// Unpacks one or more frames into user-supplied buffers.
// Updates the end index, and returns the number of unpacked frames.
// Always start with the existing vfst.method and bci.
// Do not call vfst.next to advance over the last returned value.
// In other words, do not leave any stale data in the vfst.
//
// Parameters:
// mode Restrict which frames to be decoded.
// BaseFrameStream stream of frames
// max_nframes Maximum number of frames to be filled.
// start_index Start index to the user-supplied buffers.
// frames_array Buffer to store Class or StackFrame in, starting at start_index.
// frames array is a Class<?>[] array when only getting caller
// reference, and a StackFrameInfo[] array (or derivative)
// otherwise. It should never be null.
// end_index End index to the user-supplied buffers with unpacked frames.
//
// Returns the number of frames whose information was transferred into the buffers.
//
int StackWalk::fill_in_frames(jlong mode, BaseFrameStream& stream,
int max_nframes, int start_index,
objArrayHandle frames_array,
int& end_index, TRAPS) {
log_debug(stackwalk)("fill_in_frames limit=%d start=%d frames length=%d",
max_nframes, start_index, frames_array->length());
assert(max_nframes > 0, "invalid max_nframes");
assert(start_index + max_nframes <= frames_array->length(), "oob");
int frames_decoded = 0;
for (; !stream.at_end(); stream.next()) {
Method* method = stream.method();
if (method == NULL) continue;
// skip hidden frames for default StackWalker option (i.e. SHOW_HIDDEN_FRAMES
// not set) and when StackWalker::getCallerClass is called
if (!ShowHiddenFrames && (skip_hidden_frames(mode) || get_caller_class(mode))) {
if (method->is_hidden()) {
if (log_is_enabled(Debug, stackwalk)) {
ResourceMark rm(THREAD);
outputStream* st = Log(stackwalk)::debug_stream();
st->print(" hidden method: ");
method->print_short_name(st);
st->cr();
}
continue;
}
}
int index = end_index++;
if (log_is_enabled(Debug, stackwalk)) {
ResourceMark rm(THREAD);
outputStream* st = Log(stackwalk)::debug_stream();
st->print(" %d: frame method: ", index);
method->print_short_name(st);
st->print_cr(" bci=%d", stream.bci());
}
if (!need_method_info(mode) && get_caller_class(mode) &&
index == start_index && method->caller_sensitive()) {
ResourceMark rm(THREAD);
THROW_MSG_0(vmSymbols::java_lang_UnsupportedOperationException(),
err_msg("StackWalker::getCallerClass called from @CallerSensitive %s method",
method->name_and_sig_as_C_string()));
}
// fill in StackFrameInfo and initialize MemberName
stream.fill_frame(index, frames_array, method, CHECK_0);
if (++frames_decoded >= max_nframes) break;
}
return frames_decoded;
}
// Unpacks one or more frames into user-supplied buffers.
// Updates the end index, and returns the number of unpacked frames.
// Always start with the existing vfst.method and bci.
// Do not call vfst.next to advance over the last returned value.
// In other words, do not leave any stale data in the vfst.
//
// Parameters:
// mode Restrict which frames to be decoded.
// JavaFrameStream stream of javaVFrames
// max_nframes Maximum number of frames to be filled.
// start_index Start index to the user-supplied buffers.
// frames_array Buffer to store Class or StackFrame in, starting at start_index.
// frames array is a Class<?>[] array when only getting caller
// reference, and a StackFrameInfo[] array (or derivative)
// otherwise. It should never be null.
// end_index End index to the user-supplied buffers with unpacked frames.
//
// Returns the number of frames whose information was transferred into the buffers.
