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 
62       if (return_bp != nullptr) {
63         if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
64           m_could_not_resolve_hw_bp = true;
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     CPPLanguageRuntime *cpp_runtime =
100         m_thread.GetProcess()->GetCPPLanguageRuntime();
101 
102     // If the ObjC runtime did not provide us with a step though plan then if we
103     // have it check the C++ runtime for a step though plan.
104     if (!m_sub_plan_sp.get() && cpp_runtime)
105       m_sub_plan_sp =
106           cpp_runtime->GetStepThroughTrampolinePlan(m_thread, m_stop_others);
107   }
108 
109   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
110   if (log) {
111     lldb::addr_t current_address = GetThread().GetRegisterContext()->GetPC(0);
112     if (m_sub_plan_sp) {
113       StreamString s;
114       m_sub_plan_sp->GetDescription(&s, lldb::eDescriptionLevelFull);
115       log->Printf("Found step through plan from 0x%" PRIx64 ": %s",
116                   current_address, s.GetData());
117     } else {
118       log->Printf("Couldn't find step through plan from address 0x%" PRIx64 ".",
119                   current_address);
120     }
121   }
122 }
123 
124 void ThreadPlanStepThrough::GetDescription(Stream *s,
125                                            lldb::DescriptionLevel level) {
126   if (level == lldb::eDescriptionLevelBrief)
127     s->Printf("Step through");
128   else {
129     s->PutCString("Stepping through trampoline code from: ");
130     s->Address(m_start_address, sizeof(addr_t));
131     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
132       s->Printf(" with backstop breakpoint ID: %d at address: ",
133                 m_backstop_bkpt_id);
134       s->Address(m_backstop_addr, sizeof(addr_t));
135     } else
136       s->PutCString(" unable to set a backstop breakpoint.");
137   }
138 }
139 
140 bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
141   if (m_could_not_resolve_hw_bp) {
142     if (error)
143       error->PutCString(
144           "Could not create hardware breakpoint for thread plan.");
145     return false;
146   }
147 
148   if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
149     if (error)
150       error->PutCString("Could not create backstop breakpoint.");
151     return false;
152   }
153 
154   if (!m_sub_plan_sp.get()) {
155     if (error)
156       error->PutCString("Does not have a subplan.");
157     return false;
158   }
159 
160   return true;
161 }
162 
163 bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
164   // If we have a sub-plan, it will have been asked first if we explain the
165   // stop, and we won't get asked.  The only time we would be the one directly
166   // asked this question is if we hit our backstop breakpoint.
167 
168   return HitOurBackstopBreakpoint();
169 }
170 
171 bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
172   // If we've already marked ourselves done, then we're done...
173   if (IsPlanComplete())
174     return true;
175 
176   // First, did we hit the backstop breakpoint?
177   if (HitOurBackstopBreakpoint()) {
178     SetPlanComplete(true);
179     return true;
180   }
181 
182   // If we don't have a sub-plan, then we're also done (can't see how we would
183   // ever get here without a plan, but just in case.
184 
185   if (!m_sub_plan_sp) {
186     SetPlanComplete();
187     return true;
188   }
189 
190   // If the current sub plan is not done, we don't want to stop.  Actually, we
191   // probably won't ever get here in this state, since we generally won't get
192   // asked any questions if out current sub-plan is not done...
193   if (!m_sub_plan_sp->IsPlanComplete())
194     return false;
195 
196   // If our current sub plan failed, then let's just run to our backstop.  If
197   // we can't do that then just stop.
198   if (!m_sub_plan_sp->PlanSucceeded()) {
199     if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
200       m_sub_plan_sp.reset();
201       return false;
202     } else {
203       SetPlanComplete(false);
204       return true;
205     }
206   }
207 
208   // Next see if there is a specific step through plan at our current pc (these
209   // might chain, for instance stepping through a dylib trampoline to the objc
210   // dispatch function...)
211   LookForPlanToStepThroughFromCurrentPC();
212   if (m_sub_plan_sp) {
213     PushPlan(m_sub_plan_sp);
214     return false;
215   } else {
216     SetPlanComplete();
217     return true;
218   }
219 }
220 
221 bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
222 
223 StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
224 
225 bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
226                                          bool current_plan) {
227   return true;
228 }
229 
230 bool ThreadPlanStepThrough::WillStop() { return true; }
231 
232 void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
233   if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
234     m_thread.GetProcess()->GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
235     m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
236     m_could_not_resolve_hw_bp = false;
237   }
238 }
239 
240 bool ThreadPlanStepThrough::MischiefManaged() {
241   Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
242 
243   if (!IsPlanComplete()) {
244     return false;
245   } else {
246     if (log)
247       log->Printf("Completed step through step plan.");
248 
249     ClearBackstopBreakpoint();
250     ThreadPlan::MischiefManaged();
251     return true;
252   }
253 }
254 
255 bool ThreadPlanStepThrough::HitOurBackstopBreakpoint() {
256   StopInfoSP stop_info_sp(m_thread.GetStopInfo());
257   if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
258     break_id_t stop_value = (break_id_t)stop_info_sp->GetValue();
259     BreakpointSiteSP cur_site_sp =
260         m_thread.GetProcess()->GetBreakpointSiteList().FindByID(stop_value);
261     if (cur_site_sp &&
262         cur_site_sp->IsBreakpointAtThisSite(m_backstop_bkpt_id)) {
263       StackID cur_frame_zero_id =
264           m_thread.GetStackFrameAtIndex(0)->GetStackID();
265 
266       if (cur_frame_zero_id == m_return_stack_id) {
267         Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
268         if (log)
269           log->PutCString("ThreadPlanStepThrough hit backstop breakpoint.");
270         return true;
271       }
272     }
273   }
274   return false;
275 }
276