contrib/llvm-project/lldb/source/Target/ThreadPlanStepThrough.cpp

   1 //===-- ThreadPlanStepThrough.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/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/Log.h"
  17 #include "lldb/Utility/Stream.h"
  18
  19 using namespace lldb;
  20 using namespace lldb_private;
  21
  22 // ThreadPlanStepThrough: If the current instruction is a trampoline, step
  23 // through it If it is the beginning of the prologue of a function, step
  24 // through that as well.
  25 // FIXME: At present only handles DYLD trampolines.
  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 = m_thread.GetFrameWithStackID(m_stack_id);
  48
  49     if (return_frame_sp) {
  50       m_backstop_addr = return_frame_sp->GetFrameCodeAddress().GetLoadAddress(
  51           m_thread.CalculateTarget().get());
  52       Breakpoint *return_bp =
  53           m_thread.GetProcess()
  54               ->GetTarget()
  55               .CreateBreakpoint(m_backstop_addr, true, false)
  56               .get();
  57
  58       if (return_bp != nullptr) {
  59         if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
  60           m_could_not_resolve_hw_bp = true;
  61         return_bp->SetThreadID(m_thread.GetID());
  62         m_backstop_bkpt_id = return_bp->GetID();
  63         return_bp->SetBreakpointKind("step-through-backstop");
  64       }
  65       Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
  66       if (log) {
  67         log->Printf("Setting backstop breakpoint %d at address: 0x%" PRIx64,
  68                     m_backstop_bkpt_id, m_backstop_addr);
  69       }
  70     }
  71   }
  72 }
  73
  74 ThreadPlanStepThrough::~ThreadPlanStepThrough() { ClearBackstopBreakpoint(); }
  75
  76 void ThreadPlanStepThrough::DidPush() {
  77   if (m_sub_plan_sp)
  78     PushPlan(m_sub_plan_sp);
  79 }
  80
  81 void ThreadPlanStepThrough::LookForPlanToStepThroughFromCurrentPC() {
  82   DynamicLoader *loader = m_thread.GetProcess()->GetDynamicLoader();
  83   if (loader)
  84     m_sub_plan_sp =
  85         loader->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
  86
  87   // If the DynamicLoader was unable to provide us with a ThreadPlan, then we
  88   // try the LanguageRuntimes.
  89   if (!m_sub_plan_sp) {
  90     for (LanguageRuntime *runtime :
  91          m_thread.GetProcess()->GetLanguageRuntimes()) {
  92       m_sub_plan_sp =
  93           runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
  94
  95       if (m_sub_plan_sp)
  96         break;
  97     }
  98   }
  99
 100   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 101   if (log) {
 102     lldb::addr_t current_address = GetThread().GetRegisterContext()->GetPC(0);
 103     if (m_sub_plan_sp) {
 104       StreamString s;
 105       m_sub_plan_sp->GetDescription(&s, lldb::eDescriptionLevelFull);
 106       log->Printf("Found step through plan from 0x%" PRIx64 ": %s",
 107                   current_address, s.GetData());
 108     } else {
 109       log->Printf("Couldn't find step through plan from address 0x%" PRIx64 ".",
 110                   current_address);
 111     }
 112   }
 113 }
 114
 115 void ThreadPlanStepThrough::GetDescription(Stream *s,
 116                                            lldb::DescriptionLevel level) {
 117   if (level == lldb::eDescriptionLevelBrief)
 118     s->Printf("Step through");
 119   else {
 120     s->PutCString("Stepping through trampoline code from: ");
 121     s->Address(m_start_address, sizeof(addr_t));
 122     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 123       s->Printf(" with backstop breakpoint ID: %d at address: ",
 124                 m_backstop_bkpt_id);
 125       s->Address(m_backstop_addr, sizeof(addr_t));
 126     } else
 127       s->PutCString(" unable to set a backstop breakpoint.");
 128   }
 129 }
 130
 131 bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
 132   if (m_could_not_resolve_hw_bp) {
 133     if (error)
 134       error->PutCString(
 135           "Could not create hardware breakpoint for thread plan.");
 136     return false;
 137   }
 138
 139   if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
 140     if (error)
 141       error->PutCString("Could not create backstop breakpoint.");
 142     return false;
 143   }
 144
 145   if (!m_sub_plan_sp.get()) {
 146     if (error)
 147       error->PutCString("Does not have a subplan.");
 148     return false;
 149   }
 150
 151   return true;
 152 }
 153
 154 bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
 155   // If we have a sub-plan, it will have been asked first if we explain the
 156   // stop, and we won't get asked.  The only time we would be the one directly
 157   // asked this question is if we hit our backstop breakpoint.
