1//===-- ThreadPlanStepOut.cpp ---------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "lldb/Target/ThreadPlanStepOut.h"
10#include "lldb/Breakpoint/Breakpoint.h"
11#include "lldb/Core/Value.h"
12#include "lldb/Symbol/Block.h"
13#include "lldb/Symbol/Function.h"
14#include "lldb/Symbol/Symbol.h"
15#include "lldb/Symbol/Type.h"
16#include "lldb/Target/ABI.h"
17#include "lldb/Target/Process.h"
18#include "lldb/Target/RegisterContext.h"
19#include "lldb/Target/StopInfo.h"
20#include "lldb/Target/Target.h"
21#include "lldb/Target/ThreadPlanStepOverRange.h"
22#include "lldb/Target/ThreadPlanStepThrough.h"
23#include "lldb/Utility/LLDBLog.h"
24#include "lldb/Utility/Log.h"
25#include "lldb/ValueObject/ValueObjectConstResult.h"
26
27#include <memory>
28
29using namespace lldb;
30using namespace lldb_private;
31
32uint32_t ThreadPlanStepOut::s_default_flag_values = 0;
33
34/// Computes the target frame this plan should step out to.
35static StackFrameSP
36ComputeTargetFrame(Thread &thread, uint32_t start_frame_idx,
37 std::vector<StackFrameSP> &skipped_frames) {
38 uint32_t frame_idx = start_frame_idx + 1;
39 StackFrameSP return_frame_sp = thread.GetStackFrameAtIndex(idx: frame_idx);
40 if (!return_frame_sp)
41 return nullptr;
42
43 while (return_frame_sp->IsArtificial() || return_frame_sp->IsHidden()) {
44 skipped_frames.push_back(x: return_frame_sp);
45
46 frame_idx++;
47 return_frame_sp = thread.GetStackFrameAtIndex(idx: frame_idx);
48
49 // We never expect to see an artificial frame without a regular ancestor.
50 // Defensively refuse to step out.
51 if (!return_frame_sp) {
52 LLDB_LOG(GetLog(LLDBLog::Step),
53 "Can't step out of frame with artificial ancestors");
54 return nullptr;
55 }
56 }
57 return return_frame_sp;
58}
59
60// ThreadPlanStepOut: Step out of the current frame
61ThreadPlanStepOut::ThreadPlanStepOut(
62 Thread &thread, SymbolContext *context, bool first_insn, bool stop_others,
63 Vote report_stop_vote, Vote report_run_vote, uint32_t frame_idx,
64 LazyBool step_out_avoids_code_without_debug_info,
65 bool continue_to_next_branch, bool gather_return_value)
66 : ThreadPlan(ThreadPlan::eKindStepOut, "Step out", thread, report_stop_vote,
67 report_run_vote),
68 ThreadPlanShouldStopHere(this), m_step_from_insn(LLDB_INVALID_ADDRESS),
69 m_return_bp_id(LLDB_INVALID_BREAK_ID),
70 m_return_addr(LLDB_INVALID_ADDRESS), m_stop_others(stop_others),
71 m_immediate_step_from_function(nullptr),
72 m_calculate_return_value(gather_return_value) {
73 SetFlagsToDefault();
74 SetupAvoidNoDebug(step_out_avoids_code_without_debug_info);
75
76 m_step_from_insn = thread.GetRegisterContext()->GetPC(fail_value: 0);
77
78 StackFrameSP return_frame_sp =
79 ComputeTargetFrame(thread, start_frame_idx: frame_idx, skipped_frames&: m_stepped_past_frames);
80 StackFrameSP immediate_return_from_sp(thread.GetStackFrameAtIndex(idx: frame_idx));
81
82 SetupReturnAddress(return_frame_sp, immediate_return_from_sp, frame_idx,
83 continue_to_next_branch);
84}
85
86ThreadPlanStepOut::ThreadPlanStepOut(Thread &thread, bool stop_others,
87 Vote report_stop_vote,
88 Vote report_run_vote, uint32_t frame_idx,
89 bool continue_to_next_branch,
90 bool gather_return_value)
91 : ThreadPlan(ThreadPlan::eKindStepOut, "Step out", thread, report_stop_vote,
92 report_run_vote),
93 ThreadPlanShouldStopHere(this), m_return_bp_id(LLDB_INVALID_BREAK_ID),
