1//===-- ThreadPlanStepThrough.cpp -----------------------------------------===//
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/LLDBLog.h"
17#include "lldb/Utility/Log.h"
18#include "lldb/Utility/Stream.h"
19
20using namespace lldb;
21using namespace lldb_private;
22
23// ThreadPlanStepThrough: If the current instruction is a trampoline, step
24// through it If it is the beginning of the prologue of a function, step
25// through that as well.
26
27ThreadPlanStepThrough::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(fail_value: 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 = thread.GetFrameWithStackID(stack_id: m_stack_id);
48
49 if (return_frame_sp) {
50 m_backstop_addr = return_frame_sp->GetFrameCodeAddress().GetLoadAddress(
51 target: thread.CalculateTarget().get());
52 Breakpoint *return_bp =
53 m_process.GetTarget()
54 .CreateBreakpoint(load_addr: m_backstop_addr, internal: true, request_hardware: false)
55 .get();
56
57 if (return_bp != nullptr) {
58 if (return_bp->IsHardware() && !return_bp->HasResolvedLocations())
59 m_could_not_resolve_hw_bp = true;
60 return_bp->SetThreadID(m_tid);
61 m_backstop_bkpt_id = return_bp->GetID();
62 return_bp->SetBreakpointKind("step-through-backstop");
63 }
64 Log *log = GetLog(mask: LLDBLog::Step);
65 if (log) {
66 LLDB_LOGF(log, "Setting backstop breakpoint %d at address: 0x%" PRIx64,
67 m_backstop_bkpt_id, m_backstop_addr);
68 }
69 }
70 }
71}
72
73ThreadPlanStepThrough::~ThreadPlanStepThrough() { ClearBackstopBreakpoint(); }
74
75void ThreadPlanStepThrough::DidPush() {
76 if (m_sub_plan_sp)
77 PushPlan(thread_plan_sp&: m_sub_plan_sp);
78}
79
80void ThreadPlanStepThrough::LookForPlanToStepThroughFromCurrentPC() {
81 Thread &thread = GetThread();
82 DynamicLoader *loader = thread.GetProcess()->GetDynamicLoader();
83 if (loader)
84 m_sub_plan_sp = loader->GetStepThroughTrampolinePlan(thread, stop_others: m_stop_others);
85
86 // If the DynamicLoader was unable to provide us with a ThreadPlan, then we
87 // try the LanguageRuntimes.
88 if (!m_sub_plan_sp) {
89 for (LanguageRuntime *runtime : m_process.GetLanguageRuntimes()) {
90 m_sub_plan_sp =
91 runtime->GetStepThroughTrampolinePlan(thread, stop_others: m_stop_others);
92
93 if (m_sub_plan_sp)
94 break;
95 }
96 }
97
98 Log *log = GetLog(mask: LLDBLog::Step);
99 if (log) {
100 lldb::addr_t current_address = GetThread().GetRegisterContext()->GetPC(fail_value: 0);
101 if (m_sub_plan_sp) {
102 StreamString s;
103 m_sub_plan_sp->GetDescription(s: &s, level: lldb::eDescriptionLevelFull);
104 LLDB_LOGF(log, "Found step through plan from 0x%" PRIx64 ": %s",
105 current_address, s.GetData());
106 } else {
107 LLDB_LOGF(log,
108 "Couldn't find step through plan from address 0x%" PRIx64 ".",
109 current_address);
110 }
111 }
112}
113
114void ThreadPlanStepThrough::GetDescription(Stream *s,
115 lldb::DescriptionLevel level) {
116 if (level == lldb::eDescriptionLevelBrief)
117 s->Printf(format: "Step through");
118 else {
119 s->PutCString(cstr: "Stepping through trampoline code from: ");
120 DumpAddress(s&: s->AsRawOstream(), addr: m_start_address, addr_size: sizeof(addr_t));
121 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
122 s->Printf(format: " with backstop breakpoint ID: %d at address: ",
123 m_backstop_bkpt_id);
124 DumpAddress(s&: s->AsRawOstream(), addr: m_backstop_addr, addr_size: sizeof(addr_t));
125 } else
126 s->PutCString(cstr: " unable to set a backstop breakpoint.");
127 }
128}
129
130bool ThreadPlanStepThrough::ValidatePlan(Stream *error) {
131 if (m_could_not_resolve_hw_bp) {
132 if (error)
133 error->PutCString(
134 cstr: "Could not create hardware breakpoint for thread plan.");
135 return false;
136 }
137
138 if (m_backstop_bkpt_id == LLDB_INVALID_BREAK_ID) {
139 if (error)
140 error->PutCString(cstr: "Could not create backstop breakpoint.");
141 return false;
142 }
143
144 if (!m_sub_plan_sp.get()) {
145 if (error)
146 error->PutCString(cstr: "Does not have a subplan.");
147 return false;
148 }
149
150 return true;
151}
152
153bool ThreadPlanStepThrough::DoPlanExplainsStop(Event *event_ptr) {
154 // If we have a sub-plan, it will have been asked first if we explain the
155 // stop, and we won't get asked. The only time we would be the one directly
156 // asked this question is if we hit our backstop breakpoint.
