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llvm-project/lldb/source/Target/StopInfo.cpp
Jason Molenda eaeb8ddd4a [LLDB] add arch-specific watchpoint behavior defaults to lldb 
lldb was originally designed to get the watchpoint exception behavior
from the gdb remote serial protocol stub -- exceptions are either
received before the instruction executes, or after the instruction
has executed.  This behavior was reported via two lldb extensions
to gdb RSP, so generic remote stubs like gdbserver or a JTAG stub,
would not tell lldb which behavior was correct, and it would default
to "exceptions are received after the instruction has executed".
Two architectures hard coded their correct "exceptions before
instruction" behavior, to work around this issue.

Most architectures have a fixed behavior of watchpoint exceptions,
and we can center that information in lldb.  We can allow a remote
stub to override the default behavior via our packet extensions
if it's needed on a specific target.

This patch also separates the fetching of the number of watchpoints
from whether exceptions are before/after the insn.  Currently if
lldb couldn't fetch the number of watchpoints (not really needed), it
also wouldn't get when exceptions are received, and watchpoint
handling would fail.  lldb doesn't actually use the number of
watchpoints for anything beyond printing it to the user.

Differential Revision: https://reviews.llvm.org/D143215
rdar://101426626
2023-02-14 11:35:39 -08:00

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//===-- StopInfo.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 <string>
#include "lldb/Breakpoint/Breakpoint.h"
#include "lldb/Breakpoint/BreakpointLocation.h"
#include "lldb/Breakpoint/StoppointCallbackContext.h"
#include "lldb/Breakpoint/Watchpoint.h"
#include "lldb/Core/Debugger.h"
#include "lldb/Core/ValueObject.h"
#include "lldb/Expression/UserExpression.h"
#include "lldb/Target/Process.h"
#include "lldb/Target/StopInfo.h"
#include "lldb/Target/Target.h"
#include "lldb/Target/Thread.h"
#include "lldb/Target/ThreadPlan.h"
#include "lldb/Target/ThreadPlanStepInstruction.h"
#include "lldb/Target/UnixSignals.h"
#include "lldb/Utility/LLDBLog.h"
#include "lldb/Utility/Log.h"
#include "lldb/Utility/StreamString.h"
using namespace lldb;
using namespace lldb_private;
StopInfo::StopInfo(Thread &thread, uint64_t value)
: m_thread_wp(thread.shared_from_this()),
m_stop_id(thread.GetProcess()->GetStopID()),
m_resume_id(thread.GetProcess()->GetResumeID()), m_value(value),
m_description(), m_override_should_notify(eLazyBoolCalculate),
m_override_should_stop(eLazyBoolCalculate), m_extended_info() {}
bool StopInfo::IsValid() const {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
return thread_sp->GetProcess()->GetStopID() == m_stop_id;
return false;
}
void StopInfo::MakeStopInfoValid() {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
m_stop_id = thread_sp->GetProcess()->GetStopID();
m_resume_id = thread_sp->GetProcess()->GetResumeID();
}
}
bool StopInfo::HasTargetRunSinceMe() {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
lldb::StateType ret_type = thread_sp->GetProcess()->GetPrivateState();
if (ret_type == eStateRunning) {
return true;
} else if (ret_type == eStateStopped) {
// This is a little tricky. We want to count "run and stopped again
// before you could ask this question as a "TRUE" answer to
// HasTargetRunSinceMe. But we don't want to include any running of the
// target done for expressions. So we track both resumes, and resumes
// caused by expressions, and check if there are any resumes
// NOT caused
// by expressions.
uint32_t curr_resume_id = thread_sp->GetProcess()->GetResumeID();
uint32_t last_user_expression_id =
thread_sp->GetProcess()->GetLastUserExpressionResumeID();
if (curr_resume_id == m_resume_id) {
return false;
} else if (curr_resume_id > last_user_expression_id) {
return true;
}
}
}
return false;
}
// StopInfoBreakpoint
namespace lldb_private {
class StopInfoBreakpoint : public StopInfo {
public:
StopInfoBreakpoint(Thread &thread, break_id_t break_id)
: StopInfo(thread, break_id), m_should_stop(false),
m_should_stop_is_valid(false), m_should_perform_action(true),
m_address(LLDB_INVALID_ADDRESS), m_break_id(LLDB_INVALID_BREAK_ID),
m_was_all_internal(false), m_was_one_shot(false) {
StoreBPInfo();
}
StopInfoBreakpoint(Thread &thread, break_id_t break_id, bool should_stop)
: StopInfo(thread, break_id), m_should_stop(should_stop),
m_should_stop_is_valid(true), m_should_perform_action(true),
m_address(LLDB_INVALID_ADDRESS), m_break_id(LLDB_INVALID_BREAK_ID),
m_was_all_internal(false), m_was_one_shot(false) {
StoreBPInfo();
}
~StopInfoBreakpoint() override = default;
void StoreBPInfo() {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
BreakpointSiteSP bp_site_sp(
thread_sp->GetProcess()->GetBreakpointSiteList().FindByID(m_value));
if (bp_site_sp) {
uint32_t num_owners = bp_site_sp->GetNumberOfOwners();
if (num_owners == 1) {
BreakpointLocationSP bp_loc_sp = bp_site_sp->GetOwnerAtIndex(0);
if (bp_loc_sp) {
Breakpoint & bkpt = bp_loc_sp->GetBreakpoint();
m_break_id = bkpt.GetID();
m_was_one_shot = bkpt.IsOneShot();
m_was_all_internal = bkpt.IsInternal();
}
} else {
m_was_all_internal = true;
for (uint32_t i = 0; i < num_owners; i++) {
if (!bp_site_sp->GetOwnerAtIndex(i)->GetBreakpoint().IsInternal()) {
m_was_all_internal = false;
break;
}
}
}
m_address = bp_site_sp->GetLoadAddress();
}
}
}
bool IsValidForOperatingSystemThread(Thread &thread) override {
ProcessSP process_sp(thread.GetProcess());
if (process_sp) {
BreakpointSiteSP bp_site_sp(
process_sp->GetBreakpointSiteList().FindByID(m_value));
if (bp_site_sp)
return bp_site_sp->ValidForThisThread(thread);
}
