JosephTremoulet created this revision.
JosephTremoulet added reviewers: labath, jankratochvil, compnerd.
Herald added subscribers: kristof.beyls, javed.absar.
Herald added a reviewer: jfb.
Herald added a project: LLDB.
Add __kernel_rt_sigreturn to the list of trap handlers for Linux (it's
used as such on aarch64 at least).
Skip decrement-and-recompute for trap handlers in
InitializeNonZerothFrame, as signal dispatch may point the child frame's
return address to the start of the return trampoline.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D63667
Files:
lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile
lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/TestHandleAbort.py
lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/main.c
lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
Index: lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
===================================================================
--- lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -472,20 +472,30 @@
m_sym_ctx_valid = false;
}
- bool decr_pc_and_recompute_addr_range = false;
+ bool decr_pc_and_recompute_addr_range;
- // If the symbol lookup failed...
- if (!m_sym_ctx_valid)
+ if (!m_sym_ctx_valid) {
+ // Always decrement and recompute if the symbol lookup failed
decr_pc_and_recompute_addr_range = true;
-
- // Or if we're in the middle of the stack (and not "above" an asynchronous
- // event like sigtramp), and our "current" pc is the start of a function...
- if (GetNextFrame()->m_frame_type != eTrapHandlerFrame &&
- GetNextFrame()->m_frame_type != eDebuggerFrame &&
- (!m_sym_ctx_valid ||
- (addr_range.GetBaseAddress().IsValid() &&
- addr_range.GetBaseAddress().GetSection() == m_current_pc.GetSection() &&
- addr_range.GetBaseAddress().GetOffset() == m_current_pc.GetOffset()))) {
+ } else if (GetNextFrame()->m_frame_type == eTrapHandlerFrame ||
+ GetNextFrame()->m_frame_type == eDebuggerFrame) {
+ // Don't decrement if we're "above" an asynchronous event like
+ // sigtramp.
+ decr_pc_and_recompute_addr_range = false;
+ } else if (!addr_range.GetBaseAddress().IsValid() ||
+ addr_range.GetBaseAddress().GetSection() != m_current_pc.GetSection() ||
+ addr_range.GetBaseAddress().GetOffset() != m_current_pc.GetOffset()) {
+ // If our "current" pc isn't the start of a function, no need
+ // to decrement and recompute.
+ decr_pc_and_recompute_addr_range = false;
+ } else if (IsTrapHandlerSymbol(process, m_sym_ctx)) {
+ // Signal dispatch may set the return address of the handler it calls to
+ // point to the first byte of a return trampoline (like __kernel_rt_sigreturn),
+ // so do not decrement and recompute if the symbol we already found is a trap
+ // handler.
+ decr_pc_and_recompute_addr_range = false;
+ } else {
+ // Decrement to find the function containing the call.
decr_pc_and_recompute_addr_range = true;
}
Index: lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
===================================================================
--- lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
+++ lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
@@ -396,6 +396,7 @@
void PlatformLinux::CalculateTrapHandlerSymbolNames() {
m_trap_handlers.push_back(ConstString("_sigtramp"));
+ m_trap_handlers.push_back(ConstString("__kernel_rt_sigreturn"));
}
MmapArgList PlatformLinux::GetMmapArgumentList(const ArchSpec &arch,
Index: lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/main.c
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/main.c
@@ -0,0 +1,25 @@
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+void handler(int sig)
+{
+ printf("Set a breakpoint here.\n");
+ exit(0);
+}
+
+void abort_caller() {
+ abort();
+}
+
+int main()
+{
+ if (signal(SIGABRT, handler) == SIG_ERR)
+ {
+ perror("signal");
+ return 1;
+ }
+
+ abort_caller();
+ return 2;
+}
Index: lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/TestHandleAbort.py
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/TestHandleAbort.py
@@ -0,0 +1,72 @@
+"""Test that we can unwind out of a SIGABRT handler"""
+
+from __future__ import print_function
+
+
+import os
+import re
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class HandleAbortTestCase(TestBase):
+
+ mydir = TestBase.compute_mydir(__file__)
+
+ NO_DEBUG_INFO_TESTCASE = True
+
+ @skipIfWindows # signals do not exist on Windows
+ def test_inferior_handle_sigabrt(self):
+ """Inferierior calls abort() and handles the resultant sigabrt().
+ Stopped at a breakpoint in the handler, verify that the backtrace
+ includes the function that called abort()."""
+ self.build()
+ exe = self.getBuildArtifact("a.out")
+
+ # Create a target by the debugger.
+ target = self.dbg.CreateTarget(exe)
+ self.assertTrue(target, VALID_TARGET)
+
+ # launch
+ process = target.LaunchSimple(
+ None, None, self.get_process_working_directory())
+ self.assertTrue(process, PROCESS_IS_VALID)
+ self.assertEqual(process.GetState(), lldb.eStateStopped)
+ signo = process.GetUnixSignals().GetSignalNumberFromName("SIGABRT")
+
+ thread = lldbutil.get_stopped_thread(process, lldb.eStopReasonSignal)
+ self.assertTrue(
+ thread and thread.IsValid(),
+ "Thread should be stopped due to a signal")
+ self.assertTrue(
+ thread.GetStopReasonDataCount() >= 1,
+ "There should be data in the event.")
+ self.assertEqual(thread.GetStopReasonDataAtIndex(0),
+ signo, "The stop signal should be SIGABRT")
+
+ # Continue to breakpoint in abort handler
+ bkpt = target.FindBreakpointByID(
+ lldbutil.run_break_set_by_source_regexp(self, "Set a breakpoint here"))
+ threads = lldbutil.continue_to_breakpoint(process, bkpt)
+ self.assertEqual(len(threads), 1, "Expected single thread")
+ thread = threads[0]
+
+ # Expect breakpoint in 'handler'
+ frame = thread.GetFrameAtIndex(0)
+ self.assertEqual(frame.GetDisplayFunctionName(), "handler", "Unexpected break?")
+
+ # Expect that unwinding should find 'abort_caller'
+ foundFoo = False
+ for frame in thread:
+ if frame.GetDisplayFunctionName() == "abort_caller":
+ foundFoo = True
+
+ self.assertTrue(foundFoo, "Unwinding did not find func that called abort")
+
+ # Continue until we exit.
+ process.Continue()
+ self.assertEqual(process.GetState(), lldb.eStateExited)
+ self.assertEqual(process.GetExitStatus(), 0)
Index: lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile
===================================================================
--- /dev/null
+++ lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile
@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+C_SOURCES := main.c
+
+include $(LEVEL)/Makefile.rules
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