JDK14/Java14源码在线阅读
/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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#include "precompiled.hpp"
#include "code/debugInfoRec.hpp"
#include "code/pcDesc.hpp"
#include "gc/shared/collectedHeap.inline.hpp"
#include "memory/universe.hpp"
#include "oops/oop.inline.hpp"
#include "prims/forte.hpp"
#include "runtime/frame.inline.hpp"
#include "runtime/javaCalls.hpp"
#include "runtime/thread.inline.hpp"
#include "runtime/vframe.inline.hpp"
#include "runtime/vframeArray.hpp"
// call frame copied from old .h file and renamed
typedef struct {
jint lineno; // line number in the source file
jmethodID method_id; // method executed in this frame
} ASGCT_CallFrame;
// call trace copied from old .h file and renamed
typedef struct {
JNIEnv *env_id; // Env where trace was recorded
jint num_frames; // number of frames in this trace
ASGCT_CallFrame *frames; // frames
} ASGCT_CallTrace;
// These name match the names reported by the forte quality kit
enum {
ticks_no_Java_frame = 0,
ticks_no_class_load = -1,
ticks_GC_active = -2,
ticks_unknown_not_Java = -3,
ticks_not_walkable_not_Java = -4,
ticks_unknown_Java = -5,
ticks_not_walkable_Java = -6,
ticks_unknown_state = -7,
ticks_thread_exit = -8,
ticks_deopt = -9,
ticks_safepoint = -10
};
#if INCLUDE_JVMTI
//-------------------------------------------------------
// Native interfaces for use by Forte tools.
#if !defined(IA64)
class vframeStreamForte : public vframeStreamCommon {
public:
// constructor that starts with sender of frame fr (top_frame)
vframeStreamForte(JavaThread *jt, frame fr, bool stop_at_java_call_stub);
void forte_next();
};
static bool is_decipherable_compiled_frame(JavaThread* thread, frame* fr, CompiledMethod* nm);
static bool is_decipherable_interpreted_frame(JavaThread* thread,
frame* fr,
Method** method_p,
int* bci_p);
vframeStreamForte::vframeStreamForte(JavaThread *jt,
frame fr,
bool stop_at_java_call_stub) : vframeStreamCommon(jt) {
_stop_at_java_call_stub = stop_at_java_call_stub;
_frame = fr;
// We must always have a valid frame to start filling
bool filled_in = fill_from_frame();
assert(filled_in, "invariant");
}
// Solaris SPARC Compiler1 needs an additional check on the grandparent
// of the top_frame when the parent of the top_frame is interpreted and
// the grandparent is compiled. However, in this method we do not know
// the relationship of the current _frame relative to the top_frame so
// we implement a more broad sanity check. When the previous callee is
// interpreted and the current sender is compiled, we verify that the
// current sender is also walkable. If it is not walkable, then we mark
// the current vframeStream as at the end.
void vframeStreamForte::forte_next() {
// handle frames with inlining
if (_mode == compiled_mode &&
vframeStreamCommon::fill_in_compiled_inlined_sender()) {
return;
}
// handle general case
int loop_count = 0;
int loop_max = MaxJavaStackTraceDepth * 2;
do {
loop_count++;
// By the time we get here we should never see unsafe but better
// safe then segv'd
if ((loop_max != 0 && loop_count > loop_max) || !_frame.safe_for_sender(_thread)) {
_mode = at_end_mode;
return;
}
_frame = _frame.sender(&_reg_map);
} while (!fill_from_frame());
}
// Determine if 'fr' is a decipherable compiled frame. We are already
// assured that fr is for a java compiled method.
static bool is_decipherable_compiled_frame(JavaThread* thread, frame* fr, CompiledMethod* nm) {
assert(nm->is_java_method(), "invariant");
if (thread->has_last_Java_frame() && thread->last_Java_pc() == fr->pc()) {
// We're stopped at a call into the JVM so look for a PcDesc with
// the actual pc reported by the frame.
PcDesc* pc_desc = nm->pc_desc_at(fr->pc());
// Did we find a useful PcDesc?
if (pc_desc != NULL &&
pc_desc->scope_decode_offset() != DebugInformationRecorder::serialized_null) {
return true;
}
}
// We're at some random pc in the compiled method so search for the PcDesc
// whose pc is greater than the current PC. It's done this way
// because the extra PcDescs that are recorded for improved debug
// info record the end of the region covered by the ScopeDesc
// instead of the beginning.
