1//===-- ThreadPlanStepOverBreakpoint.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/ThreadPlanStepOverBreakpoint.h"
10
11#include "lldb/Target/Process.h"
12#include "lldb/Target/RegisterContext.h"
13#include "lldb/Utility/LLDBLog.h"
14#include "lldb/Utility/Log.h"
15#include "lldb/Utility/Stream.h"
16
17using namespace lldb;
18using namespace lldb_private;
19
20// ThreadPlanStepOverBreakpoint: Single steps over a breakpoint bp_site_sp at
21// the pc.
22
23ThreadPlanStepOverBreakpoint::ThreadPlanStepOverBreakpoint(Thread &thread)
24 : ThreadPlan(
25 ThreadPlan::eKindStepOverBreakpoint, "Step over breakpoint trap",
26 thread, eVoteNo,
27 eVoteNoOpinion), // We need to report the run since this happens
28 // first in the thread plan stack when stepping over
29 // a breakpoint
30 m_breakpoint_addr(LLDB_INVALID_ADDRESS),
31 m_auto_continue(false), m_reenabled_breakpoint_site(false)
32
33{
34 m_breakpoint_addr = thread.GetRegisterContext()->GetPC();
35 m_breakpoint_site_id =
36 thread.GetProcess()->GetBreakpointSiteList().FindIDByAddress(
37 addr: m_breakpoint_addr);
38}
39
40ThreadPlanStepOverBreakpoint::~ThreadPlanStepOverBreakpoint() = default;
41
42void ThreadPlanStepOverBreakpoint::GetDescription(
43 Stream *s, lldb::DescriptionLevel level) {
44 s->Printf(format: "Single stepping past breakpoint site %" PRIu64 " at 0x%" PRIx64,
45 m_breakpoint_site_id, (uint64_t)m_breakpoint_addr);
46}
47
48bool ThreadPlanStepOverBreakpoint::ValidatePlan(Stream *error) { return true; }
49
50bool ThreadPlanStepOverBreakpoint::DoPlanExplainsStop(Event *event_ptr) {
51 StopInfoSP stop_info_sp = GetPrivateStopInfo();
52 if (stop_info_sp) {
53 StopReason reason = stop_info_sp->GetStopReason();
54
55 Log *log = GetLog(mask: LLDBLog::Step);
56 LLDB_LOG(log, "Step over breakpoint stopped for reason: {0}.",
57 Thread::StopReasonAsString(reason));
58
59 switch (reason) {
60 case eStopReasonTrace:
61 case eStopReasonNone:
62 return true;
63 case eStopReasonBreakpoint:
64 {
65 // It's a little surprising that we stop here for a breakpoint hit.
66 // However, when you single step ONTO a breakpoint we still want to call
67 // that a breakpoint hit, and trigger the actions, etc. Otherwise you
68 // would see the PC at the breakpoint without having triggered the
69 // actions, then you'd continue, the PC wouldn't change, and you'd see
70 // the breakpoint hit, which would be odd. So the lower levels fake
71 // "step onto breakpoint address" and return that as a breakpoint hit.
72 // So our trace step COULD appear as a breakpoint hit if the next
73 // instruction also contained a breakpoint. We don't want to handle
74 // that, since we really don't know what to do with breakpoint hits.
75 // But make sure we don't set ourselves to auto-continue or we'll wrench
76 // control away from the plans that can deal with this.
77 // Be careful, however, as we may have "seen a breakpoint under the PC
78 // because we stopped without changing the PC, in which case we do want
79 // to re-claim this stop so we'll try again.
80 lldb::addr_t pc_addr = GetThread().GetRegisterContext()->GetPC();
81
82 if (pc_addr == m_breakpoint_addr) {
83 LLDB_LOGF(log,
84 "Got breakpoint stop reason but pc: 0x%" PRIx64
85 "hasn't changed.",
86 pc_addr);
87 return true;
88 }
89
90 SetAutoContinue(false);
91 return false;
92 }
93 default:
94 return false;
95 }
96 }
97 return false;
98}
99
100bool ThreadPlanStepOverBreakpoint::ShouldStop(Event *event_ptr) {
101 return !ShouldAutoContinue(event_ptr);
102}
103
104bool ThreadPlanStepOverBreakpoint::StopOthers() { return true; }
105
106// This thread plan does a single instruction step over a breakpoint instruction
107// and needs to not resume other threads, so return false to stop the
108// ThreadPlanSingleThreadTimeout from timing out and trying to resume all
109// threads. If all threads gets resumed before we disable, single step and
110// re-enable the breakpoint, we can miss breakpoints on other threads.
111bool ThreadPlanStepOverBreakpoint::SupportsResumeOthers() { return false; }
112
113StateType ThreadPlanStepOverBreakpoint::GetPlanRunState() {
114 return eStateStepping;
115}
116
117bool ThreadPlanStepOverBreakpoint::DoWillResume(StateType resume_state,
118 bool current_plan) {
119 if (current_plan) {
120 BreakpointSiteSP bp_site_sp(
121 m_process.GetBreakpointSiteList().FindByAddress(addr: m_breakpoint_addr));
122 if (bp_site_sp && bp_site_sp->IsEnabled()) {
123 m_process.DisableBreakpointSite(bp_site: bp_site_sp.get());
124 m_reenabled_breakpoint_site = false;
125 }
126 }
127 return true;
128}
129
130bool ThreadPlanStepOverBreakpoint::WillStop() {
131 ReenableBreakpointSite();
132 return true;
133}
134
135void ThreadPlanStepOverBreakpoint::DidPop() { ReenableBreakpointSite(); }
136
137bool ThreadPlanStepOverBreakpoint::MischiefManaged() {
138 lldb::addr_t pc_addr = GetThread().GetRegisterContext()->GetPC();
139
140 if (pc_addr == m_breakpoint_addr) {
141 // If we are still at the PC of our breakpoint, then for some reason we
142 // didn't get a chance to run.
143 return false;
144 } else {
145 Log *log = GetLog(mask: LLDBLog::Step);
146 LLDB_LOGF(log, "Completed step over breakpoint plan.");
147 // Otherwise, re-enable the breakpoint we were stepping over, and we're
148 // done.
149 ReenableBreakpointSite();
150 ThreadPlan::MischiefManaged();
151 return true;
152 }
153}
154
155void ThreadPlanStepOverBreakpoint::ReenableBreakpointSite() {
156 if (!m_reenabled_breakpoint_site) {
157 m_reenabled_breakpoint_site = true;
158 BreakpointSiteSP bp_site_sp(
159 m_process.GetBreakpointSiteList().FindByAddress(addr: m_breakpoint_addr));
160 if (bp_site_sp) {
161 m_process.EnableBreakpointSite(bp_site: bp_site_sp.get());
162 }
163 }
164}
165void ThreadPlanStepOverBreakpoint::ThreadDestroyed() {
166 ReenableBreakpointSite();
167}
168
169void ThreadPlanStepOverBreakpoint::SetAutoContinue(bool do_it) {
170 m_auto_continue = do_it;
171}
172
173bool ThreadPlanStepOverBreakpoint::ShouldAutoContinue(Event *event_ptr) {
174 return m_auto_continue;
175}
176
177bool ThreadPlanStepOverBreakpoint::IsPlanStale() {
178 return GetThread().GetRegisterContext()->GetPC() != m_breakpoint_addr;
179}
180

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