return false;
}
StopReason GetStopReason() const override { return eStopReasonBreakpoint; }
bool ShouldStopSynchronous(Event *event_ptr) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
if (!m_should_stop_is_valid) {
// Only check once if we should stop at a breakpoint
BreakpointSiteSP bp_site_sp(
thread_sp->GetProcess()->GetBreakpointSiteList().FindByID(m_value));
if (bp_site_sp) {
ExecutionContext exe_ctx(thread_sp->GetStackFrameAtIndex(0));
StoppointCallbackContext context(event_ptr, exe_ctx, true);
bp_site_sp->BumpHitCounts();
m_should_stop = bp_site_sp->ShouldStop(&context);
} else {
Log *log = GetLog(LLDBLog::Process);
LLDB_LOGF(log,
"Process::%s could not find breakpoint site id: %" PRId64
"...",
__FUNCTION__, m_value);
m_should_stop = true;
}
m_should_stop_is_valid = true;
}
return m_should_stop;
}
return false;
}
bool DoShouldNotify(Event *event_ptr) override {
return !m_was_all_internal;
}
const char *GetDescription() override {
if (m_description.empty()) {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
BreakpointSiteSP bp_site_sp(
thread_sp->GetProcess()->GetBreakpointSiteList().FindByID(m_value));
if (bp_site_sp) {
StreamString strm;
// If we have just hit an internal breakpoint, and it has a kind
// description, print that instead of the full breakpoint printing:
if (bp_site_sp->IsInternal()) {
size_t num_owners = bp_site_sp->GetNumberOfOwners();
for (size_t idx = 0; idx < num_owners; idx++) {
const char *kind = bp_site_sp->GetOwnerAtIndex(idx)
->GetBreakpoint()
.GetBreakpointKind();
if (kind != nullptr) {
m_description.assign(kind);
return kind;
}
}
}
strm.Printf("breakpoint ");
bp_site_sp->GetDescription(&strm, eDescriptionLevelBrief);
m_description = std::string(strm.GetString());
} else {
StreamString strm;
if (m_break_id != LLDB_INVALID_BREAK_ID) {
BreakpointSP break_sp =
thread_sp->GetProcess()->GetTarget().GetBreakpointByID(
m_break_id);
if (break_sp) {
if (break_sp->IsInternal()) {
const char *kind = break_sp->GetBreakpointKind();
if (kind)
strm.Printf("internal %s breakpoint(%d).", kind, m_break_id);
else
strm.Printf("internal breakpoint(%d).", m_break_id);
} else {
strm.Printf("breakpoint %d.", m_break_id);
}
} else {
if (m_was_one_shot)
strm.Printf("one-shot breakpoint %d", m_break_id);
else
strm.Printf("breakpoint %d which has been deleted.",
m_break_id);
}
} else if (m_address == LLDB_INVALID_ADDRESS)
strm.Printf("breakpoint site %" PRIi64
" which has been deleted - unknown address",
m_value);
else
strm.Printf("breakpoint site %" PRIi64
" which has been deleted - was at 0x%" PRIx64,
m_value, m_address);
m_description = std::string(strm.GetString());
}
}
}
return m_description.c_str();
}
protected:
bool ShouldStop(Event *event_ptr) override {
// This just reports the work done by PerformAction or the synchronous
// stop. It should only ever get called after they have had a chance to
// run.
assert(m_should_stop_is_valid);
return m_should_stop;
}
void PerformAction(Event *event_ptr) override {
if (!m_should_perform_action)
return;
m_should_perform_action = false;
bool all_stopping_locs_internal = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
Log *log = GetLog(LLDBLog::Breakpoints | LLDBLog::Step);
if (!thread_sp->IsValid()) {
// This shouldn't ever happen, but just in case, don't do more harm.
if (log) {
LLDB_LOGF(log, "PerformAction got called with an invalid thread.");
}
m_should_stop = true;
m_should_stop_is_valid = true;
return;
}
BreakpointSiteSP bp_site_sp(
thread_sp->GetProcess()->GetBreakpointSiteList().FindByID(m_value));
std::unordered_set<break_id_t> precondition_breakpoints;
// Breakpoints that fail their condition check are not considered to
// have been hit. If the only locations at this site have failed their
// conditions, we should change the stop-info to none. Otherwise, if we
// hit another breakpoint on a different thread which does stop, users
// will see a breakpont hit with a failed condition, which is wrong.
// Use this variable to tell us if that is true.
bool actually_hit_any_locations = false;
if (bp_site_sp) {
// Let's copy the owners list out of the site and store them in a local
// list. That way if one of the breakpoint actions changes the site,
// then we won't be operating on a bad list.
BreakpointLocationCollection site_locations;
size_t num_owners = bp_site_sp->CopyOwnersList(site_locations);
if (num_owners == 0) {
m_should_stop = true;
actually_hit_any_locations = true; // We're going to stop, don't
// change the stop info.
} else {
// We go through each location, and test first its precondition -
// this overrides everything. Note, we only do this once per
// breakpoint - not once per location... Then check the condition.
// If the condition says to stop, then we run the callback for that
// location. If that callback says to stop as well, then we set
// m_should_stop to true; we are going to stop. But we still want to
// give all the breakpoints whose conditions say we are going to stop
// a chance to run their callbacks. Of course if any callback
// restarts the target by putting "continue" in the callback, then
// we're going to restart, without running the rest of the callbacks.
// And in this case we will end up not stopping even if another
// location said we should stop. But that's better than not running
// all the callbacks.
// There's one other complication here. We may have run an async
// breakpoint callback that said we should stop. We only want to
// override that if another breakpoint action says we shouldn't
// stop. If nobody else has an opinion, then we should stop if the
// async callback says we should. An example of this is the async
// shared library load notification breakpoint and the setting
// stop-on-sharedlibrary-events.
