1 //===-- ThreadPlanStepRange.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/ThreadPlanStepRange.h"
10 #include "lldb/Breakpoint/BreakpointLocation.h"
11 #include "lldb/Breakpoint/BreakpointSite.h"
12 #include "lldb/Core/Disassembler.h"
13 #include "lldb/Symbol/Function.h"
14 #include "lldb/Symbol/Symbol.h"
15 #include "lldb/Target/ExecutionContext.h"
16 #include "lldb/Target/Process.h"
17 #include "lldb/Target/RegisterContext.h"
18 #include "lldb/Target/StopInfo.h"
19 #include "lldb/Target/Target.h"
20 #include "lldb/Target/Thread.h"
21 #include "lldb/Target/ThreadPlanRunToAddress.h"
22 #include "lldb/Utility/Log.h"
23 #include "lldb/Utility/Stream.h"
24 
25 using namespace lldb;
26 using namespace lldb_private;
27 
28 // ThreadPlanStepRange: Step through a stack range, either stepping over or
29 // into based on the value of \a type.
30 
31 ThreadPlanStepRange::ThreadPlanStepRange(ThreadPlanKind kind, const char *name,
32                                          Thread &thread,
33                                          const AddressRange &range,
34                                          const SymbolContext &addr_context,
35                                          lldb::RunMode stop_others,
36                                          bool given_ranges_only)
37     : ThreadPlan(kind, name, thread, eVoteNoOpinion, eVoteNoOpinion),
38       m_addr_context(addr_context), m_address_ranges(),
39       m_stop_others(stop_others), m_stack_id(), m_parent_stack_id(),
40       m_no_more_plans(false), m_first_run_event(true), m_use_fast_step(false),
41       m_given_ranges_only(given_ranges_only) {
42   m_use_fast_step = GetTarget().GetUseFastStepping();
43   AddRange(range);
44   m_stack_id = thread.GetStackFrameAtIndex(0)->GetStackID();
45   StackFrameSP parent_stack = thread.GetStackFrameAtIndex(1);
46   if (parent_stack)
47     m_parent_stack_id = parent_stack->GetStackID();
48 }
49 
50 ThreadPlanStepRange::~ThreadPlanStepRange() { ClearNextBranchBreakpoint(); }
51 
52 void ThreadPlanStepRange::DidPush() {
53   // See if we can find a "next range" breakpoint:
54   SetNextBranchBreakpoint();
55 }
56 
57 bool ThreadPlanStepRange::ValidatePlan(Stream *error) {
58   if (m_could_not_resolve_hw_bp) {
59     if (error)
60       error->PutCString(
61           "Could not create hardware breakpoint for thread plan.");
62     return false;
63   }
64   return true;
65 }
66 
67 Vote ThreadPlanStepRange::ShouldReportStop(Event *event_ptr) {
68   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
69 
70   const Vote vote = IsPlanComplete() ? eVoteYes : eVoteNo;
71   LLDB_LOGF(log, "ThreadPlanStepRange::ShouldReportStop() returning vote %i\n",
72             vote);
73   return vote;
74 }
75 
76 void ThreadPlanStepRange::AddRange(const AddressRange &new_range) {
77   // For now I'm just adding the ranges.  At some point we may want to condense
78   // the ranges if they overlap, though I don't think it is likely to be very
79   // important.
80   m_address_ranges.push_back(new_range);
81 
82   // Fill the slot for this address range with an empty DisassemblerSP in the
83   // instruction ranges. I want the indices to match, but I don't want to do
84   // the work to disassemble this range if I don't step into it.
