tor-browser

commit bacf29978d812f7178c3dfa9e5021d1c95c7c5eb
parent 54a523d23d99d6f787d79104dafa9830b3c24e8e
Author: Ryan Hunt <rhunt@eqrion.net>
Date:   Thu, 18 Dec 2025 16:45:25 +0000

Bug 2002625 - wasm: Move activeSuspender updating into wasm::Context. r=yury

I'd like to move all the logic for updating the VM state when a
suspender changes into a single location. wasm::Context makes the
most sense to me.

Differential Revision: https://phabricator.services.mozilla.com/D274184

Diffstat:
M
js/src/wasm/WasmContext.cpp
 | 
11
++++++-----
M
js/src/wasm/WasmContext.h
 | 
4
++--
M
js/src/wasm/WasmPI.cpp
 | 
17
++++++-----------

3 files changed, 14 insertions(+), 18 deletions(-)
diff --git a/js/src/wasm/WasmContext.cpp b/js/src/wasm/WasmContext.cpp
@@ -56,10 +56,6 @@ void Context::initStackLimit(JSContext* cx) {
 #ifdef ENABLE_WASM_JSPI
 SuspenderObject* Context::activeSuspender() { return activeSuspender_; }
 
-void Context::setActiveSuspender(SuspenderObject* obj) {
-  activeSuspender_.set(obj);
-}
-
 void Context::trace(JSTracer* trc) {
   if (activeSuspender_) {
     TraceEdge(trc, &activeSuspender_, "suspender");
@@ -80,14 +76,19 @@ void Context::traceRoots(JSTracer* trc) {
   }
 }
 
-void Context::enterSuspendableStack(JS::NativeStackLimit newStackLimit) {
+void Context::enterSuspendableStack(SuspenderObject* suspender,
+                                    JS::NativeStackLimit newStackLimit) {
   MOZ_ASSERT(onSuspendableStack == 0);
+  MOZ_ASSERT(!activeSuspender_);
+  activeSuspender_ = suspender;
   onSuspendableStack = 1;
   stackLimit = newStackLimit;
 }
 
 void Context::leaveSuspendableStack(JSContext* cx) {
   MOZ_ASSERT(onSuspendableStack != 0);
+  MOZ_ASSERT(activeSuspender_);
+  activeSuspender_ = nullptr;
   onSuspendableStack = 0;
   initStackLimit(cx);
 }
diff --git a/js/src/wasm/WasmContext.h b/js/src/wasm/WasmContext.h
@@ -55,9 +55,9 @@ class Context {
 
 #ifdef ENABLE_WASM_JSPI
   SuspenderObject* activeSuspender();
-  void setActiveSuspender(SuspenderObject* obj);
 
-  void enterSuspendableStack(JS::NativeStackLimit newStackLimit);
+  void enterSuspendableStack(SuspenderObject* suspender,
+                             JS::NativeStackLimit newStackLimit);
   void leaveSuspendableStack(JSContext* cx);
 
   void trace(JSTracer* trc);
diff --git a/js/src/wasm/WasmPI.cpp b/js/src/wasm/WasmPI.cpp
@@ -357,7 +357,7 @@ void SuspenderObject::setMoribund(JSContext* cx) {
 
 void SuspenderObject::setActive(JSContext* cx) {
   data()->setState(SuspenderState::Active);
-  cx->wasm().enterSuspendableStack(getStackMemoryLimit());
+  cx->wasm().enterSuspendableStack(this, getStackMemoryLimit());
 #  if defined(_WIN32)
   data()->updateTIBStackFields();
 #  endif
@@ -373,7 +373,6 @@ void SuspenderObject::setSuspended(JSContext* cx) {
 
 void SuspenderObject::enter(JSContext* cx) {
   MOZ_ASSERT(state() == SuspenderState::Initial);
-  cx->wasm().setActiveSuspender(this);
   setActive(cx);
 #  ifdef DEBUG
   cx->runtime()->jitRuntime()->disallowArbitraryCode();
@@ -385,7 +384,6 @@ void SuspenderObject::suspend(JSContext* cx) {
   setSuspended(cx);
   cx->wasm().suspendedStacks_.pushFront(data());
   data()->setSuspendedBy(&cx->wasm());
-  cx->wasm().setActiveSuspender(nullptr);
 #  ifdef DEBUG
   cx->runtime()->jitRuntime()->clearDisallowArbitraryCode();
 #  endif
@@ -407,7 +405,6 @@ void SuspenderObject::suspend(JSContext* cx) {
 
 void SuspenderObject::resume(JSContext* cx) {
   MOZ_ASSERT(state() == SuspenderState::Suspended);
-  cx->wasm().setActiveSuspender(this);
   setActive(cx);
   data()->setSuspendedBy(nullptr);
   // Use barrier because object is being removed from the suspendable stack
@@ -435,18 +432,20 @@ void SuspenderObject::resume(JSContext* cx) {
 }
 
 void SuspenderObject::leave(JSContext* cx) {
-  cx->wasm().setActiveSuspender(nullptr);
 #  ifdef DEBUG
   cx->runtime()->jitRuntime()->clearDisallowArbitraryCode();
 #  endif
   // We are exiting alternative stack if state is active,
   // otherwise the stack was just suspended.
   switch (state()) {
-    case SuspenderState::Active:
+    case SuspenderState::Active: {
       setMoribund(cx);
       break;
-    case SuspenderState::Suspended:
+    }
+    case SuspenderState::Suspended: {
+      MOZ_ASSERT(cx->wasm().onSuspendableStack == 0);
       break;
+    }
     case SuspenderState::Initial:
     case SuspenderState::Moribund:
       MOZ_CRASH();
@@ -467,8 +466,6 @@ bool CallOnMainStack(JSContext* cx, CallOnMainStackFn fn, void* data) {
   Rooted<SuspenderObject*> suspender(cx, cx->wasm().activeSuspender());
   SuspenderObjectData* stacks = suspender->data();
 
-  cx->wasm().setActiveSuspender(nullptr);
-
   MOZ_ASSERT(suspender->state() == SuspenderState::Active);
   suspender->setSuspended(cx);
   // Keep suspendedBy not set -- the stack has no defined entry.
@@ -806,7 +803,6 @@ bool CallOnMainStack(JSContext* cx, CallOnMainStackFn fn, void* data) {
 
   bool ok = (res & 255) != 0;  // need only low byte
   suspender->setActive(cx);
-  cx->wasm().setActiveSuspender(suspender);
 
 #  undef INLINED_ASM
 #  undef CHECK_OFFSETS
@@ -818,7 +814,6 @@ bool CallOnMainStack(JSContext* cx, CallOnMainStackFn fn, void* data) {
 static void CleanupActiveSuspender(JSContext* cx) {
   SuspenderObject* suspender = cx->wasm().activeSuspender();
   MOZ_ASSERT(suspender);
-  cx->wasm().setActiveSuspender(nullptr);
   suspender->setMoribund(cx);
 }