lkml.org 
[lkml]   [2021]   [Sep]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCHv2 4/4] arm64: Enable perf events based hard lockup detector
    On Thu, Sep 23, 2021 at 10:10 PM Pingfan Liu <kernelfans@gmail.com> wrote:
    >
    > From: Sumit Garg <sumit.garg@linaro.org>
    >
    To Sumit, I think credits should go to you and keep you as the author.

    Please let me know if you dislike it.

    Thanks,

    Pingfan
    > 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.
    >
    > [1]: http://lore.kernel.org/linux-arm-kernel/1610712101-14929-1-git-send-email-sumit.garg@linaro.org
    >
    > Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
    > (Pingfan: adapt it to watchdog_hld async model based on [1])
    > Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
    > Cc: Catalin Marinas <catalin.marinas@arm.com>
    > Cc: Will Deacon <will@kernel.org>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
    > Cc: Mark Rutland <mark.rutland@arm.com>
    > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
    > Cc: Jiri Olsa <jolsa@redhat.com>
    > Cc: Namhyung Kim <namhyung@kernel.org>
    > Cc: Marc Zyngier <maz@kernel.org>
    > Cc: Kees Cook <keescook@chromium.org>
    > Cc: Masahiro Yamada <masahiroy@kernel.org>
    > Cc: Sami Tolvanen <samitolvanen@google.com>
    > Cc: Petr Mladek <pmladek@suse.com>
    > Cc: Andrew Morton <akpm@linux-foundation.org>
    > Cc: Wang Qing <wangqing@vivo.com>
    > Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
    > Cc: Santosh Sivaraj <santosh@fossix.org>
    > Cc: linux-kernel@vger.kernel.org
    > To: linux-arm-kernel@lists.infradead.org
    > ---
    > arch/arm64/Kconfig | 2 ++
    > arch/arm64/kernel/Makefile | 1 +
    > arch/arm64/kernel/perf_event.c | 11 ++++++++--
    > arch/arm64/kernel/watchdog_hld.c | 36 ++++++++++++++++++++++++++++++++
    > 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 5c7ae4c3954b..8287e9e1d28d 100644
    > --- a/arch/arm64/Kconfig
    > +++ b/arch/arm64/Kconfig
    > @@ -189,6 +189,8 @@ 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 3f1490bfb938..789c2fe5bb90 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 b4044469527e..a34343d0f418 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
    > @@ -1284,10 +1285,16 @@ 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_init);
    > + ret = arm_pmu_acpi_probe(armv8_pmuv3_init);
    > +
    > + hld_detector_delay_initialized = true;
    > + wake_up(&hld_detector_wait);
    > + 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..379743e0d001
    > --- /dev/null
    > +++ b/arch/arm64/kernel/watchdog_hld.c
    > @@ -0,0 +1,36 @@
    > +// 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 (!hld_detector_delay_initialized)
    > + return -EBUSY;
    > + else 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 3cbc3baf087f..2aecb0c34290 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 505480217cf1..bf7966776c55 100644
    > --- a/include/linux/perf/arm_pmu.h
    > +++ b/include/linux/perf/arm_pmu.h
    > @@ -163,6 +163,8 @@ int arm_pmu_acpi_probe(armpmu_init_fn init_fn);
    > static inline int arm_pmu_acpi_probe(armpmu_init_fn init_fn) { return 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);
    > --
    > 2.31.1
    >

    \
     
     \ /
      Last update: 2021-09-23 16:30    [W:3.046 / U:0.100 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site