* [PATCH v3 1/2] watchdog: move arm64 watchdog_hld into common code
2025-10-09 3:28 [PATCH v3 0/2] Add HARDLOCKUP_DETECTOR_PERF support for RISC-V Yunhui Cui
@ 2025-10-09 3:28 ` Yunhui Cui
2025-10-13 22:34 ` Doug Anderson
2025-10-09 3:28 ` [PATCH v3 2/2] riscv: add HARDLOCKUP_DETECTOR_PERF support Yunhui Cui
1 sibling, 1 reply; 6+ messages in thread
From: Yunhui Cui @ 2025-10-09 3:28 UTC (permalink / raw)
To: akpm, alex, anup, aou, atish.patra, catalin.marinas, cuiyunhui,
dianders, johannes, lihuafei1, mark.rutland, masahiroy, maz,
mingo, nicolas.schier, palmer, paul.walmsley, suzuki.poulose,
thorsten.blum, wangjinchao600, will, yangyicong, zhanjie9,
linux-arm-kernel, linux-kernel, linux-perf-users, linux-riscv
Move the contents of arch/arm64/watchdog_hld.c to kernel/watchdog_perf.c
to create a generic implementation that can be reused by other arch,
such as RISC-V.
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
---
arch/arm64/Kconfig | 2 +
arch/arm64/kernel/Makefile | 1 -
arch/arm64/kernel/watchdog_hld.c | 94 --------------------------------
drivers/perf/arm_pmu.c | 10 +++-
include/linux/perf/arm_pmu.h | 2 -
kernel/watchdog_perf.c | 83 ++++++++++++++++++++++++++++
lib/Kconfig.debug | 8 +++
7 files changed, 102 insertions(+), 98 deletions(-)
delete mode 100644 arch/arm64/kernel/watchdog_hld.c
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index b5438ff4772ce..4759e4969c4a6 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -231,6 +231,8 @@ config ARM64
select HAVE_GCC_PLUGINS
select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && \
HW_PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+ select WATCHDOG_PERF_ADJUST_PERIOD if HARDLOCKUP_DETECTOR_PERF && \
+ CPU_FREQ
select HAVE_HW_BREAKPOINT if PERF_EVENTS
select HAVE_IOREMAP_PROT
select HAVE_IRQ_TIME_ACCOUNTING
diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index 76f32e424065e..12d77f373fea4 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -44,7 +44,6 @@ obj-$(CONFIG_KUSER_HELPERS) += kuser32.o
obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o
obj-$(CONFIG_MODULES) += module.o module-plts.o
obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.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_KGDB) += kgdb.o
diff --git a/arch/arm64/kernel/watchdog_hld.c b/arch/arm64/kernel/watchdog_hld.c
deleted file mode 100644
index 3093037dcb7be..0000000000000
--- a/arch/arm64/kernel/watchdog_hld.c
+++ /dev/null
@@ -1,94 +0,0 @@
-// 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;
-}
-
-bool __init arch_perf_nmi_is_available(void)
-{
- /*
- * hardlockup_detector_perf_init() will success even if Pseudo-NMI turns off,
- * however, the pmu interrupts will act like a normal interrupt instead of
- * NMI and the hardlockup detector would be broken.