85   m_instruction_ranges.push_back(DisassemblerSP());
86 }
87 
88 void ThreadPlanStepRange::DumpRanges(Stream *s) {
89   size_t num_ranges = m_address_ranges.size();
90   if (num_ranges == 1) {
91     m_address_ranges[0].Dump(s, &GetTarget(), Address::DumpStyleLoadAddress);
92   } else {
93     for (size_t i = 0; i < num_ranges; i++) {
94       s->Printf(" %" PRIu64 ": ", uint64_t(i));
95       m_address_ranges[i].Dump(s, &GetTarget(), Address::DumpStyleLoadAddress);
96     }
97   }
98 }
99 
100 bool ThreadPlanStepRange::InRange() {
101   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
102   bool ret_value = false;
103   Thread &thread = GetThread();
104   lldb::addr_t pc_load_addr = thread.GetRegisterContext()->GetPC();
105 
106   size_t num_ranges = m_address_ranges.size();
107   for (size_t i = 0; i < num_ranges; i++) {
108     ret_value =
109         m_address_ranges[i].ContainsLoadAddress(pc_load_addr, &GetTarget());
110     if (ret_value)
111       break;
112   }
113 
114   if (!ret_value && !m_given_ranges_only) {
115     // See if we've just stepped to another part of the same line number...
116     StackFrame *frame = thread.GetStackFrameAtIndex(0).get();
117 
118     SymbolContext new_context(
119         frame->GetSymbolContext(eSymbolContextEverything));
120     if (m_addr_context.line_entry.IsValid() &&
121         new_context.line_entry.IsValid()) {
122       if (m_addr_context.line_entry.original_file ==
123           new_context.line_entry.original_file) {
124         if (m_addr_context.line_entry.line == new_context.line_entry.line) {
125           m_addr_context = new_context;
126           const bool include_inlined_functions =
127               GetKind() == eKindStepOverRange;
128           AddRange(m_addr_context.line_entry.GetSameLineContiguousAddressRange(
129               include_inlined_functions));
130           ret_value = true;
131           if (log) {
132             StreamString s;
133             m_addr_context.line_entry.Dump(&s, &GetTarget(), true,
134                                            Address::DumpStyleLoadAddress,
135                                            Address::DumpStyleLoadAddress, true);
136 
137             LLDB_LOGF(
138                 log,
139                 "Step range plan stepped to another range of same line: %s",
140                 s.GetData());
141           }
142         } else if (new_context.line_entry.line == 0) {
143           new_context.line_entry.line = m_addr_context.line_entry.line;
144           m_addr_context = new_context;
145           const bool include_inlined_functions =
146               GetKind() == eKindStepOverRange;
147           AddRange(m_addr_context.line_entry.GetSameLineContiguousAddressRange(
148               include_inlined_functions));
149           ret_value = true;
150           if (log) {
151             StreamString s;
152             m_addr_context.line_entry.Dump(&s, &GetTarget(), true,
153                                            Address::DumpStyleLoadAddress,
154                                            Address::DumpStyleLoadAddress, true);
155 
156             LLDB_LOGF(log,
157                       "Step range plan stepped to a range at linenumber 0 "
158                       "stepping through that range: %s",
159                       s.GetData());
160           }
161         } else if (new_context.line_entry.range.GetBaseAddress().GetLoadAddress(
162                        &GetTarget()) != pc_load_addr) {
163           // Another thing that sometimes happens here is that we step out of
164           // one line into the MIDDLE of another line.  So far I mostly see
165           // this due to bugs in the debug information. But we probably don't
166           // want to be in the middle of a line range, so in that case reset
167           // the stepping range to the line we've stepped into the middle of
168           // and continue.