94 m_return_addr(LLDB_INVALID_ADDRESS), m_stop_others(stop_others),
95 m_immediate_step_from_function(nullptr),
96 m_calculate_return_value(gather_return_value) {
97 SetFlagsToDefault();
98 m_step_from_insn = thread.GetRegisterContext()->GetPC(fail_value: 0);
99
100 StackFrameSP return_frame_sp = thread.GetStackFrameAtIndex(idx: frame_idx + 1);
101 StackFrameSP immediate_return_from_sp =
102 thread.GetStackFrameAtIndex(idx: frame_idx);
103
104 SetupReturnAddress(return_frame_sp, immediate_return_from_sp, frame_idx,
105 continue_to_next_branch);
106}
107
108void ThreadPlanStepOut::SetupReturnAddress(
109 StackFrameSP return_frame_sp, StackFrameSP immediate_return_from_sp,
110 uint32_t frame_idx, bool continue_to_next_branch) {
111 if (!return_frame_sp || !immediate_return_from_sp)
112 return; // we can't do anything here. ValidatePlan() will return false.
113
114 m_step_out_to_id = return_frame_sp->GetStackID();
115 m_immediate_step_from_id = immediate_return_from_sp->GetStackID();
116
117 // If the frame directly below the one we are returning to is inlined, we
118 // have to be a little more careful. It is non-trivial to determine the real
119 // "return code address" for an inlined frame, so we have to work our way to
120 // that frame and then step out.
121 if (immediate_return_from_sp->IsInlined()) {
122 if (frame_idx > 0) {
123 // First queue a plan that gets us to this inlined frame, and when we get
124 // there we'll queue a second plan that walks us out of this frame.
125 m_step_out_to_inline_plan_sp = std::make_shared<ThreadPlanStepOut>(
126 args&: GetThread(), args: nullptr, args: false, args&: m_stop_others, args: eVoteNoOpinion,
127 args: eVoteNoOpinion, args: frame_idx - 1, args: eLazyBoolNo, args&: continue_to_next_branch);
128 static_cast<ThreadPlanStepOut *>(m_step_out_to_inline_plan_sp.get())
129 ->SetShouldStopHereCallbacks(callbacks: nullptr, baton: nullptr);
130 m_step_out_to_inline_plan_sp->SetPrivate(true);
131 } else {
132 // If we're already at the inlined frame we're stepping through, then
133 // just do that now.
134 QueueInlinedStepPlan(queue_now: false);
135 }
136 } else {
137 // Find the return address and set a breakpoint there:
138 // FIXME - can we do this more securely if we know first_insn?
139
140 Address return_address(return_frame_sp->GetFrameCodeAddress());
141 if (continue_to_next_branch) {
142 SymbolContext return_address_sc;
143 AddressRange range;
144 Address return_address_decr_pc = return_address;
145 if (return_address_decr_pc.GetOffset() > 0)
146 return_address_decr_pc.Slide(offset: -1);
147
148 return_address_decr_pc.CalculateSymbolContext(
149 sc: &return_address_sc, resolve_scope: lldb::eSymbolContextLineEntry);
150 if (return_address_sc.line_entry.IsValid()) {
151 const bool include_inlined_functions = false;
152 range = return_address_sc.line_entry.GetSameLineContiguousAddressRange(
153 include_inlined_functions);
154 if (range.GetByteSize() > 0) {
155 return_address = m_process.AdvanceAddressToNextBranchInstruction(
156 default_stop_addr: return_address, range_bounds: range);
157 }
158 }
159 }
160 m_return_addr = return_address.GetLoadAddress(target: &m_process.GetTarget());
161
162 if (m_return_addr == LLDB_INVALID_ADDRESS)
163 return;
164
165 // Perform some additional validation on the return address.