// We'll keep the async value in async_should_stop, and track whether
// anyone said we should NOT stop in actually_said_continue.
bool async_should_stop = false;
if (m_should_stop_is_valid)
async_should_stop = m_should_stop;
bool actually_said_continue = false;
m_should_stop = false;
// We don't select threads as we go through them testing breakpoint
// conditions and running commands. So we need to set the thread for
// expression evaluation here:
ThreadList::ExpressionExecutionThreadPusher thread_pusher(thread_sp);
ExecutionContext exe_ctx(thread_sp->GetStackFrameAtIndex(0));
Process *process = exe_ctx.GetProcessPtr();
if (process->GetModIDRef().IsLastResumeForUserExpression()) {
// If we are in the middle of evaluating an expression, don't run
// asynchronous breakpoint commands or expressions. That could
// lead to infinite recursion if the command or condition re-calls
// the function with this breakpoint.
// TODO: We can keep a list of the breakpoints we've seen while
// running expressions in the nested
// PerformAction calls that can arise when the action runs a
// function that hits another breakpoint, and only stop running
// commands when we see the same breakpoint hit a second time.
m_should_stop_is_valid = true;
// It is possible that the user has a breakpoint at the same site
// as the completed plan had (e.g. user has a breakpoint
// on a module entry point, and `ThreadPlanCallFunction` ends
// also there). We can't find an internal breakpoint in the loop
// later because it was already removed on the plan completion.
// So check if the plan was completed, and stop if so.
if (thread_sp->CompletedPlanOverridesBreakpoint()) {
m_should_stop = true;
thread_sp->ResetStopInfo();
return;
}
LLDB_LOGF(log, "StopInfoBreakpoint::PerformAction - Hit a "
"breakpoint while running an expression,"
" not running commands to avoid recursion.");
bool ignoring_breakpoints =
process->GetIgnoreBreakpointsInExpressions();
// Internal breakpoints should be allowed to do their job, we
// can make sure they don't do anything that would cause recursive
// command execution:
if (!m_was_all_internal) {
m_should_stop = !ignoring_breakpoints;
LLDB_LOGF(log,
"StopInfoBreakpoint::PerformAction - in expression, "
"continuing: %s.",
m_should_stop ? "true" : "false");
Debugger::ReportWarning(
"hit breakpoint while running function, skipping commands "
"and conditions to prevent recursion",
process->GetTarget().GetDebugger().GetID());
return;
}
}
StoppointCallbackContext context(event_ptr, exe_ctx, false);
// For safety's sake let's also grab an extra reference to the
// breakpoint owners of the locations we're going to examine, since
// the locations are going to have to get back to their breakpoints,
// and the locations don't keep their owners alive. I'm just
// sticking the BreakpointSP's in a vector since I'm only using it to
// locally increment their retain counts.
std::vector<lldb::BreakpointSP> location_owners;
for (size_t j = 0; j < num_owners; j++) {
BreakpointLocationSP loc(site_locations.GetByIndex(j));
location_owners.push_back(loc->GetBreakpoint().shared_from_this());
}
for (size_t j = 0; j < num_owners; j++) {
lldb::BreakpointLocationSP bp_loc_sp = site_locations.GetByIndex(j);
StreamString loc_desc;
if (log) {
bp_loc_sp->GetDescription(&loc_desc, eDescriptionLevelBrief);
}
// If another action disabled this breakpoint or its location, then
// don't run the actions.
if (!bp_loc_sp->IsEnabled() ||
!bp_loc_sp->GetBreakpoint().IsEnabled())
continue;
// The breakpoint site may have many locations associated with it,
// not all of them valid for this thread. Skip the ones that
// aren't:
if (!bp_loc_sp->ValidForThisThread(*thread_sp)) {
if (log) {
LLDB_LOGF(log,
"Breakpoint %s hit on thread 0x%llx but it was not "
"for this thread, continuing.",
loc_desc.GetData(),
static_cast<unsigned long long>(thread_sp->GetID()));
}
continue;
}
// First run the precondition, but since the precondition is per
// breakpoint, only run it once per breakpoint.
std::pair<std::unordered_set<break_id_t>::iterator, bool> result =
precondition_breakpoints.insert(
bp_loc_sp->GetBreakpoint().GetID());
if (!result.second)
continue;
bool precondition_result =
bp_loc_sp->GetBreakpoint().EvaluatePrecondition(context);
if (!precondition_result) {
actually_said_continue = true;
continue;
}
// Next run the condition for the breakpoint. If that says we
// should stop, then we'll run the callback for the breakpoint. If
// the callback says we shouldn't stop that will win.
if (bp_loc_sp->GetConditionText() == nullptr)
actually_hit_any_locations = true;
else {
Status condition_error;
bool condition_says_stop =
bp_loc_sp->ConditionSaysStop(exe_ctx, condition_error);
if (!condition_error.Success()) {
// If the condition fails to evaluate, we are going to stop
// at it, so the location was hit.
actually_hit_any_locations = true;
const char *err_str =
condition_error.AsCString("<unknown error>");
LLDB_LOGF(log, "Error evaluating condition: \"%s\"\n", err_str);
StreamString strm;
strm << "stopped due to an error evaluating condition of "
"breakpoint ";
bp_loc_sp->GetDescription(&strm, eDescriptionLevelBrief);
strm << ": \"" << bp_loc_sp->GetConditionText() << "\"\n";
strm << err_str;
Debugger::ReportError(
strm.GetString().str(),
exe_ctx.GetTargetRef().GetDebugger().GetID());
} else {
LLDB_LOGF(log,
"Condition evaluated for breakpoint %s on thread "
"0x%llx condition_says_stop: %i.",
loc_desc.GetData(),
static_cast<unsigned long long>(thread_sp->GetID()),
condition_says_stop);
if (condition_says_stop)
actually_hit_any_locations = true;
else {
// We don't want to increment the hit count of breakpoints if
// the condition fails. We've already bumped it by the time
// we get here, so undo the bump:
bp_loc_sp->UndoBumpHitCount();
actually_said_continue = true;
continue;
}
}
}
// We've done all the checks whose failure means "we consider lldb
// not to have hit the breakpoint". Now we're going to check for
// conditions that might continue after hitting. Start with the
// ignore count:
if (!bp_loc_sp->IgnoreCountShouldStop()) {
actually_said_continue = true;
continue;
}
// Check the auto-continue bit on the location, do this before the
// callback since it may change this, but that would be for the
// NEXT hit. Note, you might think you could check auto-continue
// before the condition, and not evaluate the condition if it says
// to continue. But failing the condition means the breakpoint was
// effectively NOT HIT. So these two states are different.