PcDesc* pc_desc = nm->pc_desc_near(fr->pc() + 1);
// Now do we have a useful PcDesc?
if (pc_desc == NULL ||
pc_desc->scope_decode_offset() == DebugInformationRecorder::serialized_null) {
// No debug information is available for this PC.
//
// vframeStreamCommon::fill_from_frame() will decode the frame depending
// on the state of the thread.
//
// Case #1: If the thread is in Java (state == _thread_in_Java), then
// the vframeStreamCommon object will be filled as if the frame were a native
// compiled frame. Therefore, no debug information is needed.
//
// Case #2: If the thread is in any other state, then two steps will be performed:
// - if asserts are enabled, found_bad_method_frame() will be called and
// the assert in found_bad_method_frame() will be triggered;
// - if asserts are disabled, the vframeStreamCommon object will be filled
// as if it were a native compiled frame.
//
// Case (2) is similar to the way interpreter frames are processed in
// vframeStreamCommon::fill_from_interpreter_frame in case no valid BCI
// was found for an interpreted frame. If asserts are enabled, the assert
// in found_bad_method_frame() will be triggered. If asserts are disabled,
// the vframeStreamCommon object will be filled afterwards as if the
// interpreter were at the point of entering into the method.
return false;
}
// This PcDesc is useful however we must adjust the frame's pc
// so that the vframeStream lookups will use this same pc
fr->set_pc(pc_desc->real_pc(nm));
return true;
}
// Determine if 'fr' is a walkable interpreted frame. Returns false
// if it is not. *method_p, and *bci_p are not set when false is
// returned. *method_p is non-NULL if frame was executing a Java
// method. *bci_p is != -1 if a valid BCI in the Java method could
// be found.
// Note: this method returns true when a valid Java method is found
// even if a valid BCI cannot be found.
static bool is_decipherable_interpreted_frame(JavaThread* thread,
frame* fr,
Method** method_p,
int* bci_p) {
assert(fr->is_interpreted_frame(), "just checking");
// top frame is an interpreted frame
// check if it is walkable (i.e. valid Method* and valid bci)
// Because we may be racing a gc thread the method and/or bci
// of a valid interpreter frame may look bad causing us to
// fail the is_interpreted_frame_valid test. If the thread
// is in any of the following states we are assured that the
// frame is in fact valid and we must have hit the race.
JavaThreadState state = thread->thread_state();
bool known_valid = (state == _thread_in_native ||
state == _thread_in_vm ||
state == _thread_blocked );
if (known_valid || fr->is_interpreted_frame_valid(thread)) {
// The frame code should completely validate the frame so that
// references to Method* and bci are completely safe to access
// If they aren't the frame code should be fixed not this
// code. However since gc isn't locked out the values could be
// stale. This is a race we can never completely win since we can't
// lock out gc so do one last check after retrieving their values
// from the frame for additional safety
Method* method = fr->interpreter_frame_method();
// We've at least found a method.
// NOTE: there is something to be said for the approach that
// if we don't find a valid bci then the method is not likely
// a valid method. Then again we may have caught an interpreter
// frame in the middle of construction and the bci field is
// not yet valid.
if (!Method::is_valid_method(method)) return false;
*method_p = method; // If the Method* found is invalid, it is
// ignored by forte_fill_call_trace_given_top().
// So set method_p only if the Method is valid.
address bcp = fr->interpreter_frame_bcp();
int bci = method->validate_bci_from_bcp(bcp);
// note: bci is set to -1 if not a valid bci
*bci_p = bci;
return true;
}
return false;
}
// Determine if a Java frame can be found starting with the frame 'fr'.
//
// Check the return value of find_initial_Java_frame and the value of
// 'method_p' to decide on how use the results returned by this method.
//
// If 'method_p' is not NULL, an initial Java frame has been found and
// the stack can be walked starting from that initial frame. In this case,
// 'method_p' points to the Method that the initial frame belongs to and
// the initial Java frame is returned in initial_frame_p.
//
// find_initial_Java_frame() returns true if a Method has been found (i.e.,
// 'method_p' is not NULL) and the initial frame that belongs to that Method
// is decipherable.
//
// A frame is considered to be decipherable:
//
// - if the frame is a compiled frame and a PCDesc is available;
//
// - if the frame is an interpreter frame that is valid or the thread is
// state (_thread_in_native || state == _thread_in_vm || state == _thread_blocked).
//
// Note that find_initial_Java_frame() can return false even if an initial
// Java method was found (e.g., there is no PCDesc available for the method).
