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