1 //===-- UnwindLLDB.cpp -------------------------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "lldb/Core/Module.h"
11 #include "lldb/Core/Log.h"
12 #include "lldb/Symbol/FuncUnwinders.h"
13 #include "lldb/Symbol/Function.h"
14 #include "lldb/Symbol/UnwindPlan.h"
15 #include "lldb/Target/ABI.h"
16 #include "lldb/Target/Thread.h"
17 #include "lldb/Target/Target.h"
18 #include "lldb/Target/Process.h"
19 #include "lldb/Target/RegisterContext.h"
21 #include "UnwindLLDB.h"
22 #include "RegisterContextLLDB.h"
25 using namespace lldb_private;
27 UnwindLLDB::UnwindLLDB (Thread &thread) :
30 m_unwind_complete(false),
31 m_user_supplied_trap_handler_functions()
33 ProcessSP process_sp(thread.GetProcess());
37 process_sp->GetTarget().GetUserSpecifiedTrapHandlerNames (args);
38 size_t count = args.GetArgumentCount();
39 for (size_t i = 0; i < count; i++)
41 const char *func_name = args.GetArgumentAtIndex(i);
42 m_user_supplied_trap_handler_functions.push_back (ConstString (func_name));
48 UnwindLLDB::DoGetFrameCount()
50 if (!m_unwind_complete)
52 //#define DEBUG_FRAME_SPEED 1
54 #define FRAME_COUNT 10000
55 TimeValue time_value (TimeValue::Now());
57 if (!AddFirstFrame ())
60 ProcessSP process_sp (m_thread.GetProcess());
61 ABI *abi = process_sp ? process_sp->GetABI().get() : NULL;
63 while (AddOneMoreFrame (abi))
66 if ((m_frames.size() % FRAME_COUNT) == 0)
68 TimeValue now(TimeValue::Now());
69 uint64_t delta_t = now - time_value;
70 printf ("%u frames in %" PRIu64 ".%09llu ms (%g frames/sec)\n",
72 delta_t / TimeValue::NanoSecPerSec,
73 delta_t % TimeValue::NanoSecPerSec,
74 (float)FRAME_COUNT / ((float)delta_t / (float)TimeValue::NanoSecPerSec));
80 return m_frames.size ();
84 UnwindLLDB::AddFirstFrame ()
86 if (m_frames.size() > 0)
89 ProcessSP process_sp (m_thread.GetProcess());
90 ABI *abi = process_sp ? process_sp->GetABI().get() : NULL;
92 // First, set up the 0th (initial) frame
93 CursorSP first_cursor_sp(new Cursor ());
94 RegisterContextLLDBSP reg_ctx_sp (new RegisterContextLLDB (m_thread,
95 RegisterContextLLDBSP(),
96 first_cursor_sp->sctx,
98 if (reg_ctx_sp.get() == NULL)
101 if (!reg_ctx_sp->IsValid())
104 if (!reg_ctx_sp->GetCFA (first_cursor_sp->cfa))
107 if (!reg_ctx_sp->ReadPC (first_cursor_sp->start_pc))
110 // Everything checks out, so release the auto pointer value and let the
111 // cursor own it in its shared pointer
112 first_cursor_sp->reg_ctx_lldb_sp = reg_ctx_sp;
113 m_frames.push_back (first_cursor_sp);
115 // Update the Full Unwind Plan for this frame if not valid
116 UpdateUnwindPlanForFirstFrameIfInvalid(abi);
121 Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
124 log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
126 m_unwind_complete = true;
131 UnwindLLDB::GetOneMoreFrame (ABI* abi)
133 assert (m_frames.size() != 0 && "Get one more frame called with empty frame list");
135 // If we've already gotten to the end of the stack, don't bother to try again...
136 if (m_unwind_complete)
139 Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
141 CursorSP prev_frame = m_frames.back();
142 uint32_t cur_idx = m_frames.size();
144 CursorSP cursor_sp(new Cursor ());
145 RegisterContextLLDBSP reg_ctx_sp(new RegisterContextLLDB (m_thread,
146 prev_frame->reg_ctx_lldb_sp,
151 // We want to detect an unwind that cycles erroneously and stop backtracing.
