lldb/source/Target/ThreadPlanStepThrough.cpp

   1 //===-- ThreadPlanStepThrough.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/ThreadPlanStepThrough.h"
  10 #include "lldb/Breakpoint/Breakpoint.h"
  11 #include "lldb/Target/DynamicLoader.h"
  12 #include "lldb/Target/LanguageRuntime.h"
  13 #include "lldb/Target/Process.h"
  14 #include "lldb/Target/RegisterContext.h"
  15 #include "lldb/Target/Target.h"
  16 #include "lldb/Utility/LLDBLog.h"
  17 #include "lldb/Utility/Log.h"
  18 #include "lldb/Utility/Stream.h"
  19
  20 using namespace lldb;
  21 using namespace lldb_private;
  22
  23 // ThreadPlanStepThrough: If the current instruction is a trampoline, step
  24 // through it If it is the beginning of the prologue of a function, step
  25 // through that as well.
  26
  27 ThreadPlanStepThrough::ThreadPlanStepThrough(Thread &thread,
  28                                              StackID &m_stack_id,
  29                                              bool stop_others)
  30     : ThreadPlan(ThreadPlan::eKindStepThrough,
  31                  "Step through trampolines and prologues", thread,
  32                  eVoteNoOpinion, eVoteNoOpinion),
  33       m_start_address(0), m_backstop_bkpt_id(LLDB_INVALID_BREAK_ID),
  34       m_backstop_addr(LLDB_INVALID_ADDRESS), m_return_stack_id(m_stack_id),
  35       m_stop_others(stop_others) {
  36   LookForPlanToStepThroughFromCurrentPC();
  37
  38   // If we don't get a valid step through plan, don't bother to set up a
  39   // backstop.
  40   if (m_sub_plan_sp) {
  41     m_start_address = GetThread().GetRegisterContext()->GetPC(0);
  42
  43     // We are going to return back to the concrete frame 1, we might pass by
  44     // some inlined code that we're in the middle of by doing this, but it's
  45     // easier than trying to figure out where the inlined code might return to.
  46
  47     StackFrameSP return_frame_sp = thread.GetFrameWithStackID(m_stack_id);
  48
  49     if (return_frame_sp) {
  50       m_backstop_addr = return_frame_sp->GetFrameCodeAddress().GetLoadAddress(
  51           thread.CalculateTarget().get());
  52       Breakpoint *return_bp =
  53           m_process.GetTarget()
  54               .CreateBreakpoint(m_backstop_addr, true, false)
  55               .get();
  56
  57       if (return_bp != nullptr) {
  58         if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
  59           m_could_not_resolve_hw_bp = true;
  60         return_bp->SetThreadID(m_tid);
  61         m_backstop_bkpt_id = return_bp->GetID();
  62         return_bp->SetBreakpointKind("step-through-backstop");
  63       }
  64       Log *log = GetLog(LLDBLog::Step);
  65       if (log) {
  66         LLDB_LOGF(log, "Setting backstop breakpoint %d at address: 0x%" PRIx64,
  67                   m_backstop_bkpt_id, m_backstop_addr);
  68       }
  69     }
  70   }
  71 }
  72
  73 ThreadPlanStepThrough::~ThreadPlanStepThrough() { ClearBackstopBreakpoint(); }
  74
  75 void ThreadPlanStepThrough::DidPush() {
  76   if (m_sub_plan_sp)
  77     PushPlan(m_sub_plan_sp);
  78 }
  79
  80 void ThreadPlanStepThrough::LookForPlanToStepThroughFromCurrentPC() {
  81   Thread &thread = GetThread();
  82   DynamicLoader *loader = thread.GetProcess()->GetDynamicLoader();
  83   if (loader)
  84     m_sub_plan_sp = loader->GetStepThroughTrampolinePlan(thread, m_stop_others);
  85
  86   // If the DynamicLoader was unable to provide us with a ThreadPlan, then we
  87   // try the LanguageRuntimes.
