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