bool auto_continue_says_stop = true;
if (bp_loc_sp->IsAutoContinue())
{
LLDB_LOGF(log,
"Continuing breakpoint %s as AutoContinue was set.",
loc_desc.GetData());
// We want this stop reported, so you will know we auto-continued
// but only for external breakpoints:
if (!bp_loc_sp->GetBreakpoint().IsInternal())
thread_sp->SetShouldReportStop(eVoteYes);
auto_continue_says_stop = false;
}
bool callback_says_stop = true;
// FIXME: For now the callbacks have to run in async mode - the
// first time we restart we need
// to get out of there. So set it here.
// When we figure out how to nest breakpoint hits then this will
// change.
// Don't run async callbacks in PerformAction. They have already
// been taken into account with async_should_stop.
if (!bp_loc_sp->IsCallbackSynchronous()) {
Debugger &debugger = thread_sp->CalculateTarget()->GetDebugger();
bool old_async = debugger.GetAsyncExecution();
debugger.SetAsyncExecution(true);
callback_says_stop = bp_loc_sp->InvokeCallback(&context);
debugger.SetAsyncExecution(old_async);
if (callback_says_stop && auto_continue_says_stop)
m_should_stop = true;
else
actually_said_continue = true;
}
if (m_should_stop && !bp_loc_sp->GetBreakpoint().IsInternal())
all_stopping_locs_internal = false;
// If we are going to stop for this breakpoint, then remove the
// breakpoint.
if (callback_says_stop && bp_loc_sp &&
bp_loc_sp->GetBreakpoint().IsOneShot()) {
thread_sp->GetProcess()->GetTarget().RemoveBreakpointByID(
bp_loc_sp->GetBreakpoint().GetID());
}
// Also make sure that the callback hasn't continued the target. If
// it did, when we'll set m_should_start to false and get out of
// here.
if (HasTargetRunSinceMe()) {
m_should_stop = false;
actually_said_continue = true;
break;
}
}
// At this point if nobody actually told us to continue, we should
// give the async breakpoint callback a chance to weigh in:
if (!actually_said_continue && !m_should_stop) {
m_should_stop = async_should_stop;
}
}
// We've figured out what this stop wants to do, so mark it as valid so
// we don't compute it again.
m_should_stop_is_valid = true;
} else {
m_should_stop = true;
m_should_stop_is_valid = true;
actually_hit_any_locations = true;
Log *log_process(GetLog(LLDBLog::Process));
LLDB_LOGF(log_process,
"Process::%s could not find breakpoint site id: %" PRId64
"...",
__FUNCTION__, m_value);
}
if ((!m_should_stop || all_stopping_locs_internal) &&
thread_sp->CompletedPlanOverridesBreakpoint()) {
// Override should_stop decision when we have completed step plan
// additionally to the breakpoint
m_should_stop = true;
// We know we're stopping for a completed plan and we don't want to
// show the breakpoint stop, so compute the public stop info immediately
// here.
thread_sp->CalculatePublicStopInfo();
} else if (!actually_hit_any_locations) {
// In the end, we didn't actually have any locations that passed their
// "was I hit" checks. So say we aren't stopped.
GetThread()->ResetStopInfo();
LLDB_LOGF(log, "Process::%s all locations failed condition checks.",
__FUNCTION__);
}
LLDB_LOGF(log,
"Process::%s returning from action with m_should_stop: %d.",
__FUNCTION__, m_should_stop);
}
}
private:
bool m_should_stop;
bool m_should_stop_is_valid;
bool m_should_perform_action; // Since we are trying to preserve the "state"
// of the system even if we run functions
// etc. behind the users backs, we need to make sure we only REALLY perform
// the action once.
lldb::addr_t m_address; // We use this to capture the breakpoint site address
// when we create the StopInfo,
// in case somebody deletes it between the time the StopInfo is made and the
// description is asked for.
lldb::break_id_t m_break_id;
bool m_was_all_internal;
bool m_was_one_shot;
};
// StopInfoWatchpoint
class StopInfoWatchpoint : public StopInfo {
public:
// Make sure watchpoint is properly disabled and subsequently enabled while
// performing watchpoint actions.
class WatchpointSentry {
public:
WatchpointSentry(ProcessSP p_sp, WatchpointSP w_sp) : process_sp(p_sp),
watchpoint_sp(w_sp) {
if (process_sp && watchpoint_sp) {
const bool notify = false;
watchpoint_sp->TurnOnEphemeralMode();
process_sp->DisableWatchpoint(watchpoint_sp.get(), notify);
process_sp->AddPreResumeAction(SentryPreResumeAction, this);
}
}
void DoReenable() {
if (process_sp && watchpoint_sp) {
bool was_disabled = watchpoint_sp->IsDisabledDuringEphemeralMode();
watchpoint_sp->TurnOffEphemeralMode();
const bool notify = false;
if (was_disabled) {
process_sp->DisableWatchpoint(watchpoint_sp.get(), notify);
} else {
process_sp->EnableWatchpoint(watchpoint_sp.get(), notify);
}
}
}
~WatchpointSentry() {
DoReenable();
if (process_sp)
process_sp->ClearPreResumeAction(SentryPreResumeAction, this);
}
static bool SentryPreResumeAction(void *sentry_void) {
WatchpointSentry *sentry = (WatchpointSentry *) sentry_void;
sentry->DoReenable();
return true;
}
private:
ProcessSP process_sp;
WatchpointSP watchpoint_sp;
};
StopInfoWatchpoint(Thread &thread, break_id_t watch_id,
lldb::addr_t watch_hit_addr)
: StopInfo(thread, watch_id), m_watch_hit_addr(watch_hit_addr) {}
~StopInfoWatchpoint() override = default;
StopReason GetStopReason() const override { return eStopReasonWatchpoint; }
const char *GetDescription() override {
if (m_description.empty()) {
StreamString strm;
strm.Printf("watchpoint %" PRIi64, m_value);
m_description = std::string(strm.GetString());
}
return m_description.c_str();
}
protected:
using StopInfoWatchpointSP = std::shared_ptr<StopInfoWatchpoint>;
// This plan is used to orchestrate stepping over the watchpoint for
// architectures (e.g. ARM) that report the watch before running the watched
// access. This is the sort of job you have to defer to the thread plans,
// if you try to do it directly in the stop info and there are other threads
// that needed to process this stop you will have yanked control away from
// them and they won't behave correctly.
