Commit 23b727dc authored by Jeremy Linton's avatar Jeremy Linton Committed by Catalin Marinas
Browse files

arm64: cpufeature: Display the set of cores with a feature 



The AMU feature can be enabled on a subset of the cores in a system.
Because of that, it prints a message for each core as it is detected.
This becomes tedious when there are hundreds of cores. Instead, for
CPU features which can be enabled on a subset of the present cores,
lets wait until update_cpu_capabilities() and print the subset of cores
the feature was enabled on.

Signed-off-by: default avatarJeremy Linton <jeremy.linton@arm.com>
Reviewed-by: default avatarIonela Voinescu <ionela.voinescu@arm.com>
Tested-by: default avatarIonela Voinescu <ionela.voinescu@arm.com>
Reviewed-by: default avatarPunit Agrawal <punit.agrawal@bytedance.com>
Tested-by: default avatarPunit Agrawal <punit.agrawal@bytedance.com>
Link: https://lore.kernel.org/r/20231017052322.1211099-2-jeremy.linton@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 6465e260

arch/arm64/include/asm/cpufeature.h

+2 −0
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/bug.h>

#include <linux/jump_label.h>

#include <linux/kernel.h>

#include <linux/cpumask.h>



/*

 * CPU feature register tracking
@@ -380,6 +381,7 @@ struct arm64_cpu_capabilities { 
	 * method is robust against being called multiple times.

	 */

	const struct arm64_cpu_capabilities *match_list;

	const struct cpumask *cpus;

};



static inline int cpucap_default_scope(const struct arm64_cpu_capabilities *cap)

arch/arm64/kernel/cpufeature.c

+13 −9
Original line number Diff line number Diff line
@@ -1944,8 +1944,6 @@ int get_cpu_with_amu_feat(void) 
static void cpu_amu_enable(struct arm64_cpu_capabilities const *cap)

{

	if (has_cpuid_feature(cap, SCOPE_LOCAL_CPU)) {

		pr_info("detected CPU%d: Activity Monitors Unit (AMU)\n",

			smp_processor_id());

		cpumask_set_cpu(smp_processor_id(), &amu_cpus);



		/* 0 reference values signal broken/disabled counters */
@@ -2405,16 +2403,12 @@ static const struct arm64_cpu_capabilities arm64_features[] = { 
#endif /* CONFIG_ARM64_RAS_EXTN */

#ifdef CONFIG_ARM64_AMU_EXTN

	{

		/*

		 * The feature is enabled by default if CONFIG_ARM64_AMU_EXTN=y.

		 * Therefore, don't provide .desc as we don't want the detection

		 * message to be shown until at least one CPU is detected to

		 * support the feature.

		 */

		.desc = "Activity Monitors Unit (AMU)",

		.capability = ARM64_HAS_AMU_EXTN,

		.type = ARM64_CPUCAP_WEAK_LOCAL_CPU_FEATURE,

		.matches = has_amu,

		.cpu_enable = cpu_amu_enable,

		.cpus = &amu_cpus,

		ARM64_CPUID_FIELDS(ID_AA64PFR0_EL1, AMU, IMP)

	},

#endif /* CONFIG_ARM64_AMU_EXTN */
@@ -2981,7 +2975,7 @@ static void update_cpu_capabilities(u16 scope_mask) 
		    !caps->matches(caps, cpucap_default_scope(caps)))

			continue;



		if (caps->desc)

		if (caps->desc && !caps->cpus)

			pr_info("detected: %s\n", caps->desc);



		__set_bit(caps->capability, system_cpucaps);
@@ -3330,6 +3324,7 @@ unsigned long cpu_get_elf_hwcap2(void) 


static void __init setup_system_capabilities(void)

{

	int i;

	/*

	 * We have finalised the system-wide safe feature

	 * registers, finalise the capabilities that depend
@@ -3338,6 +3333,15 @@ static void __init setup_system_capabilities(void) 
	 */

	update_cpu_capabilities(SCOPE_SYSTEM);

	enable_cpu_capabilities(SCOPE_ALL & ~SCOPE_BOOT_CPU);



	for (i = 0; i < ARM64_NCAPS; i++) {

		const struct arm64_cpu_capabilities *caps = cpucap_ptrs[i];



		if (caps && caps->cpus && caps->desc &&

			cpumask_any(caps->cpus) < nr_cpu_ids)

			pr_info("detected: %s on CPU%*pbl\n",

				caps->desc, cpumask_pr_args(caps->cpus));

	}

}



void __init setup_cpu_features(void)