[wasm][fuzzer] Enable trap handlers only once

The fuzzer function is called multiple times with libfuzzer. Trap
handlers, however, should only be initialized once. With this CL we add
a flag to initialize trap handlers only once.

R=clemensb@chromium.org

Bug: chromium:1122590
Change-Id: Ib51a50cfe9dad5e3133de3085ad147f5a069b1bd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2384769
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69643}

test/fuzzer/fuzzer-support.cc

@@ -9,8 +9,8 @@
 #include <string.h>
 
 #include "include/libplatform/libplatform.h"
-
 #include "src/flags/flags.h"
+#include "src/trap-handler/trap-handler.h"
 
 namespace v8_fuzzer {
 
@@ -61,6 +61,12 @@ std::unique_ptr<FuzzerSupport> FuzzerSupport::fuzzer_support_;
 
 // static
 void FuzzerSupport::InitializeFuzzerSupport(int* argc, char*** argv) {
+  if (V8_TRAP_HANDLER_SUPPORTED && i::FLAG_wasm_trap_handler) {
+    constexpr bool kUseDefaultTrapHandler = true;
+    if (!v8::V8::EnableWebAssemblyTrapHandler(kUseDefaultTrapHandler)) {
+      FATAL("Could not register trap handler");
+    }
+  }
   DCHECK_NULL(FuzzerSupport::fuzzer_support_);
   FuzzerSupport::fuzzer_support_ =
       std::make_unique<v8_fuzzer::FuzzerSupport>(argc, argv);

test/fuzzer/wasm-async.cc

@@ -45,13 +45,6 @@ class AsyncFuzzerResolver : public i::wasm::CompilationResultResolver {
 };
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  if (V8_TRAP_HANDLER_SUPPORTED && i::FLAG_wasm_trap_handler) {
-    constexpr bool kUseDefaultTrapHandler = true;
-    if (!v8::V8::EnableWebAssemblyTrapHandler(kUseDefaultTrapHandler)) {
-      FATAL("Could not register trap handler");
-    }
-  }
-
   // We explicitly enable staged WebAssembly features here to increase fuzzer
   // coverage. For libfuzzer fuzzers it is not possible that the fuzzer enables
   // the flag by itself.

test/fuzzer/wasm-fuzzer-common.cc

@@ -303,12 +303,6 @@ void GenerateTestCase(Isolate* isolate, ModuleWireBytes wire_bytes,
 
 void WasmExecutionFuzzer::FuzzWasmModule(Vector<const uint8_t> data,
                                          bool require_valid) {
-  if (V8_TRAP_HANDLER_SUPPORTED && i::FLAG_wasm_trap_handler) {
-    constexpr bool kUseDefaultTrapHandler = true;
-    if (!v8::V8::EnableWebAssemblyTrapHandler(kUseDefaultTrapHandler)) {
-      FATAL("Could not register trap handler");
-    }
-  }
   // We explicitly enable staged WebAssembly features here to increase fuzzer
   // coverage. For libfuzzer fuzzers it is not possible that the fuzzer enables
   // the flag by itself.

test/fuzzer/wasm.cc

@@ -21,13 +21,6 @@
 namespace i = v8::internal;
 
 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
-  if (V8_TRAP_HANDLER_SUPPORTED && i::FLAG_wasm_trap_handler) {
-    constexpr bool kUseDefaultTrapHandler = true;
-    if (!v8::V8::EnableWebAssemblyTrapHandler(kUseDefaultTrapHandler)) {
-      FATAL("Could not register trap handler");
-    }
-  }
-
   // We explicitly enable staged WebAssembly features here to increase fuzzer
   // coverage. For libfuzzer fuzzers it is not possible that the fuzzer enables
   // the flag by itself.