class ThreadPlanStepOverWatchpoint : public ThreadPlanStepInstruction {
public:
ThreadPlanStepOverWatchpoint(Thread &thread,
StopInfoWatchpointSP stop_info_sp,
WatchpointSP watch_sp)
: ThreadPlanStepInstruction(thread, false, true, eVoteNoOpinion,
eVoteNoOpinion),
m_stop_info_sp(stop_info_sp), m_watch_sp(watch_sp) {
assert(watch_sp);
m_watch_index = watch_sp->GetHardwareIndex();
}
bool DoWillResume(lldb::StateType resume_state,
bool current_plan) override {
if (resume_state == eStateSuspended)
return true;
if (!m_did_disable_wp) {
GetThread().GetProcess()->DisableWatchpoint(m_watch_sp.get(), false);
m_did_disable_wp = true;
}
return true;
}
bool DoPlanExplainsStop(Event *event_ptr) override {
if (ThreadPlanStepInstruction::DoPlanExplainsStop(event_ptr))
return true;
StopInfoSP stop_info_sp = GetThread().GetPrivateStopInfo();
// lldb-server resets the stop info for threads that didn't get to run,
// so we might have not gotten to run, but still have a watchpoint stop
// reason, in which case this will indeed be for us.
if (stop_info_sp
&& stop_info_sp->GetStopReason() == eStopReasonWatchpoint)
return true;
return false;
}
void DidPop() override {
// Don't artifically keep the watchpoint alive.
m_watch_sp.reset();
}
bool ShouldStop(Event *event_ptr) override {
bool should_stop = ThreadPlanStepInstruction::ShouldStop(event_ptr);
bool plan_done = MischiefManaged();
if (plan_done) {
m_stop_info_sp->SetStepOverPlanComplete();
GetThread().SetStopInfo(m_stop_info_sp);
ResetWatchpoint();
}
return should_stop;
}
bool ShouldRunBeforePublicStop() override {
return true;
}
protected:
void ResetWatchpoint() {
if (!m_did_disable_wp)
return;
m_did_disable_wp = true;
GetThread().GetProcess()->EnableWatchpoint(m_watch_sp.get(), true);
m_watch_sp->SetHardwareIndex(m_watch_index);
}
private:
StopInfoWatchpointSP m_stop_info_sp;
WatchpointSP m_watch_sp;
uint32_t m_watch_index = LLDB_INVALID_INDEX32;
bool m_did_disable_wp = false;
};
bool ShouldStopSynchronous(Event *event_ptr) override {
// If we are running our step-over the watchpoint plan, stop if it's done
// and continue if it's not:
if (m_should_stop_is_valid)
return m_should_stop;
// If we are running our step over plan, then stop here and let the regular
// ShouldStop figure out what we should do: Otherwise, give our plan
// more time to get run:
if (m_using_step_over_plan)
return m_step_over_plan_complete;
Log *log = GetLog(LLDBLog::Process);
ThreadSP thread_sp(m_thread_wp.lock());
assert(thread_sp);
if (thread_sp->GetTemporaryResumeState() == eStateSuspended) {
// This is the second firing of a watchpoint so don't process it again.
LLDB_LOG(log, "We didn't run but stopped with a StopInfoWatchpoint, we "
"have already handled this one, don't do it again.");
m_should_stop = false;
m_should_stop_is_valid = true;
return m_should_stop;
}
WatchpointSP wp_sp(
thread_sp->CalculateTarget()->GetWatchpointList().FindByID(GetValue()));
// If we can no longer find the watchpoint, we just have to stop:
if (!wp_sp) {
LLDB_LOGF(log,
"Process::%s could not find watchpoint location id: %" PRId64
"...",
__FUNCTION__, GetValue());
m_should_stop = true;
m_should_stop_is_valid = true;
return true;
}
ExecutionContext exe_ctx(thread_sp->GetStackFrameAtIndex(0));
StoppointCallbackContext context(event_ptr, exe_ctx, true);
m_should_stop = wp_sp->ShouldStop(&context);
if (!m_should_stop) {
// This won't happen at present because we only allow one watchpoint per
// watched range. So we won't stop at a watched address with a disabled
// watchpoint. If we start allowing overlapping watchpoints, then we
// will have to make watchpoints be real "WatchpointSite" and delegate to
// all the watchpoints sharing the site. In that case, the code below
// would be the right thing to do.
m_should_stop_is_valid = true;
return m_should_stop;
}
// If this is a system where we need to execute the watchpoint by hand
// after the hit, queue a thread plan to do that, and then say not to stop.
// Otherwise, let the async action figure out whether the watchpoint should
// stop
ProcessSP process_sp = exe_ctx.GetProcessSP();
bool wp_triggers_after = process_sp->GetWatchpointReportedAfter();
if (!wp_triggers_after) {
// We have to step over the watchpoint before we know what to do:
StopInfoWatchpointSP me_as_siwp_sp
= std::static_pointer_cast<StopInfoWatchpoint>(shared_from_this());
ThreadPlanSP step_over_wp_sp(new ThreadPlanStepOverWatchpoint(
*(thread_sp.get()), me_as_siwp_sp, wp_sp));
Status error;
error = thread_sp->QueueThreadPlan(step_over_wp_sp, false);
// If we couldn't push the thread plan, just stop here:
if (!error.Success()) {
LLDB_LOGF(log, "Could not push our step over watchpoint plan: %s",
error.AsCString());
m_should_stop = true;
m_should_stop_is_valid = true;
return true;
} else {
// Otherwise, don't set m_should_stop, we don't know that yet. Just
// say we should continue, and tell the thread we really should do so:
thread_sp->SetShouldRunBeforePublicStop(true);
m_using_step_over_plan = true;
return false;
}
} else {
// We didn't have to do anything special
m_should_stop_is_valid = true;
return m_should_stop;
}
return m_should_stop;
}
bool ShouldStop(Event *event_ptr) override {
// This just reports the work done by PerformAction or the synchronous
// stop. It should only ever get called after they have had a chance to
// run.