 158
 159   return HitOurBackstopBreakpoint();
 160 }
 161
 162 bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
 163   // If we've already marked ourselves done, then we're done...
 164   if (IsPlanComplete())
 165     return true;
 166
 167   // First, did we hit the backstop breakpoint?
 168   if (HitOurBackstopBreakpoint()) {
 169     SetPlanComplete(true);
 170     return true;
 171   }
 172
 173   // If we don't have a sub-plan, then we're also done (can't see how we would
 174   // ever get here without a plan, but just in case.
 175
 176   if (!m_sub_plan_sp) {
 177     SetPlanComplete();
 178     return true;
 179   }
 180
 181   // If the current sub plan is not done, we don't want to stop.  Actually, we
 182   // probably won't ever get here in this state, since we generally won't get
 183   // asked any questions if out current sub-plan is not done...
 184   if (!m_sub_plan_sp->IsPlanComplete())
 185     return false;
 186
 187   // If our current sub plan failed, then let's just run to our backstop.  If
 188   // we can't do that then just stop.
 189   if (!m_sub_plan_sp->PlanSucceeded()) {
 190     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 191       m_sub_plan_sp.reset();
 192       return false;
 193     } else {
 194       SetPlanComplete(false);
 195       return true;
 196     }
 197   }
 198
 199   // Next see if there is a specific step through plan at our current pc (these
 200   // might chain, for instance stepping through a dylib trampoline to the objc
 201   // dispatch function...)
 202   LookForPlanToStepThroughFromCurrentPC();
 203   if (m_sub_plan_sp) {
 204     PushPlan(m_sub_plan_sp);
 205     return false;
 206   } else {
 207     SetPlanComplete();
 208     return true;
 209   }
 210 }
 211
 212 bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
 213
 214 StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
 215
 216 bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
 217                                          bool current_plan) {
 218   return true;
 219 }
 220
 221 bool ThreadPlanStepThrough::WillStop() { return true; }
 222
 223 void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
 224   if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
 225     m_thread.GetProcess()->GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
 226     m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
 227     m_could_not_resolve_hw_bp = false;
 228   }
 229 }
 230
 231 bool ThreadPlanStepThrough::MischiefManaged() {
 232   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 233
 234   if (!IsPlanComplete()) {
 235     return false;
 236   } else {
 237     if (log)
 238       log->Printf("Completed step through step plan.");
 239
 240     ClearBackstopBreakpoint();
 241     ThreadPlan::MischiefManaged();
 242     return true;
 243   }
 244 }
 245
 246 bool ThreadPlanStepThrough::HitOurBackstopBreakpoint() {
 247   StopInfoSP stop_info_sp(m_thread.GetStopInfo());
 248   if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
 249     break_id_t stop_value = (break_id_t)stop_info_sp->GetValue();
 250     BreakpointSiteSP cur_site_sp =
 251         m_thread.GetProcess()->GetBreakpointSiteList().FindByID(stop_value);
 252     if (cur_site_sp &&
 253         cur_site_sp->IsBreakpointAtThisSite(m_backstop_bkpt_id)) {
 254       StackID cur_frame_zero_id =
 255           m_thread.GetStackFrameAtIndex(0)->GetStackID();
 256
 257       if (cur_frame_zero_id == m_return_stack_id) {
 258         Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
 259         if (log)
 260           log->PutCString("ThreadPlanStepThrough hit backstop breakpoint.");
 261         return true;
 262       }
 263     }
 264   }
 265   return false;
 266 }