Fix Windows Arm64 unwinding

There was an issue with unwinding native code functions in case of calls to no-return function placed at an end of a function code block. The return address was not in range of the function code, so RtlLookupFunctionEntry was not finding anything, we were thinking that it was a leaf function due to that and tried to unwind using LR only, which was wrong and resulted in staying on the same instruction. Thus the unwinding ended up in an infinite loop for those cases. The fix, that matches what RtlUnwind does, is to adjust the instruction pointer at call sites back. This is arm64 specific. Close dotnet#101921
janvorli · May 15, 2024 · 356ce1a · 356ce1a
1 parent ddff593
commit 356ce1a
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Showing 3 changed files with 24 additions and 56 deletions.
diff --git a/src/coreclr/inc/clrconfigvalues.h b/src/coreclr/inc/clrconfigvalues.h
@@ -259,12 +259,7 @@ RETAIL_CONFIG_DWORD_INFO(UNSUPPORTED_legacyCorruptedStateExceptionsPolicy, W("le
 CONFIG_DWORD_INFO(INTERNAL_SuppressLostExceptionTypeAssert, W("SuppressLostExceptionTypeAssert"), 0, "")
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_UseEntryPointFilter, W("UseEntryPointFilter"), 0, "")
 RETAIL_CONFIG_DWORD_INFO(INTERNAL_Corhost_Swallow_Uncaught_Exceptions, W("Corhost_Swallow_Uncaught_Exceptions"), 0, "")
-#if defined(HOST_WINDOWS) && defined(TARGET_ARM64) 
-// disable new exception handling for Windows ARM64
-RETAIL_CONFIG_DWORD_INFO(EXTERNAL_LegacyExceptionHandling, W("LegacyExceptionHandling"), 1, "Enable legacy exception handling.");
-#else
 RETAIL_CONFIG_DWORD_INFO(EXTERNAL_LegacyExceptionHandling, W("LegacyExceptionHandling"), 0, "Enable legacy exception handling.");
-#endif // defined(WINDOWS) && defined(TARGET_ARM64)
 
 ///
 /// Garbage collector

diff --git a/src/coreclr/vm/stackwalk.cpp b/src/coreclr/vm/stackwalk.cpp
@@ -553,6 +553,13 @@ PCODE Thread::VirtualUnwindCallFrame(T_CONTEXT* pContext,
     UINT_PTR            uImageBase;
     PT_RUNTIME_FUNCTION pFunctionEntry;
 
+#if !defined(TARGET_UNIX) && defined(CONTEXT_UNWOUND_TO_CALL)
+    if ((pContext->ContextFlags & CONTEXT_UNWOUND_TO_CALL) != 0)
+    {
+        uControlPc -= STACKWALK_CONTROLPC_ADJUST_OFFSET;
+    }
+#endif // !TARGET_UNIX && CONTEXT_UNWOUND_TO_CALL
+
     if (pCodeInfo == NULL)
     {
 #ifndef TARGET_UNIX
@@ -592,7 +599,23 @@ PCODE Thread::VirtualUnwindCallFrame(T_CONTEXT* pContext,
 
     if (pFunctionEntry)
     {
-        uControlPc = VirtualUnwindNonLeafCallFrame(pContext, pContextPointers, pFunctionEntry, uImageBase);
+    #ifdef HOST_64BIT
+        UINT64              EstablisherFrame;
+    #else  // HOST_64BIT
+        DWORD               EstablisherFrame;
+    #endif // HOST_64BIT
+        PVOID               HandlerData;
+
+        RtlVirtualUnwind(0,
+                         uImageBase,
+                         uControlPc,
+                         pFunctionEntry,
+                         pContext,
+                         &HandlerData,
+                         &EstablisherFrame,
+                         pContextPointers);
+
+        uControlPc = GetIP(pContext);
     }
     else
     {
@@ -661,54 +684,6 @@ PCODE Thread::VirtualUnwindLeafCallFrame(T_CONTEXT* pContext)
     return uControlPc;
 }
 
-// static
-PCODE Thread::VirtualUnwindNonLeafCallFrame(T_CONTEXT* pContext, KNONVOLATILE_CONTEXT_POINTERS* pContextPointers,
-    PT_RUNTIME_FUNCTION pFunctionEntry, UINT_PTR uImageBase)
-{
-    CONTRACTL
-    {
-        NOTHROW;
-        GC_NOTRIGGER;
-        PRECONDITION(CheckPointer(pContext, NULL_NOT_OK));
-        PRECONDITION(CheckPointer(pContextPointers, NULL_OK));
-        PRECONDITION(CheckPointer(pFunctionEntry, NULL_OK));
-    }
-    CONTRACTL_END;
-
-    PCODE           uControlPc = GetIP(pContext);
-#ifdef HOST_64BIT
-    UINT64              EstablisherFrame;
-#else  // HOST_64BIT
-    DWORD               EstablisherFrame;
-#endif // HOST_64BIT
-    PVOID               HandlerData;
-
-    if (NULL == pFunctionEntry)
-    {
-#ifndef TARGET_UNIX
-        pFunctionEntry  = RtlLookupFunctionEntry(uControlPc,
-                                                 ARM_ONLY((DWORD*))(&uImageBase),
-                                                 NULL);
-#endif
-        if (NULL == pFunctionEntry)
-        {
-            return (PCODE)NULL;
-        }
-    }
-
-    RtlVirtualUnwind(0,
-                     uImageBase,
-                     uControlPc,
-                     pFunctionEntry,
-                     pContext,
-                     &HandlerData,
-                     &EstablisherFrame,
-                     pContextPointers);
-
-    uControlPc = GetIP(pContext);
-    return uControlPc;
-}
-
 extern void* g_hostingApiReturnAddress;
 
 // static

diff --git a/src/coreclr/vm/threads.h b/src/coreclr/vm/threads.h
@@ -2369,8 +2369,6 @@ class Thread
     static UINT_PTR VirtualUnwindCallFrame(PREGDISPLAY pRD, EECodeInfo * pCodeInfo = NULL);
 #ifndef DACCESS_COMPILE
     static PCODE VirtualUnwindLeafCallFrame(T_CONTEXT* pContext);
-    static PCODE VirtualUnwindNonLeafCallFrame(T_CONTEXT* pContext, T_KNONVOLATILE_CONTEXT_POINTERS* pContextPointers = NULL,
-        PT_RUNTIME_FUNCTION pFunctionEntry = NULL, UINT_PTR uImageBase = 0);
     static UINT_PTR VirtualUnwindToFirstManagedCallFrame(T_CONTEXT* pContext);
 #endif // DACCESS_COMPILE
 #endif // FEATURE_EH_FUNCLETS