The patch titled
Subject: arm64: add hw_nmi_get_sample_period for preparation of lockup detector
has been added to the -mm mm-nonmm-unstable branch. Its filename is
arm64-add-hw_nmi_get_sample_period-for-preparation-of-lockup-detector.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/arm64-add-hw_nmi_get_sample_period-for-preparation-of-lockup-detector.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Lecopzer Chen <lecopzer.chen@xxxxxxxxxxxx>
Subject: arm64: add hw_nmi_get_sample_period for preparation of lockup detector
Date: Fri, 19 May 2023 10:18:41 -0700
Set safe maximum CPU frequency to 5 GHz 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.
Link: https://lkml.kernel.org/r/20230519101840.v5.17.Ia9d02578e89c3f44d3cb12eec8b0176603c8ab2f@changeid
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>
Signed-off-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Chen-Yu Tsai <wens@xxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Daniel Thompson <daniel.thompson@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Guenter Roeck <groeck@xxxxxxxxxxxx>
Cc: Ian Rogers <irogers@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Masayoshi Mizuma <msys.mizuma@xxxxxxxxx>
Cc: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: "Ravi V. Shankar" <ravi.v.shankar@xxxxxxxxx>
Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Cc: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Cc: Tzung-Bi Shih <tzungbi@xxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/Makefile | 1 +
arch/arm64/kernel/watchdog_hld.c | 24 ++++++++++++++++++++++++
2 files changed, 25 insertions(+)
--- a/arch/arm64/kernel/Makefile~arm64-add-hw_nmi_get_sample_period-for-preparation-of-lockup-detector
+++ a/arch/arm64/kernel/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += ftrace
obj-$(CONFIG_MODULES) += module.o
obj-$(CONFIG_ARM64_MODULE_PLTS) += module-plts.o
obj-$(CONFIG_PERF_EVENTS) += perf_regs.o perf_callchain.o
+obj-$(CONFIG_HARDLOCKUP_DETECTOR_PERF) += watchdog_hld.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_CPU_PM) += sleep.o suspend.o
obj-$(CONFIG_CPU_IDLE) += cpuidle.o
--- /dev/null
+++ a/arch/arm64/kernel/watchdog_hld.c
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/cpufreq.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;
+}
_
Patches currently in -mm which might be from lecopzer.chen@xxxxxxxxxxxx are
watchdog-remove-watchdog_default.patch
watchdog-hardlockup-change-watchdog_nmi_enable-to-void.patch
watchdog-perf-adapt-the-watchdog_perf-interface-for-async-model.patch
arm64-add-hw_nmi_get_sample_period-for-preparation-of-lockup-detector.patch
