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/LLDBLog.h" 25 #include "lldb/Utility/Log.h" 26 27 #include <memory> 28 29 using namespace lldb; 30 using namespace lldb_private; 31 32 uint32_t ThreadPlanStepOut::s_default_flag_values = 0; 33 34 // ThreadPlanStepOut: Step out of the current frame 35 ThreadPlanStepOut::ThreadPlanStepOut( 36 Thread &thread, SymbolContext *context, bool first_insn, bool stop_others, 37 Vote report_stop_vote, Vote report_run_vote, uint32_t frame_idx, 38 LazyBool step_out_avoids_code_without_debug_info, 39 bool continue_to_next_branch, bool gather_return_value) 40 : ThreadPlan(ThreadPlan::eKindStepOut, "Step out", thread, report_stop_vote, 41 report_run_vote), 42 ThreadPlanShouldStopHere(this), m_step_from_insn(LLDB_INVALID_ADDRESS), 43 m_return_bp_id(LLDB_INVALID_BREAK_ID), 44 m_return_addr(LLDB_INVALID_ADDRESS), m_stop_others(stop_others), 45 m_immediate_step_from_function(nullptr), 46 m_calculate_return_value(gather_return_value) { 47 Log *log = GetLog(LLDBLog::Step); 48 SetFlagsToDefault(); 49 SetupAvoidNoDebug(step_out_avoids_code_without_debug_info); 50 51 m_step_from_insn = thread.GetRegisterContext()->GetPC(0); 52 53 uint32_t return_frame_index = frame_idx + 1; 54 StackFrameSP return_frame_sp(thread.GetStackFrameAtIndex(return_frame_index)); 55 StackFrameSP immediate_return_from_sp(thread.GetStackFrameAtIndex(frame_idx)); 56 57 if (!return_frame_sp || !immediate_return_from_sp) 58 return; // we can't do anything here. ValidatePlan() will return false. 59 60 // While stepping out, behave as-if artificial frames are not present. 61 while (return_frame_sp->IsArtificial()) { 62 m_stepped_past_frames.push_back(return_frame_sp); 63 64 ++return_frame_index; 65 return_frame_sp = thread.GetStackFrameAtIndex(return_frame_index); 66 67 // We never expect to see an artificial frame without a regular ancestor. 68 // If this happens, log the issue and defensively refuse to step out. 69 if (!return_frame_sp) { 70 LLDB_LOG(log, "Can't step out of frame with artificial ancestors"); 71 return; 72 } 73 } 74 75 m_step_out_to_id = return_frame_sp->GetStackID(); 76 m_immediate_step_from_id = immediate_return_from_sp->GetStackID(); 77 78 // If the frame directly below the one we are returning to is inlined, we 79 // have to be a little more careful. It is non-trivial to determine the real 80 // "return code address" for an inlined frame, so we have to work our way to 81 // that frame and then step out. 82 if (immediate_return_from_sp->IsInlined()) { 83 if (frame_idx > 0) { 84 // First queue a plan that gets us to this inlined frame, and when we get 85 // there we'll queue a second plan that walks us out of this frame. 86 m_step_out_to_inline_plan_sp = std::make_shared<ThreadPlanStepOut>( 87 thread, nullptr, false, stop_others, eVoteNoOpinion, eVoteNoOpinion, 88 frame_idx - 1, eLazyBoolNo, continue_to_next_branch); 89 static_cast<ThreadPlanStepOut *>(m_step_out_to_inline_plan_sp.get()) 90 ->SetShouldStopHereCallbacks(nullptr, nullptr); 91 m_step_out_to_inline_plan_sp->SetPrivate(true); 92 } else { 93 // If we're already at the inlined frame we're stepping through, then 94 // just do that now. 95 QueueInlinedStepPlan(false); 96 } 97 } else { 98 // Find the return address and set a breakpoint there: 99 // FIXME - can we do this more securely if we know first_insn? 100 101 Address return_address(return_frame_sp->GetFrameCodeAddress()); 102 if (continue_to_next_branch) { 103 SymbolContext return_address_sc; 