152 // Don't want this maximum unwind limit to be too low -- if you have a backtrace
153 // with an "infinitely recursing" bug, it will crash when the stack blows out
154 // and the first 35,000 frames are uninteresting - it's the top most 5 frames that
155 // you actually care about. So you can't just cap the unwind at 10,000 or something.
156 // Realistically anything over around 200,000 is going to blow out the stack space.
157 // If we're still unwinding at that point, we're probably never going to finish.
158 if (cur_idx > 300000)
161 log->Printf ("%*sFrame %d unwound too many frames, assuming unwind has gone astray, stopping.",
162 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
166 if (reg_ctx_sp.get() == NULL)
168 // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
169 // true. Subsequent calls to TryFallbackUnwindPlan() will return false.
170 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
172 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
173 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
174 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
177 return GetOneMoreFrame (abi);
181 log->Printf ("%*sFrame %d did not get a RegisterContext, stopping.",
182 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
186 if (!reg_ctx_sp->IsValid())
188 // We failed to get a valid RegisterContext.
189 // See if the regctx below this on the stack has a fallback unwind plan it can use.
190 // Subsequent calls to TryFallbackUnwindPlan() will return false.
191 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
193 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
194 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
195 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
198 return GetOneMoreFrame (abi);
202 log->Printf("%*sFrame %d invalid RegisterContext for this frame, stopping stack walk",
203 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
206 if (!reg_ctx_sp->GetCFA (cursor_sp->cfa))
208 // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
209 // true. Subsequent calls to TryFallbackUnwindPlan() will return false.
210 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
212 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
213 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
214 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
217 return GetOneMoreFrame (abi);
221 log->Printf("%*sFrame %d did not get CFA for this frame, stopping stack walk",
222 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
225 if (abi && !abi->CallFrameAddressIsValid(cursor_sp->cfa))
227 // On Mac OS X, the _sigtramp asynchronous signal trampoline frame may not have
228 // its (constructed) CFA aligned correctly -- don't do the abi alignment check for
230 if (reg_ctx_sp->IsTrapHandlerFrame() == false)
232 // See if we can find a fallback unwind plan for THIS frame. It may be
233 // that the UnwindPlan we're using for THIS frame was bad and gave us a
235 // If that's not it, then see if we can change the UnwindPlan for the frame
236 // below us ("NEXT") -- see if using that other UnwindPlan gets us a better
238 if (reg_ctx_sp->TryFallbackUnwindPlan() == false
239 || reg_ctx_sp->GetCFA (cursor_sp->cfa) == false
240 || abi->CallFrameAddressIsValid(cursor_sp->cfa) == false)
242 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
244 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
245 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
246 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
249 return GetOneMoreFrame (abi);
253 log->Printf("%*sFrame %d did not get a valid CFA for this frame, stopping stack walk",
254 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
260 log->Printf("%*sFrame %d had a bad CFA value but we switched the UnwindPlan being used and got one that looks more realistic.",
261 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
265 if (!reg_ctx_sp->ReadPC (cursor_sp->start_pc))
267 // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
268 // true. Subsequent calls to TryFallbackUnwindPlan() will return false.
269 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
271 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
272 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
273 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
276 return GetOneMoreFrame (abi);
280 log->Printf("%*sFrame %d did not get PC for this frame, stopping stack walk",
281 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
284 if (abi && !abi->CodeAddressIsValid (cursor_sp->start_pc))
286 // If the RegisterContextLLDB has a fallback UnwindPlan, it will switch to that and return
287 // true. Subsequent calls to TryFallbackUnwindPlan() will return false.
288 if (prev_frame->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
290 // TryFallbackUnwindPlan for prev_frame succeeded and updated reg_ctx_lldb_sp field of
291 // prev_frame. However, cfa field of prev_frame still needs to be updated. Hence updating it.
