1 /*
2 * Copyright (c) 2012, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "classfile/javaThreadStatus.hpp"
26 #include "code/codeCache.inline.hpp"
27 #include "code/debugInfoRec.hpp"
28 #include "code/nmethod.hpp"
29 #include "interpreter/interpreter.hpp"
30 #include "jfr/jfrEvents.hpp"
31 #include "jfr/periodic/sampling/jfrCPUTimeThreadSampler.hpp"
32 #include "jfr/periodic/sampling/jfrSampleMonitor.hpp"
33 #include "jfr/periodic/sampling/jfrSampleRequest.hpp"
34 #include "jfr/periodic/sampling/jfrThreadSampling.hpp"
35 #include "jfr/recorder/stacktrace/jfrStackTrace.hpp"
36 #include "jfr/utilities/jfrTypes.hpp"
37 #include "memory/resourceArea.hpp"
38 #include "oops/method.hpp"
39 #include "runtime/continuation.hpp"
40 #include "runtime/frame.inline.hpp"
41 #include "runtime/javaThread.inline.hpp"
42 #include "runtime/stackFrameStream.inline.hpp"
43
44 template <typename EventType>
45 static inline void send_sample_event(const JfrTicks& start_time, const JfrTicks& end_time, traceid sid, traceid tid) {
46 EventType event(UNTIMED);
47 event.set_starttime(start_time);
48 event.set_endtime(end_time);
131
132 // Step to sender.
133 stream.next();
134
135 // If the top frame is in a continuation, check that the sender frame is too.
136 if (in_continuation && !is_in_continuation(*stream.current(), jt)) {
137 // Leave sender frame empty.
138 return true;
139 }
140
141 sender_frame = *stream.current();
142
143 assert(request._sample_pc != nullptr, "invariant");
144 assert(request._sample_bcp != nullptr, "invariant");
145 assert(Method::is_valid_method(static_cast<const Method*>(request._sample_pc)), "invariant");
146 assert(static_cast<const Method*>(request._sample_pc)->is_native() ||
147 static_cast<const Method*>(request._sample_pc)->contains(static_cast<address>(request._sample_bcp)), "invariant");
148 return true;
149 }
150
151 static inline const PcDesc* get_pc_desc(nmethod* nm, void* pc) {
152 assert(nm != nullptr, "invariant");
153 assert(pc != nullptr, "invariant");
154 return nm->pc_desc_near(static_cast<address>(pc));
155 }
156
157 static inline bool is_valid(const PcDesc* pc_desc) {
158 return pc_desc != nullptr && pc_desc->scope_decode_offset() != DebugInformationRecorder::serialized_null;
159 }
160
161 static bool compute_top_frame(const JfrSampleRequest& request, frame& top_frame, bool& in_continuation, JavaThread* jt, bool& biased) {
162 assert(jt != nullptr, "invariant");
163
164 if (!jt->has_last_Java_frame()) {
165 return false;
166 }
167
168 if (is_interpreter(request)) {
169 return compute_sender_frame(const_cast<JfrSampleRequest&>(request), top_frame, in_continuation, jt);
170 }
171
192 if (stream.current()->is_safepoint_blob_frame()) {
193 if (sampled_nm != nullptr) {
194 // Move to the physical sender frame of the SafepointBlob stub frame using the frame size, not the logical iterator.
195 const int safepoint_blob_stub_frame_size = stream.current()->cb()->frame_size();
196 intptr_t* const sender_sp = stream.current()->unextended_sp() + safepoint_blob_stub_frame_size;
197 if (sender_sp > sampled_sp) {
198 const address saved_exception_pc = jt->saved_exception_pc();
199 assert(saved_exception_pc != nullptr, "invariant");
200 const nmethod* const exception_nm = CodeCache::find_blob(saved_exception_pc)->as_nmethod();
201 assert(exception_nm != nullptr, "invariant");
202 if (exception_nm == sampled_nm && sampled_nm->is_at_poll_return(saved_exception_pc)) {
203 // We sit at the poll return site in the sampled compiled nmethod with only the return address on the stack.
204 // The sampled_nm compiled frame is no longer extant, but we might be able to reconstruct a synthetic
205 // compiled frame at this location. We do this by overlaying a reconstructed frame on top of
206 // the huge SafepointBlob stub frame. Of course, the synthetic frame only contains random stack memory,
207 // but it is safe because stack walking cares only about the form of the frame (i.e., an sp and a pc).