assert(m_should_stop_is_valid);
return m_should_stop;
}
void PerformAction(Event *event_ptr) override {
Log *log = GetLog(LLDBLog::Watchpoints);
// We're going to calculate if we should stop or not in some way during the
// course of this code. Also by default we're going to stop, so set that
// here.
m_should_stop = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
WatchpointSP wp_sp(
thread_sp->CalculateTarget()->GetWatchpointList().FindByID(
GetValue()));
if (wp_sp) {
// This sentry object makes sure the current watchpoint is disabled
// while performing watchpoint actions, and it is then enabled after we
// are finished.
ExecutionContext exe_ctx(thread_sp->GetStackFrameAtIndex(0));
ProcessSP process_sp = exe_ctx.GetProcessSP();
WatchpointSentry sentry(process_sp, wp_sp);
/*
* MIPS: Last 3bits of the watchpoint address are masked by the kernel.
* For example:
* 'n' is at 0x120010d00 and 'm' is 0x120010d04. When a watchpoint is
* set at 'm', then
* watch exception is generated even when 'n' is read/written. To handle
* this case,
* server emulates the instruction at PC and finds the base address of
* the load/store
* instruction and appends it in the description of the stop-info
* packet. If watchpoint
* is not set on this address by user then this do not stop.
*/
if (m_watch_hit_addr != LLDB_INVALID_ADDRESS) {
WatchpointSP wp_hit_sp =
thread_sp->CalculateTarget()->GetWatchpointList().FindByAddress(
m_watch_hit_addr);
if (!wp_hit_sp) {
m_should_stop = false;
wp_sp->IncrementFalseAlarmsAndReviseHitCount();
}
}
if (wp_sp->GetHitCount() <= wp_sp->GetIgnoreCount()) {
m_should_stop = false;
m_should_stop_is_valid = true;
}
Debugger &debugger = exe_ctx.GetTargetRef().GetDebugger();
if (m_should_stop && wp_sp->GetConditionText() != nullptr) {
// We need to make sure the user sees any parse errors in their
// condition, so we'll hook the constructor errors up to the
// debugger's Async I/O.
ExpressionResults result_code;
EvaluateExpressionOptions expr_options;
expr_options.SetUnwindOnError(true);
expr_options.SetIgnoreBreakpoints(true);
ValueObjectSP result_value_sp;
Status error;
result_code = UserExpression::Evaluate(
exe_ctx, expr_options, wp_sp->GetConditionText(),
llvm::StringRef(), result_value_sp, error);
if (result_code == eExpressionCompleted) {
if (result_value_sp) {
Scalar scalar_value;
if (result_value_sp->ResolveValue(scalar_value)) {
if (scalar_value.ULongLong(1) == 0) {
// The condition failed, which we consider "not having hit
// the watchpoint" so undo the hit count here.
wp_sp->UndoHitCount();
m_should_stop = false;
} else
m_should_stop = true;
LLDB_LOGF(log,
"Condition successfully evaluated, result is %s.\n",
m_should_stop ? "true" : "false");
} else {
m_should_stop = true;
LLDB_LOGF(
log,
"Failed to get an integer result from the expression.");
}
}
} else {
const char *err_str = error.AsCString("<unknown error>");
LLDB_LOGF(log, "Error evaluating condition: \"%s\"\n", err_str);
StreamString strm;
strm << "stopped due to an error evaluating condition of "
"watchpoint ";
wp_sp->GetDescription(&strm, eDescriptionLevelBrief);
strm << ": \"" << wp_sp->GetConditionText() << "\"\n";
strm << err_str;
Debugger::ReportError(strm.GetString().str(),
exe_ctx.GetTargetRef().GetDebugger().GetID());
}
}
// If the condition says to stop, we run the callback to further decide
// whether to stop.
if (m_should_stop) {
// FIXME: For now the callbacks have to run in async mode - the
// first time we restart we need
// to get out of there. So set it here.
// When we figure out how to nest watchpoint hits then this will
// change.
bool old_async = debugger.GetAsyncExecution();
debugger.SetAsyncExecution(true);
StoppointCallbackContext context(event_ptr, exe_ctx, false);
bool stop_requested = wp_sp->InvokeCallback(&context);
debugger.SetAsyncExecution(old_async);
// Also make sure that the callback hasn't continued the target. If
// it did, when we'll set m_should_stop to false and get out of here.
if (HasTargetRunSinceMe())
m_should_stop = false;
if (m_should_stop && !stop_requested) {
// We have been vetoed by the callback mechanism.
