arch/s390/kernel/cpufeature.c

Source file repositories/reference/linux-study-clean/arch/s390/kernel/cpufeature.c

File Facts

System
Linux kernel
Corpus path
arch/s390/kernel/cpufeature.c
Extension
.c
Size
1216 bytes
Lines
53
Domain
Architecture Layer
Bucket
arch/s390
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct s390_cpu_feature {
	unsigned int type	: 4;
	unsigned int num	: 28;
};

static struct s390_cpu_feature s390_cpu_features[MAX_CPU_FEATURES] = {
	[S390_CPU_FEATURE_MSA]	= {.type = TYPE_HWCAP, .num = HWCAP_NR_MSA},
	[S390_CPU_FEATURE_VXRS]	= {.type = TYPE_HWCAP, .num = HWCAP_NR_VXRS},
	[S390_CPU_FEATURE_UV]	= {.type = TYPE_FACILITY, .num = 158},
	[S390_CPU_FEATURE_D288]	= {.type = TYPE_MACHINE, .num = MFEATURE_DIAG288},
};

/*
 * cpu_have_feature - Test CPU features on module initialization
 */
int cpu_have_feature(unsigned int num)
{
	struct s390_cpu_feature *feature;

	if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
		return 0;
	feature = &s390_cpu_features[num];
	switch (feature->type) {
	case TYPE_HWCAP:
		return !!(elf_hwcap & BIT(feature->num));
	case TYPE_FACILITY:
		return test_facility(feature->num);
	case TYPE_MACHINE:
		return test_machine_feature(feature->num);
	default:
		WARN_ON_ONCE(1);
		return 0;
	}
}
EXPORT_SYMBOL(cpu_have_feature);

Annotation

Implementation Notes