From 2caf6fb6e7ed437829ce1f48dd5e070ff5df7d39 Mon Sep 17 00:00:00 2001 From: "github-actions[bot]" <41898282+github-actions[bot]@users.noreply.github.com> Date: Mon, 7 Feb 2022 11:14:58 -0800 Subject: [PATCH] [release/6.0] Fix exception propagation over HW exception frame on macOS arm64 (#64262) * Fix exception propagation over HW exception frame on macOS arm64 There is a problem unwinding over the PAL_DispatchExceptionWrapper to the actual hardware exception location. The unwinder is unable to get distinct LR and PC in that frame and sets both of them to the same value. This is caused by the fact that the PAL_DispatchExceptionWrapper is just an injected fake frame and there was no real call. Calls always return with LR and PC set to the same value. The fix unifies the hardware exception frame unwinding with Linux where we had problems unwinding over signal handler trampoline, so PAL_VirtualUnwind skips the trampoline and now also the PAL_DispatchExceptionWrapper frame by copying the context of the exception as the unwound context. * Fix GC stress C - wrong context being restored The context that is restored in the PAL_DispatchException needs to be the one from the exception, not the original saved one. That ensures that the registers updated by the GC in GC stress C in the context are properly restored after the execution is resumed. * Fix exception context leak in GC stress C The PAL_SEHException had the records allocated on stack, so the direct context restoration after the EH for GC stress C completed leaked those. Co-authored-by: Jan Vorlicek --- .../pal/src/exception/machexception.cpp | 18 ++---- src/coreclr/pal/src/exception/seh-unwind.cpp | 16 ++--- src/coreclr/pal/src/exception/signal.cpp | 7 +-- src/coreclr/pal/src/include/pal/seh.hpp | 5 ++ .../coreclr/GitHub_62058/test62058.cs | 60 +++++++++++++++++++ .../coreclr/GitHub_62058/test62058.csproj | 9 +++ 6 files changed, 90 insertions(+), 25 deletions(-) create mode 100644 src/tests/Regressions/coreclr/GitHub_62058/test62058.cs create mode 100644 src/tests/Regressions/coreclr/GitHub_62058/test62058.csproj diff --git a/src/coreclr/pal/src/exception/machexception.cpp b/src/coreclr/pal/src/exception/machexception.cpp index e5aebdf652c6a..eca89e0a204c6 100644 --- a/src/coreclr/pal/src/exception/machexception.cpp +++ b/src/coreclr/pal/src/exception/machexception.cpp @@ -369,19 +369,13 @@ void PAL_DispatchException(PCONTEXT pContext, PEXCEPTION_RECORD pExRecord, MachE { CPalThread *pThread = InternalGetCurrentThread(); - CONTEXT *contextRecord; - EXCEPTION_RECORD *exceptionRecord; - AllocateExceptionRecords(&exceptionRecord, &contextRecord); + CONTEXT *contextRecord = pContext; + g_hardware_exception_context_locvar_offset = (int)((char*)&contextRecord - (char*)__builtin_frame_address(0)); - *contextRecord = *pContext; - *exceptionRecord = *pExRecord; - - contextRecord->ContextFlags |= CONTEXT_EXCEPTION_ACTIVE; + pContext->ContextFlags |= CONTEXT_EXCEPTION_ACTIVE; bool continueExecution; - { - // The exception object takes ownership of the exceptionRecord and contextRecord - PAL_SEHException exception(exceptionRecord, contextRecord); + PAL_SEHException exception(pExRecord, pContext, true); TRACE("PAL_DispatchException(EC %08x EA %p)\n", pExRecord->ExceptionCode, pExRecord->ExceptionAddress); @@ -389,8 +383,8 @@ void PAL_DispatchException(PCONTEXT pContext, PEXCEPTION_RECORD pExRecord, MachE if (continueExecution) { // Make a copy of the exception records so that we can free them before restoring the context - *pContext = *contextRecord; - *pExRecord = *exceptionRecord; + *pContext = *exception.ExceptionPointers.ContextRecord; + *pExRecord = *exception.ExceptionPointers.ExceptionRecord; } // The exception records are destroyed by the PAL_SEHException destructor now. diff --git a/src/coreclr/pal/src/exception/seh-unwind.cpp b/src/coreclr/pal/src/exception/seh-unwind.cpp index 9a1f5d0b5e89d..a9ddb179d5f82 100644 --- a/src/coreclr/pal/src/exception/seh-unwind.cpp +++ b/src/coreclr/pal/src/exception/seh-unwind.cpp @@ -476,7 +476,9 @@ void GetContextPointers(unw_cursor_t *cursor, unw_context_t *unwContext, KNONVOL #ifndef HOST_WINDOWS -extern int g_common_signal_handler_context_locvar_offset; +// Frame pointer relative offset of a local containing a pointer to the windows style context of a location +// where a hardware exception occured. +int g_hardware_exception_context_locvar_offset = 0; BOOL PAL_VirtualUnwind(CONTEXT *context, KNONVOLATILE_CONTEXT_POINTERS *contextPointers) { @@ -486,19 +488,17 @@ BOOL PAL_VirtualUnwind(CONTEXT *context, KNONVOLATILE_CONTEXT_POINTERS *contextP DWORD64 