//
// If 'method_p' is NULL, it was not possible to find a Java frame when
// walking the stack starting from 'fr'. In this case find_initial_Java_frame
// returns false.
static bool find_initial_Java_frame(JavaThread* thread,
frame* fr,
frame* initial_frame_p,
Method** method_p,
int* bci_p) {
// It is possible that for a frame containing a compiled method
// we can capture the method but no bci. If we get no
// bci the frame isn't walkable but the method is usable.
// Therefore we init the returned Method* to NULL so the
// caller can make the distinction.
*method_p = NULL;
// On the initial call to this method the frame we get may not be
// recognizable to us. This should only happen if we are in a JRT_LEAF
// or something called by a JRT_LEAF method.
frame candidate = *fr;
// If the starting frame we were given has no codeBlob associated with
// it see if we can find such a frame because only frames with codeBlobs
// are possible Java frames.
if (fr->cb() == NULL) {
// See if we can find a useful frame
int loop_count;
int loop_max = MaxJavaStackTraceDepth * 2;
RegisterMap map(thread, false);
for (loop_count = 0; loop_max == 0 || loop_count < loop_max; loop_count++) {
if (!candidate.safe_for_sender(thread)) return false;
candidate = candidate.sender(&map);
if (candidate.cb() != NULL) break;
}
if (candidate.cb() == NULL) return false;
}
// We have a frame known to be in the codeCache
// We will hopefully be able to figure out something to do with it.
int loop_count;
int loop_max = MaxJavaStackTraceDepth * 2;
RegisterMap map(thread, false);
for (loop_count = 0; loop_max == 0 || loop_count < loop_max; loop_count++) {
if (candidate.is_entry_frame()) {
// jcw is NULL if the java call wrapper couldn't be found
JavaCallWrapper *jcw = candidate.entry_frame_call_wrapper_if_safe(thread);
// If initial frame is frame from StubGenerator and there is no
// previous anchor, there are no java frames associated with a method
if (jcw == NULL || jcw->is_first_frame()) {
return false;
}
}
if (candidate.is_interpreted_frame()) {
if (is_decipherable_interpreted_frame(thread, &candidate, method_p, bci_p)) {
*initial_frame_p = candidate;
return true;
}
// Hopefully we got some data
return false;
}
if (candidate.cb()->is_compiled()) {
CompiledMethod* nm = candidate.cb()->as_compiled_method();
*method_p = nm->method();
// If the frame is not decipherable, then the value of -1
// for the BCI is used to signal that no BCI is available.
// Furthermore, the method returns false in this case.
//
// If a decipherable frame is available, the BCI value will
// not be used.
*bci_p = -1;
*initial_frame_p = candidate;
// Native wrapper code is trivial to decode by vframeStream
if (nm->is_native_method()) return true;
// If the frame is not decipherable, then a PC was found
// that does not have a PCDesc from which a BCI can be obtained.
// Nevertheless, a Method was found.
if (!is_decipherable_compiled_frame(thread, &candidate, nm)) {
return false;
}
// is_decipherable_compiled_frame may modify candidate's pc
*initial_frame_p = candidate;
assert(nm->pc_desc_at(candidate.pc()) != NULL, "debug information must be available if the frame is decipherable");
return true;
}
// Must be some stub frame that we don't care about
if (!candidate.safe_for_sender(thread)) return false;
candidate = candidate.sender(&map);
// If it isn't in the code cache something is wrong
// since once we find a frame in the code cache they
// all should be there.
if (candidate.cb() == NULL) return false;
}
return false;
}
static void forte_fill_call_trace_given_top(JavaThread* thd,
ASGCT_CallTrace* trace,
int depth,
frame top_frame) {
NoHandleMark nhm;
frame initial_Java_frame;
Method* method;
int bci = -1; // assume BCI is not available for method
// update with correct information if available
int count;
count = 0;
assert(trace->frames != NULL, "trace->frames must be non-NULL");
// Walk the stack starting from 'top_frame' and search for an initial Java frame.
find_initial_Java_frame(thd, &top_frame, &initial_Java_frame, &method, &bci);
// Check if a Java Method has been found.
if (method == NULL) return;
if (!Method::is_valid_method(method)) {
trace->num_frames = ticks_GC_active; // -2
return;
}
vframeStreamForte st(thd, initial_Java_frame, false);
for (; !st.at_end() && count < depth; st.forte_next(), count++) {
bci = st.bci();
method = st.method();
if (!Method::is_valid_method(method)) {
// we throw away everything we've gathered in this sample since
// none of it is safe
trace->num_frames = ticks_GC_active; // -2
return;
}
trace->frames[count].method_id = method->find_jmethod_id_or_null();
if (!method->is_native()) {
trace->frames[count].lineno = bci;
} else {
trace->frames[count].lineno = -3;
}
}
trace->num_frames = count;
return;
}
// Forte Analyzer AsyncGetCallTrace() entry point. Currently supported
// on Linux X86, Solaris SPARC and Solaris X86.