292 if ( !(prev_frame->reg_ctx_lldb_sp->GetCFA(prev_frame->cfa)))
295 return GetOneMoreFrame (abi);
299 log->Printf("%*sFrame %d did not get a valid PC, stopping stack walk",
300 cur_idx < 100 ? cur_idx : 100, "", cur_idx);
303 // Infinite loop where the current cursor is the same as the previous one...
304 if (prev_frame->start_pc == cursor_sp->start_pc && prev_frame->cfa == cursor_sp->cfa)
307 log->Printf ("th%d pc of this frame is the same as the previous frame and CFAs for both frames are identical -- stopping unwind", m_thread.GetIndexID());
311 cursor_sp->reg_ctx_lldb_sp = reg_ctx_sp;
316 UnwindLLDB::UpdateUnwindPlanForFirstFrameIfInvalid (ABI *abi)
318 // This function is called for First Frame only.
319 assert (m_frames.size() == 1 && "No. of cursor frames are not 1");
321 bool old_m_unwind_complete = m_unwind_complete;
322 CursorSP old_m_candidate_frame = m_candidate_frame;
324 // Try to unwind 2 more frames using the Unwinder. It uses Full UnwindPlan
325 // and if Full UnwindPlan fails, then uses FallBack UnwindPlan. Also
326 // update the cfa of Frame 0 (if required).
327 AddOneMoreFrame(abi);
329 // Remove all the frames added by above function as the purpose of
330 // using above function was just to check whether Unwinder of Frame 0
332 for(uint32_t i=1; i<m_frames.size(); i++)
335 // Restore status after calling AddOneMoreFrame
336 m_unwind_complete = old_m_unwind_complete;
337 m_candidate_frame = old_m_candidate_frame;
343 UnwindLLDB::AddOneMoreFrame (ABI *abi)
345 Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_UNWIND));
347 // Frame zero is a little different
348 if (m_frames.empty())
351 // If we've already gotten to the end of the stack, don't bother to try again...
352 if (m_unwind_complete)
355 CursorSP new_frame = m_candidate_frame;
356 if (new_frame == nullptr)
357 new_frame = GetOneMoreFrame(abi);
359 if (new_frame == nullptr)
362 log->Printf ("th%d Unwind of this thread is complete.", m_thread.GetIndexID());
363 m_unwind_complete = true;
367 m_frames.push_back(new_frame);
369 // If we can get one more frame further then accept that we get back a correct frame.
370 m_candidate_frame = GetOneMoreFrame(abi);
371 if (m_candidate_frame)
374 // We can't go further from the frame returned by GetOneMore frame. Lets try to get a
375 // different frame with using the fallback unwind plan.
376 if (!m_frames[m_frames.size() - 2]->reg_ctx_lldb_sp->TryFallbackUnwindPlan())
378 // We don't have a valid fallback unwind plan. Accept the frame as it is. This is a
379 // valid situation when we are at the bottom of the stack.
383 // Remove the possibly incorrect frame from the frame list and try to add a different one with
384 // the newly selected fallback unwind plan.
386 CursorSP new_frame_v2 = GetOneMoreFrame(abi);
387 if (new_frame_v2 == nullptr)
389 // We haven't got a new frame from the fallback unwind plan. Accept the frame from the
390 // original unwind plan. This is a valid situation when we are at the bottom of the stack.
391 m_frames.push_back(new_frame);
395 // Push the new frame to the list and try to continue from this frame. If we can get a new frame
396 // then accept it as the correct one.
397 m_frames.push_back(new_frame_v2);
398 m_candidate_frame = GetOneMoreFrame(abi);
399 if (m_candidate_frame)
401 // If control reached here then TryFallbackUnwindPlan had succeeded for Cursor::m_frames[m_frames.size() - 2].
402 // It also succeeded to Unwind next 2 frames i.e. m_frames[m_frames.size() - 1] and a frame after that.
403 // For Cursor::m_frames[m_frames.size() - 2], reg_ctx_lldb_sp field was already updated during TryFallbackUnwindPlan
404 // call above. However, cfa field still needs to be updated. Hence updating it here and then returning.
