Reland "Reland: [wasm] Check correctness of thread-local write protection"

This is a reland of 1c0cca0f. It is
modified now to use V8_HAS_PTHREAD_JIT_WRITE_PROTECT and is rebased on
https://crrev.com/c/3085271 which fixes the definition of that macro.

Original change's description:
> Reland: [wasm] Check correctness of thread-local write protection
>
> The fix landed as a separate CL: https://crrev.com/c/3081522
> This is an unmodified reland.
>
> Original description:
> We make an undocumented assumption in {CodeSpaceWriteScope} that a
> single thread will only work on one module at a time. If this is
> violated, the thread-local {code_space_write_nesting_level_} would
> prevent the second module from being switched to writable.
>
> This CL adds a second thread local (in debug only) to check that if
> there is already a {CodeSpaceWriteScope} open that it contains the same
> {NativeModule} as any nested scope.
>
> R=jkummerow@chromium.org
>
> Bug: v8:11974
> Cq-Include-Trybots: luci.v8.try:v8_linux_gc_stress_dbg_ng
> Cq-Include-Trybots: luci.v8.try:v8_mac64_gc_stress_dbg_ng
> Change-Id: Id827b6ca472f695e4500584349aba159aa07eed1
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3080578
> Commit-Queue: Clemens Backes <clemensb@chromium.org>
> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#76177}

Bug: v8:11974
Change-Id: Iffc510e85c8c56f26bfa88115ed3a8bdd33ef422
Cq-Include-Trybots: luci.v8.try:v8_linux_gc_stress_dbg_ng
Cq-Include-Trybots: luci.v8.try:v8_mac64_gc_stress_dbg_ng
Cq-Include-Trybots: luci.v8.try:v8_mac_arm64_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_mac_arm64_dbg_ng
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3085269Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#76235}

src/wasm/code-space-access.cc

@@ -12,6 +12,12 @@ namespace internal {
 namespace wasm {
 
 thread_local int CodeSpaceWriteScope::code_space_write_nesting_level_ = 0;
+// The thread-local counter (above) is only valid if a single thread only works
+// on one module at a time. This second thread-local checks that.
+#if defined(DEBUG) && !V8_HAS_PTHREAD_JIT_WRITE_PROTECT
+thread_local NativeModule* CodeSpaceWriteScope::current_native_module_ =
+    nullptr;
+#endif
 
 // TODO(jkummerow): Background threads could permanently stay in
 // writable mode; only the main thread has to switch back and forth.
@@ -20,6 +26,12 @@ CodeSpaceWriteScope::CodeSpaceWriteScope(NativeModule*) {
 #else  // !V8_HAS_PTHREAD_JIT_WRITE_PROTECT
 CodeSpaceWriteScope::CodeSpaceWriteScope(NativeModule* native_module)
     : native_module_(native_module) {
+#ifdef DEBUG
+  if (code_space_write_nesting_level_ == 0) {
+    current_native_module_ = native_module;
+  }
+  DCHECK_EQ(native_module, current_native_module_);
+#endif  // DEBUG
 #endif  // !V8_HAS_PTHREAD_JIT_WRITE_PROTECT
   if (code_space_write_nesting_level_ == 0) SetWritable();
   code_space_write_nesting_level_++;

src/wasm/code-space-access.h

@@ -55,6 +55,9 @@ class V8_NODISCARD CodeSpaceWriteScope final {
 
  private:
   static thread_local int code_space_write_nesting_level_;
+#if defined(DEBUG) && !V8_HAS_PTHREAD_JIT_WRITE_PROTECT
+  static thread_local NativeModule* current_native_module_;
+#endif
 
   void SetWritable() const;
   void SetExecutable() const;