//
int StackWalk::fill_in_frames(jlong mode, JavaFrameStream& stream,
int max_nframes, int start_index,
objArrayHandle frames_array,
int& end_index, TRAPS) {
if (TraceStackWalk) {
tty->print_cr("fill_in_frames limit=%d start=%d frames length=%d",
max_nframes, start_index, frames_array->length());
}
assert(max_nframes > 0, "invalid max_nframes");
assert(start_index + max_nframes <= frames_array->length(), "oob");
int frames_decoded = 0;
for (; !stream.at_end(); stream.next()) {
Method* method = stream.method();
int bci = stream.bci();
if (method == NULL) continue;
if (!ShowHiddenFrames && StackWalk::skip_hidden_frames(mode)) {
if (method->is_hidden()) {
if (TraceStackWalk) {
tty->print(" hidden method: "); method->print_short_name();
tty->print("\n");
}
continue;
}
}
int index = end_index++;
if (TraceStackWalk) {
tty->print(" %d: frame method: ", index); method->print_short_name();
tty->print_cr(" bci=%d", bci);
}
// fill in StackFrameInfo and initialize MemberName
if (live_frame_info(mode)) {
assert (use_frames_array(mode), "Bad mode for get live frame");
Handle stackFrame(frames_array->obj_at(index));
fill_live_stackframe(stackFrame, method, bci, stream.java_frame(), CHECK_0);
} else if (need_method_info(mode)) {
assert (use_frames_array(mode), "Bad mode for get stack frame");
Handle stackFrame(frames_array->obj_at(index));
fill_stackframe(stackFrame, method, bci);
} else {
assert (use_frames_array(mode) == false, "Bad mode for get caller class");
frames_array->obj_at_put(index, method->method_holder()->java_mirror());
}
if (++frames_decoded >= max_nframes) break;
}
return frames_decoded;
}
// Walk the next batch of stack frames
//
// Parameters:
// stackStream StackStream object
// mode Stack walking mode.
// magic Must be valid value to continue the stack walk
// frame_count Number of frames to be decoded.
// start_index Start index to the user-supplied buffers.
// classes_array Buffer to store classes in, starting at start_index.
// frames_array Buffer to store StackFrame in, starting at start_index.
// NULL if not used.
//
// Returns the end index of frame filled in the buffer.
//
jint StackWalk::moreFrames(Handle stackStream, jlong mode, jlong magic,
int frame_count, int start_index,
objArrayHandle classes_array,
objArrayHandle frames_array,
TRAPS)
{
JavaThread* jt = (JavaThread*)THREAD;
StackWalkAnchor* existing_anchor = StackWalkAnchor::from_current(jt, magic, classes_array);
if (existing_anchor == NULL) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers", 0L);
}
if ((need_method_info(mode) || live_frame_info(mode)) && frames_array.is_null()) {
THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", 0L);
}
if (TraceStackWalk) {
tty->print_cr("StackWalk::moreFrames frame_count %d existing_anchor " PTR_FORMAT " start %d frames %d",
frame_count, p2i(existing_anchor), start_index, classes_array->length());
}
int end_index = start_index;
if (frame_count <= 0) {
return end_index; // No operation.
}
int count = frame_count + start_index;
assert (classes_array->length() >= count, "not enough space in buffers");
StackWalkAnchor& anchor = (*existing_anchor);
vframeStream& vfst = anchor.vframe_stream();
if (!vfst.at_end()) {
vfst.next(); // this was the last frame decoded in the previous batch
if (!vfst.at_end()) {
int n = fill_in_frames(mode, vfst, frame_count, start_index, classes_array,
frames_array, end_index, CHECK_0);
if (n < 1) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: later decode failed", 0L);
}
return end_index;
}
}
return end_index;
}
// Begins stack walking.
//
// Parameters:
// stackStream StackStream object
// mode Stack walking mode.
// skip_frames Number of frames to be skipped.
// frame_count Number of frames to be traversed.
// start_index Start index to the user-supplied buffers.
// classes_array Buffer to store classes in, starting at start_index.
// frames_array Buffer to store StackFrame in, starting at start_index.
// NULL if not used.
//
// Returns Object returned from AbstractStackWalker::doStackWalk call.
