8304725: AsyncGetCallTrace can cause SIGBUS on M1

Reviewed-by: dholmes, stuefe, mbaesken

src/hotspot/share/code/nmethod.cpp

@@ -2136,7 +2136,11 @@ PcDesc* PcDescContainer::find_pc_desc_internal(address pc, bool approximate, con
 
   if (match_desc(upper, pc_offset, approximate)) {
     assert(upper == linear_search(search, pc_offset, approximate), "search ok");
-    _pc_desc_cache.add_pc_desc(upper);
+    if (!Thread::current_in_asgct()) {
+      // we don't want to modify the cache if we're in ASGCT
+      // which is typically called in a signal handler
+      _pc_desc_cache.add_pc_desc(upper);
+    }
     return upper;
   } else {
     assert(nullptr == linear_search(search, pc_offset, approximate), "search ok");

src/hotspot/share/prims/forte.cpp

@@ -606,6 +606,9 @@ void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
     return;
   }
 
+  // signify to other code in the VM that we're in ASGCT
+  ThreadInAsgct tia(thread);
+
   switch (thread->thread_state()) {
   case _thread_new:
   case _thread_uninitialized:

src/hotspot/share/runtime/thread.hpp

@@ -631,6 +631,31 @@ protected:
     assert(_wx_state == expected, "wrong state");
   }
 #endif // __APPLE__ && AARCH64
+
+ private:
+  bool _in_asgct = false;
+ public:
+  bool in_asgct() const { return _in_asgct; }
+  void set_in_asgct(bool value) { _in_asgct = value; }
+  static bool current_in_asgct() {
+    Thread *cur = Thread::current_or_null_safe();
+    return cur != nullptr && cur->in_asgct();
+  }
+};
+
+class ThreadInAsgct {
+ private:
+  Thread* _thread;
+ public:
+  ThreadInAsgct(Thread* thread) : _thread(thread) {
+    assert(thread != nullptr, "invariant");
+    assert(!thread->in_asgct(), "invariant");
+    thread->set_in_asgct(true);
+  }
+  ~ThreadInAsgct() {
+    assert(_thread->in_asgct(), "invariant");
+    _thread->set_in_asgct(false);
+  }
 };
 
 // Inline implementation of Thread::current()