157
158 return HitOurBackstopBreakpoint();
159}
160
161bool ThreadPlanStepThrough::ShouldStop(Event *event_ptr) {
162 // If we've already marked ourselves done, then we're done...
163 if (IsPlanComplete())
164 return true;
165
166 // First, did we hit the backstop breakpoint?
167 if (HitOurBackstopBreakpoint()) {
168 SetPlanComplete(true);
169 return true;
170 }
171
172 // If we don't have a sub-plan, then we're also done (can't see how we would
173 // ever get here without a plan, but just in case.
174
175 if (!m_sub_plan_sp) {
176 SetPlanComplete();
177 return true;
178 }
179
180 // If the current sub plan is not done, we don't want to stop. Actually, we
181 // probably won't ever get here in this state, since we generally won't get
182 // asked any questions if out current sub-plan is not done...
183 if (!m_sub_plan_sp->IsPlanComplete())
184 return false;
185
186 // If our current sub plan failed, then let's just run to our backstop. If
187 // we can't do that then just stop.
188 if (!m_sub_plan_sp->PlanSucceeded()) {
189 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
190 m_sub_plan_sp.reset();
191 return false;
192 } else {
193 SetPlanComplete(false);
194 return true;
195 }
196 }
197
198 // Next see if there is a specific step through plan at our current pc (these
199 // might chain, for instance stepping through a dylib trampoline to the objc
200 // dispatch function...)
201 LookForPlanToStepThroughFromCurrentPC();
202 if (m_sub_plan_sp) {
203 PushPlan(thread_plan_sp&: m_sub_plan_sp);
204 return false;
205 } else {
206 SetPlanComplete();
207 return true;
208 }
209}
210
211bool ThreadPlanStepThrough::StopOthers() { return m_stop_others; }
212
213StateType ThreadPlanStepThrough::GetPlanRunState() { return eStateRunning; }
214
215bool ThreadPlanStepThrough::DoWillResume(StateType resume_state,
216 bool current_plan) {
217 return true;
218}
219
220bool ThreadPlanStepThrough::WillStop() { return true; }
221
222void ThreadPlanStepThrough::ClearBackstopBreakpoint() {
223 if (m_backstop_bkpt_id != LLDB_INVALID_BREAK_ID) {
224 m_process.GetTarget().RemoveBreakpointByID(break_id: m_backstop_bkpt_id);
225 m_backstop_bkpt_id = LLDB_INVALID_BREAK_ID;
226 m_could_not_resolve_hw_bp = false;
227 }
228}
229
230bool ThreadPlanStepThrough::MischiefManaged() {
231 Log *log = GetLog(mask: LLDBLog::Step);
232
233 if (!IsPlanComplete()) {
234 return false;
235 } else {
236 LLDB_LOGF(log, "Completed step through step plan.");
237
238 ClearBackstopBreakpoint();
239 ThreadPlan::MischiefManaged();
240 return true;
241 }
242}
243
244bool ThreadPlanStepThrough::HitOurBackstopBreakpoint() {
245 Thread &thread = GetThread();
246 StopInfoSP stop_info_sp(thread.GetStopInfo());
247 if (stop_info_sp && stop_info_sp->GetStopReason() == eStopReasonBreakpoint) {
248 break_id_t stop_value = (break_id_t)stop_info_sp->GetValue();
249 BreakpointSiteSP cur_site_sp =
250 m_process.GetBreakpointSiteList().FindByID(site_id: stop_value);
251 if (cur_site_sp &&
252 cur_site_sp->IsBreakpointAtThisSite(bp_id: m_backstop_bkpt_id)) {
253 StackID cur_frame_zero_id = thread.GetStackFrameAtIndex(idx: 0)->GetStackID();
254
255 if (cur_frame_zero_id == m_return_stack_id) {
256 Log *log = GetLog(mask: LLDBLog::Step);
257 if (log)
258 log->PutCString(cstr: "ThreadPlanStepThrough hit backstop breakpoint.");
259 return true;
260 }
261 }
262 }
263 return false;
264}
265

source code of lldb/source/Target/ThreadPlanStepThrough.cpp