Commit c2854801 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64: Fix perf profiling asynchronous interrupt handlers 



Interrupt entry sets the soft mask to IRQS_ALL_DISABLED to match the
hard irq disabled state. So when should_hard_irq_enable() returns true
because we want PMI interrupts in irq handlers, MSR[EE] is enabled but
PMIs just get soft-masked. Fix this by clearing IRQS_PMI_DISABLED before
enabling MSR[EE].

This also tidies some of the warnings, no need to duplicate them in
both should_hard_irq_enable() and do_hard_irq_enable().

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230121100156.2824054-1-npiggin@gmail.com
parent bc88ef66

arch/powerpc/include/asm/hw_irq.h

+29 −12
Original line number Diff line number Diff line
@@ -173,6 +173,15 @@ static inline notrace unsigned long irq_soft_mask_or_return(unsigned long mask) 
	return flags;

}



static inline notrace unsigned long irq_soft_mask_andc_return(unsigned long mask)

{

	unsigned long flags = irq_soft_mask_return();



	irq_soft_mask_set(flags & ~mask);



	return flags;

}



static inline unsigned long arch_local_save_flags(void)

{

	return irq_soft_mask_return();
@@ -331,10 +340,11 @@ bool power_pmu_wants_prompt_pmi(void); 
 * is a different soft-masked interrupt pending that requires hard

 * masking.

 */

static inline bool should_hard_irq_enable(void)

static inline bool should_hard_irq_enable(struct pt_regs *regs)

{

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {

		WARN_ON(irq_soft_mask_return() == IRQS_ENABLED);

		WARN_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED);

		WARN_ON(!(get_paca()->irq_happened & PACA_IRQ_HARD_DIS));

		WARN_ON(mfmsr() & MSR_EE);

	}
@@ -347,8 +357,17 @@ static inline bool should_hard_irq_enable(void) 
	 *

	 * TODO: Add test for 64e

	 */

	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !power_pmu_wants_prompt_pmi())

	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64)) {

		if (!power_pmu_wants_prompt_pmi())

			return false;

		/*

		 * If PMIs are disabled then IRQs should be disabled as well,

		 * so we shouldn't see this condition, check for it just in

		 * case because we are about to enable PMIs.

		 */

		if (WARN_ON_ONCE(regs->softe & IRQS_PMI_DISABLED))

			return false;

	}



	if (get_paca()->irq_happened & PACA_IRQ_MUST_HARD_MASK)

		return false;
@@ -358,18 +377,16 @@ static inline bool should_hard_irq_enable(void) 


/*

 * Do the hard enabling, only call this if should_hard_irq_enable is true.

 * This allows PMI interrupts to profile irq handlers.

 */

static inline void do_hard_irq_enable(void)

{

	if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {

		WARN_ON(irq_soft_mask_return() == IRQS_ENABLED);

		WARN_ON(get_paca()->irq_happened & PACA_IRQ_MUST_HARD_MASK);

		WARN_ON(mfmsr() & MSR_EE);

	}

	/*

	 * This allows PMI interrupts (and watchdog soft-NMIs) through.

	 * There is no other reason to enable this way.

	 * Asynch interrupts come in with IRQS_ALL_DISABLED,

	 * PACA_IRQ_HARD_DIS, and MSR[EE]=0.

	 */

	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64))

		irq_soft_mask_andc_return(IRQS_PMI_DISABLED);

	get_paca()->irq_happened &= ~PACA_IRQ_HARD_DIS;

	__hard_irq_enable();

}
@@ -452,7 +469,7 @@ static inline bool arch_irq_disabled_regs(struct pt_regs *regs) 
	return !(regs->msr & MSR_EE);

}



static __always_inline bool should_hard_irq_enable(void)

static __always_inline bool should_hard_irq_enable(struct pt_regs *regs)

{

	return false;

}

arch/powerpc/kernel/dbell.c

+1 −1
Original line number Diff line number Diff line
@@ -27,7 +27,7 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(doorbell_exception) 


	ppc_msgsync();



	if (should_hard_irq_enable())

	if (should_hard_irq_enable(regs))

		do_hard_irq_enable();



	kvmppc_clear_host_ipi(smp_processor_id());

arch/powerpc/kernel/irq.c

+1 −1
Original line number Diff line number Diff line
@@ -238,7 +238,7 @@ static void __do_irq(struct pt_regs *regs, unsigned long oldsp) 
	irq = static_call(ppc_get_irq)();



	/* We can hard enable interrupts now to allow perf interrupts */

	if (should_hard_irq_enable())

	if (should_hard_irq_enable(regs))

		do_hard_irq_enable();



	/* And finally process it */

arch/powerpc/kernel/time.c

+1 −1
Original line number Diff line number Diff line
@@ -515,7 +515,7 @@ DEFINE_INTERRUPT_HANDLER_ASYNC(timer_interrupt) 
	}



	/* Conditionally hard-enable interrupts. */

	if (should_hard_irq_enable()) {

	if (should_hard_irq_enable(regs)) {

		/*

		 * Ensure a positive value is written to the decrementer, or

		 * else some CPUs will continue to take decrementer exceptions.