166 uint32_t permissions = 0;
167 Log *log = GetLog(mask: LLDBLog::Step);
168 if (!m_process.GetLoadAddressPermissions(load_addr: m_return_addr, permissions)) {
169 LLDB_LOGF(log, "ThreadPlanStepOut(%p): Return address (0x%" PRIx64
170 ") permissions not found.", static_cast<void *>(this),
171 m_return_addr);
172 } else if (!(permissions & ePermissionsExecutable)) {
173 m_constructor_errors.Printf(format: "Return address (0x%" PRIx64
174 ") did not point to executable memory.",
175 m_return_addr);
176 LLDB_LOGF(log, "ThreadPlanStepOut(%p): %s", static_cast<void *>(this),
177 m_constructor_errors.GetData());
178 return;
179 }
180
181 Breakpoint *return_bp =
182 GetTarget().CreateBreakpoint(load_addr: m_return_addr, internal: true, request_hardware: false).get();
183
184 if (return_bp != nullptr) {
185 if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
186 m_could_not_resolve_hw_bp = true;
187 return_bp->SetThreadID(m_tid);
188 m_return_bp_id = return_bp->GetID();
189 return_bp->SetBreakpointKind("step-out");
190 }
191
192 if (immediate_return_from_sp) {
193 const SymbolContext &sc =
194 immediate_return_from_sp->GetSymbolContext(resolve_scope: eSymbolContextFunction);
195 if (sc.function) {
196 m_immediate_step_from_function = sc.function;
197 }
198 }
199 }
200}
201
202void ThreadPlanStepOut::SetupAvoidNoDebug(
203 LazyBool step_out_avoids_code_without_debug_info) {
204 bool avoid_nodebug = true;
205 switch (step_out_avoids_code_without_debug_info) {
206 case eLazyBoolYes:
207 avoid_nodebug = true;
208 break;
209 case eLazyBoolNo:
210 avoid_nodebug = false;
211 break;
212 case eLazyBoolCalculate:
213 avoid_nodebug = GetThread().GetStepOutAvoidsNoDebug();
214 break;
215 }
216 if (avoid_nodebug)
217 GetFlags().Set(ThreadPlanShouldStopHere::eStepOutAvoidNoDebug);
218 else
219 GetFlags().Clear(mask: ThreadPlanShouldStopHere::eStepOutAvoidNoDebug);
220}
221
222void ThreadPlanStepOut::DidPush() {
223 Thread &thread = GetThread();
224 if (m_step_out_to_inline_plan_sp)
225 thread.QueueThreadPlan(plan_sp&: m_step_out_to_inline_plan_sp, abort_other_plans: false);
226 else if (m_step_through_inline_plan_sp)
227 thread.QueueThreadPlan(plan_sp&: m_step_through_inline_plan_sp, abort_other_plans: false);
228}
229
230ThreadPlanStepOut::~ThreadPlanStepOut() {
231 if (m_return_bp_id != LLDB_INVALID_BREAK_ID)
232 GetTarget().RemoveBreakpointByID(break_id: m_return_bp_id);
233}
234
235void ThreadPlanStepOut::GetDescription(Stream *s,
236 lldb::DescriptionLevel level) {
237 if (level == lldb::eDescriptionLevelBrief)
238 s->Printf(format: "step out");
239 else {
240 if (m_step_out_to_inline_plan_sp)
241 s->Printf(format: "Stepping out to inlined frame so we can walk through it.");
242 else if (m_step_through_inline_plan_sp)
243 s->Printf(format: "Stepping out by stepping through inlined function.");
244 else {
245 s->Printf(format: "Stepping out from ");
246 Address tmp_address;
247 if (tmp_address.SetLoadAddress(load_addr: m_step_from_insn, target: &GetTarget())) {
248 tmp_address.Dump(s, exe_scope: &m_process, style: Address::DumpStyleResolvedDescription,
249 fallback_style: Address::DumpStyleLoadAddress);
250 } else {
251 s->Printf(format: "address 0x%" PRIx64 "", (uint64_t)m_step_from_insn);
252 }
253
254 // FIXME: find some useful way to present the m_return_id, since there may
255 // be multiple copies of the
256 // same function on the stack.