208 // We also do not have to worry about stackbanging because we currently have a huge SafepointBlob stub frame
209 // on the stack. For extra assurance, we know that we can create this frame size at this
210 // very location because we just popped such a frame before we hit the return poll site.
211 //
212 // Let's attempt to correct for the safepoint bias.
213 const PcDesc* const pc_desc = get_pc_desc(sampled_nm, sampled_pc);
214 if (is_valid(pc_desc)) {
215 intptr_t* const synthetic_sp = sender_sp - sampled_nm->frame_size();
216 intptr_t* const synthetic_fp = sender_sp AARCH64_ONLY( - frame::sender_sp_offset);
217 top_frame = frame(synthetic_sp, synthetic_sp, synthetic_fp, pc_desc->real_pc(sampled_nm), sampled_nm);
218 in_continuation = is_in_continuation(top_frame, jt);
219 return true;
220 }
221 }
222 }
223 }
224 stream.next(); // skip the SafepointBlob stub frame
225 }
226
227 assert(!stream.current()->is_safepoint_blob_frame(), "invariant");
228
229 biased = true;
230
231 // Search the first frame that is above the sampled sp.
232 for (; !stream.is_done(); stream.next()) {
233 frame* const current = stream.current();
234
235 if (current->real_fp() <= sampled_sp) {
236 // Continue searching for a matching frame.
237 continue;
238 }
|
1 /*
2 * Copyright (c) 2012, 2026, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "classfile/javaThreadStatus.hpp"
26 #include "code/codeCache.inline.hpp"
27 #include "code/debugInfoRec.hpp"
28 #include "code/nmethod.hpp"
29 #include "code/pcDesc.hpp"
30 #include "interpreter/interpreter.hpp"
31 #include "jfr/jfrEvents.hpp"
32 #include "jfr/periodic/sampling/jfrCPUTimeThreadSampler.hpp"
33 #include "jfr/periodic/sampling/jfrSampleMonitor.hpp"
34 #include "jfr/periodic/sampling/jfrSampleRequest.hpp"
35 #include "jfr/periodic/sampling/jfrThreadSampling.hpp"
36 #include "jfr/recorder/stacktrace/jfrStackTrace.hpp"
37 #include "jfr/utilities/jfrTypes.hpp"
38 #include "memory/resourceArea.hpp"
39 #include "oops/method.hpp"
40 #include "runtime/continuation.hpp"
41 #include "runtime/frame.inline.hpp"
42 #include "runtime/javaThread.inline.hpp"
43 #include "runtime/stackFrameStream.inline.hpp"
44
45 template <typename EventType>
46 static inline void send_sample_event(const JfrTicks& start_time, const JfrTicks& end_time, traceid sid, traceid tid) {
47 EventType event(UNTIMED);
48 event.set_starttime(start_time);
49 event.set_endtime(end_time);
132
133 // Step to sender.
134 stream.next();
135
136 // If the top frame is in a continuation, check that the sender frame is too.
137 if (in_continuation && !is_in_continuation(*stream.current(), jt)) {
138 // Leave sender frame empty.
139 return true;
140 }
141
142 sender_frame = *stream.current();
143
144 assert(request._sample_pc != nullptr, "invariant");
145 assert(request._sample_bcp != nullptr, "invariant");
146 assert(Method::is_valid_method(static_cast<const Method*>(request._sample_pc)), "invariant");
147 assert(static_cast<const Method*>(request._sample_pc)->is_native() ||
148 static_cast<const Method*>(request._sample_pc)->contains(static_cast<address>(request._sample_bcp)), "invariant");
149 return true;
150 }
151
152 static inline PcDesc* get_pc_desc(nmethod* nm, void* pc) {
153 assert(nm != nullptr, "invariant");
154 assert(pc != nullptr, "invariant");
155 return nm->pc_desc_near(static_cast<address>(pc));
156 }
157
158 static inline bool is_valid(const PcDesc* pc_desc) {
159 return pc_desc != nullptr && pc_desc->scope_decode_offset() != DebugInformationRecorder::serialized_null;
160 }
161
162 static bool compute_top_frame(const JfrSampleRequest& request, frame& top_frame, bool& in_continuation, JavaThread* jt, bool& biased) {
163 assert(jt != nullptr, "invariant");
164
165 if (!jt->has_last_Java_frame()) {
166 return false;
167 }
168
169 if (is_interpreter(request)) {
170 return compute_sender_frame(const_cast<JfrSampleRequest&>(request), top_frame, in_continuation, jt);
171 }
172
193 if (stream.current()->is_safepoint_blob_frame()) {
194 if (sampled_nm != nullptr) {
195 // Move to the physical sender frame of the SafepointBlob stub frame using the frame size, not the logical iterator.
