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Commit 56dfa7fa authored by Benjamin Herrenschmidt's avatar Benjamin Herrenschmidt
Browse files

powerpc/irq: Fix bug with new lazy IRQ handling code 



We had a case where we could turn on hard interrupts while
leaving the PACA_IRQ_HARD_DIS bit set in the PACA. This can
in turn cause a BUG_ON() to hit in __check_irq_replay() due
to interrupt state getting out of sync.

The assembly code was also way too convoluted. Instead, we
now leave it to the C code to do the right thing which ends
up being smaller and more readable.

Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 810b4de2

arch/powerpc/kernel/entry_64.S

+0 −18
Original line number Diff line number Diff line
@@ -767,16 +767,6 @@ do_work: 
	SOFT_DISABLE_INTS(r3,r4)

1:	bl	.preempt_schedule_irq



	/* Hard-disable interrupts again (and update PACA) */

#ifdef CONFIG_PPC_BOOK3E

	wrteei	0

#else

	ld	r10,PACAKMSR(r13) /* Get kernel MSR without EE */

	mtmsrd	r10,1

#endif /* CONFIG_PPC_BOOK3E */

	li	r0,PACA_IRQ_HARD_DIS

	stb	r0,PACAIRQHAPPENED(r13)



	/* Re-test flags and eventually loop */

	clrrdi	r9,r1,THREAD_SHIFT

	ld	r4,TI_FLAGS(r9)
@@ -787,14 +777,6 @@ do_work: 
user_work:

#endif /* CONFIG_PREEMPT */



	/* Enable interrupts */

#ifdef CONFIG_PPC_BOOK3E

	wrteei	1

#else

	ori	r10,r10,MSR_EE

	mtmsrd	r10,1

#endif /* CONFIG_PPC_BOOK3E */



	andi.	r0,r4,_TIF_NEED_RESCHED

	beq	1f

	bl	.restore_interrupts

arch/powerpc/kernel/irq.c

+7 −1
Original line number Diff line number Diff line
@@ -260,11 +260,17 @@ EXPORT_SYMBOL(arch_local_irq_restore); 
 * if they are currently disabled. This is typically called before

 * schedule() or do_signal() when returning to userspace. We do it

 * in C to avoid the burden of dealing with lockdep etc...

 *

 * NOTE: This is called with interrupts hard disabled but not marked

 * as such in paca->irq_happened, so we need to resync this.

 */

void restore_interrupts(void)

{

	if (irqs_disabled())

	if (irqs_disabled()) {

		local_paca->irq_happened |= PACA_IRQ_HARD_DIS;

		local_irq_enable();

	} else

		__hard_irq_enable();

}



#endif /* CONFIG_PPC64 */