169           m_addr_context = new_context;
170           m_address_ranges.clear();
171           AddRange(m_addr_context.line_entry.range);
172           ret_value = true;
173           if (log) {
174             StreamString s;
175             m_addr_context.line_entry.Dump(&s, &GetTarget(), true,
176                                            Address::DumpStyleLoadAddress,
177                                            Address::DumpStyleLoadAddress, true);
178 
179             LLDB_LOGF(log,
180                       "Step range plan stepped to the middle of new "
181                       "line(%d): %s, continuing to clear this line.",
182                       new_context.line_entry.line, s.GetData());
183           }
184         }
185       }
186     }
187   }
188 
189   if (!ret_value && log)
190     LLDB_LOGF(log, "Step range plan out of range to 0x%" PRIx64, pc_load_addr);
191 
192   return ret_value;
193 }
194 
195 bool ThreadPlanStepRange::InSymbol() {
196   lldb::addr_t cur_pc = GetThread().GetRegisterContext()->GetPC();
197   if (m_addr_context.function != nullptr) {
198     return m_addr_context.function->GetAddressRange().ContainsLoadAddress(
199         cur_pc, &GetTarget());
200   } else if (m_addr_context.symbol && m_addr_context.symbol->ValueIsAddress()) {
201     AddressRange range(m_addr_context.symbol->GetAddressRef(),
202                        m_addr_context.symbol->GetByteSize());
203     return range.ContainsLoadAddress(cur_pc, &GetTarget());
204   }
205   return false;
206 }
207 
208 // FIXME: This should also handle inlining if we aren't going to do inlining in
209 // the
210 // main stack.
211 //
212 // Ideally we should remember the whole stack frame list, and then compare that
213 // to the current list.
214 
215 lldb::FrameComparison ThreadPlanStepRange::CompareCurrentFrameToStartFrame() {
216   FrameComparison frame_order;
217   Thread &thread = GetThread();
218   StackID cur_frame_id = thread.GetStackFrameAtIndex(0)->GetStackID();
219 
220   if (cur_frame_id == m_stack_id) {
221     frame_order = eFrameCompareEqual;
222   } else if (cur_frame_id < m_stack_id) {
223     frame_order = eFrameCompareYounger;
224   } else {
225     StackFrameSP cur_parent_frame = thread.GetStackFrameAtIndex(1);
226     StackID cur_parent_id;
227     if (cur_parent_frame)
228       cur_parent_id = cur_parent_frame->GetStackID();
229     if (m_parent_stack_id.IsValid() && cur_parent_id.IsValid() &&
230         m_parent_stack_id == cur_parent_id)
231       frame_order = eFrameCompareSameParent;
232     else
233       frame_order = eFrameCompareOlder;
234   }
235   return frame_order;
236 }
237 
238 bool ThreadPlanStepRange::StopOthers() {
239   switch (m_stop_others) {
240   case lldb::eOnlyThisThread:
241     return true;
242   case lldb::eOnlyDuringStepping:
243     // If there is a call in the range of the next branch breakpoint,
244     // then we should always run all threads, since a call can execute
245     // arbitrary code which might for instance take a lock that's held
246     // by another thread.
247     return !m_found_calls;
248   case lldb::eAllThreads:
249     return false;
250   }
251   llvm_unreachable("Unhandled run mode!");
252 }
253 
254 InstructionList *ThreadPlanStepRange::GetInstructionsForAddress(
255     lldb::addr_t addr, size_t &range_index, size_t &insn_offset) {
256   size_t num_ranges = m_address_ranges.size();
257   for (size_t i = 0; i < num_ranges; i++) {
258     if (m_address_ranges[i].ContainsLoadAddress(addr, &GetTarget())) {
259       // Some joker added a zero size range to the stepping range...
260       if (m_address_ranges[i].GetByteSize() == 0)
261         return nullptr;
262 
263       if (!m_instruction_ranges[i]) {
264         // Disassemble the address range given:
265         const char *plugin_name = nullptr;
266         const char *flavor = nullptr;
267         m_instruction_ranges[i] = Disassembler::DisassembleRange(
268             GetTarget().GetArchitecture(), plugin_name, flavor, GetTarget(),
269             m_address_ranges[i]);
270       }
271       if (!m_instruction_ranges[i])
272         return nullptr;
273       else {
274         // Find where we are in the instruction list as well.  If we aren't at
275         // an instruction, return nullptr. In this case, we're probably lost,
276         // and shouldn't try to do anything fancy.