- */
- return arm_pmu_irq_is_nmi();
-}
-
-static int watchdog_perf_update_period(void *data)
-{
- int cpu = smp_processor_id();
- u64 max_cpu_freq, new_period;
-
- max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL;
- if (!max_cpu_freq)
- return 0;
-
- new_period = watchdog_thresh * max_cpu_freq;
- hardlockup_detector_perf_adjust_period(new_period);
-
- return 0;
-}
-
-static int watchdog_freq_notifier_callback(struct notifier_block *nb,
- unsigned long val, void *data)
-{
- struct cpufreq_policy *policy = data;
- int cpu;
-
- if (val != CPUFREQ_CREATE_POLICY)
- return NOTIFY_DONE;
-
- /*
- * Let each online CPU related to the policy update the period by their
- * own. This will serialize with the framework on start/stop the lockup
- * detector (softlockup_{start,stop}_all) and avoid potential race
- * condition. Otherwise we may have below theoretical race condition:
- * (core 0/1 share the same policy)
- * [core 0] [core 1]
- * hardlockup_detector_event_create()
- * hw_nmi_get_sample_period()
- * (cpufreq registered, notifier callback invoked)
- * watchdog_freq_notifier_callback()
- * watchdog_perf_update_period()
- * (since core 1's event's not yet created,
- * the period is not set)
- * perf_event_create_kernel_counter()
- * (event's period is SAFE_MAX_CPU_FREQ)
- */
- for_each_cpu(cpu, policy->cpus)
- smp_call_on_cpu(cpu, watchdog_perf_update_period, NULL, false);
-
- return NOTIFY_DONE;
-}
-
-static struct notifier_block watchdog_freq_notifier = {
- .notifier_call = watchdog_freq_notifier_callback,
-};
-
-static int __init init_watchdog_freq_notifier(void)
-{
- return cpufreq_register_notifier(&watchdog_freq_notifier,
- CPUFREQ_POLICY_NOTIFIER);
-}
-core_initcall(init_watchdog_freq_notifier);
diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
index 5c310e803dd78..ca4e1d07b61cb 100644
--- a/drivers/perf/arm_pmu.c
+++ b/drivers/perf/arm_pmu.c
@@ -17,6 +17,7 @@
#include <linux/cpu_pm.h>
#include <linux/export.h>
#include <linux/kernel.h>
+#include <linux/nmi.h>
#include <linux/perf/arm_pmu.h>
#include <linux/slab.h>
#include <linux/sched/clock.h>
@@ -696,10 +697,17 @@ 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)
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
+bool arch_perf_nmi_is_available(void)
{
+ /*
+ * watchdog_hardlockup_probe() will success even if Pseudo-NMI turns off,
+ * however, the pmu interrupts will act like a normal interrupt instead of
+ * NMI and the hardlockup detector would be broken.
+ */
return has_nmi;
}
+#endif
/*
* PMU hardware loses all context when a CPU goes offline.
diff --git a/include/linux/perf/arm_pmu.h b/include/linux/perf/arm_pmu.h
index 93c9a26492fcf..6b53fb453fd63 100644
--- a/include/linux/perf/arm_pmu.h
+++ b/include/linux/perf/arm_pmu.h
@@ -184,8 +184,6 @@ 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);
void armpmu_free(struct arm_pmu *pmu);
diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c
index d3ca70e3c256a..a61e35fc9673e 100644
--- a/kernel/watchdog_perf.c
+++ b/kernel/watchdog_perf.c
@@ -15,6 +15,7 @@
#include <linux/panic.h>
#include <linux/nmi.h>
#include <linux/atomic.h>
+#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/sched/debug.h>
@@ -306,3 +307,85 @@ void __init hardlockup_config_perf_event(const char *str)
wd_hw_attr.type = PERF_TYPE_RAW;
wd_hw_attr.config = config;
}
+
+#ifdef CONFIG_WATCHDOG_PERF_ADJUST_PERIOD
+/*
+ * 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
+ * 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
+__weak 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;
+}
+
+static int watchdog_perf_update_period(void *data)
+{
+ int cpu = smp_processor_id();
+ u64 max_cpu_freq, new_period;
+
+ max_cpu_freq = cpufreq_get_hw_max_freq(cpu) * 1000UL;
+ if (!max_cpu_freq)
+ return 0;
+
+ new_period = watchdog_thresh * max_cpu_freq;
+ hardlockup_detector_perf_adjust_period(new_period);
+
+ return 0;
+}
+
+static int watchdog_freq_notifier_callback(struct notifier_block *nb,
+ unsigned long val, void *data)
+{
+ struct cpufreq_policy *policy = data;
+ int cpu;
+
+ if (val != CPUFREQ_CREATE_POLICY)
+ return NOTIFY_DONE;
+
+ /*
+ * Let each online CPU related to the policy update the period by their
+ * own. This will serialize with the framework on start/stop the lockup
+ * detector (softlockup_{start,stop}_all) and avoid potential race
+ * condition. Otherwise we may have below theoretical race condition:
+ * (core 0/1 share the same policy)
+ * [core 0] [core 1]
+ * hardlockup_detector_event_create()
+ * hw_nmi_get_sample_period()
+ * (cpufreq registered, notifier callback invoked)
+ * watchdog_freq_notifier_callback()
+ * watchdog_perf_update_period()
+ * (since core 1's event's not yet created,
+ * the period is not set)
+ * perf_event_create_kernel_counter()
+ * (event's period is SAFE_MAX_CPU_FREQ)
+ */
+ for_each_cpu(cpu, policy->cpus)
+ smp_call_on_cpu(cpu, watchdog_perf_update_period, NULL, false);
+
+ return NOTIFY_DONE;
+}
+
+static struct notifier_block watchdog_freq_notifier = {
+ .notifier_call = watchdog_freq_notifier_callback,
+};
+
+static int __init init_watchdog_freq_notifier(void)
+{
+ return cpufreq_register_notifier(&watchdog_freq_notifier,
+ CPUFREQ_POLICY_NOTIFIER);
+}
+core_initcall(init_watchdog_freq_notifier);
+#endif
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 099abf128ce67..ceba3e28cb0d0 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1200,6 +1200,14 @@ config HARDLOCKUP_DETECTOR_PERF
depends on !HAVE_HARDLOCKUP_DETECTOR_ARCH
select HARDLOCKUP_DETECTOR_COUNTS_HRTIMER
+config WATCHDOG_PERF_ADJUST_PERIOD
+ bool
+ help
+ Adjust the watchdog hardlockup detector's period based on CPU max
+ frequency. Uses cpufreq if available; falls back to a safe 5 GHz
+ default otherwise. Registers a cpufreq notifier to update the period
+ automatically.
