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arm64/capabilities: Make use of system wide safe value
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Now that we can reliably read the system wide safe value for a
feature register, use that to compute the system capability.
This patch also replaces the 'feature-register-specific'
methods with a generic routine to check the capability.

Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Tested-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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Suzuki K. Poulose authored and Catalin Marinas committed Oct 21, 2015
1 parent dbb4e15 commit da8d02d
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Showing 2 changed files with 60 additions and 20 deletions.
1 change: 1 addition & 0 deletions arch/arm64/include/asm/cpufeature.h
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@ struct arm64_cpu_capabilities {
};

struct { /* Feature register checking */
u32 sys_reg;
int field_pos;
int min_field_value;
};
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79 changes: 59 additions & 20 deletions arch/arm64/kernel/cpufeature.c
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Original file line number Diff line number Diff line change
Expand Up @@ -586,34 +586,31 @@ feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
return val >= entry->min_field_value;
}

#define __ID_FEAT_CHK(reg) \
static bool __maybe_unused \
has_##reg##_feature(const struct arm64_cpu_capabilities *entry) \
{ \
u64 val; \
\
val = read_cpuid(reg##_el1); \
return feature_matches(val, entry); \
}
static bool
has_cpuid_feature(const struct arm64_cpu_capabilities *entry)
{
u64 val;

__ID_FEAT_CHK(id_aa64pfr0);
__ID_FEAT_CHK(id_aa64mmfr1);
__ID_FEAT_CHK(id_aa64isar0);
val = read_system_reg(entry->sys_reg);
return feature_matches(val, entry);
}

static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "GIC system register CPU interface",
.capability = ARM64_HAS_SYSREG_GIC_CPUIF,
.matches = has_id_aa64pfr0_feature,
.field_pos = 24,
.matches = has_cpuid_feature,
.sys_reg = SYS_ID_AA64PFR0_EL1,
.field_pos = ID_AA64PFR0_GIC_SHIFT,
.min_field_value = 1,
},
#ifdef CONFIG_ARM64_PAN
{
.desc = "Privileged Access Never",
.capability = ARM64_HAS_PAN,
.matches = has_id_aa64mmfr1_feature,
.field_pos = 20,
.matches = has_cpuid_feature,
.sys_reg = SYS_ID_AA64MMFR1_EL1,
.field_pos = ID_AA64MMFR1_PAN_SHIFT,
.min_field_value = 1,
.enable = cpu_enable_pan,
},
Expand All @@ -622,8 +619,9 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "LSE atomic instructions",
.capability = ARM64_HAS_LSE_ATOMICS,
.matches = has_id_aa64isar0_feature,
.field_pos = 20,
.matches = has_cpuid_feature,
.sys_reg = SYS_ID_AA64ISAR0_EL1,
.field_pos = ID_AA64ISAR0_ATOMICS_SHIFT,
.min_field_value = 2,
},
#endif /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
Expand Down Expand Up @@ -675,6 +673,47 @@ static inline void set_sys_caps_initialised(void)
sys_caps_initialised = true;
}

/*
* __raw_read_system_reg() - Used by a STARTING cpu before cpuinfo is populated.
*/
static u64 __raw_read_system_reg(u32 sys_id)
{
switch (sys_id) {
case SYS_ID_PFR0_EL1: return (u64)read_cpuid(ID_PFR0_EL1);
case SYS_ID_PFR1_EL1: return (u64)read_cpuid(ID_PFR1_EL1);
case SYS_ID_DFR0_EL1: return (u64)read_cpuid(ID_DFR0_EL1);
case SYS_ID_MMFR0_EL1: return (u64)read_cpuid(ID_MMFR0_EL1);
case SYS_ID_MMFR1_EL1: return (u64)read_cpuid(ID_MMFR1_EL1);
case SYS_ID_MMFR2_EL1: return (u64)read_cpuid(ID_MMFR2_EL1);
case SYS_ID_MMFR3_EL1: return (u64)read_cpuid(ID_MMFR3_EL1);
case SYS_ID_ISAR0_EL1: return (u64)read_cpuid(ID_ISAR0_EL1);
case SYS_ID_ISAR1_EL1: return (u64)read_cpuid(ID_ISAR1_EL1);
case SYS_ID_ISAR2_EL1: return (u64)read_cpuid(ID_ISAR2_EL1);
case SYS_ID_ISAR3_EL1: return (u64)read_cpuid(ID_ISAR3_EL1);
case SYS_ID_ISAR4_EL1: return (u64)read_cpuid(ID_ISAR4_EL1);
case SYS_ID_ISAR5_EL1: return (u64)read_cpuid(ID_ISAR4_EL1);
case SYS_MVFR0_EL1: return (u64)read_cpuid(MVFR0_EL1);
case SYS_MVFR1_EL1: return (u64)read_cpuid(MVFR1_EL1);
case SYS_MVFR2_EL1: return (u64)read_cpuid(MVFR2_EL1);

case SYS_ID_AA64PFR0_EL1: return (u64)read_cpuid(ID_AA64PFR0_EL1);
case SYS_ID_AA64PFR1_EL1: return (u64)read_cpuid(ID_AA64PFR0_EL1);
case SYS_ID_AA64DFR0_EL1: return (u64)read_cpuid(ID_AA64DFR0_EL1);
case SYS_ID_AA64DFR1_EL1: return (u64)read_cpuid(ID_AA64DFR0_EL1);
case SYS_ID_AA64MMFR0_EL1: return (u64)read_cpuid(ID_AA64MMFR0_EL1);
case SYS_ID_AA64MMFR1_EL1: return (u64)read_cpuid(ID_AA64MMFR1_EL1);
case SYS_ID_AA64ISAR0_EL1: return (u64)read_cpuid(ID_AA64ISAR0_EL1);
case SYS_ID_AA64ISAR1_EL1: return (u64)read_cpuid(ID_AA64ISAR1_EL1);

case SYS_CNTFRQ_EL0: return (u64)read_cpuid(CNTFRQ_EL0);
case SYS_CTR_EL0: return (u64)read_cpuid(CTR_EL0);
case SYS_DCZID_EL0: return (u64)read_cpuid(DCZID_EL0);
default:
BUG();
return 0;
}
}

/*
* Park the CPU which doesn't have the capability as advertised
* by the system.
Expand Down Expand Up @@ -719,13 +758,13 @@ void verify_local_cpu_capabilities(void)

caps = arm64_features;
for (i = 0; caps[i].desc; i++) {
if (!cpus_have_cap(caps[i].capability))
if (!cpus_have_cap(caps[i].capability) || !caps[i].sys_reg)
continue;
/*
* If the new CPU misses an advertised feature, we cannot proceed
* further, park the cpu.
*/
if (!caps[i].matches(&caps[i]))
if (!feature_matches(__raw_read_system_reg(caps[i].sys_reg), &caps[i]))
fail_incapable_cpu("arm64_features", &caps[i]);
if (caps[i].enable)
caps[i].enable(NULL);
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