//
oop StackWalk::walk(Handle stackStream, jlong mode,
int skip_frames, int frame_count, int start_index,
objArrayHandle classes_array,
objArrayHandle frames_array,
TRAPS) {
JavaThread* jt = (JavaThread*)THREAD;
if (TraceStackWalk) {
tty->print_cr("Start walking: mode " JLONG_FORMAT " skip %d frames batch size %d",
mode, skip_frames, frame_count);
}
if (need_method_info(mode)) {
if (frames_array.is_null()) {
THROW_MSG_(vmSymbols::java_lang_NullPointerException(), "frames_array is NULL", NULL);
}
}
Klass* stackWalker_klass = SystemDictionary::StackWalker_klass();
Klass* abstractStackWalker_klass = SystemDictionary::AbstractStackWalker_klass();
methodHandle m_doStackWalk(THREAD, Universe::do_stack_walk_method());
// Open up a traversable stream onto my stack.
// This stream will be made available by *reference* to the inner Java call.
StackWalkAnchor anchor(jt);
vframeStream& vfst = anchor.vframe_stream();
{
// Skip all methods from AbstractStackWalker and StackWalk (enclosing method)
if (!fill_in_stacktrace(mode)) {
while (!vfst.at_end()) {
InstanceKlass* ik = vfst.method()->method_holder();
if (ik != stackWalker_klass &&
ik != abstractStackWalker_klass && ik->super() != abstractStackWalker_klass) {
break;
}
if (TraceStackWalk) {
tty->print(" skip "); vfst.method()->print_short_name(); tty->print("\n");
}
vfst.next();
}
}
// For exceptions, skip Throwable::fillInStackTrace and <init> methods
// of the exception class and superclasses
if (fill_in_stacktrace(mode)) {
bool skip_to_fillInStackTrace = false;
bool skip_throwableInit_check = false;
while (!vfst.at_end() && !skip_throwableInit_check) {
InstanceKlass* ik = vfst.method()->method_holder();
Method* method = vfst.method();
if (!skip_to_fillInStackTrace) {
if (ik == SystemDictionary::Throwable_klass() &&
method->name() == vmSymbols::fillInStackTrace_name()) {
// this frame will be skipped
skip_to_fillInStackTrace = true;
}
} else if (!(ik->is_subclass_of(SystemDictionary::Throwable_klass()) &&
method->name() == vmSymbols::object_initializer_name())) {
// there are none or we've seen them all - either way stop checking
skip_throwableInit_check = true;
break;
}
if (TraceStackWalk) {
tty->print("stack walk: skip "); vfst.method()->print_short_name(); tty->print("\n");
}
vfst.next();
}
}
// stack frame has been traversed individually and resume stack walk
// from the stack frame at depth == skip_frames.
for (int n=0; n < skip_frames && !vfst.at_end(); vfst.next(), n++) {
if (TraceStackWalk) {
tty->print(" skip "); vfst.method()->print_short_name();
tty->print_cr(" frame id: " PTR_FORMAT " pc: " PTR_FORMAT,
p2i(vfst.frame_id()), p2i(vfst.frame_pc()));
}
}
}
// The Method* pointer in the vfst has a very short shelf life. Grab it now.
int end_index = start_index;
int numFrames = 0;
if (!vfst.at_end()) {
numFrames = fill_in_frames(mode, vfst, frame_count, start_index, classes_array,
frames_array, end_index, CHECK_NULL);
if (numFrames < 1) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "stack walk: decode failed", NULL);
}
}
// JVM_CallStackWalk walks the stack and fills in stack frames, then calls to
// Java method java.lang.StackStreamFactory.AbstractStackWalker::doStackWalk
// which calls the implementation to consume the stack frames.
// When JVM_CallStackWalk returns, it invalidates the stack stream.
JavaValue result(T_OBJECT);
JavaCallArguments args(stackStream);
args.push_long(anchor.address_value());
args.push_int(skip_frames);
args.push_int(frame_count);
args.push_int(start_index);
args.push_int(end_index);
// Link the thread and vframe stream into the callee-visible object
anchor.setup_magic_on_entry(classes_array);
JavaCalls::call(&result, m_doStackWalk, &args, THREAD);
// Do this before anything else happens, to disable any lingering stream objects
bool ok = anchor.cleanup_magic_on_exit(classes_array);
// Throw pending exception if we must
(void) (CHECK_NULL);
if (!ok) {
THROW_MSG_(vmSymbols::java_lang_InternalError(), "doStackWalk: corrupted buffers on exit", NULL);
}
// Return normally
return (oop)result.get_jobject();
}
