Commit a13d0f8d authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

Merge tag 'irqchip-fixes-5.13-2' of... 

Merge tag 'irqchip-fixes-5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms into irq/urgent

Pull irqchip fixes from Marc Zyngier:

- Fix GICv3 NMI handling where an IRQ could be mistakenly handled
  as a NMI, with disatrous effects

Link: https://lore.kernel.org/r/20210610171127.2404752-1-maz@kernel.org
parents 009c9aa5 382e6e17

drivers/irqchip/irq-gic-v3.c

+35 −1
Original line number Diff line number Diff line
@@ -642,11 +642,45 @@ static inline void gic_handle_nmi(u32 irqnr, struct pt_regs *regs) 
		nmi_exit();

}



static u32 do_read_iar(struct pt_regs *regs)

{

	u32 iar;



	if (gic_supports_nmi() && unlikely(!interrupts_enabled(regs))) {

		u64 pmr;



		/*

		 * We were in a context with IRQs disabled. However, the

		 * entry code has set PMR to a value that allows any

		 * interrupt to be acknowledged, and not just NMIs. This can

		 * lead to surprising effects if the NMI has been retired in

		 * the meantime, and that there is an IRQ pending. The IRQ

		 * would then be taken in NMI context, something that nobody

		 * wants to debug twice.

		 *

		 * Until we sort this, drop PMR again to a level that will

		 * actually only allow NMIs before reading IAR, and then

		 * restore it to what it was.

		 */

		pmr = gic_read_pmr();

		gic_pmr_mask_irqs();

		isb();



		iar = gic_read_iar();



		gic_write_pmr(pmr);

	} else {

		iar = gic_read_iar();

	}



	return iar;

}



static asmlinkage void __exception_irq_entry gic_handle_irq(struct pt_regs *regs)

{

	u32 irqnr;



	irqnr = gic_read_iar();

	irqnr = do_read_iar(regs);



	/* Check for special IDs first */

	if ((irqnr >= 1020 && irqnr <= 1023))