257
258 s->Printf(format: " returning to frame at ");
259 if (tmp_address.SetLoadAddress(load_addr: m_return_addr, target: &GetTarget())) {
260 tmp_address.Dump(s, exe_scope: &m_process, style: Address::DumpStyleResolvedDescription,
261 fallback_style: Address::DumpStyleLoadAddress);
262 } else {
263 s->Printf(format: "address 0x%" PRIx64 "", (uint64_t)m_return_addr);
264 }
265
266 if (level == eDescriptionLevelVerbose)
267 s->Printf(format: " using breakpoint site %d", m_return_bp_id);
268 }
269 }
270
271 if (m_stepped_past_frames.empty())
272 return;
273
274 s->Printf(format: "\n");
275 for (StackFrameSP frame_sp : m_stepped_past_frames) {
276 s->Printf(format: "Stepped out past: ");
277 frame_sp->DumpUsingSettingsFormat(strm: s);
278 }
279}
280
281bool ThreadPlanStepOut::ValidatePlan(Stream *error) {
282 if (m_step_out_to_inline_plan_sp)
283 return m_step_out_to_inline_plan_sp->ValidatePlan(error);
284
285 if (m_step_through_inline_plan_sp)
286 return m_step_through_inline_plan_sp->ValidatePlan(error);
287
288 if (m_could_not_resolve_hw_bp) {
289 if (error)
290 error->PutCString(
291 cstr: "Could not create hardware breakpoint for thread plan.");
292 return false;
293 }
294
295 if (m_return_bp_id == LLDB_INVALID_BREAK_ID) {
296 if (error) {
297 error->PutCString(cstr: "Could not create return address breakpoint.");
298 if (m_constructor_errors.GetSize() > 0) {
299 error->PutCString(cstr: " ");
300 error->PutCString(cstr: m_constructor_errors.GetString());
301 }
302 }
303 return false;
304 }
305
306 return true;
307}
308
309bool ThreadPlanStepOut::DoPlanExplainsStop(Event *event_ptr) {
310 // If the step out plan is done, then we just need to step through the
311 // inlined frame.
312 if (m_step_out_to_inline_plan_sp) {
313 return m_step_out_to_inline_plan_sp->MischiefManaged();
314 } else if (m_step_through_inline_plan_sp) {
315 if (m_step_through_inline_plan_sp->MischiefManaged()) {
316 CalculateReturnValue();
317 SetPlanComplete();
318 return true;
319 } else
320 return false;
321 } else if (m_step_out_further_plan_sp) {
322 return m_step_out_further_plan_sp->MischiefManaged();
323 }
324
325 // We don't explain signals or breakpoints (breakpoints that handle stepping
326 // in or out will be handled by a child plan.
327
328 StopInfoSP stop_info_sp = GetPrivateStopInfo();
329 if (stop_info_sp) {
330 StopReason reason = stop_info_sp->GetStopReason();
331 if (reason == eStopReasonBreakpoint) {
332 // If this is OUR breakpoint, we're fine, otherwise we don't know why
333 // this happened...
334 BreakpointSiteSP site_sp(
335 m_process.GetBreakpointSiteList().FindByID(site_id: stop_info_sp->GetValue()));
336 if (site_sp && site_sp->IsBreakpointAtThisSite(bp_id: m_return_bp_id)) {
337 bool done;
338
339 StackID frame_zero_id =
340 GetThread().GetStackFrameAtIndex(idx: 0)->GetStackID();
341
342 if (m_step_out_to_id == frame_zero_id)
343 done = true;
344 else if (m_step_out_to_id < frame_zero_id) {
345 // Either we stepped past the breakpoint, or the stack ID calculation
346 // was incorrect and we should probably stop.
347 done = true;
348 } else {
349 done = (m_immediate_step_from_id < frame_zero_id);
350 }
351
352 if (done) {
353 if (InvokeShouldStopHereCallback(operation: eFrameCompareOlder, status&: m_status)) {
354 CalculateReturnValue();
355 SetPlanComplete();
356 }
357 }
358
359 // If there was only one owner, then we're done. But if we also hit
360 // some user breakpoint on our way out, we should mark ourselves as
361 // done, but also not claim to explain the stop, since it is more
362 // important to report the user breakpoint than the step out
363 // completion.
