gdbstub initial code, v8 && ptrace

[Oleg Nesterov]

On 09/06, Oleg Nesterov wrote:
>
> OK, I am stupid. Indeed, say, "return UTRACE_STOP | UTRACE_SIGNAL_IGN"
> from under "case UTRACE_SIGNAL_REPORT" changes utrace_report->result,
> and confuses other tracers.
>
> Probably we can ignore ptrace, but this also means ugdb conflicts
> with itself and should be fixed.

Yes.

I am a bit confused... OK, ugdb is wrong wrt multitracing.
UTRACE_SIGNAL_REPORT case shouldn't return "UTRACE_STOP | UTRACE_SIGNAL_IGN",
it should return "UTRACE_STOP | UTRACE_SIGNAL_REPORT" to keep report->result.
But it needs to return UTRACE_SIGNAL_DELIVER?

Probably we can check orig_ka != NULL and treat orig_ka == NULL as
UTRACE_SIGNAL_REPORT. Hopefully this can't be confused with
UTRACE_SIGNAL_HANDLER.

Not sure about UTRACE_SIGNAL_HOLD, but this is very unlikely race.

I need to re-read utrace_get_signal() with a fresh head.

Oleg.