104 AddressRange range; 105 Address return_address_decr_pc = return_address; 106 if (return_address_decr_pc.GetOffset() > 0) 107 return_address_decr_pc.Slide(-1); 108 109 return_address_decr_pc.CalculateSymbolContext( 110 &return_address_sc, lldb::eSymbolContextLineEntry); 111 if (return_address_sc.line_entry.IsValid()) { 112 const bool include_inlined_functions = false; 113 range = return_address_sc.line_entry.GetSameLineContiguousAddressRange( 114 include_inlined_functions); 115 if (range.GetByteSize() > 0) { 116 return_address = m_process.AdvanceAddressToNextBranchInstruction( 117 return_address, range); 118 } 119 } 120 } 121 m_return_addr = return_address.GetLoadAddress(&m_process.GetTarget()); 122 123 if (m_return_addr == LLDB_INVALID_ADDRESS) 124 return; 125 126 // Perform some additional validation on the return address. 127 uint32_t permissions = 0; 128 if (!m_process.GetLoadAddressPermissions(m_return_addr, permissions)) { 129 LLDB_LOGF(log, "ThreadPlanStepOut(%p): Return address (0x%" PRIx64 130 ") permissions not found.", static_cast<void *>(this), 131 m_return_addr); 132 } else if (!(permissions & ePermissionsExecutable)) { 133 m_constructor_errors.Printf("Return address (0x%" PRIx64 134 ") did not point to executable memory.", 135 m_return_addr); 136 LLDB_LOGF(log, "ThreadPlanStepOut(%p): %s", static_cast<void *>(this), 137 m_constructor_errors.GetData()); 138 return; 139 } 140 141 Breakpoint *return_bp = 142 GetTarget().CreateBreakpoint(m_return_addr, true, false).get(); 143 144 if (return_bp != nullptr) { 145 if (return_bp->IsHardware() && !return_bp->HasResolvedLocations()) 146 m_could_not_resolve_hw_bp = true; 147 return_bp->SetThreadID(m_tid); 148 m_return_bp_id = return_bp->GetID(); 149 return_bp->SetBreakpointKind("step-out"); 150 } 151 152 if (immediate_return_from_sp) { 153 const SymbolContext &sc = 154 immediate_return_from_sp->GetSymbolContext(eSymbolContextFunction); 155 if (sc.function) { 156 m_immediate_step_from_function = sc.function; 157 } 158 } 159 } 160 } 161 162 void ThreadPlanStepOut::SetupAvoidNoDebug( 163 LazyBool step_out_avoids_code_without_debug_info) { 164 bool avoid_nodebug = true; 165 switch (step_out_avoids_code_without_debug_info) { 166 case eLazyBoolYes: 167 avoid_nodebug = true; 168 break; 169 case eLazyBoolNo: 170 avoid_nodebug = false; 171 break; 172 case eLazyBoolCalculate: 173 avoid_nodebug = GetThread().GetStepOutAvoidsNoDebug(); 174 break; 175 } 176 if (avoid_nodebug) 177 GetFlags().Set(ThreadPlanShouldStopHere::eStepOutAvoidNoDebug); 178 else 179 GetFlags().Clear(ThreadPlanShouldStopHere::eStepOutAvoidNoDebug); 180 } 181 182 void ThreadPlanStepOut::DidPush() { 183 Thread &thread = GetThread(); 184 if (m_step_out_to_inline_plan_sp) 185 thread.QueueThreadPlan(m_step_out_to_inline_plan_sp, false); 186 else if (m_step_through_inline_plan_sp) 187 thread.QueueThreadPlan(m_step_through_inline_plan_sp, false); 188 } 189 190 ThreadPlanStepOut::~ThreadPlanStepOut() { 191 if (m_return_bp_id != LLDB_INVALID_BREAK_ID) 192 GetTarget().RemoveBreakpointByID(m_return_bp_id); 193 } 194 195 void ThreadPlanStepOut::GetDescription(Stream *s, 196 lldb::DescriptionLevel level) { 197 if (level == lldb::eDescriptionLevelBrief) 198 s->Printf("step out"); 199 else { 200 if (m_step_out_to_inline_plan_sp) 201 s->Printf("Stepping out to inlined frame so we can walk through it."); 202 else if (m_step_through_inline_plan_sp) 203 s->Printf("Stepping out by stepping through inlined function."); 204 else { 205 s->Printf("Stepping out from "); 206 Address tmp_address; 207 if (tmp_address.SetLoadAddress(m_step_from_insn, &GetTarget())) { 208 tmp_address.Dump(s, &m_process, Address::DumpStyleResolvedDescription, 209 Address::DumpStyleLoadAddress); 210 } else { 211 s->Printf("address 0x%" PRIx64 "", (uint64_t)m_step_from_insn); 212 } 213 214 // FIXME: find some useful way to present the m_return_id, since there may 215 // be multiple copies of the 216 // same function on the stack. 