364
365 if (site_sp->GetNumberOfConstituents() == 1)
366 return true;
367 }
368 return false;
369 } else if (IsUsuallyUnexplainedStopReason(reason))
370 return false;
371 else
372 return true;
373 }
374 return true;
375}
376
377bool ThreadPlanStepOut::ShouldStop(Event *event_ptr) {
378 if (IsPlanComplete())
379 return true;
380
381 bool done = false;
382 if (m_step_out_to_inline_plan_sp) {
383 if (m_step_out_to_inline_plan_sp->MischiefManaged()) {
384 // Now step through the inlined stack we are in:
385 if (QueueInlinedStepPlan(queue_now: true)) {
386 // If we can't queue a plan to do this, then just call ourselves done.
387 m_step_out_to_inline_plan_sp.reset();
388 SetPlanComplete(false);
389 return true;
390 } else
391 done = true;
392 } else
393 return m_step_out_to_inline_plan_sp->ShouldStop(event_ptr);
394 } else if (m_step_through_inline_plan_sp) {
395 if (m_step_through_inline_plan_sp->MischiefManaged())
396 done = true;
397 else
398 return m_step_through_inline_plan_sp->ShouldStop(event_ptr);
399 } else if (m_step_out_further_plan_sp) {
400 if (m_step_out_further_plan_sp->MischiefManaged())
401 m_step_out_further_plan_sp.reset();
402 else
403 return m_step_out_further_plan_sp->ShouldStop(event_ptr);
404 }
405
406 if (!done) {
407 StopInfoSP stop_info_sp = GetPrivateStopInfo();
408 if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
409 StackID frame_zero_id = GetThread().GetStackFrameAtIndex(idx: 0)->GetStackID();
410 done = !(frame_zero_id < m_step_out_to_id);
411 }
412 }
413
414 // The normal step out computations think we are done, so all we need to do
415 // is consult the ShouldStopHere, and we are done.
416
417 if (done) {
418 if (InvokeShouldStopHereCallback(operation: eFrameCompareOlder, status&: m_status)) {
419 CalculateReturnValue();
420 SetPlanComplete();
421 } else {
422 m_step_out_further_plan_sp =
423 QueueStepOutFromHerePlan(flags&: m_flags, operation: eFrameCompareOlder, status&: m_status);
424 done = false;
425 }
426 }
427
428 return done;
429}
430
431bool ThreadPlanStepOut::StopOthers() { return m_stop_others; }
432
433StateType ThreadPlanStepOut::GetPlanRunState() { return eStateRunning; }
434
435bool ThreadPlanStepOut::DoWillResume(StateType resume_state,
436 bool current_plan) {
437 if (m_step_out_to_inline_plan_sp || m_step_through_inline_plan_sp)
438 return true;
439
440 if (m_return_bp_id == LLDB_INVALID_BREAK_ID)
441 return false;
442
443 if (current_plan) {
444 Breakpoint *return_bp = GetTarget().GetBreakpointByID(break_id: m_return_bp_id).get();
445 if (return_bp != nullptr)
446 return_bp->SetEnabled(true);
447 }
448 return true;
449}
450
451bool ThreadPlanStepOut::WillStop() {
452 if (m_return_bp_id != LLDB_INVALID_BREAK_ID) {
453 Breakpoint *return_bp = GetTarget().GetBreakpointByID(break_id: m_return_bp_id).get();
454 if (return_bp != nullptr)
455 return_bp->SetEnabled(false);
456 }
457
458 return true;
459}
460
461bool ThreadPlanStepOut::MischiefManaged() {
462 if (IsPlanComplete()) {
463 // Did I reach my breakpoint? If so I'm done.
464 //
465 // I also check the stack depth, since if we've blown past the breakpoint
466 // for some
467 // reason and we're now stopping for some other reason altogether, then
468 // we're done with this step out operation.
