[lldb] [Process/NetBSD] Use global enable bits for watchpoints

[mgorny]

Summary

Set global enable bits (i.e. bits 1, 3, 5, 7) to enable watchpoints
on NetBSD rather than the local enable bits (0, 2, 4, 6). The former
are necessary for watchpoints to be correctly recognized by the NetBSD
kernel. The latter cause them to be reported as trace points.

[mgorny]

Removed XFAIL for tests fixed by this.

[mgorny]

Ping.

[labath]

Sorry about the delay, I was OOO last week. BTW, the usual rate of pinging on a patch is one week https://llvm.org/docs/DeveloperPolicy.html#code-reviews.

If the NetBSD kernel really sets the global-enable flag in the dr7 register, I'd be tempted to try to make it crash/misbehave by setting a hardware breakpoint somewhere in the early entry code (before it gets a chance to clear it, if it even does that), ideally in the breakpoint handler so it triggers an infinite loop :). However, that is not relevant to this patch...

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

733

Not a big deal, but I'd find 1 << (2*wp_index + 1) less surprising..

[mgorny]

That's probably one of the reasons why NetBSD normally prevents unprivileged users from setting DRs.

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

733

Will do.

[mgorny]

Updated per review.

[krytarowski]

I would follow the same kernel behavior here as Linux, but that can be done independently.

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/hello_watchlocation/TestWatchLocation.py

@expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Most of the MIPS boards provide only one H/W watchpoints, and S/W
     # watchpoints are not supported yet
     @expectedFailureAll(triple=re.compile('^mips'))
     # SystemZ and PowerPC also currently supports only one H/W watchpoint
     @expectedFailureAll(archs=['powerpc64le', 's390x'])
     @skipIfDarwin
-    @expectedFailureNetBSD
     def test_hello_watchlocation(self):
         """Test watching a location with '-s size' option."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
         # Add a breakpoint to set a watchpoint when stopped on the breakpoint.

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/hello_watchpoint/TestMyFirstWatchpoint.py

def setUp(self):
         self.decl = line_number(self.source,
                                 '// Watchpoint variable declaration.')
         self.exe_name = self.getBuildArtifact('a.out')
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     @add_test_categories(["basic_process"])
     def test_hello_watchpoint_using_watchpoint_set(self):
         """Test a simple sequence of watchpoint creation and watchpoint hit."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/multiple_hits/TestMultipleHits.py

class MultipleHitsTestCase(TestBase):
     mydir = TestBase.compute_mydir(__file__)
     NO_DEBUG_INFO_TESTCASE = True
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @skipIf(bugnumber="llvm.org/pr30758", oslist=["linux"], archs=["arm", "aarch64", "powerpc64le"])
     @skipIfwatchOS
-    @expectedFailureNetBSD
     def test(self):
         self.build()
         exe = self.getBuildArtifact("a.out")
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(target and target.IsValid(), VALID_TARGET)
 
         bp = target.BreakpointCreateByName("main")
         self.assertTrue(bp and bp.IsValid(), "Breakpoint is valid")

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/multiple_threads/TestWatchpointMultipleThreads.py

class WatchpointForMultipleThreadsTestCase(TestBase):
 
     mydir = TestBase.compute_mydir(__file__)
     NO_DEBUG_INFO_TESTCASE = True
     main_spec = lldb.SBFileSpec("main.cpp", False)
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @skipIfNetBSD
     def test_watchpoint_before_thread_start(self):
         """Test that we can hit a watchpoint we set before starting another thread"""
         self.do_watchpoint_test("Before running the thread")
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @skipIfNetBSD
     def test_watchpoint_after_thread_start(self):
         """Test that we can hit a watchpoint we set after starting another thread"""
         self.do_watchpoint_test("After running the thread")
 
     def do_watchpoint_test(self, line):
         self.build()
         lldbutil.run_to_source_breakpoint(self, line, self.main_spec)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/step_over_watchpoint/TestStepOverWatchpoint.py

@expectedFailureAll(
             'arm'],
         bugnumber="llvm.org/pr26031")
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
     @expectedFailureAll(oslist=["ios", "watchos", "tvos", "bridgeos"], bugnumber="<rdar://problem/34027183>")  # watchpoint tests aren't working on arm64
-    @expectedFailureNetBSD
     @add_test_categories(["basic_process"])
     def test(self):
         """Test stepping over watchpoints."""
         self.build()
         exe = self.getBuildArtifact("a.out")
 
         target = self.dbg.CreateTarget(exe)
         self.assertTrue(self.target, VALID_TARGET)

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_commands/TestWatchpointCommands.py

def setUp(self):
         self.exe_name = self.testMethodName
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_rw_watchpoint(self):
         """Test read_write watchpoint and expect to stop two times."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
def test_rw_watchpoint_delete(self):
         self.expect("process status",
                     substrs=['exited'])
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_rw_watchpoint_set_ignore_count(self):
         """Test watchpoint ignore count and expect to not to stop at all."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
def test_rw_watchpoint_set_ignore_count(self):
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 2', 'ignore_count = 2'])
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_rw_disable_after_first_stop(self):
         """Test read_write watchpoint but disable it after the first stop."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
def test_rw_disable_after_first_stop(self):
         self.expect("watchpoint list -v",
                     substrs=['hit_count = 1'])
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_rw_disable_then_enable(self):
         """Test read_write watchpoint, disable initially, then enable it."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_commands/command/TestWatchpointCommandLLDB.py

