Support Linux signal return trampolines in frame initialization

Summary:
Add __kernel_rt_sigreturn to the list of trap handlers for Linux (it's
used as such on aarch64 at least), and __restore_rt as well (used on
x86_64).

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.

Parse the 'S' flag for signal handlers from eh_frame augmentation, and
propagate it to the unwind plan.

Reviewers: labath, jankratochvil, compnerd, jfb, jasonmolenda

Reviewed By: jasonmolenda

Subscribers: clayborg, MaskRay, wuzish, nemanjai, kbarton, jrtc27, atanasyan, jsji, javed.absar, kristof.beyls, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D63667

llvm-svn: 366580

28 files changed, 169 insertions, 12 deletions

diff --git a/lldb/include/lldb/Symbol/UnwindPlan.h b/lldb/include/lldb/Symbol/UnwindPlan.h
index 2b49acaafa0..fc3e3ccf4ff 100644
--- a/lldb/include/lldb/Symbol/UnwindPlan.h
+++ b/lldb/include/lldb/Symbol/UnwindPlan.h
@@ -370,6 +370,7 @@ public:
         m_return_addr_register(LLDB_INVALID_REGNUM), m_source_name(),
         m_plan_is_sourced_from_compiler(eLazyBoolCalculate),
         m_plan_is_valid_at_all_instruction_locations(eLazyBoolCalculate),
+        m_plan_is_for_signal_trap(eLazyBoolCalculate),
         m_lsda_address(), m_personality_func_addr() {}
 
   // Performs a deep copy of the plan, including all the rows (expensive).
@@ -463,6 +464,17 @@ public:
     m_plan_is_valid_at_all_instruction_locations = valid_at_all_insn;
   }
 
+  // Is this UnwindPlan for a signal trap frame?  If so, then its saved pc
+  // may have been set manually by the signal dispatch code and therefore
+  // not follow a call to the child frame.
+  lldb_private::LazyBool GetUnwindPlanForSignalTrap() const {
+    return m_plan_is_for_signal_trap;
+  }
+
+  void SetUnwindPlanForSignalTrap(lldb_private::LazyBool is_for_signal_trap) {
+    m_plan_is_for_signal_trap = is_for_signal_trap;
+  }
+
   int GetRowCount() const;
 
   void Clear() {
@@ -472,6 +484,7 @@ public:
     m_source_name.Clear();
     m_plan_is_sourced_from_compiler = eLazyBoolCalculate;
     m_plan_is_valid_at_all_instruction_locations = eLazyBoolCalculate;
+    m_plan_is_for_signal_trap = eLazyBoolCalculate;
     m_lsda_address.Clear();
     m_personality_func_addr.Clear();
   }
@@ -502,6 +515,7 @@ private:
       m_source_name; // for logging, where this UnwindPlan originated from
   lldb_private::LazyBool m_plan_is_sourced_from_compiler;
   lldb_private::LazyBool m_plan_is_valid_at_all_instruction_locations;
+  lldb_private::LazyBool m_plan_is_for_signal_trap;
 
