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(). To cope with that, overriding watchdog_nmi_probe() to let the watchdog framework know PMU not ready, and inform the framework to re-initialize lockup detection once PMU has been initialized. [1]: http://lore.kernel.org/linux-arm-kernel/1610712101-14929-1-git-send-email-sumit.garg@xxxxxxxxxx Co-developed-by: Sumit Garg <sumit.garg@xxxxxxxxxx> Signed-off-by: Sumit Garg <sumit.garg@xxxxxxxxxx> Co-developed-by: Pingfan Liu <kernelfans@xxxxxxxxx> Signed-off-by: Pingfan Liu <kernelfans@xxxxxxxxx> Signed-off-by: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx> --- arch/arm64/Kconfig | 2 ++ arch/arm64/kernel/Makefile | 1 + arch/arm64/kernel/perf_event.c | 10 +++++++-- arch/arm64/kernel/watchdog_hld.c | 37 ++++++++++++++++++++++++++++++++ drivers/perf/arm_pmu.c | 5 +++++ include/linux/perf/arm_pmu.h | 2 ++ 6 files changed, 55 insertions(+), 2 deletions(-) create mode 100644 arch/arm64/kernel/watchdog_hld.c diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index c842878f8133..9c24052c5360 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -190,6 +190,8 @@ config ARM64 select HAVE_NMI select HAVE_PATA_PLATFORM select HAVE_PERF_EVENTS + select HAVE_PERF_EVENTS_NMI if ARM64_PSEUDO_NMI + select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI select HAVE_PERF_REGS select HAVE_PERF_USER_STACK_DUMP select HAVE_REGS_AND_STACK_ACCESS_API diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 88b3e2a21408..3e62a8877ed7 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -46,6 +46,7 @@ obj-$(CONFIG_MODULES) += module.o obj-$(CONFIG_ARM64_MODULE_PLTS) += module-plts.o obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o +obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF) += watchdog_hld.o obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o obj-$(CONFIG_CPU_PM) += sleep.o suspend.o obj-$(CONFIG_CPU_IDLE) += cpuidle.o diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index cab678ed6618..f44ad669c18f 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -23,6 +23,7 @@ #include <linux/platform_device.h> #include <linux/sched_clock.h> #include <linux/smp.h> +#include <linux/nmi.h> /* ARMv8 Cortex-A53 specific event types. */ #define ARMV8_A53_PERFCTR_PREF_LINEFILL 0xC2 @@ -1380,10 +1381,15 @@ static struct platform_driver armv8_pmu_driver = { 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_pmu_init); + ret = arm_pmu_acpi_probe(armv8_pmuv3_pmu_init); + + retry_lockup_detector_init(); + return ret; } device_initcall(armv8_pmu_driver_init) diff --git a/arch/arm64/kernel/watchdog_hld.c b/arch/arm64/kernel/watchdog_hld.c new file mode 100644 index 000000000000..c085e99b3cd2 --- /dev/null +++ b/arch/arm64/kernel/watchdog_hld.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/nmi.h> +#include <linux/cpufreq.h> +#include <linux/perf/arm_pmu.h> + +/* + * Safe maximum CPU frequency in case a particular platform doesn't implement + * cpufreq driver. Although, architecture doesn't put any restrictions on + * maximum frequency but 5 GHz seems to be safe maximum given the available + * Arm CPUs in the market which are clocked much less than 5 GHz. On the other + * hand, we can't make it much higher as it would lead to a large hard-lockup + * detection timeout on parts which are running slower (eg. 1GHz on + * Developerbox) and doesn't possess a cpufreq driver. + */ +#define SAFE_MAX_CPU_FREQ 5000000000UL // 5 GHz +u64 hw_nmi_get_sample_period(int watchdog_thresh) +{ + unsigned int cpu = smp_processor_id(); + unsigned long max_cpu_freq; + + max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL; + if (!max_cpu_freq) + max_cpu_freq = SAFE_MAX_CPU_FREQ; + + return (u64)max_cpu_freq * watchdog_thresh; +} + +int __init watchdog_nmi_probe(void) +{ + if (!allow_lockup_detector_init_retry) + return -EBUSY; + + if (!arm_pmu_irq_is_nmi()) + return -ENODEV; + + return hardlockup_detector_perf_init(); +} diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c index 295cc7952d0e..e77f4897fca2 100644 --- a/drivers/perf/arm_pmu.c +++ b/drivers/perf/arm_pmu.c @@ -697,6 +697,11 @@ static int armpmu_get_cpu_irq(struct arm_pmu *pmu, int cpu) return per_cpu(hw_events->irq, cpu); } +bool arm_pmu_irq_is_nmi(void) +{ + return has_nmi; +} + /* * PMU hardware loses all context when a CPU goes offline. * When a CPU is hotplugged back in, since some hardware registers are diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h index 2512e2f9cd4e..9325d01adc3e 100644 --- a/include/linux/perf/arm_pmu.h +++ b/include/linux/perf/arm_pmu.h @@ -169,6 +169,8 @@ void kvm_host_pmu_init(struct arm_pmu *pmu); #define kvm_host_pmu_init(x) do { } while(0) #endif +bool arm_pmu_irq_is_nmi(void); + /* Internal functions only for core arm_pmu code */ struct arm_pmu *armpmu_alloc(void); struct arm_pmu *armpmu_alloc_atomic(void); -- 2.25.1
