Files
clang-p2996/lldb/source/Target/ThreadPlanBase.cpp
David Spickett 0caba6c8dc Reland "[lldb] Implement basic support for reverse-continue" (#123906)" (#123945)
This reverts commit 22561cfb44 and fixes
b7b9ccf449 (#112079).

The problem is that x86_64 and Arm 32-bit have memory regions above the
stack that are readable but not writeable. First Arm:
```
(lldb) memory region --all
<...>
[0x00000000fffcf000-0x00000000ffff0000) rw- [stack]
[0x00000000ffff0000-0x00000000ffff1000) r-x [vectors]
[0x00000000ffff1000-0xffffffffffffffff) ---
```
Then x86_64:
```
$ cat /proc/self/maps
<...>
7ffdcd148000-7ffdcd16a000 rw-p 00000000 00:00 0                          [stack]
7ffdcd193000-7ffdcd196000 r--p 00000000 00:00 0                          [vvar]
7ffdcd196000-7ffdcd197000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]
```
Compare this to AArch64 where the test did pass:
```
$ cat /proc/self/maps
<...>
ffffb87dc000-ffffb87dd000 r--p 00000000 00:00 0                          [vvar]
ffffb87dd000-ffffb87de000 r-xp 00000000 00:00 0                          [vdso]
ffffb87de000-ffffb87e0000 r--p 0002a000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
ffffb87e0000-ffffb87e2000 rw-p 0002c000 00:3c 76927217                   /usr/lib/aarch64-linux-gnu/ld-linux-aarch64.so.1
fffff4216000-fffff4237000 rw-p 00000000 00:00 0                          [stack]
```
To solve this, look up the memory region of the stack pointer (using
https://lldb.llvm.org/resources/lldbgdbremote.html#qmemoryregioninfo-addr)
and constrain the read to within that region. Since we know the stack is
all readable and writeable.

I have also added skipIfRemote to the tests, since getting them working
in that context is too complex to be worth it.

Memory write failures now display the range they tried to write, and
register write errors will show the name of the register where possible.

The patch also includes a workaround for a an issue where the test code
could mistake an `x` response that happens to begin with an `O` for an
output packet (stdout). This workaround will not be necessary one we
start using the [new
implementation](https://discourse.llvm.org/t/rfc-fixing-incompatibilties-of-the-x-packet-w-r-t-gdb/84288)
of the `x` packet.