   Address m_lsda_address; // Where the language specific data area exists in the
                           // module - used
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile b/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile
new file mode 100644
index 00000000000..b09a579159d
--- /dev/null
+++ b/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/Makefile
@@ -0,0 +1,5 @@
+LEVEL = ../../../make
+
+C_SOURCES := main.c
+
+include $(LEVEL)/Makefile.rules
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/TestHandleAbort.py b/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/TestHandleAbort.py
new file mode 100644
index 00000000000..022ad929162
--- /dev/null
+++ b/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):
+        """Inferior 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)
diff --git a/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/main.c b/lldb/packages/Python/lldbsuite/test/functionalities/signal/handle-abrt/main.c
new file mode 100644
index 00000000000..c2daea1e84e
--- /dev/null
+++ b/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;
+}
diff --git a/lldb/source/Plugins/ABI/MacOSX-arm/ABIMacOSX_arm.cpp b/lldb/source/Plugins/ABI/MacOSX-arm/ABIMacOSX_arm.cpp
index 362a80be4b0..f2d01dba69d 100644
--- a/lldb/source/Plugins/ABI/MacOSX-arm/ABIMacOSX_arm.cpp
+++ b/lldb/source/Plugins/ABI/MacOSX-arm/ABIMacOSX_arm.cpp
@@ -1846,6 +1846,7 @@ bool ABIMacOSX_arm::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("arm-apple-ios default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 
   return true;
 }
diff --git a/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp b/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp
index 368e3721324..fd788e7902b 100644
--- a/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp
+++ b/lldb/source/Plugins/ABI/MacOSX-arm64/ABIMacOSX_arm64.cpp
@@ -2011,6 +2011,7 @@ bool ABIMacOSX_arm64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("arm64-apple-darwin default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.cpp b/lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.cpp
index 67371b432ff..adb40cf1e7e 100644
--- a/lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.cpp
+++ b/lldb/source/Plugins/ABI/MacOSX-i386/ABIMacOSX_i386.cpp
@@ -1055,6 +1055,7 @@ bool ABIMacOSX_i386::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("i386 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp b/lldb/source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
index dd47ac7cbe3..b0747147bfa 100644
--- a/lldb/source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
+++ b/lldb/source/Plugins/ABI/SysV-arm/ABISysV_arm.cpp
@@ -1960,6 +1960,7 @@ bool ABISysV_arm::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("arm default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 
   return true;
 }
diff --git a/lldb/source/Plugins/ABI/SysV-arm64/ABISysV_arm64.cpp b/lldb/source/Plugins/ABI/SysV-arm64/ABISysV_arm64.cpp
index 1d547121e23..f9647ef7d49 100644
--- a/lldb/source/Plugins/ABI/SysV-arm64/ABISysV_arm64.cpp
+++ b/lldb/source/Plugins/ABI/SysV-arm64/ABISysV_arm64.cpp
@@ -1958,6 +1958,7 @@ bool ABISysV_arm64::CreateFunctionEntryUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("arm64 at-func-entry default");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 
   return true;
 }
@@ -1982,6 +1983,7 @@ bool ABISysV_arm64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("arm64 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 
   return true;
 }
diff --git a/lldb/source/Plugins/ABI/SysV-hexagon/ABISysV_hexagon.cpp b/lldb/source/Plugins/ABI/SysV-hexagon/ABISysV_hexagon.cpp
index 93647564fe2..ae836851162 100644
--- a/lldb/source/Plugins/ABI/SysV-hexagon/ABISysV_hexagon.cpp
+++ b/lldb/source/Plugins/ABI/SysV-hexagon/ABISysV_hexagon.cpp
@@ -1247,6 +1247,7 @@ bool ABISysV_hexagon::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("hexagon default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/SysV-i386/ABISysV_i386.cpp b/lldb/source/Plugins/ABI/SysV-i386/ABISysV_i386.cpp
index 05f5dba9068..41148b7f426 100644
--- a/lldb/source/Plugins/ABI/SysV-i386/ABISysV_i386.cpp
+++ b/lldb/source/Plugins/ABI/SysV-i386/ABISysV_i386.cpp
@@ -785,6 +785,7 @@ bool ABISysV_i386::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("i386 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/SysV-mips/ABISysV_mips.cpp b/lldb/source/Plugins/ABI/SysV-mips/ABISysV_mips.cpp
index 121c7300b96..9d15cb57bd0 100644
--- a/lldb/source/Plugins/ABI/SysV-mips/ABISysV_mips.cpp
+++ b/lldb/source/Plugins/ABI/SysV-mips/ABISysV_mips.cpp
@@ -997,6 +997,7 @@ bool ABISysV_mips::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("mips default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/SysV-mips64/ABISysV_mips64.cpp b/lldb/source/Plugins/ABI/SysV-mips64/ABISysV_mips64.cpp
index 18011cfb6b9..3f3b807a47c 100644
--- a/lldb/source/Plugins/ABI/SysV-mips64/ABISysV_mips64.cpp
+++ b/lldb/source/Plugins/ABI/SysV-mips64/ABISysV_mips64.cpp
@@ -1168,6 +1168,7 @@ bool ABISysV_mips64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("mips64 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/ABI/SysV-ppc/ABISysV_ppc.cpp b/lldb/source/Plugins/ABI/SysV-ppc/ABISysV_ppc.cpp
index faa995033ac..3f2d49c7df0 100644
--- a/lldb/source/Plugins/ABI/SysV-ppc/ABISysV_ppc.cpp
+++ b/lldb/source/Plugins/ABI/SysV-ppc/ABISysV_ppc.cpp
@@ -910,6 +910,7 @@ bool ABISysV_ppc::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("ppc default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(dwarf_lr);
   return true;
 }
diff --git a/lldb/source/Plugins/ABI/SysV-ppc64/ABISysV_ppc64.cpp b/lldb/source/Plugins/ABI/SysV-ppc64/ABISysV_ppc64.cpp
index aa7907550f2..66f812df3d6 100644
--- a/lldb/source/Plugins/ABI/SysV-ppc64/ABISysV_ppc64.cpp
+++ b/lldb/source/Plugins/ABI/SysV-ppc64/ABISysV_ppc64.cpp
@@ -1017,6 +1017,7 @@ bool ABISysV_ppc64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("ppc64 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(pc_reg_num);
   return true;
 }
diff --git a/lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp b/lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp
index 6c7b45f6339..255db1d2dfb 100644
--- a/lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp
+++ b/lldb/source/Plugins/ABI/SysV-x86_64/ABISysV_x86_64.cpp
@@ -1034,6 +1034,7 @@ bool ABISysV_x86_64::CreateDefaultUnwindPlan(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("x86_64 default unwind plan");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   return true;
 }
 