  88   if (!m_sub_plan_sp) {
  89     for (LanguageRuntime *runtime : m_process.GetLanguageRuntimes()) {
  90       m_sub_plan_sp =
  91           runtime->GetStepThroughTrampolinePlan(thread, m_stop_others);
  92
  93       if (m_sub_plan_sp)
  94         break;
  95     }
  96   }
  97
  98   Log *log = GetLog(LLDBLog::Step);
  99   if (log) {
 100     lldb::addr_t current_address = GetThread().GetRegisterContext()->GetPC(0);
 101     if (m_sub_plan_sp) {
 102       StreamString s;
 103       m_sub_plan_sp->GetDescription(&s, lldb::eDescriptionLevelFull);
 104       LLDB_LOGF(log, "Found step through plan from 0x%" PRIx64 ": %s",
 105                 current_address, s.GetData());
 106     } else {
 107       LLDB_LOGF(log,
 108                 "Couldn't find step through plan from address 0x%" PRIx64 ".",
 109                 current_address);
 110     }
 111   }
 112 }
 113
 114 void ThreadPlanStepThrough::GetDescription(Stream *s,
 115                                            lldb::DescriptionLevel level) {
 116   if (level == lldb::eDescriptionLevelBrief)
 117     s->Printf("Step through");
 118   else {
 119     s->PutCString("Stepping through trampoline code from: ");
 120     DumpAddress(s->AsRawOstream(), m_start_address, sizeof(addr_t));
 121     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 122       s->Printf(" with backstop breakpoint ID: %d at address: ",
 123                 m_backstop_bkpt_id);
 124       DumpAddress(s->AsRawOstream(), m_backstop_addr, sizeof(addr_t));
 125     } else
 126       s->PutCString(" unable to set a backstop breakpoint.");
 127   }
 128 }
 129
 130 bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
 131   if (m_could_not_resolve_hw_bp) {
 132     if (error)
 133       error->PutCString(
 134           "Could not create hardware breakpoint for thread plan.");
 135     return false;
 136   }
 137
 138   if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
 139     if (error)
 140       error->PutCString("Could not create backstop breakpoint.");
 141     return false;
 142   }
 143
 144   if (!m_sub_plan_sp.get()) {
 145     if (error)
 146       error->PutCString("Does not have a subplan.");
 147     return false;
 148   }
 149
 150   return true;
 151 }
 152
 153 bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
 154   // If we have a sub-plan, it will have been asked first if we explain the
 155   // stop, and we won't get asked.  The only time we would be the one directly
 156   // asked this question is if we hit our backstop breakpoint.
 157
 158   return HitOurBackstopBreakpoint();
 159 }
 160
 161 bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
 162   // If we've already marked ourselves done, then we're done...
 163   if (IsPlanComplete())
 164     return true;
 165
 166   // First, did we hit the backstop breakpoint?
 167   if (HitOurBackstopBreakpoint()) {
 168     SetPlanComplete(true);
 169     return true;
 170   }
 171
 172   // If we don't have a sub-plan, then we're also done (can't see how we would
 173   // ever get here without a plan, but just in case.
 174
 175   if (!m_sub_plan_sp) {
 176     SetPlanComplete();
 177     return true;
 178   }
 179
 180   // If the current sub plan is not done, we don't want to stop.  Actually, we
 181   // probably won't ever get here in this state, since we generally won't get
 182   // asked any questions if out current sub-plan is not done...
 183   if (!m_sub_plan_sp->IsPlanComplete())
 184     return false;
 185
 186   // If our current sub plan failed, then let's just run to our backstop.  If
 187   // we can't do that then just stop.
 188   if (!m_sub_plan_sp->PlanSucceeded()) {
 189     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 190       m_sub_plan_sp.reset();
 191       return false;
 192     } else {
 193       SetPlanComplete(false);
 194       return true;
 195     }
 196   }
 197
 198   // Next see if there is a specific step through plan at our current pc (these
 199   // might chain, for instance stepping through a dylib trampoline to the objc
 200   // dispatch function...)
 201   LookForPlanToStepThroughFromCurrentPC();
 202   if (m_sub_plan_sp) {
 203     PushPlan(m_sub_plan_sp);
 204     return false;
 205   } else {
 206     SetPlanComplete();
 207     return true;
 208   }
 209 }
 210
 211 bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
 212
 213 StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
 214
 215 bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
 216                                          bool current_plan) {
 217   return true;
 218 }
 219
 220 bool ThreadPlanStepThrough::WillStop() { return true; }
 221
 222 void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
 223   if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 224     m_process.GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
 225     m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
 226     m_could_not_resolve_hw_bp = false;
 227   }
 228 }
 229
 230 bool ThreadPlanStepThrough::MischiefManaged() {
 231   Log *log = GetLog(LLDBLog::Step);
 232
 233   if (!IsPlanComplete()) {
 234     return false;
 235   } else {
 236     LLDB_LOGF(log, "Completed step through step plan.");
 237
 238     ClearBackstopBreakpoint();
 239     ThreadPlan::MischiefManaged();
 240     return true;
 241   }
 242 }
 243
 244 bool ThreadPlanStepThrough::HitOurBackstopBreakpoint() {
 245   Thread &thread = GetThread();
 246   StopInfoSP stop_info_sp(thread.GetStopInfo());
 247   if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
 248     break_id_t stop_value = (break_id_t)stop_info_sp->GetValue();
 249     BreakpointSiteSP cur_site_sp =
 250         m_process.GetBreakpointSiteList().FindByID(stop_value);
 251     if (cur_site_sp &&
 252         cur_site_sp->IsBreakpointAtThisSite(m_backstop_bkpt_id)) {
 253       StackID cur_frame_zero_id = thread.GetStackFrameAtIndex(0)->GetStackID();
 254
 255       if (cur_frame_zero_id == m_return_stack_id) {
 256         Log *log = GetLog(LLDBLog::Step);
 257         if (log)
 258           log->PutCString("ThreadPlanStepThrough hit backstop breakpoint.");
 259         return true;
 260       }
 261     }
 262   }
 263   return false;
 264 }