277 
278         insn_offset =
279             m_instruction_ranges[i]
280                 ->GetInstructionList()
281                 .GetIndexOfInstructionAtLoadAddress(addr, GetTarget());
282         if (insn_offset == UINT32_MAX)
283           return nullptr;
284         else {
285           range_index = i;
286           return &m_instruction_ranges[i]->GetInstructionList();
287         }
288       }
289     }
290   }
291   return nullptr;
292 }
293 
294 void ThreadPlanStepRange::ClearNextBranchBreakpoint() {
295   if (m_next_branch_bp_sp) {
296     Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
297     LLDB_LOGF(log, "Removing next branch breakpoint: %d.",
298               m_next_branch_bp_sp->GetID());
299     GetTarget().RemoveBreakpointByID(m_next_branch_bp_sp->GetID());
300     m_next_branch_bp_sp.reset();
301     m_could_not_resolve_hw_bp = false;
302     m_found_calls = false;
303   }
304 }
305 
306 bool ThreadPlanStepRange::SetNextBranchBreakpoint() {
307   if (m_next_branch_bp_sp)
308     return true;
309 
310   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
311   // Stepping through ranges using breakpoints doesn't work yet, but with this
312   // off we fall back to instruction single stepping.
313   if (!m_use_fast_step)
314     return false;
315 
316   // clear the m_found_calls, we'll rediscover it for this range.
317   m_found_calls = false;
318 
319   lldb::addr_t cur_addr = GetThread().GetRegisterContext()->GetPC();
320   // Find the current address in our address ranges, and fetch the disassembly
321   // if we haven't already:
322   size_t pc_index;
323   size_t range_index;
324   InstructionList *instructions =
325       GetInstructionsForAddress(cur_addr, range_index, pc_index);
326   if (instructions == nullptr)
327     return false;
328   else {
329     const bool ignore_calls = GetKind() == eKindStepOverRange;
330     uint32_t branch_index = instructions->GetIndexOfNextBranchInstruction(
331         pc_index, ignore_calls, &m_found_calls);
332     Address run_to_address;
333 
334     // If we didn't find a branch, run to the end of the range.
335     if (branch_index == UINT32_MAX) {
336       uint32_t last_index = instructions->GetSize() - 1;
337       if (last_index - pc_index > 1) {
338         InstructionSP last_inst =
339             instructions->GetInstructionAtIndex(last_index);
340         size_t last_inst_size = last_inst->GetOpcode().GetByteSize();
341         run_to_address = last_inst->GetAddress();
342         run_to_address.Slide(last_inst_size);
343       }
344     } else if (branch_index - pc_index > 1) {
345       run_to_address =
346           instructions->GetInstructionAtIndex(branch_index)->GetAddress();
347     }
348 
349     if (run_to_address.IsValid()) {
350       const bool is_internal = true;
351       m_next_branch_bp_sp =
352           GetTarget().CreateBreakpoint(run_to_address, is_internal, false);
353       if (m_next_branch_bp_sp) {
354 
355         if (m_next_branch_bp_sp->IsHardware() &&
356             !m_next_branch_bp_sp->HasResolvedLocations())
357           m_could_not_resolve_hw_bp = true;
358 
359         if (log) {
360           lldb::break_id_t bp_site_id = LLDB_INVALID_BREAK_ID;
361           BreakpointLocationSP bp_loc =
362               m_next_branch_bp_sp->GetLocationAtIndex(0);
363           if (bp_loc) {
364             BreakpointSiteSP bp_site = bp_loc->GetBreakpointSite();
365             if (bp_site) {
366               bp_site_id = bp_site->GetID();
367             }
368           }
369           LLDB_LOGF(log,
370                     "ThreadPlanStepRange::SetNextBranchBreakpoint - Setting "
371                     "breakpoint %d (site %d) to run to address 0x%" PRIx64,
372                     m_next_branch_bp_sp->GetID(), bp_site_id,
373                     run_to_address.GetLoadAddress(&m_process.GetTarget()));
374         }
375 
376         m_next_branch_bp_sp->SetThreadID(m_tid);
377         m_next_branch_bp_sp->SetBreakpointKind("next-branch-location");
378 
379         return true;
380       } else
381         return false;
382     }
383   }
384   return false;
385 }
386 
387 bool ThreadPlanStepRange::NextRangeBreakpointExplainsStop(
388     lldb::StopInfoSP stop_info_sp) {
389   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
390   if (!m_next_branch_bp_sp)
391     return false;
392 
393   break_id_t bp_site_id = stop_info_sp->GetValue();
394   BreakpointSiteSP bp_site_sp =
395       m_process.GetBreakpointSiteList().FindByID(bp_site_id);
396   if (!bp_site_sp)
397     return false;
398   else if (!bp_site_sp->IsBreakpointAtThisSite(m_next_branch_bp_sp->GetID()))
399     return false;
400   else {
401     // If we've hit the next branch breakpoint, then clear it.