diff --git a/lldb/source/Plugins/Instruction/ARM/EmulateInstructionARM.cpp b/lldb/source/Plugins/Instruction/ARM/EmulateInstructionARM.cpp
index 6323889c2e0..19a987b0f00 100644
--- a/lldb/source/Plugins/Instruction/ARM/EmulateInstructionARM.cpp
+++ b/lldb/source/Plugins/Instruction/ARM/EmulateInstructionARM.cpp
@@ -14507,6 +14507,7 @@ bool EmulateInstructionARM::CreateFunctionEntryUnwind(UnwindPlan &unwind_plan) {
   unwind_plan.SetSourceName("EmulateInstructionARM");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(dwarf_lr);
   return true;
 }
diff --git a/lldb/source/Plugins/Instruction/ARM64/EmulateInstructionARM64.cpp b/lldb/source/Plugins/Instruction/ARM64/EmulateInstructionARM64.cpp
index d7e8e049134..6ab968539c4 100644
--- a/lldb/source/Plugins/Instruction/ARM64/EmulateInstructionARM64.cpp
+++ b/lldb/source/Plugins/Instruction/ARM64/EmulateInstructionARM64.cpp
@@ -479,6 +479,7 @@ bool EmulateInstructionARM64::CreateFunctionEntryUnwind(
   unwind_plan.SetSourceName("EmulateInstructionARM64");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(gpr_lr_arm64);
   return true;
 }
diff --git a/lldb/source/Plugins/Instruction/MIPS/EmulateInstructionMIPS.cpp b/lldb/source/Plugins/Instruction/MIPS/EmulateInstructionMIPS.cpp
index cbf3dda7896..21b6296745b 100644
--- a/lldb/source/Plugins/Instruction/MIPS/EmulateInstructionMIPS.cpp
+++ b/lldb/source/Plugins/Instruction/MIPS/EmulateInstructionMIPS.cpp
@@ -1150,6 +1150,7 @@ bool EmulateInstructionMIPS::CreateFunctionEntryUnwind(
   unwind_plan.SetSourceName("EmulateInstructionMIPS");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(dwarf_ra_mips);
 
   return true;
diff --git a/lldb/source/Plugins/Instruction/MIPS64/EmulateInstructionMIPS64.cpp b/lldb/source/Plugins/Instruction/MIPS64/EmulateInstructionMIPS64.cpp
index 69f0278d143..5fabbeb756c 100644
--- a/lldb/source/Plugins/Instruction/MIPS64/EmulateInstructionMIPS64.cpp
+++ b/lldb/source/Plugins/Instruction/MIPS64/EmulateInstructionMIPS64.cpp
@@ -1042,6 +1042,7 @@ bool EmulateInstructionMIPS64::CreateFunctionEntryUnwind(
   unwind_plan.SetSourceName("EmulateInstructionMIPS64");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(dwarf_ra_mips64);
 
   return true;
diff --git a/lldb/source/Plugins/Instruction/PPC64/EmulateInstructionPPC64.cpp b/lldb/source/Plugins/Instruction/PPC64/EmulateInstructionPPC64.cpp
index c77fa04fc7d..4b8d8dd2228 100644
--- a/lldb/source/Plugins/Instruction/PPC64/EmulateInstructionPPC64.cpp
+++ b/lldb/source/Plugins/Instruction/PPC64/EmulateInstructionPPC64.cpp
@@ -135,6 +135,7 @@ bool EmulateInstructionPPC64::CreateFunctionEntryUnwind(
   unwind_plan.SetSourceName("EmulateInstructionPPC64");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetReturnAddressRegister(gpr_lr_ppc64le);
   return true;
 }
diff --git a/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp b/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
index d0ad2f34d11..52d72f5e6fd 100644
--- a/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
+++ b/lldb/source/Plugins/Platform/Linux/PlatformLinux.cpp
@@ -396,6 +396,8 @@ PlatformLinux::DebugProcess(ProcessLaunchInfo &launch_info, Debugger &debugger,
 
 void PlatformLinux::CalculateTrapHandlerSymbolNames() {
   m_trap_handlers.push_back(ConstString("_sigtramp"));
+  m_trap_handlers.push_back(ConstString("__kernel_rt_sigreturn"));
+  m_trap_handlers.push_back(ConstString("__restore_rt"));
 }
 
