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Closed by commit rG92b036dea24b: debugserver should advance pc past
builtin_debugtrap insn (authored by jasonmolenda).
Changed prior to commit:
https://reviews.llvm.org/D91238?vs=305040&id=305042#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D91238/new/
https://reviews.llvm.org/D91238
Files:
lldb/test/API/macosx/builtin-debugtrap/Makefile
lldb/test/API/macosx/builtin-debugtrap/TestBuiltinDebugTrap.py
lldb/test/API/macosx/builtin-debugtrap/main.cpp
lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp
Index: lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp
===================================================================
--- lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp
+++ lldb/tools/debugserver/source/MacOSX/arm64/DNBArchImplARM64.cpp
@@ -524,6 +524,28 @@
return true;
}
+ // detect a __builtin_debugtrap instruction pattern ("brk #0xf000")
+ // and advance the $pc past it, so that the user can continue execution.
+ // Generally speaking, this knowledge should be centralized in lldb,
+ // recognizing the builtin_trap instruction and knowing how to advance
+ // the pc past it, so that continue etc work.
+ if (exc.exc_data.size() == 2 && exc.exc_data[0] == EXC_ARM_BREAKPOINT) {
+ nub_addr_t pc = GetPC(INVALID_NUB_ADDRESS);
+ if (pc != INVALID_NUB_ADDRESS && pc > 0) {
+ DNBBreakpoint *bp =
+ m_thread->Process()->Breakpoints().FindByAddress(pc);
+ if (bp == nullptr) {
+ uint8_t insnbuf[4];
+ if (m_thread->Process()->ReadMemory(pc, 4, insnbuf) == 4) {
+ uint8_t builtin_debugtrap_insn[4] = {0x00, 0x00, 0x3e,
+ 0xd4}; // brk #0xf000
+ if (memcmp(insnbuf, builtin_debugtrap_insn, 4) == 0) {
+ SetPC(pc + 4);
+ }
+ }
+ }
+ }
+ }
break;
}
return false;
Index: lldb/test/API/macosx/builtin-debugtrap/main.cpp
===================================================================
--- /dev/null
+++ lldb/test/API/macosx/builtin-debugtrap/main.cpp
@@ -0,0 +1,11 @@
+#include <stdio.h>
+int global = 0;
+int main()
+{
+ global = 5; // Set a breakpoint here
+ __builtin_debugtrap();
+ global = 10;
+ __builtin_trap();
+ global = 15;
+ return global;
+}
Index: lldb/test/API/macosx/builtin-debugtrap/TestBuiltinDebugTrap.py
===================================================================
--- /dev/null
+++ lldb/test/API/macosx/builtin-debugtrap/TestBuiltinDebugTrap.py
@@ -0,0 +1,70 @@
+"""
+Test that lldb can continue past a __builtin_debugtrap, but not a __builtin_trap
+"""
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+
+class BuiltinDebugTrapTestCase(TestBase):
+
+ mydir = TestBase.compute_mydir(__file__)
+
+ NO_DEBUG_INFO_TESTCASE = True
+
+ # Currently this depends on behavior in debugserver to
+ # advance the pc past __builtin_trap instructions so that
+ # continue works. Everyone is in agreement that this
+ # should be moved up into lldb instead of depending on the
+ # remote stub rewriting the pc values.
+ @skipUnlessDarwin
+
+ def test(self):
+ self.build()
+ (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+ self, "// Set a breakpoint here", lldb.SBFileSpec("main.cpp"))
+
+ # Continue to __builtin_debugtrap()
+ process.Continue()
+ if self.TraceOn():
+ self.runCmd("f")
+ self.runCmd("bt")
+ self.runCmd("ta v global")
+
+ self.assertEqual(process.GetSelectedThread().GetStopReason(),
+ lldb.eStopReasonException)
+
+ list = target.FindGlobalVariables("global", 1, lldb.eMatchTypeNormal)
+ self.assertEqual(list.GetSize(), 1)
+ global_value = list.GetValueAtIndex(0)
+
+ self.assertEqual(global_value.GetValueAsUnsigned(), 5)
+
+ # Continue to the __builtin_trap() -- we should be able to
+ # continue past __builtin_debugtrap.
+ process.Continue()
+ if self.TraceOn():
+ self.runCmd("f")
+ self.runCmd("bt")
+ self.runCmd("ta v global")
+
+ self.assertEqual(process.GetSelectedThread().GetStopReason(),
+ lldb.eStopReasonException)
+
+ # "global" is now 10.
+ self.assertEqual(global_value.GetValueAsUnsigned(), 10)
+
+ # We should be at the same point as before -- cannot advance
+ # past a __builtin_trap().
+ process.Continue()
+ if self.TraceOn():
+ self.runCmd("f")
+ self.runCmd("bt")
+ self.runCmd("ta v global")
+
+ self.assertEqual(process.GetSelectedThread().GetStopReason(),
+ lldb.eStopReasonException)
+
+ # "global" is still 10.
+ self.assertEqual(global_value.GetValueAsUnsigned(), 10)
Index: lldb/test/API/macosx/builtin-debugtrap/Makefile
===================================================================
--- /dev/null
+++ lldb/test/API/macosx/builtin-debugtrap/Makefile
@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules
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