Write return address in deopt stubs, too.

Author: peter-hofer

substratevm/src/com.oracle.svm.core.graal.amd64/src/com/oracle/svm/core/graal/amd64/SubstrateAMD64Backend.java

@@ -1361,11 +1361,10 @@ public void enter(CompilationResultBuilder tasm) {
             asm.maybeEmitIndirectTargetMarker();
 
             /*
-             * Keep the return address slot. This keeps the stack walkable, which is crucial for the
-             * interruptible phase of lazy deoptimization. (The return address points to the deopt
-             * stub, while the original return address is stored in the deopt slot.)
+             * Keep the return address slot. The correct return address is written in the stub
+             * itself (read more there). The original return address is stored in the deopt slot.
              *
-             * This also ensures that the stack pointer is aligned properly.
+             * Keeping the return address also ensures that the stack pointer is aligned properly.
              */
             asm.subq(registerConfig.getFrameRegister(), FrameAccess.returnAddressSize());
 

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/deopt/Deoptimizer.java

@@ -828,6 +828,14 @@ private static boolean isNonNullValue(UnsignedWord pointer) {
     @DeoptStub(stubType = StubType.EntryStub)
     @Uninterruptible(reason = "Rewriting stack; gpReturnValue holds object reference.")
     public static UnsignedWord lazyDeoptStubObjectReturn(Pointer originalStackPointer, UnsignedWord gpReturnValue, UnsignedWord fpReturnValue) {
+        /*
+         * Establish the correct return address for this stub to make the stack walkable. The return
+         * address could have been overwritten by an interrupt or signal handler if the ABI doesn't
+         * guarantee a safe zone below the stack pointer.
+         */
+        CodePointer returnAddress = DeoptimizationSupport.getLazyDeoptStubObjectReturnPointer();
+        FrameAccess.singleton().writeReturnAddress(CurrentIsolate.getCurrentThread(), originalStackPointer, returnAddress);
+
         try {
             assert PointerUtils.isAMultiple(KnownIntrinsics.readStackPointer(), Word.unsigned(ConfigurationValues.getTarget().stackAlignment));
             assert Options.LazyDeoptimization.getValue();
@@ -855,6 +863,10 @@ public static UnsignedWord lazyDeoptStubObjectReturn(Pointer originalStackPointe
     @DeoptStub(stubType = StubType.EntryStub)
     @Uninterruptible(reason = "Rewriting stack.")
     public static UnsignedWord lazyDeoptStubPrimitiveReturn(Pointer originalStackPointer, UnsignedWord gpReturnValue, UnsignedWord fpReturnValue) {
+        /* Establish the correct return address for this stub (see ObjectReturn stub for details) */
+        CodePointer returnAddress = DeoptimizationSupport.getLazyDeoptStubPrimitiveReturnPointer();
+        FrameAccess.singleton().writeReturnAddress(CurrentIsolate.getCurrentThread(), originalStackPointer, returnAddress);
+
         /*
          * Note: when we dispatch an exception, we enter lazyDeoptStubObjectReturn instead, since
          * that involves returning an exception object.
@@ -1005,6 +1017,10 @@ private static DeoptimizedFrame constructLazilyDeoptimizedFrameInterruptibly0(Po
     @DeoptStub(stubType = StubType.EntryStub)
     @Uninterruptible(reason = "Frame holds Objects in unmanaged storage.")
     public static UnsignedWord eagerDeoptStub(Pointer originalStackPointer, UnsignedWord gpReturnValue, UnsignedWord fpReturnValue) {
+        /* Establish the correct return address for this stub to make the stack walkable. */
+        CodePointer returnAddress = DeoptimizationSupport.getEagerDeoptStubPointer();
+        FrameAccess.singleton().writeReturnAddress(CurrentIsolate.getCurrentThread(), originalStackPointer, returnAddress);
+
         try {
             assert PointerUtils.isAMultiple(KnownIntrinsics.readStackPointer(), Word.unsigned(ConfigurationValues.getTarget().stackAlignment));
             VMError.guarantee(VMThreads.StatusSupport.isStatusJava(), "Deopt stub execution must not be visible to other threads.");