m_should_stop = false;
}
}
// Finally, if we are going to stop, print out the new & old values:
if (m_should_stop) {
wp_sp->CaptureWatchedValue(exe_ctx);
Debugger &debugger = exe_ctx.GetTargetRef().GetDebugger();
StreamSP output_sp = debugger.GetAsyncOutputStream();
wp_sp->DumpSnapshots(output_sp.get());
output_sp->EOL();
output_sp->Flush();
}
} else {
Log *log_process(GetLog(LLDBLog::Process));
LLDB_LOGF(log_process,
"Process::%s could not find watchpoint id: %" PRId64 "...",
__FUNCTION__, m_value);
}
LLDB_LOGF(log,
"Process::%s returning from action with m_should_stop: %d.",
__FUNCTION__, m_should_stop);
m_should_stop_is_valid = true;
}
}
private:
void SetStepOverPlanComplete() {
assert(m_using_step_over_plan);
m_step_over_plan_complete = true;
}
bool m_should_stop = false;
bool m_should_stop_is_valid = false;
lldb::addr_t m_watch_hit_addr;
bool m_step_over_plan_complete = false;
bool m_using_step_over_plan = false;
};
// StopInfoUnixSignal
class StopInfoUnixSignal : public StopInfo {
public:
StopInfoUnixSignal(Thread &thread, int signo, const char *description)
: StopInfo(thread, signo) {
SetDescription(description);
}
~StopInfoUnixSignal() override = default;
StopReason GetStopReason() const override { return eStopReasonSignal; }
bool ShouldStopSynchronous(Event *event_ptr) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
return thread_sp->GetProcess()->GetUnixSignals()->GetShouldStop(m_value);
return false;
}
bool ShouldStop(Event *event_ptr) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
return thread_sp->GetProcess()->GetUnixSignals()->GetShouldStop(m_value);
return false;
}
// If should stop returns false, check if we should notify of this event
bool DoShouldNotify(Event *event_ptr) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
bool should_notify =
thread_sp->GetProcess()->GetUnixSignals()->GetShouldNotify(m_value);
if (should_notify) {
StreamString strm;
strm.Printf(
"thread %d received signal: %s", thread_sp->GetIndexID(),
thread_sp->GetProcess()->GetUnixSignals()->GetSignalAsCString(
m_value));
Process::ProcessEventData::AddRestartedReason(event_ptr,
strm.GetData());
}
return should_notify;
}
return true;
}
void WillResume(lldb::StateType resume_state) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
if (!thread_sp->GetProcess()->GetUnixSignals()->GetShouldSuppress(
m_value))
thread_sp->SetResumeSignal(m_value);
}
}
const char *GetDescription() override {
if (m_description.empty()) {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp) {
StreamString strm;
const char *signal_name =
thread_sp->GetProcess()->GetUnixSignals()->GetSignalAsCString(
m_value);
if (signal_name)
strm.Printf("signal %s", signal_name);
else
strm.Printf("signal %" PRIi64, m_value);
m_description = std::string(strm.GetString());
}
}
return m_description.c_str();
}
};
// StopInfoTrace
class StopInfoTrace : public StopInfo {
public:
StopInfoTrace(Thread &thread) : StopInfo(thread, LLDB_INVALID_UID) {}
~StopInfoTrace() override = default;
StopReason GetStopReason() const override { return eStopReasonTrace; }
const char *GetDescription() override {
if (m_description.empty())
return "trace";
else
return m_description.c_str();
}
};
// StopInfoException
class StopInfoException : public StopInfo {
public:
StopInfoException(Thread &thread, const char *description)
: StopInfo(thread, LLDB_INVALID_UID) {
if (description)
SetDescription(description);
}
~StopInfoException() override = default;
StopReason GetStopReason() const override { return eStopReasonException; }
const char *GetDescription() override {
if (m_description.empty())
return "exception";
else
return m_description.c_str();
}
};
// StopInfoProcessorTrace
class StopInfoProcessorTrace : public StopInfo {
public:
StopInfoProcessorTrace(Thread &thread, const char *description)
: StopInfo(thread, LLDB_INVALID_UID) {
if (description)
SetDescription(description);
}
~StopInfoProcessorTrace() override = default;
StopReason GetStopReason() const override {
return eStopReasonProcessorTrace;
}
const char *GetDescription() override {
if (m_description.empty())
return "processor trace event";
else
return m_description.c_str();
}
};
// StopInfoThreadPlan
class StopInfoThreadPlan : public StopInfo {
public:
StopInfoThreadPlan(ThreadPlanSP &plan_sp, ValueObjectSP &return_valobj_sp,
ExpressionVariableSP &expression_variable_sp)
: StopInfo(plan_sp->GetThread(), LLDB_INVALID_UID), m_plan_sp(plan_sp),
m_return_valobj_sp(return_valobj_sp),
m_expression_variable_sp(expression_variable_sp) {}
~StopInfoThreadPlan() override = default;
StopReason GetStopReason() const override { return eStopReasonPlanComplete; }
const char *GetDescription() override {
if (m_description.empty()) {
StreamString strm;
m_plan_sp->GetDescription(&strm, eDescriptionLevelBrief);
m_description = std::string(strm.GetString());
}
return m_description.c_str();
}
ValueObjectSP GetReturnValueObject() { return m_return_valobj_sp; }
ExpressionVariableSP GetExpressionVariable() {
return m_expression_variable_sp;
}
protected:
bool ShouldStop(Event *event_ptr) override {
if (m_plan_sp)
return m_plan_sp->ShouldStop(event_ptr);
else
return StopInfo::ShouldStop(event_ptr);
}
private:
ThreadPlanSP m_plan_sp;
ValueObjectSP m_return_valobj_sp;
ExpressionVariableSP m_expression_variable_sp;
};
// StopInfoExec
class StopInfoExec : public StopInfo {
public:
StopInfoExec(Thread &thread) : StopInfo(thread, LLDB_INVALID_UID) {}
~StopInfoExec() override = default;
bool ShouldStop(Event *event_ptr) override {
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
return thread_sp->GetProcess()->GetStopOnExec();
return false;
}
StopReason GetStopReason() const override { return eStopReasonExec; }
const char *GetDescription() override { return "exec"; }
protected:
void PerformAction(Event *event_ptr) override {
// Only perform the action once
if (m_performed_action)
return;
m_performed_action = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
