#893: Fix [no_Java_frame] on ARM64

Author: apangin

ddprof-lib/src/main/cpp/stackFrame.h

@@ -74,6 +74,7 @@ class StackFrame {
   bool unwindStub(instruction_t *entry, const char *name, uintptr_t &pc,
                   uintptr_t &sp, uintptr_t &fp);
   bool unwindCompiled(NMethod *nm, uintptr_t &pc, uintptr_t &sp, uintptr_t &fp);
+  bool unwindAtomicStub(const void*& pc);
 
   void adjustSP(const void *entry, const void *pc, uintptr_t &sp);
 

ddprof-lib/src/main/cpp/stackFrame_aarch64.cpp

@@ -136,6 +136,19 @@ bool StackFrame::unwindCompiled(NMethod *nm, uintptr_t &pc, uintptr_t &sp,
   return true;
 }
 
+bool StackFrame::unwindAtomicStub(const void*& pc) {
+  // VM threads may call generated atomic stubs, which are not normally walkable
+  const void* lr = (const void*)link();
+  if (VMStructs::libjvm()->contains(lr)) {
+    NMethod* nm = CodeHeap::findNMethod(pc);
+    if (nm != NULL && strncmp(nm->name(), "Stub", 4) == 0) {
+      pc = lr;
+      return true;
+    }
+  }
+  return false;
+}
+
 void StackFrame::adjustSP(const void *entry, const void *pc, uintptr_t &sp) {
   instruction_t *ip = (instruction_t *)pc;
   if (ip > entry && (ip[-1] == 0xa9bf27ff ||

ddprof-lib/src/main/cpp/stackFrame_arm.cpp

@@ -112,6 +112,11 @@ void StackFrame::adjustSP(const void *entry, const void *pc, uintptr_t &sp) {
   // Not needed
 }
 
+bool StackFrame::unwindAtomicStub(const void*& pc) {
+  // Not needed
+  return false;
+}
+
 bool StackFrame::skipFaultInstruction() { return false; }
 
 bool StackFrame::checkInterruptedSyscall() {

ddprof-lib/src/main/cpp/stackFrame_i386.cpp

@@ -119,6 +119,11 @@ void StackFrame::adjustSP(const void *entry, const void *pc, uintptr_t &sp) {
   // Not needed
 }
 
+bool StackFrame::unwindAtomicStub(const void*& pc) {
+  // Not needed
+  return false;
+}
+
 bool StackFrame::skipFaultInstruction() { return false; }
 
 bool StackFrame::checkInterruptedSyscall() {

ddprof-lib/src/main/cpp/stackFrame_ppc64.cpp

@@ -147,6 +147,11 @@ void StackFrame::adjustSP(const void *entry, const void *pc, uintptr_t &sp) {
   // Not needed
 }
 
+bool StackFrame::unwindAtomicStub(const void*& pc) {
+  // Not needed
+  return false;
+}
+
 bool StackFrame::skipFaultInstruction() { return false; }
 
 bool StackFrame::checkInterruptedSyscall() {

ddprof-lib/src/main/cpp/stackFrame_x64.cpp

@@ -145,6 +145,11 @@ void StackFrame::adjustSP(const void *entry, const void *pc, uintptr_t &sp) {
   // Not needed
 }
 
+bool StackFrame::unwindAtomicStub(const void*& pc) {
+  // Not needed
+  return false;
+}
+
 // Skip failed MOV instruction by writing 0 to destination register
 bool StackFrame::skipFaultInstruction() {
   unsigned int insn = *(unsigned int *)pc();

ddprof-lib/src/main/cpp/stackWalker.cpp

@@ -71,6 +71,7 @@ int StackWalker::walkFP(void *ucontext, const void **callchain, int max_depth,
   uintptr_t sp;
   uintptr_t bottom = (uintptr_t)&sp + MAX_WALK_SIZE;
 
+  StackFrame frame(ucontext);
   if (ucontext == NULL) {
     pc = __builtin_return_address(0);
     fp = (uintptr_t)__builtin_frame_address(1);
@@ -92,7 +93,7 @@ int StackWalker::walkFP(void *ucontext, const void **callchain, int max_depth,
       *truncated = true;
       break;
     }
-    if (CodeHeap::contains(pc)) {
+    if (CodeHeap::contains(pc) && !(depth == 0 && frame.unwindAtomicStub(pc))) {
       java_ctx->set(pc, sp, fp);
       break;
     }
@@ -154,7 +155,7 @@ int StackWalker::walkDwarf(void *ucontext, const void **callchain,
       *truncated = true;
       break;
     }
-    if (CodeHeap::contains(pc)) {
+    if (CodeHeap::contains(pc) && !(depth == 0 && frame.unwindAtomicStub(pc))) {
       const void* page_start = (const void*)((uintptr_t)pc & ~0xfffUL);
       frame.adjustSP(page_start, pc, sp);
       java_ctx->set(pc, sp, fp);