405 if ( !(m_frames[m_frames.size() - 2]->reg_ctx_lldb_sp->GetCFA(m_frames[m_frames.size() - 2]->cfa)))
410 // The new frame hasn't helped in unwinding. Fall back to the original one as the default unwind
411 // plan is usually more reliable then the fallback one.
413 m_frames.push_back(new_frame);
418 UnwindLLDB::DoGetFrameInfoAtIndex (uint32_t idx, addr_t& cfa, addr_t& pc)
420 if (m_frames.size() == 0)
422 if (!AddFirstFrame())
426 ProcessSP process_sp (m_thread.GetProcess());
427 ABI *abi = process_sp ? process_sp->GetABI().get() : NULL;
429 while (idx >= m_frames.size() && AddOneMoreFrame (abi))
432 if (idx < m_frames.size ())
434 cfa = m_frames[idx]->cfa;
435 pc = m_frames[idx]->start_pc;
441 lldb::RegisterContextSP
442 UnwindLLDB::DoCreateRegisterContextForFrame (StackFrame *frame)
444 lldb::RegisterContextSP reg_ctx_sp;
445 uint32_t idx = frame->GetConcreteFrameIndex ();
449 return m_thread.GetRegisterContext();
452 if (m_frames.size() == 0)
454 if (!AddFirstFrame())
458 ProcessSP process_sp (m_thread.GetProcess());
459 ABI *abi = process_sp ? process_sp->GetABI().get() : NULL;
461 while (idx >= m_frames.size())
463 if (!AddOneMoreFrame (abi))
467 const uint32_t num_frames = m_frames.size();
468 if (idx < num_frames)
470 Cursor *frame_cursor = m_frames[idx].get();
471 reg_ctx_sp = frame_cursor->reg_ctx_lldb_sp;
476 UnwindLLDB::RegisterContextLLDBSP
477 UnwindLLDB::GetRegisterContextForFrameNum (uint32_t frame_num)
479 RegisterContextLLDBSP reg_ctx_sp;
480 if (frame_num < m_frames.size())
481 reg_ctx_sp = m_frames[frame_num]->reg_ctx_lldb_sp;
486 UnwindLLDB::SearchForSavedLocationForRegister (uint32_t lldb_regnum, lldb_private::UnwindLLDB::RegisterLocation ®loc, uint32_t starting_frame_num, bool pc_reg)
488 int64_t frame_num = starting_frame_num;
489 if (static_cast<size_t>(frame_num) >= m_frames.size())
492 // Never interrogate more than one level while looking for the saved pc value. If the value
493 // isn't saved by frame_num, none of the frames lower on the stack will have a useful value.
496 UnwindLLDB::RegisterSearchResult result;
497 result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
498 if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound)
503 while (frame_num >= 0)
505 UnwindLLDB::RegisterSearchResult result;
506 result = m_frames[frame_num]->reg_ctx_lldb_sp->SavedLocationForRegister (lldb_regnum, regloc);
508 // We descended down to the live register context aka stack frame 0 and are reading the value
509 // out of a live register.
510 if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound
511 && regloc.type == UnwindLLDB::RegisterLocation::eRegisterInLiveRegisterContext)
516 // If we have unwind instructions saying that register N is saved in register M in the middle of
517 // the stack (and N can equal M here, meaning the register was not used in this function), then
518 // change the register number we're looking for to M and keep looking for a concrete location
519 // down the stack, or an actual value from a live RegisterContext at frame 0.
520 if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound
521 && regloc.type == UnwindLLDB::RegisterLocation::eRegisterInRegister
524 result = UnwindLLDB::RegisterSearchResult::eRegisterNotFound;
525 lldb_regnum = regloc.location.register_number;
528 if (result == UnwindLLDB::RegisterSearchResult::eRegisterFound)
530 if (result == UnwindLLDB::RegisterSearchResult::eRegisterIsVolatile)