//
// Async-safe version of GetCallTrace being called from a signal handler
// when a LWP gets interrupted by SIGPROF but the stack traces are filled
// with different content (see below).
//
// This function must only be called when JVM/TI
// CLASS_LOAD events have been enabled since agent startup. The enabled
// event will cause the jmethodIDs to be allocated at class load time.
// The jmethodIDs cannot be allocated in a signal handler because locks
// cannot be grabbed in a signal handler safely.
//
// void (*AsyncGetCallTrace)(ASGCT_CallTrace *trace, jint depth, void* ucontext)
//
// Called by the profiler to obtain the current method call stack trace for
// a given thread. The thread is identified by the env_id field in the
// ASGCT_CallTrace structure. The profiler agent should allocate a ASGCT_CallTrace
// structure with enough memory for the requested stack depth. The VM fills in
// the frames buffer and the num_frames field.
//
// Arguments:
//
// trace - trace data structure to be filled by the VM.
// depth - depth of the call stack trace.
// ucontext - ucontext_t of the LWP
//
// ASGCT_CallTrace:
// typedef struct {
// JNIEnv *env_id;
// jint num_frames;
// ASGCT_CallFrame *frames;
// } ASGCT_CallTrace;
//
// Fields:
// env_id - ID of thread which executed this trace.
// num_frames - number of frames in the trace.
// (< 0 indicates the frame is not walkable).
// frames - the ASGCT_CallFrames that make up this trace. Callee followed by callers.
//
// ASGCT_CallFrame:
// typedef struct {
// jint lineno;
// jmethodID method_id;
// } ASGCT_CallFrame;
//
// Fields:
// 1) For Java frame (interpreted and compiled),
// lineno - bci of the method being executed or -1 if bci is not available
// method_id - jmethodID of the method being executed
// 2) For native method
// lineno - (-3)
// method_id - jmethodID of the method being executed
extern "C" {
JNIEXPORT
void AsyncGetCallTrace(ASGCT_CallTrace *trace, jint depth, void* ucontext) {
JavaThread* thread;
if (trace->env_id == NULL ||
(thread = JavaThread::thread_from_jni_environment(trace->env_id)) == NULL ||
thread->is_exiting()) {
// bad env_id, thread has exited or thread is exiting
trace->num_frames = ticks_thread_exit; // -8
return;
}
if (thread->in_deopt_handler()) {
// thread is in the deoptimization handler so return no frames
trace->num_frames = ticks_deopt; // -9
return;
}
assert(JavaThread::current() == thread,
"AsyncGetCallTrace must be called by the current interrupted thread");
if (!JvmtiExport::should_post_class_load()) {
trace->num_frames = ticks_no_class_load; // -1
return;
}
if (Universe::heap()->is_gc_active()) {
trace->num_frames = ticks_GC_active; // -2
return;
}
switch (thread->thread_state()) {
case _thread_new:
case _thread_uninitialized:
case _thread_new_trans:
// We found the thread on the threads list above, but it is too
// young to be useful so return that there are no Java frames.
trace->num_frames = 0;
break;
case _thread_in_native:
case _thread_in_native_trans:
case _thread_blocked:
case _thread_blocked_trans:
case _thread_in_vm:
case _thread_in_vm_trans:
{
frame fr;
// param isInJava == false - indicate we aren't in Java code
if (!thread->pd_get_top_frame_for_signal_handler(&fr, ucontext, false)) {
trace->num_frames = ticks_unknown_not_Java; // -3 unknown frame
} else {
if (!thread->has_last_Java_frame()) {
trace->num_frames = 0; // No Java frames
} else {
trace->num_frames = ticks_not_walkable_not_Java; // -4 non walkable frame by default
forte_fill_call_trace_given_top(thread, trace, depth, fr);
// This assert would seem to be valid but it is not.
// It would be valid if we weren't possibly racing a gc
// thread. A gc thread can make a valid interpreted frame
// look invalid. It's a small window but it does happen.
// The assert is left here commented out as a reminder.
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