deps: V8: cherry-pick 475c8cdf9a95

Original commit message:

    [ptr-compr] Fix multi-cage mode

    This CL introduces PtrComprCageAccessScope which sets/restores current
    thread's pointer compression cage base values. It's supposed to be used
    by V8 jobs accessing V8 heap outside of v8::Isolate::Scope or
    i::LocalHeap or i::LocalIsolate scopes (they already ensure that the
    cage base values are properly initialized).
    For all other build modes PtrComprCageAccessScope is a no-op.

    For simplicity reasons the multi-cage mode is made incompatible with
    external code space.

    Bug: v8:13788, v8:14292
    Change-Id: I06c2d19a1eb7254fa7af07a17617e22d98abea9f
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4846592
    Reviewed-by: Jakob Linke <[email protected]>
    Reviewed-by: Jakob Kummerow <[email protected]>
    Commit-Queue: Igor Sheludko <[email protected]>
    Reviewed-by: Dominik Inführ <[email protected]>
    Cr-Commit-Position: refs/heads/main@{#90075}

Refs: v8/v8@475c8cd
PR-URL: #50680
Refs: https://bugs.chromium.org/p/v8/issues/detail?id=14292
Reviewed-By: Ben Noordhuis <[email protected]>
Reviewed-By: Darshan Sen <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: James M Snell <[email protected]>

Author: kvakil

deps/v8/BUILD.gn

@@ -500,6 +500,7 @@ if (v8_enable_short_builtin_calls == "") {
 if (v8_enable_external_code_space == "") {
   v8_enable_external_code_space =
       v8_enable_pointer_compression &&
+      v8_enable_pointer_compression_shared_cage &&
       (v8_current_cpu == "x64" || v8_current_cpu == "arm64")
 }
 if (v8_enable_maglev == "") {
@@ -683,6 +684,12 @@ assert(
     !v8_enable_pointer_compression_shared_cage || v8_enable_pointer_compression,
     "Can't share a pointer compression cage if pointers aren't compressed")
 
+assert(
+    !v8_enable_pointer_compression ||
+        v8_enable_pointer_compression_shared_cage ||
+        !v8_enable_external_code_space,
+    "Multi-cage pointer compression mode is not compatible with external code space")
+
 assert(
     !v8_enable_pointer_compression_shared_cage || v8_current_cpu == "x64" ||
         v8_current_cpu == "arm64" || v8_current_cpu == "riscv64" ||

deps/v8/src/api/api.cc

@@ -9227,6 +9227,14 @@ void Isolate::TerminateExecution() {
 
 bool Isolate::IsExecutionTerminating() {
   i::Isolate* i_isolate = reinterpret_cast<i::Isolate*>(this);
+#ifdef DEBUG
+  // This method might be called on a thread that's not bound to any Isolate
+  // and thus pointer compression schemes might have cage base value unset.
+  // Read-only roots accessors contain type DCHECKs which require access to
+  // V8 heap in order to check the object type. So, allow heap access here
+  // to let the checks work.
+  i::PtrComprCageAccessScope ptr_compr_cage_access_scope(i_isolate);
+#endif  // DEBUG
   return i_isolate->is_execution_terminating();
 }
 
@@ -9898,6 +9906,14 @@ void Isolate::LowMemoryNotification() {
     i::NestedTimedHistogramScope idle_notification_scope(
         i_isolate->counters()->gc_low_memory_notification());
     TRACE_EVENT0("v8", "V8.GCLowMemoryNotification");
+#ifdef DEBUG
+    // This method might be called on a thread that's not bound to any Isolate
+    // and thus pointer compression schemes might have cage base value unset.
+    // Read-only roots accessors contain type DCHECKs which require access to
+    // V8 heap in order to check the object type. So, allow heap access here
+    // to let the checks work.
+    i::PtrComprCageAccessScope ptr_compr_cage_access_scope(i_isolate);
+#endif  // DEBUG
     i_isolate->heap()->CollectAllAvailableGarbage(
         i::GarbageCollectionReason::kLowMemoryNotification);
   }