469
470 Log *log = GetLog(mask: LLDBLog::Step);
471 if (log)
472 LLDB_LOGF(log, "Completed step out plan.");
473 if (m_return_bp_id != LLDB_INVALID_BREAK_ID) {
474 GetTarget().RemoveBreakpointByID(break_id: m_return_bp_id);
475 m_return_bp_id = LLDB_INVALID_BREAK_ID;
476 }
477
478 ThreadPlan::MischiefManaged();
479 return true;
480 } else {
481 return false;
482 }
483}
484
485bool ThreadPlanStepOut::QueueInlinedStepPlan(bool queue_now) {
486 // Now figure out the range of this inlined block, and set up a "step through
487 // range" plan for that. If we've been provided with a context, then use the
488 // block in that context.
489 Thread &thread = GetThread();
490 StackFrameSP immediate_return_from_sp(thread.GetStackFrameAtIndex(idx: 0));
491 if (!immediate_return_from_sp)
492 return false;
493
494 Log *log = GetLog(mask: LLDBLog::Step);
495 if (log) {
496 StreamString s;
497 immediate_return_from_sp->Dump(strm: &s, show_frame_index: true, show_fullpaths: false);
498 LLDB_LOGF(log, "Queuing inlined frame to step past: %s.", s.GetData());
499 }
500
501 Block *from_block = immediate_return_from_sp->GetFrameBlock();
502 if (from_block) {
503 Block *inlined_block = from_block->GetContainingInlinedBlock();
504 if (inlined_block) {
505 size_t num_ranges = inlined_block->GetNumRanges();
506 AddressRange inline_range;
507 if (inlined_block->GetRangeAtIndex(range_idx: 0, range&: inline_range)) {
508 SymbolContext inlined_sc;
509 inlined_block->CalculateSymbolContext(sc: &inlined_sc);
510 inlined_sc.target_sp = GetTarget().shared_from_this();
511 RunMode run_mode =
512 m_stop_others ? lldb::eOnlyThisThread : lldb::eAllThreads;
513 const LazyBool avoid_no_debug = eLazyBoolNo;
514
515 m_step_through_inline_plan_sp =
516 std::make_shared<ThreadPlanStepOverRange>(
517 args&: thread, args&: inline_range, args&: inlined_sc, args&: run_mode, args: avoid_no_debug);
518 ThreadPlanStepOverRange *step_through_inline_plan_ptr =
519 static_cast<ThreadPlanStepOverRange *>(
520 m_step_through_inline_plan_sp.get());
521 m_step_through_inline_plan_sp->SetPrivate(true);
522
523 step_through_inline_plan_ptr->SetOkayToDiscard(true);
524 StreamString errors;
525 if (!step_through_inline_plan_ptr->ValidatePlan(error: &errors)) {
526 // FIXME: Log this failure.
527 delete step_through_inline_plan_ptr;
528 return false;
529 }
530
531 for (size_t i = 1; i < num_ranges; i++) {
532 if (inlined_block->GetRangeAtIndex(range_idx: i, range&: inline_range))
533 step_through_inline_plan_ptr->AddRange(new_range: inline_range);
534 }
535
536 if (queue_now)
537 thread.QueueThreadPlan(plan_sp&: m_step_through_inline_plan_sp, abort_other_plans: false);
538 return true;
539 }
540 }
541 }
542
543 return false;
544}
545
546void ThreadPlanStepOut::CalculateReturnValue() {
547 if (m_return_valobj_sp)
548 return;
549
550 if (!m_calculate_return_value)
551 return;
552
553 if (m_immediate_step_from_function != nullptr) {
554 CompilerType return_compiler_type =
555 m_immediate_step_from_function->GetCompilerType()
556 .GetFunctionReturnType();
557 if (return_compiler_type) {
558 lldb::ABISP abi_sp = m_process.GetABI();
559 if (abi_sp)
560 m_return_valobj_sp =
561 abi_sp->GetReturnValueObject(thread&: GetThread(), type&: return_compiler_type);
562 }
563 }
564}
565
566bool ThreadPlanStepOut::IsPlanStale() {
567 // If we are still lower on the stack than the frame we are returning to,
568 // then there's something for us to do. Otherwise, we're stale.
569
570 StackID frame_zero_id = GetThread().GetStackFrameAtIndex(idx: 0)->GetStackID();
571 return !(frame_zero_id < m_step_out_to_id);
572}
573

source code of lldb/source/Target/ThreadPlanStepOut.cpp