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