Messages in this thread | | | Date | Tue, 26 Jan 2021 14:18:19 +0000 | From | Will Deacon <> | Subject | Re: [PATCH v5] arm64: Enable perf events based hard lockup detector |
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Hi Sumit,
On Fri, Jan 15, 2021 at 05:31:41PM +0530, Sumit Garg wrote: > With the recent feature added to enable perf events to use pseudo NMIs > as interrupts on platforms which support GICv3 or later, its now been > possible to enable hard lockup detector (or NMI watchdog) on arm64 > platforms. So enable corresponding support. > > One thing to note here is that normally lockup detector is initialized > just after the early initcalls but PMU on arm64 comes up much later as > device_initcall(). So we need to re-initialize lockup detection once > PMU has been initialized. > > Signed-off-by: Sumit Garg <sumit.garg@linaro.org> > ---
[...]
> diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c > index 3605f77a..bafb7c8 100644 > --- a/arch/arm64/kernel/perf_event.c > +++ b/arch/arm64/kernel/perf_event.c > @@ -23,6 +23,8 @@ > #include <linux/platform_device.h> > #include <linux/sched_clock.h> > #include <linux/smp.h> > +#include <linux/nmi.h> > +#include <linux/cpufreq.h> > > /* ARMv8 Cortex-A53 specific event types. */ > #define ARMV8_A53_PERFCTR_PREF_LINEFILL 0xC2 > @@ -1246,12 +1248,30 @@ static struct platform_driver armv8_pmu_driver = { > .probe = armv8_pmu_device_probe, > }; > > +static int __init lockup_detector_init_fn(void *data) > +{ > + lockup_detector_init(); > + return 0; > +} > + > static int __init armv8_pmu_driver_init(void) > { > + int ret; > + > if (acpi_disabled) > - return platform_driver_register(&armv8_pmu_driver); > + ret = platform_driver_register(&armv8_pmu_driver); > else > - return arm_pmu_acpi_probe(armv8_pmuv3_init); > + ret = arm_pmu_acpi_probe(armv8_pmuv3_init); > + > + /* > + * Try to re-initialize lockup detector after PMU init in > + * case PMU events are triggered via NMIs. > + */ > + if (ret == 0 && arm_pmu_irq_is_nmi()) > + smp_call_on_cpu(raw_smp_processor_id(), lockup_detector_init_fn, > + NULL, false); > + > + return ret;
What's wrong with the alternative approach outlined by Mark:
https://lore.kernel.org/r/20210113130235.GB19011@C02TD0UTHF1T.local
?
Will
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