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
ThreadPlanStepThrough(Thread & thread,StackID & m_stack_id,bool stop_others)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 LLDB_LOGF(log, "Setting backstop breakpoint %d at address: 0x%" PRIx64,
68 m_backstop_bkpt_id, m_backstop_addr);
69 }
70 }
71 }
72 }
73
~ThreadPlanStepThrough()74 ThreadPlanStepThrough::~ThreadPlanStepThrough() { ClearBackstopBreakpoint(); }
75
DidPush()76 void ThreadPlanStepThrough::DidPush() {
77 if (m_sub_plan_sp)
78 PushPlan(m_sub_plan_sp);
79 }
80
LookForPlanToStepThroughFromCurrentPC()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 LLDB_LOGF(log, "Found step through plan from 0x%" PRIx64 ": %s",
107 current_address, s.GetData());
108 } else {
109 LLDB_LOGF(log,
110 "Couldn't find step through plan from address 0x%" PRIx64 ".",
111 current_address);
112 }
113 }
114 }
115
GetDescription(Stream * s,lldb::DescriptionLevel level)116 void ThreadPlanStepThrough::GetDescription(Stream *s,
117 lldb::DescriptionLevel level) {
118 if (level == lldb::eDescriptionLevelBrief)
119 s->Printf("Step through");
120 else {
121 s->PutCString("Stepping through trampoline code from: ");
122 DumpAddress(s->AsRawOstream(), m_start_address, sizeof(addr_t));
123 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
124 s->Printf(" with backstop breakpoint ID: %d at address: ",
125 m_backstop_bkpt_id);
126 DumpAddress(s->AsRawOstream(), m_backstop_addr, sizeof(addr_t));
127 } else
128 s->PutCString(" unable to set a backstop breakpoint.");
129 }
130 }
131
ValidatePlan(Stream * error)132 bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
133 if (m_could_not_resolve_hw_bp) {
134 if (error)
135 error->PutCString(
136 "Could not create hardware breakpoint for thread plan.");
137 return false;
138 }
139
140 if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
141 if (error)
142 error->PutCString("Could not create backstop breakpoint.");
143 return false;
144 }
145
146 if (!m_sub_plan_sp.get()) {
147 if (error)
148 error->PutCString("Does not have a subplan.");
149 return false;
150 }
151
152 return true;
153 }
154
DoPlanExplainsStop(Event * event_ptr)155 bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
156 // If we have a sub-plan, it will have been asked first if we explain the
157 // stop, and we won't get asked. The only time we would be the one directly
158 // asked this question is if we hit our backstop breakpoint.
159
160 return HitOurBackstopBreakpoint();
161 }
162
ShouldStop(Event * event_ptr)163 bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
164 // If we've already marked ourselves done, then we're done...
165 if (IsPlanComplete())
166 return true;
167
168 // First, did we hit the backstop breakpoint?
169 if (HitOurBackstopBreakpoint()) {
170 SetPlanComplete(true);
171 return true;
172 }
173
174 // If we don't have a sub-plan, then we're also done (can't see how we would
175 // ever get here without a plan, but just in case.
176
177 if (!m_sub_plan_sp) {
178 SetPlanComplete();
179 return true;
180 }
181
182 // If the current sub plan is not done, we don't want to stop. Actually, we
183 // probably won't ever get here in this state, since we generally won't get
184 // asked any questions if out current sub-plan is not done...
185 if (!m_sub_plan_sp->IsPlanComplete())
186 return false;
187
188 // If our current sub plan failed, then let's just run to our backstop. If
189 // we can't do that then just stop.
190 if (!m_sub_plan_sp->PlanSucceeded()) {
191 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
192 m_sub_plan_sp.reset();
193 return false;
194 } else {
195 SetPlanComplete(false);
196 return true;
197 }
198 }
199
200 // Next see if there is a specific step through plan at our current pc (these
201 // might chain, for instance stepping through a dylib trampoline to the objc
202 // dispatch function...)
203 LookForPlanToStepThroughFromCurrentPC();
204 if (m_sub_plan_sp) {
205 PushPlan(m_sub_plan_sp);
206 return false;
207 } else {
208 SetPlanComplete();
209 return true;
210 }
211 }
212
StopOthers()213 bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
214
GetPlanRunState()215 StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
216
DoWillResume(StateType resume_state,bool current_plan)217 bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
218 bool current_plan) {
219 return true;
220 }
221
WillStop()222 bool ThreadPlanStepThrough::WillStop() { return true; }
223
ClearBackstopBreakpoint()224 void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
225 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
226 m_thread.GetProcess()->GetTarget().RemoveBreakpointByID(m_backstop_bkpt_id);
227 m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
228 m_could_not_resolve_hw_bp = false;
229 }
230 }
231
MischiefManaged()232 bool ThreadPlanStepThrough::MischiefManaged() {
233 Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_STEP));
234
235 if (!IsPlanComplete()) {
236 return false;
237 } else {
238 LLDB_LOGF(log, "Completed step through step plan.");
239
240 ClearBackstopBreakpoint();
241 ThreadPlan::MischiefManaged();
242 return true;
243 }
244 }
245
HitOurBackstopBreakpoint()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 }
267