402     size_t num_owners = bp_site_sp->GetNumberOfOwners();
403     bool explains_stop = true;
404     // If all the owners are internal, then we are probably just stepping over
405     // this range from multiple threads, or multiple frames, so we want to
406     // continue.  If one is not internal, then we should not explain the stop,
407     // and let the user breakpoint handle the stop.
408     for (size_t i = 0; i < num_owners; i++) {
409       if (!bp_site_sp->GetOwnerAtIndex(i)->GetBreakpoint().IsInternal()) {
410         explains_stop = false;
411         break;
412       }
413     }
414     LLDB_LOGF(log,
415               "ThreadPlanStepRange::NextRangeBreakpointExplainsStop - Hit "
416               "next range breakpoint which has %" PRIu64
417               " owners - explains stop: %u.",
418               (uint64_t)num_owners, explains_stop);
419     ClearNextBranchBreakpoint();
420     return explains_stop;
421   }
422 }
423 
424 bool ThreadPlanStepRange::WillStop() { return true; }
425 
426 StateType ThreadPlanStepRange::GetPlanRunState() {
427   if (m_next_branch_bp_sp)
428     return eStateRunning;
429   else
430     return eStateStepping;
431 }
432 
433 bool ThreadPlanStepRange::MischiefManaged() {
434   // If we have pushed some plans between ShouldStop & MischiefManaged, then
435   // we're not done...
436   // I do this check first because we might have stepped somewhere that will
437   // fool InRange into
438   // thinking it needs to step past the end of that line.  This happens, for
439   // instance, when stepping over inlined code that is in the middle of the
440   // current line.
441 
442   if (!m_no_more_plans)
443     return false;
444 
445   bool done = true;
446   if (!IsPlanComplete()) {
447     if (InRange()) {
448       done = false;
449     } else {
450       FrameComparison frame_order = CompareCurrentFrameToStartFrame();
451       done = (frame_order != eFrameCompareOlder) ? m_no_more_plans : true;
452     }
453   }
454 
455   if (done) {
456     Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
457     LLDB_LOGF(log, "Completed step through range plan.");
458     ClearNextBranchBreakpoint();
459     ThreadPlan::MischiefManaged();
460     return true;
461   } else {
462     return false;
463   }
464 }
465 
466 bool ThreadPlanStepRange::IsPlanStale() {
467   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
468   FrameComparison frame_order = CompareCurrentFrameToStartFrame();
469 
470   if (frame_order == eFrameCompareOlder) {
471     if (log) {
472       LLDB_LOGF(log, "ThreadPlanStepRange::IsPlanStale returning true, we've "
473                      "stepped out.");
474     }
475     return true;
476   } else if (frame_order == eFrameCompareEqual && InSymbol()) {
477     // If we are not in a place we should step through, we've gotten stale. One
478     // tricky bit here is that some stubs don't push a frame, so we should.
479     // check that we are in the same symbol.
480     if (!InRange()) {
481       // Set plan Complete when we reach next instruction just after the range
482       lldb::addr_t addr = GetThread().GetRegisterContext()->GetPC() - 1;
483       size_t num_ranges = m_address_ranges.size();
484       for (size_t i = 0; i < num_ranges; i++) {
485         bool in_range =
486             m_address_ranges[i].ContainsLoadAddress(addr, &GetTarget());
487         if (in_range) {
488           SetPlanComplete();
489         }
490       }
491       return true;
492     }
493   }
494   return false;
495 }
496