217 218 s->Printf(" returning to frame at "); 219 if (tmp_address.SetLoadAddress(m_return_addr, &GetTarget())) { 220 tmp_address.Dump(s, &m_process, Address::DumpStyleResolvedDescription, 221 Address::DumpStyleLoadAddress); 222 } else { 223 s->Printf("address 0x%" PRIx64 "", (uint64_t)m_return_addr); 224 } 225 226 if (level == eDescriptionLevelVerbose) 227 s->Printf(" using breakpoint site %d", m_return_bp_id); 228 } 229 } 230 231 if (m_stepped_past_frames.empty()) 232 return; 233 234 s->Printf("\n"); 235 for (StackFrameSP frame_sp : m_stepped_past_frames) { 236 s->Printf("Stepped out past: "); 237 frame_sp->DumpUsingSettingsFormat(s); 238 } 239 } 240 241 bool ThreadPlanStepOut::ValidatePlan(Stream *error) { 242 if (m_step_out_to_inline_plan_sp) 243 return m_step_out_to_inline_plan_sp->ValidatePlan(error); 244 245 if (m_step_through_inline_plan_sp) 246 return m_step_through_inline_plan_sp->ValidatePlan(error); 247 248 if (m_could_not_resolve_hw_bp) { 249 if (error) 250 error->PutCString( 251 "Could not create hardware breakpoint for thread plan."); 252 return false; 253 } 254 255 if (m_return_bp_id == LLDB_INVALID_BREAK_ID) { 256 if (error) { 257 error->PutCString("Could not create return address breakpoint."); 258 if (m_constructor_errors.GetSize() > 0) { 259 error->PutCString(" "); 260 error->PutCString(m_constructor_errors.GetString()); 261 } 262 } 263 return false; 264 } 265 266 return true; 267 } 268 269 bool ThreadPlanStepOut::DoPlanExplainsStop(Event *event_ptr) { 270 // If the step out plan is done, then we just need to step through the 271 // inlined frame. 272 if (m_step_out_to_inline_plan_sp) { 273 return m_step_out_to_inline_plan_sp->MischiefManaged(); 274 } else if (m_step_through_inline_plan_sp) { 275 if (m_step_through_inline_plan_sp->MischiefManaged()) { 276 CalculateReturnValue(); 277 SetPlanComplete(); 278 return true; 279 } else 280 return false; 281 } else if (m_step_out_further_plan_sp) { 282 return m_step_out_further_plan_sp->MischiefManaged(); 283 } 284 285 // We don't explain signals or breakpoints (breakpoints that handle stepping 286 // in or out will be handled by a child plan. 287 288 StopInfoSP stop_info_sp = GetPrivateStopInfo(); 289 if (stop_info_sp) { 290 StopReason reason = stop_info_sp->GetStopReason(); 291 if (reason == eStopReasonBreakpoint) { 292 // If this is OUR breakpoint, we're fine, otherwise we don't know why 293 // this happened... 294 BreakpointSiteSP site_sp( 295 m_process.GetBreakpointSiteList().FindByID(stop_info_sp->GetValue())); 296 if (site_sp && site_sp->IsBreakpointAtThisSite(m_return_bp_id)) { 297 bool done; 298 299 StackID frame_zero_id = 300 GetThread().GetStackFrameAtIndex(0)->GetStackID(); 301 302 if (m_step_out_to_id == frame_zero_id) 303 done = true; 304 else if (m_step_out_to_id < frame_zero_id) { 305 // Either we stepped past the breakpoint, or the stack ID calculation 306 // was incorrect and we should probably stop. 307 done = true; 308 } else { 309 done = (m_immediate_step_from_id < frame_zero_id); 310 } 311 312 if (done) { 313 if (InvokeShouldStopHereCallback(eFrameCompareOlder, m_status)) { 314 CalculateReturnValue(); 315 SetPlanComplete(); 316 } 317 } 318 319 // If there was only one owner, then we're done. But if we also hit 320 // some user breakpoint on our way out, we should mark ourselves as 321 // done, but also not claim to explain the stop, since it is more 322 // important to report the user breakpoint than the step out 323 // completion. 