 MmapArgList PlatformLinux::GetMmapArgumentList(const ArchSpec &arch,
diff --git a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
index 76646d8897d..786c4a5df49 100644
--- a/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
+++ b/lldb/source/Plugins/Process/Utility/RegisterContextLLDB.cpp
@@ -472,20 +472,30 @@ void RegisterContextLLDB::InitializeNonZerothFrame() {
     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;
   }
 
diff --git a/lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp b/lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
index d4258274a38..5e275e34c3b 100644
--- a/lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
+++ b/lldb/source/Plugins/SymbolFile/Breakpad/SymbolFileBreakpad.cpp
@@ -495,6 +495,7 @@ SymbolFileBreakpad::GetUnwindPlan(const Address &address,
   auto plan_sp = std::make_shared<UnwindPlan>(lldb::eRegisterKindLLDB);
   plan_sp->SetSourceName("breakpad STACK CFI");
   plan_sp->SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  plan_sp->SetUnwindPlanForSignalTrap(eLazyBoolNo);
   plan_sp->SetSourcedFromCompiler(eLazyBoolYes);
   plan_sp->SetPlanValidAddressRange(
       AddressRange(base + init_record->Address, *init_record->Size,
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
index 43041ca1bb2..946d99cc0ce 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
+++ b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
@@ -1328,6 +1328,7 @@ bool x86AssemblyInspectionEngine::GetNonCallSiteUnwindPlanFromAssembly(
   unwind_plan.SetSourceName("assembly insn profiling");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolNo);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolYes);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
 
   return true;
 }
diff --git a/lldb/source/Symbol/ArmUnwindInfo.cpp b/lldb/source/Symbol/ArmUnwindInfo.cpp
index b9fd84b1e70..fdf4e30b2db 100644
--- a/lldb/source/Symbol/ArmUnwindInfo.cpp
+++ b/lldb/source/Symbol/ArmUnwindInfo.cpp
@@ -344,6 +344,7 @@ bool ArmUnwindInfo::GetUnwindPlan(Target &target, const Address &addr,
   unwind_plan.SetSourceName("ARM.exidx unwind info");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetRegisterKind(eRegisterKindDWARF);
 
   return true;
diff --git a/lldb/source/Symbol/CompactUnwindInfo.cpp b/lldb/source/Symbol/CompactUnwindInfo.cpp
index 3a2a4d3a09e..1a634f29736 100644
--- a/lldb/source/Symbol/CompactUnwindInfo.cpp
+++ b/lldb/source/Symbol/CompactUnwindInfo.cpp
@@ -737,6 +737,7 @@ bool CompactUnwindInfo::CreateUnwindPlan_x86_64(Target &target,
   unwind_plan.SetSourceName("compact unwind info");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetRegisterKind(eRegisterKindEHFrame);
 
   unwind_plan.SetLSDAAddress(function_info.lsda_address);
@@ -1008,6 +1009,7 @@ bool CompactUnwindInfo::CreateUnwindPlan_i386(Target &target,
   unwind_plan.SetSourceName("compact unwind info");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetRegisterKind(eRegisterKindEHFrame);
 
   unwind_plan.SetLSDAAddress(function_info.lsda_address);
@@ -1304,6 +1306,7 @@ bool CompactUnwindInfo::CreateUnwindPlan_arm64(Target &target,
   unwind_plan.SetSourceName("compact unwind info");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetRegisterKind(eRegisterKindEHFrame);
 
   unwind_plan.SetLSDAAddress(function_info.lsda_address);
@@ -1437,6 +1440,7 @@ bool CompactUnwindInfo::CreateUnwindPlan_armv7(Target &target,
   unwind_plan.SetSourceName("compact unwind info");
   unwind_plan.SetSourcedFromCompiler(eLazyBoolYes);
   unwind_plan.SetUnwindPlanValidAtAllInstructions(eLazyBoolNo);
+  unwind_plan.SetUnwindPlanForSignalTrap(eLazyBoolNo);
   unwind_plan.SetRegisterKind(eRegisterKindEHFrame);
 
   unwind_plan.SetLSDAAddress(function_info.lsda_address);
diff --git a/lldb/source/Symbol/DWARFCallFrameInfo.cpp b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
index 0ab9fa4b7bb..64bd22bd5cd 100644
--- a/lldb/source/Symbol/DWARFCallFrameInfo.cpp
+++ b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
@@ -19,6 +19,7 @@
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/Timer.h"
 #include <list>
+#include <cstring>
 
 using namespace lldb;
 using namespace lldb_private;
@@ -601,6 +602,9 @@ bool DWARFCallFrameInfo::FDEToUnwindPlan(dw_offset_t dwarf_offset,
     }
     offset += aug_data_len;
   }
+  unwind_plan.SetUnwindPlanForSignalTrap(
+    strchr(cie->augmentation, 'S') ? eLazyBoolYes : eLazyBoolNo);
+
   Address lsda_data;
   Address personality_function_ptr;