src/os_cpu/linux_aarch64/vm/os_linux_aarch64.cpp

rev 12502 : 8172144: AArch64: Implement "JEP 270: Reserved Stack Areas for Critical Sections"
Reviewed-by: duke

@@ -85,10 +85,11 @@
 #define REG_FP REG_RBP
 #define SPELL_REG_SP "rsp"
 #define SPELL_REG_FP "rbp"
 #else
 #define REG_FP 29
+#define REG_LR 30
 
 #define SPELL_REG_SP "sp"
 #define SPELL_REG_FP "x29"
 #endif
 

@@ -180,10 +181,50 @@
   intptr_t* fp;
   ExtendedPC epc = fetch_frame_from_context(ucVoid, &sp, &fp);
   return frame(sp, fp, epc.pc());
 }
 
+bool os::Linux::get_frame_at_stack_banging_point(JavaThread* thread, ucontext_t* uc, frame* fr) {
+  address pc = (address) os::Linux::ucontext_get_pc(uc);
+  if (Interpreter::contains(pc)) {
+    // interpreter performs stack banging after the fixed frame header has
+    // been generated while the compilers perform it before. To maintain
+    // semantic consistency between interpreted and compiled frames, the
+    // method returns the Java sender of the current frame.
+    *fr = os::fetch_frame_from_context(uc);
+    if (!fr->is_first_java_frame()) {
+      assert(fr->safe_for_sender(thread), "Safety check");
+      *fr = fr->java_sender();
+    }
+  } else {
+    // more complex code with compiled code
+    assert(!Interpreter::contains(pc), "Interpreted methods should have been handled above");
+    CodeBlob* cb = CodeCache::find_blob(pc);
+    if (cb == NULL || !cb->is_nmethod() || cb->is_frame_complete_at(pc)) {
+      // Not sure where the pc points to, fallback to default
+      // stack overflow handling
+      return false;
+    } else {
+      // In compiled code, the stack banging is performed before LR
+      // has been saved in the frame.  LR is live, and SP and FP
+      // belong to the caller.
+      intptr_t* fp = os::Linux::ucontext_get_fp(uc);
+      intptr_t* sp = os::Linux::ucontext_get_sp(uc);
+      void* pc = (void*)(uc->uc_mcontext.regs[REG_LR]
+                         - NativeInstruction::instruction_size);
+      *fr = frame(sp, fp, pc);
+      if (!fr->is_java_frame()) {
+        assert(fr->safe_for_sender(thread), "Safety check");
+        assert(!fr->is_first_frame(), "Safety check");
+        *fr = fr->java_sender();
+      }
+    }
+  }
+  assert(fr->is_java_frame(), "Safety check");
+  return true;
+}
+
 // By default, gcc always saves frame pointer rfp on this stack. This
 // may get turned off by -fomit-frame-pointer.
 frame os::get_sender_for_C_frame(frame* fr) {
 #ifdef BUILTIN_SIM
   return frame(fr->sender_sp(), fr->link(), fr->sender_pc());

@@ -311,10 +352,28 @@
       if (thread->on_local_stack(addr)) {
         // stack overflow
         if (thread->in_stack_yellow_reserved_zone(addr)) {
           thread->disable_stack_yellow_reserved_zone();
           if (thread->thread_state() == _thread_in_Java) {
+            if (thread->in_stack_reserved_zone(addr)) {
+              frame fr;
+              if (os::Linux::get_frame_at_stack_banging_point(thread, uc, &fr)) {
+                assert(fr.is_java_frame(), "Must be a Java frame");
+                frame activation =
+                  SharedRuntime::look_for_reserved_stack_annotated_method(thread, fr);
+                if (activation.sp() != NULL) {
+                  thread->disable_stack_reserved_zone();
+                  if (activation.is_interpreted_frame()) {
+                    thread->set_reserved_stack_activation((address)(
+                      activation.fp() + frame::interpreter_frame_initial_sp_offset));
+                  } else {
+                    thread->set_reserved_stack_activation((address)activation.unextended_sp());
+                  }
+                  return 1;
+                }
+              }
+            }
             // Throw a stack overflow exception.  Guard pages will be reenabled
             // while unwinding the stack.
             stub = SharedRuntime::continuation_for_implicit_exception(thread, pc, SharedRuntime::STACK_OVERFLOW);
           } else {
             // Thread was in the vm or native code.  Return and try to finish.