deps/v8/src/common/ptr-compr-inl.h

@@ -91,11 +91,16 @@ Address V8HeapCompressionScheme::DecompressTaggedSigned(Tagged_t raw_value) {
 template <typename TOnHeapAddress>
 Address V8HeapCompressionScheme::DecompressTagged(TOnHeapAddress on_heap_addr,
                                                   Tagged_t raw_value) {
-#if defined(V8_COMPRESS_POINTERS_IN_SHARED_CAGE)
+#ifdef V8_COMPRESS_POINTERS
   Address cage_base = base();
+#ifdef V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+  DCHECK_WITH_MSG(cage_base != kNullAddress,
+                  "V8HeapCompressionScheme::base is not initialized for "
+                  "current thread");
+#endif  // V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
 #else
   Address cage_base = GetPtrComprCageBaseAddress(on_heap_addr);
-#endif
+#endif  // V8_COMPRESS_POINTERS
   Address result = cage_base + static_cast<Address>(raw_value);
   V8_ASSUME(static_cast<uint32_t>(result) == raw_value);
   return result;
@@ -191,11 +196,16 @@ Address ExternalCodeCompressionScheme::DecompressTaggedSigned(
 template <typename TOnHeapAddress>
 Address ExternalCodeCompressionScheme::DecompressTagged(
     TOnHeapAddress on_heap_addr, Tagged_t raw_value) {
-#if defined(V8_COMPRESS_POINTERS_IN_SHARED_CAGE)
+#ifdef V8_COMPRESS_POINTERS
   Address cage_base = base();
+#ifdef V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+  DCHECK_WITH_MSG(cage_base != kNullAddress,
+                  "ExternalCodeCompressionScheme::base is not initialized for "
+                  "current thread");
+#endif  // V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
 #else
   Address cage_base = GetPtrComprCageBaseAddress(on_heap_addr);
-#endif
+#endif  // V8_COMPRESS_POINTERS
   Address result = cage_base + static_cast<Address>(raw_value);
   V8_ASSUME(static_cast<uint32_t>(result) == raw_value);
   return result;
@@ -275,6 +285,19 @@ V8_INLINE PtrComprCageBase GetPtrComprCageBase(Tagged<HeapObject> object) {
   return GetPtrComprCageBaseFromOnHeapAddress(object.ptr());
 }
 
+#ifdef V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+
+PtrComprCageAccessScope::PtrComprCageAccessScope(Isolate* isolate)
+    : cage_base_(V8HeapCompressionScheme::base()) {
+  V8HeapCompressionScheme::InitBase(isolate->cage_base());
+}
+
+PtrComprCageAccessScope::~PtrComprCageAccessScope() {
+  V8HeapCompressionScheme::InitBase(cage_base_);
+}
+
+#endif  // V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+
 }  // namespace internal
 }  // namespace v8
 

deps/v8/src/common/ptr-compr.h

@@ -55,8 +55,8 @@ class V8HeapCompressionScheme {
  private:
   // These non-inlined accessors to base_ field are used in component builds
   // where cross-component access to thread local variables is not allowed.
-  static Address base_non_inlined();
-  static void set_base_non_inlined(Address base);
+  static V8_EXPORT_PRIVATE Address base_non_inlined();
+  static V8_EXPORT_PRIVATE void set_base_non_inlined(Address base);
 
 #ifdef V8_COMPRESS_POINTERS_IN_SHARED_CAGE
   static V8_EXPORT_PRIVATE uintptr_t base_ V8_CONSTINIT;
@@ -156,6 +156,29 @@ static inline void WriteMaybeUnalignedValue(Address p, V value) {
   }
 }
 
+// When multi-cage pointer compression mode is enabled this scope object
+// saves current cage's base values and sets them according to given Isolate.
+// For all other configurations this scope object is a no-op.
+class PtrComprCageAccessScope final {
+ public:
+#ifdef V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+  V8_INLINE explicit PtrComprCageAccessScope(Isolate* isolate);
+  V8_INLINE ~PtrComprCageAccessScope();
+#else
+  V8_INLINE explicit PtrComprCageAccessScope(Isolate* isolate) {}
+  V8_INLINE ~PtrComprCageAccessScope() {}
+#endif
+
+ private:
+#ifdef V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+  const Address cage_base_;
+#ifdef V8_EXTERNAL_CODE_SPACE
+// In case this configuration is necessary the code cage base must be saved too.
+#error Multi-cage pointer compression with external code space is not supported
+#endif  // V8_EXTERNAL_CODE_SPACE
+#endif  // V8_COMPRESS_POINTERS_IN_ISOLATE_CAGE
+};
+
 }  // namespace v8::internal
 
