1 //===-- ThreadPlanStepThrough.cpp -------------------------------*- C++ -*-===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "lldb/Target/ThreadPlanStepThrough.h"
11 #include "lldb/Breakpoint/Breakpoint.h"
12 #include "lldb/Target/CPPLanguageRuntime.h"
13 #include "lldb/Target/DynamicLoader.h"
14 #include "lldb/Target/ObjCLanguageRuntime.h"
15 #include "lldb/Target/Process.h"
16 #include "lldb/Target/RegisterContext.h"
17 #include "lldb/Target/Target.h"
18 #include "lldb/Utility/Log.h"
19 #include "lldb/Utility/Stream.h"
20 
21 using namespace lldb;
22 using namespace lldb_private;
23 
24 //----------------------------------------------------------------------
25 // ThreadPlanStepThrough: If the current instruction is a trampoline, step
26 // through it If it is the beginning of the prologue of a function, step
27 // through that as well.
28 // FIXME: At present only handles DYLD trampolines.
29 //----------------------------------------------------------------------
30 
31 ThreadPlanStepThrough::ThreadPlanStepThrough(Thread &thread,
32                                              StackID &m_stack_id,
33                                              bool stop_others)
34     : ThreadPlan(ThreadPlan::eKindStepThrough,
35                  "Step through trampolines and prologues", thread,
36                  eVoteNoOpinion, eVoteNoOpinion),
37       m_start_address(0), m_backstop_bkpt_id(LLDB_INVALID_BREAK_ID),
38       m_backstop_addr(LLDB_INVALID_ADDRESS), m_return_stack_id(m_stack_id),
39       m_stop_others(stop_others) {
40   LookForPlanToStepThroughFromCurrentPC();
41 
42   // If we don't get a valid step through plan, don't bother to set up a
43   // backstop.
44   if (m_sub_plan_sp) {
45     m_start_address = GetThread().GetRegisterContext()->GetPC(0);
46 
47     // We are going to return back to the concrete frame 1, we might pass by
48     // some inlined code that we're in the middle of by doing this, but it's
49     // easier than trying to figure out where the inlined code might return to.
50 
51     StackFrameSP return_frame_sp = m_thread.GetFrameWithStackID(m_stack_id);
52 
53     if (return_frame_sp) {
54       m_backstop_addr = return_frame_sp->GetFrameCodeAddress().GetLoadAddress(
55           m_thread.CalculateTarget().get());
56       Breakpoint *return_bp =
57           m_thread.GetProcess()
58               ->GetTarget()
59               .CreateBreakpoint(m_backstop_addr, true, false)
60               .get();
61       if (return_bp != nullptr) {
62         return_bp->SetThreadID(m_thread.GetID());
63         m_backstop_bkpt_id = return_bp->GetID();
64         return_bp->SetBreakpointKind("step-through-backstop");
65       }
66       Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
67       if (log) {
68         log->Printf("Setting backstop breakpoint %d at address: 0x%" PRIx64,
69                     m_backstop_bkpt_id, m_backstop_addr);
70       }
71     }
72   }
73 }
74 
75 ThreadPlanStepThrough::~ThreadPlanStepThrough() { ClearBackstopBreakpoint(); }
76 
77 void ThreadPlanStepThrough::DidPush() {
78   if (m_sub_plan_sp)
79     PushPlan(m_sub_plan_sp);
80 }
81 
82 void ThreadPlanStepThrough::LookForPlanToStepThroughFromCurrentPC() {
83   DynamicLoader *loader = m_thread.GetProcess()->GetDynamicLoader();
84   if (loader)
85     m_sub_plan_sp =
86         loader->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
87 
88   // If that didn't come up with anything, try the ObjC runtime plugin:
89   if (!m_sub_plan_sp.get()) {
90     ObjCLanguageRuntime *objc_runtime =
91         m_thread.GetProcess()->GetObjCLanguageRuntime();
92     if (objc_runtime)
93       m_sub_plan_sp =
94           objc_runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
95 
96     CPPLanguageRuntime *cpp_runtime =
97         m_thread.GetProcess()->GetCPPLanguageRuntime();
98 
99     // If the ObjC runtime did not provide us with a step though plan then if we
100     // have it check the C++ runtime for a step though plan.