+
config HARDLOCKUP_DETECTOR_BUDDY
bool
depends on HARDLOCKUP_DETECTOR
--
2.39.5
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v3 2/2] riscv: add HARDLOCKUP_DETECTOR_PERF support
2025-10-09 3:28 [PATCH v3 0/2] Add HARDLOCKUP_DETECTOR_PERF support for RISC-V Yunhui Cui
2025-10-09 3:28 ` [PATCH v3 1/2] watchdog: move arm64 watchdog_hld into common code Yunhui Cui
@ 2025-10-09 3:28 ` Yunhui Cui
2025-10-13 22:35 ` Doug Anderson
2025-10-13 23:09 ` Paul Walmsley
1 sibling, 2 replies; 6+ messages in thread
From: Yunhui Cui @ 2025-10-09 3:28 UTC (permalink / raw)
To: akpm, alex, anup, aou, atish.patra, catalin.marinas, cuiyunhui,
dianders, johannes, lihuafei1, mark.rutland, masahiroy, maz,
mingo, nicolas.schier, palmer, paul.walmsley, suzuki.poulose,
thorsten.blum, wangjinchao600, will, yangyicong, zhanjie9,
linux-arm-kernel, linux-kernel, linux-perf-users, linux-riscv
Enable the HARDLOCKUP_DETECTOR_PERF function based on RISC-V SSE.
Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com>
---
arch/riscv/Kconfig | 4 ++++
drivers/perf/riscv_pmu_sbi.c | 10 ++++++++++
2 files changed, 14 insertions(+)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index badbb2b366946..6a7b4d2517c4b 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -186,6 +186,10 @@ config RISCV
select HAVE_PAGE_SIZE_4KB
select HAVE_PCI
select HAVE_PERF_EVENTS
+ select HAVE_PERF_EVENTS_NMI if RISCV_PMU_SBI_SSE
+ select HAVE_HARDLOCKUP_DETECTOR_PERF if PERF_EVENTS && HAVE_PERF_EVENTS_NMI
+ select WATCHDOG_PERF_ADJUST_PERIOD if HARDLOCKUP_DETECTOR_PERF && \
+ CPU_FREQ
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_POSIX_CPU_TIMERS_TASK_WORK
diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
index c852f64a50221..0c7c5924687c9 100644
--- a/drivers/perf/riscv_pmu_sbi.c
+++ b/drivers/perf/riscv_pmu_sbi.c
@@ -22,6 +22,7 @@
#include <linux/sched/clock.h>
#include <linux/soc/andes/irq.h>
#include <linux/workqueue.h>
+#include <linux/nmi.h>
#include <asm/errata_list.h>
#include <asm/sbi.h>
@@ -1192,6 +1193,13 @@ static int pmu_sbi_setup_sse(struct riscv_pmu *pmu)
}
#endif
+#ifdef CONFIG_HARDLOCKUP_DETECTOR_PERF
+bool arch_perf_nmi_is_available(void)
+{
+ return IS_ENABLED(CONFIG_RISCV_PMU_SBI_SSE);
+}
+#endif
+
static int pmu_sbi_starting_cpu(unsigned int cpu, struct hlist_node *node)
{
struct riscv_pmu *pmu = hlist_entry_safe(node, struct riscv_pmu, node);
@@ -1618,6 +1626,8 @@ static int __init pmu_sbi_devinit(void)
/* Notify legacy implementation that SBI pmu is available*/
riscv_pmu_legacy_skip_init();
+ lockup_detector_retry_init();
+
return ret;
}
device_initcall(pmu_sbi_devinit)
--
2.39.5
^ permalink raw reply related [flat|nested] 6+ messages in thread