[release/6.0] Fix exception propagation over HW exception frame on macOS arm64

src/coreclr/pal/src/exception/machexception.cpp

@@ -369,28 +369,22 @@ 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);
 
         continueExecution = SEHProcessException(&exception);
         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.

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)
     {

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))
     {

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_ */
 

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();
+        }
+    }
+}

src/tests/Regressions/coreclr/GitHub_62058/test62058.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <CLRTestPriority>1</CLRTestPriority>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="test62058.cs" />
+  </ItemGroup>
+</Project>