101     if (!m_sub_plan_sp.get() && cpp_runtime)
102       m_sub_plan_sp =
103           cpp_runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
104   }
105 
106   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
107   if (log) {
108     lldb::addr_t current_address = GetThread().GetRegisterContext()->GetPC(0);
109     if (m_sub_plan_sp) {
110       StreamString s;
111       m_sub_plan_sp->GetDescription(&s, lldb::eDescriptionLevelFull);
112       log->Printf("Found step through plan from 0x%" PRIx64 ": %s",
113                   current_address, s.GetData());
114     } else {
115       log->Printf("Couldn't find step through plan from address 0x%" PRIx64 ".",
116                   current_address);
117     }
118   }
119 }
120 
121 void ThreadPlanStepThrough::GetDescription(Stream *s,
122                                            lldb::DescriptionLevel level) {
123   if (level == lldb::eDescriptionLevelBrief)
124     s->Printf("Step through");
125   else {
126     s->PutCString("Stepping through trampoline code from: ");
127     s->Address(m_start_address, sizeof(addr_t));
128     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
129       s->Printf(" with backstop breakpoint ID: %d at address: ",
130                 m_backstop_bkpt_id);
131       s->Address(m_backstop_addr, sizeof(addr_t));
132     } else
133       s->PutCString(" unable to set a backstop breakpoint.");
134   }
135 }
136 
137 bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
138   return m_sub_plan_sp.get() != nullptr;
139 }
140 
141 bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
142   // If we have a sub-plan, it will have been asked first if we explain the
143   // stop, and we won't get asked.  The only time we would be the one directly
144   // asked this question is if we hit our backstop breakpoint.
145 
146   return HitOurBackstopBreakpoint();
147 }
148 
149 bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
150   // If we've already marked ourselves done, then we're done...
151   if (IsPlanComplete())
152     return true;
153 
154   // First, did we hit the backstop breakpoint?
155   if (HitOurBackstopBreakpoint()) {
156     SetPlanComplete(true);
157     return true;
158   }
159 
160   // If we don't have a sub-plan, then we're also done (can't see how we would
161   // ever get here without a plan, but just in case.
162 
163   if (!m_sub_plan_sp) {
164     SetPlanComplete();
165     return true;
166   }
167 
168   // If the current sub plan is not done, we don't want to stop.  Actually, we
169   // probably won't ever get here in this state, since we generally won't get
170   // asked any questions if out current sub-plan is not done...
171   if (!m_sub_plan_sp->IsPlanComplete())
172     return false;
173 
174   // If our current sub plan failed, then let's just run to our backstop.  If
175   // we can't do that then just stop.
176   if (!m_sub_plan_sp->PlanSucceeded()) {
177     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
178       m_sub_plan_sp.reset();
179       return false;
180     } else {
181       SetPlanComplete(false);
182       return true;
183     }
184   }
185 
186   // Next see if there is a specific step through plan at our current pc (these
187   // might chain, for instance stepping through a dylib trampoline to the objc
188   // dispatch function...)
189   LookForPlanToStepThroughFromCurrentPC();
190   if (m_sub_plan_sp) {
191     PushPlan(m_sub_plan_sp);
192     return false;
193   } else {
194     SetPlanComplete();
195     return true;
196   }
197 }
198 
199 bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
200 
201 StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
202 
203 bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
204                                          bool current_plan) {
205   return true;
206 }
207 
208 bool ThreadPlanStepThrough::WillStop() { return true; }
209 
210 void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
211   if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
212     m_thread.GetProcess()->GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
213     m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
214   }
215 }
216 
217 bool ThreadPlanStepThrough::MischiefManaged() {
218   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
219 
220   if (!IsPlanComplete()) {
221     return false;
222   } else {
223     if (log)
224       log->Printf("Completed step through step plan.");
225 
226     ClearBackstopBreakpoint();
227     ThreadPlan::MischiefManaged();
228     return true;
229   }
230 }
231 
232 bool ThreadPlanStepThrough::HitOurBackstopBreakpoint() {
233   StopInfoSP stop_info_sp(m_thread.GetStopInfo());
234   if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
235     break_id_t stop_value = (break_id_t)stop_info_sp->GetValue();
236     BreakpointSiteSP cur_site_sp =
237         m_thread.GetProcess()->GetBreakpointSiteList().FindByID(stop_value);
238     if (cur_site_sp &&
239         cur_site_sp->IsBreakpointAtThisSite(m_backstop_bkpt_id)) {
240       StackID cur_frame_zero_id =
241           m_thread.GetStackFrameAtIndex(0)->GetStackID();
242 
243       if (cur_frame_zero_id == m_return_stack_id) {
244         Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
245         if (log)
246           log->PutCString("ThreadPlanStepThrough hit backstop breakpoint.");
247         return true;
248       }
249     }
250   }
251   return false;
252 }
253