324 325 if (site_sp->GetNumberOfConstituents() == 1) 326 return true; 327 } 328 return false; 329 } else if (IsUsuallyUnexplainedStopReason(reason)) 330 return false; 331 else 332 return true; 333 } 334 return true; 335 } 336 337 bool ThreadPlanStepOut::ShouldStop(Event *event_ptr) { 338 if (IsPlanComplete()) 339 return true; 340 341 bool done = false; 342 if (m_step_out_to_inline_plan_sp) { 343 if (m_step_out_to_inline_plan_sp->MischiefManaged()) { 344 // Now step through the inlined stack we are in: 345 if (QueueInlinedStepPlan(true)) { 346 // If we can't queue a plan to do this, then just call ourselves done. 347 m_step_out_to_inline_plan_sp.reset(); 348 SetPlanComplete(false); 349 return true; 350 } else 351 done = true; 352 } else 353 return m_step_out_to_inline_plan_sp->ShouldStop(event_ptr); 354 } else if (m_step_through_inline_plan_sp) { 355 if (m_step_through_inline_plan_sp->MischiefManaged()) 356 done = true; 357 else 358 return m_step_through_inline_plan_sp->ShouldStop(event_ptr); 359 } else if (m_step_out_further_plan_sp) { 360 if (m_step_out_further_plan_sp->MischiefManaged()) 361 m_step_out_further_plan_sp.reset(); 362 else 363 return m_step_out_further_plan_sp->ShouldStop(event_ptr); 364 } 365 366 if (!done) { 367 StackID frame_zero_id = GetThread().GetStackFrameAtIndex(0)->GetStackID(); 368 done = !(frame_zero_id < m_step_out_to_id); 369 } 370 371 // The normal step out computations think we are done, so all we need to do 372 // is consult the ShouldStopHere, and we are done. 373 374 if (done) { 375 if (InvokeShouldStopHereCallback(eFrameCompareOlder, m_status)) { 376 CalculateReturnValue(); 377 SetPlanComplete(); 378 } else { 379 m_step_out_further_plan_sp = 380 QueueStepOutFromHerePlan(m_flags, eFrameCompareOlder, m_status); 381 done = false; 382 } 383 } 384 385 return done; 386 } 387 388 bool ThreadPlanStepOut::StopOthers() { return m_stop_others; } 389 390 StateType ThreadPlanStepOut::GetPlanRunState() { return eStateRunning; } 391 392 bool ThreadPlanStepOut::DoWillResume(StateType resume_state, 393 bool current_plan) { 394 if (m_step_out_to_inline_plan_sp || m_step_through_inline_plan_sp) 395 return true; 396 397 if (m_return_bp_id == LLDB_INVALID_BREAK_ID) 398 return false; 399 400 if (current_plan) { 401 Breakpoint *return_bp = GetTarget().GetBreakpointByID(m_return_bp_id).get(); 402 if (return_bp != nullptr) 403 return_bp->SetEnabled(true); 404 } 405 return true; 406 } 407 408 bool ThreadPlanStepOut::WillStop() { 409 if (m_return_bp_id != LLDB_INVALID_BREAK_ID) { 410 Breakpoint *return_bp = GetTarget().GetBreakpointByID(m_return_bp_id).get(); 411 if (return_bp != nullptr) 412 return_bp->SetEnabled(false); 413 } 414 415 return true; 416 } 417 418 bool ThreadPlanStepOut::MischiefManaged() { 419 if (IsPlanComplete()) { 420 // Did I reach my breakpoint? If so I'm done. 421 // 422 // I also check the stack depth, since if we've blown past the breakpoint 423 // for some 424 // reason and we're now stopping for some other reason altogether, then 425 // we're done with this step out operation. 