thread_sp->GetProcess()->DidExec();
}
bool m_performed_action = false;
};
// StopInfoFork
class StopInfoFork : public StopInfo {
public:
StopInfoFork(Thread &thread, lldb::pid_t child_pid, lldb::tid_t child_tid)
: StopInfo(thread, child_pid), m_child_pid(child_pid),
m_child_tid(child_tid) {}
~StopInfoFork() override = default;
bool ShouldStop(Event *event_ptr) override { return false; }
StopReason GetStopReason() const override { return eStopReasonFork; }
const char *GetDescription() override { return "fork"; }
protected:
void PerformAction(Event *event_ptr) override {
// Only perform the action once
if (m_performed_action)
return;
m_performed_action = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
thread_sp->GetProcess()->DidFork(m_child_pid, m_child_tid);
}
bool m_performed_action = false;
private:
lldb::pid_t m_child_pid;
lldb::tid_t m_child_tid;
};
// StopInfoVFork
class StopInfoVFork : public StopInfo {
public:
StopInfoVFork(Thread &thread, lldb::pid_t child_pid, lldb::tid_t child_tid)
: StopInfo(thread, child_pid), m_child_pid(child_pid),
m_child_tid(child_tid) {}
~StopInfoVFork() override = default;
bool ShouldStop(Event *event_ptr) override { return false; }
StopReason GetStopReason() const override { return eStopReasonVFork; }
const char *GetDescription() override { return "vfork"; }
protected:
void PerformAction(Event *event_ptr) override {
// Only perform the action once
if (m_performed_action)
return;
m_performed_action = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
thread_sp->GetProcess()->DidVFork(m_child_pid, m_child_tid);
}
bool m_performed_action = false;
private:
lldb::pid_t m_child_pid;
lldb::tid_t m_child_tid;
};
// StopInfoVForkDone
class StopInfoVForkDone : public StopInfo {
public:
StopInfoVForkDone(Thread &thread) : StopInfo(thread, 0) {}
~StopInfoVForkDone() override = default;
bool ShouldStop(Event *event_ptr) override { return false; }
StopReason GetStopReason() const override { return eStopReasonVForkDone; }
const char *GetDescription() override { return "vforkdone"; }
protected:
void PerformAction(Event *event_ptr) override {
// Only perform the action once
if (m_performed_action)
return;
m_performed_action = true;
ThreadSP thread_sp(m_thread_wp.lock());
if (thread_sp)
thread_sp->GetProcess()->DidVForkDone();
}
bool m_performed_action = false;
};
} // namespace lldb_private
StopInfoSP StopInfo::CreateStopReasonWithBreakpointSiteID(Thread &thread,
break_id_t break_id) {
return StopInfoSP(new StopInfoBreakpoint(thread, break_id));
}
StopInfoSP StopInfo::CreateStopReasonWithBreakpointSiteID(Thread &thread,
break_id_t break_id,
bool should_stop) {
return StopInfoSP(new StopInfoBreakpoint(thread, break_id, should_stop));
}
StopInfoSP
StopInfo::CreateStopReasonWithWatchpointID(Thread &thread, break_id_t watch_id,
lldb::addr_t watch_hit_addr) {
return StopInfoSP(new StopInfoWatchpoint(thread, watch_id, watch_hit_addr));
}
StopInfoSP StopInfo::CreateStopReasonWithSignal(Thread &thread, int signo,
const char *description) {
thread.GetProcess()->GetUnixSignals()->IncrementSignalHitCount(signo);
return StopInfoSP(new StopInfoUnixSignal(thread, signo, description));
}
StopInfoSP StopInfo::CreateStopReasonToTrace(Thread &thread) {
return StopInfoSP(new StopInfoTrace(thread));
}
StopInfoSP StopInfo::CreateStopReasonWithPlan(
ThreadPlanSP &plan_sp, ValueObjectSP return_valobj_sp,
ExpressionVariableSP expression_variable_sp) {
return StopInfoSP(new StopInfoThreadPlan(plan_sp, return_valobj_sp,
expression_variable_sp));
}
StopInfoSP StopInfo::CreateStopReasonWithException(Thread &thread,
const char *description) {
return StopInfoSP(new StopInfoException(thread, description));
}
StopInfoSP StopInfo::CreateStopReasonProcessorTrace(Thread &thread,
const char *description) {
return StopInfoSP(new StopInfoProcessorTrace(thread, description));
}
StopInfoSP StopInfo::CreateStopReasonWithExec(Thread &thread) {
return StopInfoSP(new StopInfoExec(thread));
}
StopInfoSP StopInfo::CreateStopReasonFork(Thread &thread,
lldb::pid_t child_pid,
lldb::tid_t child_tid) {
return StopInfoSP(new StopInfoFork(thread, child_pid, child_tid));
}
StopInfoSP StopInfo::CreateStopReasonVFork(Thread &thread,
lldb::pid_t child_pid,
lldb::tid_t child_tid) {
return StopInfoSP(new StopInfoVFork(thread, child_pid, child_tid));
}
StopInfoSP StopInfo::CreateStopReasonVForkDone(Thread &thread) {
return StopInfoSP(new StopInfoVForkDone(thread));
}
ValueObjectSP StopInfo::GetReturnValueObject(StopInfoSP &stop_info_sp) {
if (stop_info_sp &&
stop_info_sp->GetStopReason() == eStopReasonPlanComplete) {
StopInfoThreadPlan *plan_stop_info =
static_cast<StopInfoThreadPlan *>(stop_info_sp.get());
return plan_stop_info->GetReturnValueObject();
} else
return ValueObjectSP();
}
ExpressionVariableSP StopInfo::GetExpressionVariable(StopInfoSP &stop_info_sp) {
if (stop_info_sp &&
stop_info_sp->GetStopReason() == eStopReasonPlanComplete) {
StopInfoThreadPlan *plan_stop_info =
static_cast<StopInfoThreadPlan *>(stop_info_sp.get());
return plan_stop_info->GetExpressionVariable();
} else
return ExpressionVariableSP();
}
lldb::ValueObjectSP
StopInfo::GetCrashingDereference(StopInfoSP &stop_info_sp,
lldb::addr_t *crashing_address) {
if (!stop_info_sp) {
return ValueObjectSP();
}
const char *description = stop_info_sp->GetDescription();
if (!description) {
return ValueObjectSP();
}
ThreadSP thread_sp = stop_info_sp->GetThread();
if (!thread_sp) {
return ValueObjectSP();
}
StackFrameSP frame_sp = thread_sp->GetSelectedFrame();
if (!frame_sp) {
return ValueObjectSP();
}
const char address_string[] = "address=";
const char *address_loc = strstr(description, address_string);
if (!address_loc) {
return ValueObjectSP();
}
address_loc += (sizeof(address_string) - 1);
uint64_t address = strtoull(address_loc, nullptr, 0);
if (crashing_address) {
*crashing_address = address;
}
return frame_sp->GuessValueForAddress(address);
}
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