mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-22 17:01:14 +00:00
![Douglas Anderson](/assets/img/avatar_default.png)
On arm64, NMI support needs to be detected at runtime. Add a weak function to the perf hardlockup detector so that an architecture can implement it to detect whether NMIs are available. Link: https://lkml.kernel.org/r/20230519101840.v5.15.Ic55cb6f90ef5967d8aaa2b503a4e67c753f64d3a@changeid Signed-off-by: Douglas Anderson <dianders@chromium.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chen-Yu Tsai <wens@csie.org> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Colin Cross <ccross@android.com> Cc: Daniel Thompson <daniel.thompson@linaro.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Guenter Roeck <groeck@chromium.org> Cc: Ian Rogers <irogers@google.com> Cc: Lecopzer Chen <lecopzer.chen@mediatek.com> Cc: Marc Zyngier <maz@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masayoshi Mizuma <msys.mizuma@gmail.com> Cc: Matthias Kaehlcke <mka@chromium.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Petr Mladek <pmladek@suse.com> Cc: Pingfan Liu <kernelfans@gmail.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: Stephen Boyd <swboyd@chromium.org> Cc: Sumit Garg <sumit.garg@linaro.org> Cc: Tzung-Bi Shih <tzungbi@chromium.org> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
261 lines
6.6 KiB
C
261 lines
6.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Detect hard lockups on a system using perf
|
|
*
|
|
* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
|
|
*
|
|
* Note: Most of this code is borrowed heavily from the original softlockup
|
|
* detector, so thanks to Ingo for the initial implementation.
|
|
* Some chunks also taken from the old x86-specific nmi watchdog code, thanks
|
|
* to those contributors as well.
|
|
*/
|
|
|
|
#define pr_fmt(fmt) "NMI watchdog: " fmt
|
|
|
|
#include <linux/nmi.h>
|
|
#include <linux/atomic.h>
|
|
#include <linux/module.h>
|
|
#include <linux/sched/debug.h>
|
|
|
|
#include <asm/irq_regs.h>
|
|
#include <linux/perf_event.h>
|
|
|
|
static DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
|
|
static DEFINE_PER_CPU(struct perf_event *, dead_event);
|
|
static struct cpumask dead_events_mask;
|
|
|
|
static atomic_t watchdog_cpus = ATOMIC_INIT(0);
|
|
|
|
#ifdef CONFIG_HARDLOCKUP_CHECK_TIMESTAMP
|
|
static DEFINE_PER_CPU(ktime_t, last_timestamp);
|
|
static DEFINE_PER_CPU(unsigned int, nmi_rearmed);
|
|
static ktime_t watchdog_hrtimer_sample_threshold __read_mostly;
|
|
|
|
void watchdog_update_hrtimer_threshold(u64 period)
|
|
{
|
|
/*
|
|
* The hrtimer runs with a period of (watchdog_threshold * 2) / 5
|
|
*
|
|
* So it runs effectively with 2.5 times the rate of the NMI
|
|
* watchdog. That means the hrtimer should fire 2-3 times before
|
|
* the NMI watchdog expires. The NMI watchdog on x86 is based on
|
|
* unhalted CPU cycles, so if Turbo-Mode is enabled the CPU cycles
|
|
* might run way faster than expected and the NMI fires in a
|
|
* smaller period than the one deduced from the nominal CPU
|
|
* frequency. Depending on the Turbo-Mode factor this might be fast
|
|
* enough to get the NMI period smaller than the hrtimer watchdog
|
|
* period and trigger false positives.
|
|
*
|
|
* The sample threshold is used to check in the NMI handler whether
|
|
* the minimum time between two NMI samples has elapsed. That
|
|
* prevents false positives.
|
|
*
|
|
* Set this to 4/5 of the actual watchdog threshold period so the
|
|
* hrtimer is guaranteed to fire at least once within the real
|
|
* watchdog threshold.
|
|
*/
|
|
watchdog_hrtimer_sample_threshold = period * 2;
|
|
}
|
|
|
|
static bool watchdog_check_timestamp(void)
|
|
{
|
|
ktime_t delta, now = ktime_get_mono_fast_ns();
|
|
|
|
delta = now - __this_cpu_read(last_timestamp);
|
|
if (delta < watchdog_hrtimer_sample_threshold) {
|
|
/*
|
|
* If ktime is jiffies based, a stalled timer would prevent
|
|
* jiffies from being incremented and the filter would look
|
|
* at a stale timestamp and never trigger.
|
|
*/
|
|
if (__this_cpu_inc_return(nmi_rearmed) < 10)
|
|
return false;
|
|
}
|
|
__this_cpu_write(nmi_rearmed, 0);
|
|
__this_cpu_write(last_timestamp, now);
|
|
return true;
|
|
}
|
|
#else
|
|
static inline bool watchdog_check_timestamp(void)
|
|
{
|
|
return true;
|
|
}
|
|
#endif
|
|
|
|
static struct perf_event_attr wd_hw_attr = {
|
|
.type = PERF_TYPE_HARDWARE,
|
|
.config = PERF_COUNT_HW_CPU_CYCLES,
|
|
.size = sizeof(struct perf_event_attr),
|
|
.pinned = 1,
|
|
.disabled = 1,
|
|
};
|
|
|
|
/* Callback function for perf event subsystem */
|
|
static void watchdog_overflow_callback(struct perf_event *event,
|
|
struct perf_sample_data *data,
|
|
struct pt_regs *regs)
|
|
{
|
|
/* Ensure the watchdog never gets throttled */
|
|
event->hw.interrupts = 0;
|
|
|
|
if (!watchdog_check_timestamp())
|
|
return;
|
|
|
|
watchdog_hardlockup_check(smp_processor_id(), regs);
|
|
}
|
|
|
|
static int hardlockup_detector_event_create(void)
|
|
{
|
|
unsigned int cpu;
|
|
struct perf_event_attr *wd_attr;
|
|
struct perf_event *evt;
|
|
|
|
/*
|
|
* Preemption is not disabled because memory will be allocated.