426 427 Log *log = GetLog(LLDBLog::Step); 428 if (log) 429 LLDB_LOGF(log, "Completed step out plan."); 430 if (m_return_bp_id != LLDB_INVALID_BREAK_ID) { 431 GetTarget().RemoveBreakpointByID(m_return_bp_id); 432 m_return_bp_id = LLDB_INVALID_BREAK_ID; 433 } 434 435 ThreadPlan::MischiefManaged(); 436 return true; 437 } else { 438 return false; 439 } 440 } 441 442 bool ThreadPlanStepOut::QueueInlinedStepPlan(bool queue_now) { 443 // Now figure out the range of this inlined block, and set up a "step through 444 // range" plan for that. If we've been provided with a context, then use the 445 // block in that context. 446 Thread &thread = GetThread(); 447 StackFrameSP immediate_return_from_sp(thread.GetStackFrameAtIndex(0)); 448 if (!immediate_return_from_sp) 449 return false; 450 451 Log *log = GetLog(LLDBLog::Step); 452 if (log) { 453 StreamString s; 454 immediate_return_from_sp->Dump(&s, true, false); 455 LLDB_LOGF(log, "Queuing inlined frame to step past: %s.", s.GetData()); 456 } 457 458 Block *from_block = immediate_return_from_sp->GetFrameBlock(); 459 if (from_block) { 460 Block *inlined_block = from_block->GetContainingInlinedBlock(); 461 if (inlined_block) { 462 size_t num_ranges = inlined_block->GetNumRanges(); 463 AddressRange inline_range; 464 if (inlined_block->GetRangeAtIndex(0, inline_range)) { 465 SymbolContext inlined_sc; 466 inlined_block->CalculateSymbolContext(&inlined_sc); 467 inlined_sc.target_sp = GetTarget().shared_from_this(); 468 RunMode run_mode = 469 m_stop_others ? lldb::eOnlyThisThread : lldb::eAllThreads; 470 const LazyBool avoid_no_debug = eLazyBoolNo; 471 472 m_step_through_inline_plan_sp = 473 std::make_shared<ThreadPlanStepOverRange>( 474 thread, inline_range, inlined_sc, run_mode, avoid_no_debug); 475 ThreadPlanStepOverRange *step_through_inline_plan_ptr = 476 static_cast<ThreadPlanStepOverRange *>( 477 m_step_through_inline_plan_sp.get()); 478 m_step_through_inline_plan_sp->SetPrivate(true); 479 480 step_through_inline_plan_ptr->SetOkayToDiscard(true); 481 StreamString errors; 482 if (!step_through_inline_plan_ptr->ValidatePlan(&errors)) { 483 // FIXME: Log this failure. 484 delete step_through_inline_plan_ptr; 485 return false; 486 } 487 488 for (size_t i = 1; i < num_ranges; i++) { 489 if (inlined_block->GetRangeAtIndex(i, inline_range)) 490 step_through_inline_plan_ptr->AddRange(inline_range); 491 } 492 493 if (queue_now) 494 thread.QueueThreadPlan(m_step_through_inline_plan_sp, false); 495 return true; 496 } 497 } 498 } 499 500 return false; 501 } 502 503 void ThreadPlanStepOut::CalculateReturnValue() { 504 if (m_return_valobj_sp) 505 return; 506 507 if (!m_calculate_return_value) 508 return; 509 510 if (m_immediate_step_from_function != nullptr) { 511 CompilerType return_compiler_type = 512 m_immediate_step_from_function->GetCompilerType() 513 .GetFunctionReturnType(); 514 if (return_compiler_type) { 515 lldb::ABISP abi_sp = m_process.GetABI(); 516 if (abi_sp) 517 m_return_valobj_sp = 518 abi_sp->GetReturnValueObject(GetThread(), return_compiler_type); 519 } 520 } 521 } 522 523 bool ThreadPlanStepOut::IsPlanStale() { 524 // If we are still lower on the stack than the frame we are returning to, 525 // then there's something for us to do. Otherwise, we're stale. 526 527 StackID frame_zero_id = GetThread().GetStackFrameAtIndex(0)->GetStackID(); 528 return !(frame_zero_id < m_step_out_to_id); 529 } 530