196 const int safepoint_blob_stub_frame_size = stream.current()->cb()->frame_size();
197 intptr_t* const sender_sp = stream.current()->unextended_sp() + safepoint_blob_stub_frame_size;
198 if (sender_sp > sampled_sp) {
199 const address saved_exception_pc = jt->saved_exception_pc();
200 assert(saved_exception_pc != nullptr, "invariant");
201 const nmethod* const exception_nm = CodeCache::find_blob(saved_exception_pc)->as_nmethod();
202 assert(exception_nm != nullptr, "invariant");
203 if (exception_nm == sampled_nm && sampled_nm->is_at_poll_return(saved_exception_pc)) {
204 // We sit at the poll return site in the sampled compiled nmethod with only the return address on the stack.
205 // The sampled_nm compiled frame is no longer extant, but we might be able to reconstruct a synthetic
206 // compiled frame at this location. We do this by overlaying a reconstructed frame on top of
207 // the huge SafepointBlob stub frame. Of course, the synthetic frame only contains random stack memory,
208 // but it is safe because stack walking cares only about the form of the frame (i.e., an sp and a pc).
209 // We also do not have to worry about stackbanging because we currently have a huge SafepointBlob stub frame
210 // on the stack. For extra assurance, we know that we can create this frame size at this
211 // very location because we just popped such a frame before we hit the return poll site.
212 //
213 // For frames that need stack repair, special care is needed. This is because the general stack-walking code
214 // reads the frame size from the stack, but here that memory is already overwritten by the SafepointBlob.
215 // If we are careful, we don't need to reconstruct a frame that needs stack repair, because we can process
216 // the nmethod directly, unpacking it in the first part of the stack trace.
217 // To accomplish this, we must provide both the PcDesc and the nmethod to the stack-walking code,
218 // which is done by updating the JfrSampleRequest. A special marker, NEEDS_STACK_REPAIR, is set in the bcp field.
219 // In this case, the top_frame becomes the sender frame of the nmethod, similar to how interpreter frames are handled.
220 //
221 // Let's attempt to correct for the safepoint bias
222 PcDesc* const pc_desc = get_pc_desc(sampled_nm, sampled_pc);
223 if (is_valid(pc_desc)) {
224 intptr_t* const synthetic_sp = sender_sp - sampled_nm->frame_size();
225 in_continuation = Continuation::get_continuation_entry_for_sp(jt, synthetic_sp) != nullptr;
226 if (sampled_nm->needs_stack_repair()) {
227 JfrSampleRequest& modified_request = const_cast<JfrSampleRequest&>(request);
228 modified_request._sample_pc = pc_desc;
229 modified_request._sample_sp = sampled_nm;
230 modified_request._sample_bcp = reinterpret_cast<address>(JfrSampleRequestFrameType::NEEDS_STACK_REPAIR);
231 if (!stream.is_done()) {
232 stream.next();
233 // If the needs stack repair frame is in a continuation, check that the sender frame is too.
234 if (in_continuation && !is_in_continuation(*stream.current(), jt)) {
235 // Leave sender frame empty.
236 return true;
237 }
238 // The top_frame becomes the sender of the nmethod that needs stack repair.
239 top_frame = *stream.current();
240 }
241 return true;
242 }
243 intptr_t* const synthetic_fp = sender_sp AARCH64_ONLY( - frame::sender_sp_offset);
244 top_frame = frame(synthetic_sp, synthetic_sp, synthetic_fp, pc_desc->real_pc(sampled_nm), sampled_nm);
245 return true;
246 }
247 }
248 }
249 }
250 stream.next(); // skip the SafepointBlob stub frame
251 }
252
253 assert(!stream.current()->is_safepoint_blob_frame(), "invariant");
254
255 biased = true;
256
257 // Search the first frame that is above the sampled sp.
258 for (; !stream.is_done(); stream.next()) {
259 frame* const current = stream.current();
260
261 if (current->real_fp() <= sampled_sp) {
262 // Continue searching for a matching frame.
263 continue;
264 }
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