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Commit ca8f2d7f authored by Paul Mackerras's avatar Paul Mackerras Committed by Ingo Molnar
Browse files

perf_counter: powerpc: add nmi_enter/nmi_exit calls 



Impact: fix potential deadlocks on powerpc

Now that the core is using in_nmi() (added in e30e08f6, "perf_counter:
fix NMI race in task clock"), we need the powerpc perf_counter_interrupt
to call nmi_enter() and nmi_exit() in those cases where the interrupt
happens when interrupts are soft-disabled.

If interrupts were soft-enabled, we can treat it as a regular interrupt
and do irq_enter/irq_exit around the whole routine. This lets us get rid
of the test_perf_counter_pending() call at the end of
perf_counter_interrupt, thus simplifying things a little.

Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <18909.31952.873098.336615@cargo.ozlabs.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 6c0b3244

arch/powerpc/kernel/perf_counter.c

+17 −14
Original line number Diff line number Diff line
@@ -714,7 +714,7 @@ hw_perf_counter_init(struct perf_counter *counter) 
 * here so there is no possibility of being interrupted.

 */

static void record_and_restart(struct perf_counter *counter, long val,

			       struct pt_regs *regs)

			       struct pt_regs *regs, int nmi)

{

	s64 prev, delta, left;

	int record = 0;
@@ -749,7 +749,7 @@ static void record_and_restart(struct perf_counter *counter, long val, 
	 * Finally record data if requested.

	 */

	if (record)

		perf_counter_overflow(counter, 1, regs, 0);

		perf_counter_overflow(counter, nmi, regs, 0);

}



/*
@@ -762,6 +762,17 @@ static void perf_counter_interrupt(struct pt_regs *regs) 
	struct perf_counter *counter;

	long val;

	int found = 0;

	int nmi;



	/*

	 * If interrupts were soft-disabled when this PMU interrupt

	 * occurred, treat it as an NMI.

	 */

	nmi = !regs->softe;

	if (nmi)

		nmi_enter();

	else

		irq_enter();



	for (i = 0; i < cpuhw->n_counters; ++i) {

		counter = cpuhw->counter[i];
@@ -769,7 +780,7 @@ static void perf_counter_interrupt(struct pt_regs *regs) 
		if ((int)val < 0) {

			/* counter has overflowed */

			found = 1;

			record_and_restart(counter, val, regs);

			record_and_restart(counter, val, regs, nmi);

		}

	}
@@ -796,19 +807,11 @@ static void perf_counter_interrupt(struct pt_regs *regs) 
	 */

	mtspr(SPRN_MMCR0, cpuhw->mmcr[0]);



	/*

	 * If we need a wakeup, check whether interrupts were soft-enabled

	 * when we took the interrupt.  If they were, we can wake stuff up

	 * immediately; otherwise we'll have do the wakeup when interrupts

	 * get soft-enabled.

	 */

	if (test_perf_counter_pending() && regs->softe) {

		irq_enter();

		clear_perf_counter_pending();

		perf_counter_do_pending();

	if (nmi)

		nmi_exit();

	else

		irq_exit();

}

}



void hw_perf_counter_setup(int cpu)

{