Re: [RFC][PATCH] i386: Per node IDT

[Zwane Mwaikambo <zwane@arm.linux.org.uk>]

Hi Oleg,

On Mon, 11 Jul 2005, Oleg Nesterov wrote:

> > The change is so that we can send IRQs higher than 256 to do_IRQ. That 
> > looks like it tries to check if we came in via system_call since we'd save 
> > the system call number as orig_eax. Now that i think about it, doesn't 
> > that path always get taken when we interrupt userspace and have pending 
> > signals on return from interrupt?
> 
> As far as I can see, we always have orig_eax < 0 on interrupt, because
> 
> irq_entries_start:
> 	pushl $vector-256	<-----  orig_eax
> 	jmp common_interrupt
> 
> and NR_IRQS < 256. So if we have pending signals on return from interrupt,
> do_signal() will not corrupt userspace registers when regs->eax == -ERESTART...
> accidentally.
> 
> Probably it makes sense to change it to
> 	pushl $vector - 0xFFFF - 1
> 
> and in do_IRQ()
> 	int irq = regs->orig_eax & 0xFFFF
> 
> if you need to send IRQs higher than 256 to do_IRQ.

Good catch, thanks i'll change that!

	Zwane

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/