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