/TestConcurrentTwoWatchpointsOneDelayBreakpoint.py
@@ -15,7 +15,6 @@ class ConcurrentTwoWatchpointsOneDelayBreakpoint(ConcurrentEventsBase):
     @skipIfFreeBSD  # timing out on buildbot
     # Atomic sequences are not supported yet for MIPS in LLDB.
     @skipIf(triple='^mips')
-    @expectedFailureNetBSD
     @add_test_categories(["watchpoint"])
     def test(self):
         """Test two threads that trigger a watchpoint and one (1 second delay) breakpoint thread. """
diff --git a/lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestSetWatchlocation.py b/lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestSetWatchlocation.py
index 28e18620ab1..97559212b17 100644
--- a/lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestSetWatchlocation.py
+++ b/lldb/packages/Python/lldbsuite/test/python_api/watchpoint/watchlocation/TestSetWatchlocation.py
@@ -28,7 +28,6 @@ class SetWatchlocationAPITestCase(TestBase):
         self.violating_func = "do_bad_thing_with_location"
 
     @add_test_categories(['pyapi'])
-    @expectedFailureNetBSD
     def test_watch_location(self):
         """Exercise SBValue.WatchPointee() API to set a watchpoint."""
         self.build()