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