---------

Co-authored-by: Pavel Labath <pavel@labath.sk>
2025-01-30 14:03:01 +00:00

203 lines
6.5 KiB
C++

//===-- ThreadPlanBase.cpp ------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "lldb/Target/ThreadPlanBase.h"
//
#include "lldb/Breakpoint/Breakpoint.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Breakpoint/BreakpointSite.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/RegisterContext.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/Stream.h"
using namespace lldb;
using namespace lldb_private;
// ThreadPlanBase: This one always stops, and never has anything particular to
// do.
// FIXME: The "signal handling" policies should probably go here.
ThreadPlanBase::ThreadPlanBase(Thread &thread)
: ThreadPlan(ThreadPlan::eKindBase, "base plan", thread, eVoteYes,
eVoteNoOpinion) {
// Set the tracer to a default tracer.
// FIXME: need to add a thread settings variable to pix various tracers...
#define THREAD_PLAN_USE_ASSEMBLY_TRACER 1
#ifdef THREAD_PLAN_USE_ASSEMBLY_TRACER
ThreadPlanTracerSP new_tracer_sp(new ThreadPlanAssemblyTracer(thread));
#else
ThreadPlanTracerSP new_tracer_sp(new ThreadPlanTracer(m_thread));
#endif
new_tracer_sp->EnableTracing(thread.GetTraceEnabledState());
SetThreadPlanTracer(new_tracer_sp);
SetIsControllingPlan(true);
}
ThreadPlanBase::~ThreadPlanBase() = default;
void ThreadPlanBase::GetDescription(Stream *s, lldb::DescriptionLevel level) {
s->Printf("Base thread plan.");
}
bool ThreadPlanBase::ValidatePlan(Stream *error) { return true; }
bool ThreadPlanBase::DoPlanExplainsStop(Event *event_ptr) {
// The base plan should defer to its tracer, since by default it always
// handles the stop.
return !TracerExplainsStop();
}
Vote ThreadPlanBase::ShouldReportStop(Event *event_ptr) {
StopInfoSP stop_info_sp = GetThread().GetStopInfo();
if (stop_info_sp) {
bool should_notify = stop_info_sp->ShouldNotify(event_ptr);
if (should_notify)
return eVoteYes;
else
return eVoteNoOpinion;
} else
return eVoteNoOpinion;
}
bool ThreadPlanBase::ShouldStop(Event *event_ptr) {
m_report_stop_vote = eVoteYes;
m_report_run_vote = eVoteYes;
Log *log = GetLog(LLDBLog::Step);
StopInfoSP stop_info_sp = GetPrivateStopInfo();
if (stop_info_sp) {
StopReason reason = stop_info_sp->GetStopReason();
switch (reason) {
case eStopReasonInvalid:
case eStopReasonNone:
// This
m_report_run_vote = eVoteNoOpinion;
m_report_stop_vote = eVoteNo;
return false;
case eStopReasonBreakpoint:
case eStopReasonWatchpoint:
if (stop_info_sp->ShouldStopSynchronous(event_ptr)) {
// If we are going to stop for a breakpoint, then unship the other
// plans at this point. Don't force the discard, however, so
// Controlling plans can stay in place if they want to.
LLDB_LOGF(
log,
"Base plan discarding thread plans for thread tid = 0x%4.4" PRIx64
" (breakpoint hit.)",
m_tid);
GetThread().DiscardThreadPlans(false);
return true;
}
// If we aren't going to stop at this breakpoint, and it is internal,
// don't report this stop or the subsequent running event. Otherwise we
// will post the stopped & running, but the stopped event will get marked
// with "restarted" so the UI will know to wait and expect the consequent
// "running".
if (stop_info_sp->ShouldNotify(event_ptr)) {
m_report_stop_vote = eVoteYes;
m_report_run_vote = eVoteYes;
} else {
m_report_stop_vote = eVoteNo;
m_report_run_vote = eVoteNo;
}
return false;
// TODO: the break below was missing, was this intentional??? If so
// please mention it
break;
case eStopReasonException:
// If we crashed, discard thread plans and stop. Don't force the
// discard, however, since on rerun the target may clean up this
// exception and continue normally from there.
LLDB_LOGF(
log,
"Base plan discarding thread plans for thread tid = 0x%4.4" PRIx64
" (exception: %s)",
m_tid, stop_info_sp->GetDescription());
GetThread().DiscardThreadPlans(false);
return true;
case eStopReasonExec:
// If we crashed, discard thread plans and stop. Don't force the
// discard, however, since on rerun the target may clean up this
// exception and continue normally from there.
LLDB_LOGF(
log,
"Base plan discarding thread plans for thread tid = 0x%4.4" PRIx64
" (exec.)",
m_tid);
GetThread().DiscardThreadPlans(false);
return true;
case eStopReasonThreadExiting:
case eStopReasonSignal:
if (stop_info_sp->ShouldStop(event_ptr)) {
LLDB_LOGF(
log,
"Base plan discarding thread plans for thread tid = 0x%4.4" PRIx64
" (signal: %s)",
m_tid, stop_info_sp->GetDescription());
GetThread().DiscardThreadPlans(false);
return true;
} else {
// We're not going to stop, but while we are here, let's figure out
// whether to report this.
if (stop_info_sp->ShouldNotify(event_ptr))
m_report_stop_vote = eVoteYes;
else
m_report_stop_vote = eVoteNo;
}
return false;
default:
return true;
}
} else {
m_report_run_vote = eVoteNoOpinion;
m_report_stop_vote = eVoteNo;
}
// If there's no explicit reason to stop, then we will continue.
return false;
}
bool ThreadPlanBase::StopOthers() { return false; }
StateType ThreadPlanBase::GetPlanRunState() { return eStateRunning; }
bool ThreadPlanBase::WillStop() { return true; }
bool ThreadPlanBase::DoWillResume(lldb::StateType resume_state,
bool current_plan) {
// Reset these to the default values so we don't set them wrong, then not get
// asked for a while, then return the wrong answer.
m_report_run_vote = eVoteNoOpinion;
m_report_stop_vote = eVoteNo;
return true;
}
// The base plan is never done.
bool ThreadPlanBase::MischiefManaged() {
// The base plan is never done.
return false;
}
RunDirection ThreadPlanBase::GetDirection() const {
return m_process.GetBaseDirection();
}