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. [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/kernel/Makefile | 1 + arch/arm64/kernel/watchdog_hld.c | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) create mode 100644 arch/arm64/kernel/watchdog_hld.c diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 1add7b01efa7..122b50bfcc0e 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -51,6 +51,7 @@ 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/watchdog_hld.c b/arch/arm64/kernel/watchdog_hld.c new file mode 100644 index 000000000000..de43318e4dd6 --- /dev/null +++ b/arch/arm64/kernel/watchdog_hld.c @@ -0,0 +1,25 @@ +// 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; +} + -- 2.34.1
