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replay: allow runstate shutdown->running when replaying trace

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When replaying a trace, it is possible to go from shutdown to running
with a reverse-debugging step. This can be useful if the problem being
debugged triggers a reset or shutdown.

This can be tested by making a recording of a machine that shuts down,
then using -action shutdown=pause when replaying it. Continuing to the
end of the trace then reverse-stepping in gdb crashes due to invalid
runstate transition.

Just permitting the transition seems to be all that's necessary for
reverse-debugging to work well in such a state.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Pavel Dovgalyuk <Pavel.Dovgalyuk@ispras.ru>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Message-Id: <20240813050638.446172-5-npiggin@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240813202329.1237572-13-alex.bennee@linaro.org>
This commit is contained in:
Nicholas Piggin 2024-08-13 21:23:20 +01:00 committed by Alex Bennée
parent 4926b6e644
commit 9dbab31d9e
3 changed files with 31 additions and 3 deletions
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1
include/sysemu/runstate.h
View file

@ -9,6 +9,7 @@ void runstate_set(RunState new_state);
RunState runstate_get(void);
bool runstate_is_running(void);
bool runstate_needs_reset(void);
void runstate_replay_enable(void);
typedef void VMChangeStateHandler(void *opaque, bool running, RunState state);

2
replay/replay.c
View file

@ -385,6 +385,8 @@ static void replay_enable(const char *fname, int mode)
replay_fetch_data_kind();
}
runstate_replay_enable();
replay_init_events();
}

31
system/runstate.c
View file

@ -181,6 +181,12 @@ static const RunStateTransition runstate_transitions_def[] = {
{ RUN_STATE__MAX, RUN_STATE__MAX },
};
static const RunStateTransition replay_play_runstate_transitions_def[] = {
{ RUN_STATE_SHUTDOWN, RUN_STATE_RUNNING},
{ RUN_STATE__MAX, RUN_STATE__MAX },
};
static bool runstate_valid_transitions[RUN_STATE__MAX][RUN_STATE__MAX];
bool runstate_check(RunState state)
@ -188,14 +194,33 @@ bool runstate_check(RunState state)
return current_run_state == state;
}
static void runstate_init(void)
static void transitions_set_valid(const RunStateTransition *rst)
{
const RunStateTransition *p;
memset(&runstate_valid_transitions, 0, sizeof(runstate_valid_transitions));
for (p = &runstate_transitions_def[0]; p->from != RUN_STATE__MAX; p++) {
for (p = rst; p->from != RUN_STATE__MAX; p++) {
runstate_valid_transitions[p->from][p->to] = true;
}
}
void runstate_replay_enable(void)
{
assert(replay_mode != REPLAY_MODE_NONE);
if (replay_mode == REPLAY_MODE_PLAY) {
/*
* When reverse-debugging, it is possible to move state from
* shutdown to running.
*/
transitions_set_valid(&replay_play_runstate_transitions_def[0]);
}
}
static void runstate_init(void)
{
memset(&runstate_valid_transitions, 0, sizeof(runstate_valid_transitions));
transitions_set_valid(&runstate_transitions_def[0]);
qemu_mutex_init(&vmstop_lock);
}