Re: [PATCH 4/5] x86: wire up TIF_NOTIFY_SIGNAL

Jens Axboe
2020-10-15T14:31:28Z

On 10/15/20 8:11 AM, Thomas Gleixner wrote:
> On Thu, Oct 15 2020 at 07:17, Jens Axboe wrote:
>> --- a/arch/x86/kernel/signal.c
>> +++ b/arch/x86/kernel/signal.c
>> @@ -808,7 +808,10 @@ void arch_do_signal(struct pt_regs *regs, unsigned long ti_work)
>> {
>> struct ksignal ksig;
>>
>> - if (get_signal(&ksig)) {
>> + if (ti_work & _TIF_NOTIFY_SIGNAL)
>> + tracehook_notify_signal();
>> +
>> + if ((ti_work & _TIF_SIGPENDING) && get_signal(&ksig)) {
>> /* Whee! Actually deliver the signal. */
>> handle_signal(&ksig, regs);
>> return;
>
> Instead of adding this to every architectures signal magic, we can
> handle TIF_NOTIFY_SIGNAL in the core code:
>
> static void handle_singal_work(ti_work, regs)
> {
> if (ti_work & _TIF_NOTIFY_SIGNAL)
> tracehook_notify_signal();
>
> arch_do_signal(ti_work, regs);
> }
>
> loop {
> if (ti_work & (SIGPENDING | NOTIFY_SIGNAL))
> handle_signal_work(ti_work, regs);
> }

We could, should probably make it:

static void handle_signal_work(ti_work, regs)
{
if (ti_work & _TIF_NOTIFY_SIGNAL)
tracehook_notify_signal();

if (ti_work & _TIF_SIGPENDING)
arch_do_signal(regs);
}

and then we can skip modifying arch_do_signal() all together, as it'll
only be called if _TIF_SIGPENDING is set.

--
Jens Axboe