Fix race in artInvokeInterfaceTrampoline().

When artInvokeInterfaceTrampoline() didn't get a resolved
interface method, it was calling FindMethodFromCode<>()
where the interface method was resolved and then a virtual
method for it was looked up. It then tried to retrieve the
interface method from the DexCache where it would usualy be
found as it was just stored there by the method resolution.
However, another thread could have just evicted that entry.

Instead of adding another call to LookupResolvedMethod(),
use the fact that artInvokeInterfaceTrampoline() already
explicitly inlines all the FindMethodFromCode<>() except
for the interface method resolution, so we can simply do
the resolution and then take the existing path for the rest
of the work.

Test: m test-art-host-gtest
Test: testrunner.py --host
Bug: 30627598
Change-Id: I62ca9c4e108ab6a3ee700b55d3b19c8f0f63f1d2

1 files changed, 5 insertions, 6 deletions

diff --git a/runtime/entrypoints/entrypoint_utils-inl.h b/runtime/entrypoints/entrypoint_utils-inl.h
index a6c5d6c7aa..be3e4f811a 100644
--- a/runtime/entrypoints/entrypoint_utils-inl.h
+++ b/runtime/entrypoints/entrypoint_utils-inl.h
@@ -476,7 +476,7 @@ inline ArtMethod* FindMethodFromCode(uint32_t method_idx,
     case kDirect:
       return resolved_method;
     case kVirtual: {
-      mirror::Class* klass = (*this_object)->GetClass();
+      ObjPtr<mirror::Class> klass = (*this_object)->GetClass();
       uint16_t vtable_index = resolved_method->GetMethodIndex();
       if (access_check &&
           (!klass->HasVTable() ||
@@ -509,7 +509,7 @@ inline ArtMethod* FindMethodFromCode(uint32_t method_idx,
         // It is not an interface. If the referring class is in the class hierarchy of the
         // referenced class in the bytecode, we use its super class. Otherwise, we throw
         // a NoSuchMethodError.
-        mirror::Class* super_class = nullptr;
+        ObjPtr<mirror::Class> super_class = nullptr;
         if (method_reference_class->IsAssignableFrom(h_referring_class.Get())) {
           super_class = h_referring_class->GetSuperClass();
         }
@@ -554,11 +554,10 @@ inline ArtMethod* FindMethodFromCode(uint32_t method_idx,
     case kInterface: {
       uint32_t imt_index = ImTable::GetImtIndex(resolved_method);
       PointerSize pointer_size = class_linker->GetImagePointerSize();
-      ArtMethod* imt_method = (*this_object)->GetClass()->GetImt(pointer_size)->
-          Get(imt_index, pointer_size);
+      ObjPtr<mirror::Class> klass = (*this_object)->GetClass();
+      ArtMethod* imt_method = klass->GetImt(pointer_size)->Get(imt_index, pointer_size);
       if (!imt_method->IsRuntimeMethod()) {
         if (kIsDebugBuild) {
-          mirror::Class* klass = (*this_object)->GetClass();
           ArtMethod* method = klass->FindVirtualMethodForInterface(
               resolved_method, class_linker->GetImagePointerSize());
           CHECK_EQ(imt_method, method) << ArtMethod::PrettyMethod(resolved_method) << " / "
@@ -568,7 +567,7 @@ inline ArtMethod* FindMethodFromCode(uint32_t method_idx,
         }
         return imt_method;
       } else {
-        ArtMethod* interface_method = (*this_object)->GetClass()->FindVirtualMethodForInterface(
+        ArtMethod* interface_method = klass->FindVirtualMethodForInterface(
             resolved_method, class_linker->GetImagePointerSize());
         if (UNLIKELY(interface_method == nullptr)) {
           ThrowIncompatibleClassChangeErrorClassForInterfaceDispatch(resolved_method,