 #endif  // V8_COMMON_PTR_COMPR_H_

deps/v8/src/execution/isolate.cc

@@ -3933,6 +3933,14 @@ Isolate::~Isolate() {
 
 void Isolate::InitializeThreadLocal() {
   thread_local_top()->Initialize(this);
+#ifdef DEBUG
+  // This method might be called on a thread that's not bound to any Isolate
+  // and thus pointer compression schemes might have cage base value unset.
+  // Read-only roots accessors contain type DCHECKs which require access to
+  // V8 heap in order to check the object type. So, allow heap access here
+  // to let the checks work.
+  i::PtrComprCageAccessScope ptr_compr_cage_access_scope(this);
+#endif  // DEBUG
   clear_pending_exception();
   clear_pending_message();
   clear_scheduled_exception();

deps/v8/src/execution/v8threads.cc

@@ -124,6 +124,10 @@ bool ThreadManager::RestoreThread() {
     InitThread(access);
     return false;
   }
+  // In case multi-cage pointer compression mode is enabled ensure that
+  // current thread's cage base values are properly initialized.
+  PtrComprCageAccessScope ptr_compr_cage_access_scope(isolate_);
+
   ThreadState* state = per_thread->thread_state();
   char* from = state->data();
   from = isolate_->handle_scope_implementer()->RestoreThread(from);
@@ -274,6 +278,14 @@ void ThreadManager::EagerlyArchiveThread() {
 }
 
 void ThreadManager::FreeThreadResources() {
+#ifdef DEBUG
+  // This method might be called on a thread that's not bound to any Isolate
+  // and thus pointer compression schemes might have cage base value unset.
+  // Read-only roots accessors contain type DCHECKs which require access to
+  // V8 heap in order to check the object type. So, allow heap access here
+  // to let the checks work.
+  PtrComprCageAccessScope ptr_compr_cage_access_scope(isolate_);
+#endif  // DEBUG
   DCHECK(!isolate_->has_pending_exception());
   DCHECK(!isolate_->external_caught_exception());
   DCHECK_NULL(isolate_->try_catch_handler());

deps/v8/src/heap/collection-barrier.cc

@@ -51,7 +51,12 @@ class BackgroundCollectionInterruptTask : public CancelableTask {
 
  private:
   // v8::internal::CancelableTask overrides.
-  void RunInternal() override { heap_->CheckCollectionRequested(); }
+  void RunInternal() override {
+    // In case multi-cage pointer compression mode is enabled ensure that
+    // current thread's cage base values are properly initialized.
+    PtrComprCageAccessScope ptr_compr_cage_access_scope(heap_->isolate());
+    heap_->CheckCollectionRequested();
+  }
 
   Heap* heap_;
 };

deps/v8/src/heap/concurrent-marking.cc

@@ -153,6 +153,11 @@ class ConcurrentMarking::JobTaskMajor : public v8::JobTask {
 
   // v8::JobTask overrides.
   void Run(JobDelegate* delegate) override {
+    // In case multi-cage pointer compression mode is enabled ensure that
+    // current thread's cage base values are properly initialized.
+    PtrComprCageAccessScope ptr_compr_cage_access_scope(
+        concurrent_marking_->heap_->isolate());
+
     if (delegate->IsJoiningThread()) {
       // TRACE_GC is not needed here because the caller opens the right scope.
       concurrent_marking_->RunMajor(delegate, code_flush_mode_,
@@ -197,6 +202,11 @@ class ConcurrentMarking::JobTaskMinor : public v8::JobTask {
 
   // v8::JobTask overrides.
   void Run(JobDelegate* delegate) override {
+    // In case multi-cage pointer compression mode is enabled ensure that
+    // current thread's cage base values are properly initialized.
+    PtrComprCageAccessScope ptr_compr_cage_access_scope(
+        concurrent_marking_->heap_->isolate());
+
     if (delegate->IsJoiningThread()) {
       TRACE_GC_WITH_FLOW(concurrent_marking_->heap_->tracer(),
                          GCTracer::Scope::MINOR_MS_MARK_PARALLEL, trace_id_,

deps/v8/src/heap/incremental-marking-job.cc

@@ -91,6 +91,9 @@ void IncrementalMarkingJob::Task::RunInternal() {
   VMState<GC> state(isolate());
   TRACE_EVENT_CALL_STATS_SCOPED(isolate(), "v8",
                                 "V8.IncrementalMarkingJob.Task");
+  // In case multi-cage pointer compression mode is enabled ensure that
+  // current thread's cage base values are properly initialized.
+  PtrComprCageAccessScope ptr_compr_cage_access_scope(isolate());
 
   isolate()->stack_guard()->ClearStartIncrementalMarking();
 

deps/v8/src/heap/local-heap.cc

@@ -48,6 +48,7 @@ void LocalHeap::VerifyCurrent() const {
 LocalHeap::LocalHeap(Heap* heap, ThreadKind kind,
                      std::unique_ptr<PersistentHandles> persistent_handles)
     : heap_(heap),
+      ptr_compr_cage_access_scope_(heap->isolate()),
       is_main_thread_(kind == ThreadKind::kMain),
       state_(ThreadState::Parked()),
       allocation_failed_(false),