curPc = CONTEXTGetPC(context); -#ifndef __APPLE__ - // Check if the PC is the return address from the SEHProcessException in the common_signal_handler. - // If that's the case, extract its local variable containing the windows style context of the hardware + // Check if the PC is the return address from the SEHProcessException. + // If that's the case, extract its local variable containing a pointer to the windows style context of the hardware // exception and return that. This skips the hardware signal handler trampoline that the libunwind - // cannot cross on some systems. + // cannot cross on some systems. On macOS, it skips a similar trampoline we create in HijackFaultingThread. if ((void*)curPc == g_SEHProcessExceptionReturnAddress) { - CONTEXT* signalContext = (CONTEXT*)(CONTEXTGetFP(context) + g_common_signal_handler_context_locvar_offset); - memcpy_s(context, sizeof(CONTEXT), signalContext, sizeof(CONTEXT)); + CONTEXT* exceptionContext = *(CONTEXT**)(CONTEXTGetFP(context) + g_hardware_exception_context_locvar_offset); + memcpy_s(context, sizeof(CONTEXT), exceptionContext, sizeof(CONTEXT)); return TRUE; } -#endif if ((context->ContextFlags & CONTEXT_EXCEPTION_ACTIVE) != 0) { diff --git a/src/coreclr/pal/src/exception/signal.cpp b/src/coreclr/pal/src/exception/signal.cpp index 59b513b87204e..4d9e8582acf94 100644 --- a/src/coreclr/pal/src/exception/signal.cpp +++ b/src/coreclr/pal/src/exception/signal.cpp @@ -114,10 +114,6 @@ struct sigaction g_previous_sigabrt; #if !HAVE_MACH_EXCEPTIONS -// Offset of the local variable containing pointer to windows style context in the common_signal_handler function. -// This offset is relative to the frame pointer. -int g_common_signal_handler_context_locvar_offset = 0; - // TOP of special stack for handling stack overflow volatile void* g_stackOverflowHandlerStack = NULL; @@ -931,11 +927,12 @@ static bool common_signal_handler(int code, siginfo_t *siginfo, void *sigcontext #if !HAVE_MACH_EXCEPTIONS sigset_t signal_set; CONTEXT signalContextRecord; + CONTEXT* signalContextRecordPtr = &signalContextRecord; EXCEPTION_RECORD exceptionRecord; native_context_t *ucontext; ucontext = (native_context_t *)sigcontext; - g_common_signal_handler_context_locvar_offset = (int)((char*)&signalContextRecord - (char*)__builtin_frame_address(0)); + g_hardware_exception_context_locvar_offset = (int)((char*)&signalContextRecordPtr - (char*)__builtin_frame_address(0)); if (code == (SIGSEGV | StackOverflowFlag)) { diff --git a/src/coreclr/pal/src/include/pal/seh.hpp b/src/coreclr/pal/src/include/pal/seh.hpp index 6ad89df0fdd65..327fe0d7fb03e 100644 --- a/src/coreclr/pal/src/include/pal/seh.hpp +++ b/src/coreclr/pal/src/include/pal/seh.hpp @@ -145,5 +145,10 @@ CorUnix::PAL_ERROR SEHDisable(CorUnix::CPalThread *pthrCurrent); } +// Offset of the local variable containing pointer to windows style context in the common_signal_handler / PAL_DispatchException function. +// This offset is relative to the frame pointer. +extern int g_hardware_exception_context_locvar_offset; + + #endif /* _PAL_SEH_HPP_ */ diff --git a/src/tests/Regressions/coreclr/GitHub_62058/test62058.cs b/src/tests/Regressions/coreclr/GitHub_62058/test62058.cs new file mode 100644 index 0000000000000..bffbf999e7396 --- /dev/null +++ b/src/tests/Regressions/coreclr/GitHub_62058/test62058.cs @@ -0,0 +1,60 @@ +// Licensed to the .NET Foundation under one or more agreements. +// The .NET Foundation licenses this file to you under the MIT license. + +using System; + +public class Program +{ + private interface IFoo + { + bool IsValid { get; } + } + + private class Foo : IFoo + { + public bool IsValid { get; set; } + } + + public static int Main(string[] args) + { + bool warmup = new Foo().IsValid; + CatchIgnore(() => + CatchRethrow(() => + { + IFoo[] foos = {new Foo(), null}; + foreach (var foo in foos) + { + bool check = foo.IsValid; + } + })); + + return 100; + } + + public static void CatchRethrow(Action action) + { + try + { + action.Invoke(); + } + catch (Exception e) + { + Console.Out.WriteLine("catch"); + Console.Out.Flush(); + throw new Exception("catch", e); + } + } + + public static void CatchIgnore(Action action) + { + try + { + action.Invoke(); + } + catch (Exception) + { + Console.Out.WriteLine("ignore"); + Console.Out.Flush(); + } + } +} diff --git a/src/tests/Regressions/coreclr/GitHub_62058/test62058.csproj b/src/tests/Regressions/coreclr/GitHub_62058/test62058.csproj new file mode 100644 index 0000000000000..0fce5a0556f40 --- /dev/null +++ b/src/tests/Regressions/coreclr/GitHub_62058/test62058.csproj @@ -0,0 +1,9 @@ + + + Exe + 1 + + + + +