|
|
* Ensure CPU-locality by calling this in per-CPU kthread.
|
|
*/
|
|
WARN_ON(!is_percpu_thread());
|
|
cpu = raw_smp_processor_id();
|
|
wd_attr = &wd_hw_attr;
|
|
wd_attr->sample_period = hw_nmi_get_sample_period(watchdog_thresh);
|
|
|
|
/* Try to register using hardware perf events */
|
|
evt = perf_event_create_kernel_counter(wd_attr, cpu, NULL,
|
|
watchdog_overflow_callback, NULL);
|
|
if (IS_ERR(evt)) {
|
|
pr_debug("Perf event create on CPU %d failed with %ld\n", cpu,
|
|
PTR_ERR(evt));
|
|
return PTR_ERR(evt);
|
|
}
|
|
this_cpu_write(watchdog_ev, evt);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* watchdog_hardlockup_enable - Enable the local event
|
|
*
|
|
* @cpu: The CPU to enable hard lockup on.
|
|
*/
|
|
void watchdog_hardlockup_enable(unsigned int cpu)
|
|
{
|
|
WARN_ON_ONCE(cpu != smp_processor_id());
|
|
|
|
if (hardlockup_detector_event_create())
|
|
return;
|
|
|
|
/* use original value for check */
|
|
if (!atomic_fetch_inc(&watchdog_cpus))
|
|
pr_info("Enabled. Permanently consumes one hw-PMU counter.\n");
|
|
|
|
perf_event_enable(this_cpu_read(watchdog_ev));
|
|
}
|
|
|
|
/**
|
|
* watchdog_hardlockup_disable - Disable the local event
|
|
*
|
|
* @cpu: The CPU to enable hard lockup on.
|
|
*/
|
|
void watchdog_hardlockup_disable(unsigned int cpu)
|
|
{
|
|
struct perf_event *event = this_cpu_read(watchdog_ev);
|
|
|
|
WARN_ON_ONCE(cpu != smp_processor_id());
|
|
|
|
if (event) {
|
|
perf_event_disable(event);
|
|
this_cpu_write(watchdog_ev, NULL);
|
|
this_cpu_write(dead_event, event);
|
|
cpumask_set_cpu(smp_processor_id(), &dead_events_mask);
|
|
atomic_dec(&watchdog_cpus);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* hardlockup_detector_perf_cleanup - Cleanup disabled events and destroy them
|
|
*
|
|
* Called from lockup_detector_cleanup(). Serialized by the caller.
|
|
*/
|
|
void hardlockup_detector_perf_cleanup(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_cpu(cpu, &dead_events_mask) {
|
|
struct perf_event *event = per_cpu(dead_event, cpu);
|
|
|
|
/*
|
|
* Required because for_each_cpu() reports unconditionally
|
|
* CPU0 as set on UP kernels. Sigh.
|
|
*/
|
|
if (event)
|
|
perf_event_release_kernel(event);
|
|
per_cpu(dead_event, cpu) = NULL;
|
|
}
|
|
cpumask_clear(&dead_events_mask);
|
|
}
|
|
|
|
/**
|
|
* hardlockup_detector_perf_stop - Globally stop watchdog events
|
|
*
|
|
* Special interface for x86 to handle the perf HT bug.
|
|
*/
|
|
void __init hardlockup_detector_perf_stop(void)
|
|
{
|
|
int cpu;
|
|
|
|
lockdep_assert_cpus_held();
|
|
|
|
for_each_online_cpu(cpu) {
|
|
struct perf_event *event = per_cpu(watchdog_ev, cpu);
|
|
|
|
if (event)
|
|
perf_event_disable(event);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* hardlockup_detector_perf_restart - Globally restart watchdog events
|
|
*
|
|
* Special interface for x86 to handle the perf HT bug.
|
|
*/
|
|
void __init hardlockup_detector_perf_restart(void)
|
|
{
|
|
int cpu;
|
|
|
|
lockdep_assert_cpus_held();
|
|
|
|
if (!(watchdog_enabled & WATCHDOG_HARDLOCKUP_ENABLED))
|
|
return;
|
|
|
|
for_each_online_cpu(cpu) {
|
|
struct perf_event *event = per_cpu(watchdog_ev, cpu);
|
|
|
|
if (event)
|
|
perf_event_enable(event);
|
|
}
|
|
}
|
|
|
|
bool __weak __init arch_perf_nmi_is_available(void)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
/**
|
|
* watchdog_hardlockup_probe - Probe whether NMI event is available at all
|
|
*/
|
|
int __init watchdog_hardlockup_probe(void)
|
|
{
|
|
int ret;
|
|
|
|
if (!arch_perf_nmi_is_available())
|
|
return -ENODEV;
|
|
|
|
ret = hardlockup_detector_event_create();
|
|
|
|
if (ret) {
|
|
pr_info("Perf NMI watchdog permanently disabled\n");
|
|
} else {
|
|
perf_event_release_kernel(this_cpu_read(watchdog_ev));
|
|
this_cpu_write(watchdog_ev, NULL);
|
|
}
|
|
return ret;
|
|
}
|