class WatchpointLLDBCommandTestCase(TestBase):
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         bugnumber="llvm.org/pr27710")
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     def test_watchpoint_command(self):
         """Test 'watchpoint command'."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
class WatchpointLLDBCommandTestCase(TestBase):
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         bugnumber="llvm.org/pr27710")
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     def test_watchpoint_command_can_disable_a_watchpoint(self):
         """Test that 'watchpoint command' action can disable a watchpoint after it is triggered."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_commands/command/TestWatchpointCommandPython.py

class WatchpointPythonCommandTestCase(TestBase):
     @skipIfFreeBSD  # timing out on buildbot
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         bugnumber="llvm.org/pr27710")
-    @expectedFailureNetBSD
     def test_watchpoint_command(self):
         """Test 'watchpoint command'."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 
class WatchpointPythonCommandTestCase(TestBase):
     @skipIfFreeBSD  # timing out on buildbot
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         bugnumber="llvm.org/pr27710")
-    @expectedFailureNetBSD
     def test_continue_in_watchpoint_command(self):
         """Test continue in a watchpoint command."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_commands/condition/TestWatchpointConditionCmd.py

class WatchpointConditionCmdTestCase(TestBase):
 
     @expectedFailureAll(
         oslist=["linux"],
         archs=["aarch64"],
         bugnumber="llvm.org/pr27710")
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     def test_watchpoint_cond(self):
         """Test watchpoint condition."""
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 
         exe = self.getBuildArtifact(self.exe_name)
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_disable/TestWatchpointDisable.py

class TestWatchpointSetEnable(TestBase):
     def test_disable_works (self):
         """Set a watchpoint, disable it, and make sure it doesn't get hit."""
         self.build()
         self.do_test(False)
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     def test_disable_enable_works (self):
         """Set a watchpoint, disable it, and make sure it doesn't get hit."""
         self.build()
         self.do_test(True)
 
     def do_test(self, test_enable):
         """Set a watchpoint, disable it and make sure it doesn't get hit."""
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_set_command/TestWatchLocationWithWatchSet.py

@expectedFailureAll(
         oslist=["linux"],
         archs=[
             'aarch64',
             'arm'],
         bugnumber="llvm.org/pr26031")
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
-    @expectedFailureNetBSD
     def test_watchlocation_using_watchpoint_set(self):
         """Test watching a location with 'watchpoint set expression -w write -s size' option."""
         self.build()
         self.setTearDownCleanup()
 
         exe = self.getBuildArtifact("a.out")
         self.runCmd("file " + exe, CURRENT_EXECUTABLE_SET)
 

lldb/packages/Python/lldbsuite/test/functionalities/watchpoint/watchpoint_size/TestWatchpointSizes.py

def setUp(self):
         self.exe_name = self.getBuildArtifact("a.out")
         self.d = {'C_SOURCES': self.source, 'EXE': self.exe_name}
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_byte_size_watchpoints_with_byte_selection(self):
         """Test to selectively watch different bytes in a 8-byte array."""
         self.run_watchpoint_size_test('byteArray', 8, '1')
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_two_byte_watchpoints_with_word_selection(self):
         """Test to selectively watch different words in an 8-byte word array."""
         self.run_watchpoint_size_test('wordArray', 4, '2')
 
     @expectedFailureAll(
         oslist=["windows"],
         bugnumber="llvm.org/pr24446: WINDOWS XFAIL TRIAGE - Watchpoints not supported on Windows")
     # Read-write watchpoints not supported on SystemZ
     @expectedFailureAll(archs=['s390x'])
-    @expectedFailureNetBSD
     def test_four_byte_watchpoints_with_dword_selection(self):
         """Test to selectively watch two double words in an 8-byte dword array."""
         self.run_watchpoint_size_test('dwordArray', 2, '4')
 
     def run_watchpoint_size_test(self, arrayName, array_size, watchsize):
         self.build(dictionary=self.d)
         self.setTearDownCleanup(dictionary=self.d)
 

lldb/source/Plugins/Process/NetBSD/NativeRegisterContextNetBSD_x86_64.cpp

Status NativeRegisterContextNetBSD_x86_64::IsWatchpointVacant(uint32_t wp_index,
   Status error = ReadRegister(reg_info, reg_value);
   if (error.Fail()) {
     is_vacant = false;
     return error;
   }
 
   uint64_t control_bits = reg_value.GetAsUInt64();
 
-  is_vacant = !(control_bits & (1 << (2 * wp_index)));
+  is_vacant = !(control_bits & (1 << (2 * wp_index + 1)));
 
   return error;
 }
 
 Status NativeRegisterContextNetBSD_x86_64::SetHardwareWatchpointWithIndex(
     lldb::addr_t addr, size_t size, uint32_t watch_flags, uint32_t wp_index) {
 
   if (wp_index >= NumSupportedHardwareWatchpoints())
Status NativeRegisterContextNetBSD_x86_64::SetHardwareWatchpointWithIndex(
   RegisterValue reg_value;
   const RegisterInfo *const reg_info_dr7 =
       GetRegisterInfoAtIndex(lldb_dr7_x86_64);
   error = ReadRegister(reg_info_dr7, reg_value);
   if (error.Fail())
     return error;
 
   // for watchpoints 0, 1, 2, or 3, respectively, set bits 1, 3, 5, or 7
-  uint64_t enable_bit = 1 << (2 * wp_index);
+  uint64_t enable_bit = 1 << (2 * wp_index + 1);
 
   // set bits 16-17, 20-21, 24-25, or 28-29
   // with 0b01 for write, and 0b11 for read/write
   uint64_t rw_bits = watch_flags << (16 + 4 * wp_index);
 
   // set bits 18-19, 22-23, 26-27, or 30-31
   // with 0b00, 0b01, 0b10, or 0b11
   // for 1, 2, 8 (if supported), or 4 bytes, respectively