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/*
* Contains CPU feature definitions
*
* Copyright (C) 2015 ARM Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define pr_fmt(fmt) "alternatives: " fmt
#include <linux/types.h>
#include <asm/cpu.h>
#include <asm/cpufeature.h>
#include <asm/processor.h>
#include <linux/irqchip/arm-gic-v3.h>
static bool
feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
{
int val = cpuid_feature_extract_field(reg, entry->field_pos);
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); \
}
__ID_FEAT_CHK(id_aa64pfr0);
__ID_FEAT_CHK(id_aa64mmfr1);
__ID_FEAT_CHK(id_aa64isar0);
static bool has_useable_gicv3_cpuif(const struct arm64_cpu_capabilities *entry)
{
bool has_sre;
if (!has_id_aa64pfr0_feature(entry))
return false;
has_sre = gic_enable_sre();
if (!has_sre)
pr_warn_once("%s present but disabled by higher exception level\n",
entry->desc);
return has_sre;
}
static const struct arm64_cpu_capabilities arm64_features[] = {
{
.desc = "GIC system register CPU interface",
.capability = ARM64_HAS_SYSREG_GIC_CPUIF,
.matches = has_useable_gicv3_cpuif,
.field_pos = 24,
.min_field_value = 1,
},
#ifdef CONFIG_ARM64_PAN
{
.desc = "Privileged Access Never",
.capability = ARM64_HAS_PAN,
.matches = has_id_aa64mmfr1_feature,
.field_pos = 20,
.min_field_value = 1,
.enable = cpu_enable_pan,
},
#endif /* CONFIG_ARM64_PAN */
#if defined(CONFIG_AS_LSE) && defined(CONFIG_ARM64_LSE_ATOMICS)
{
.desc = "LSE atomic instructions",
.capability = ARM64_HAS_LSE_ATOMICS,
.matches = has_id_aa64isar0_feature,
.field_pos = 20,
.min_field_value = 2,
},
#endif /* CONFIG_AS_LSE && CONFIG_ARM64_LSE_ATOMICS */
{},
};
void check_cpu_capabilities(const struct arm64_cpu_capabilities *caps,
const char *info)
{
int i;
for (i = 0; caps[i].desc; i++) {
if (!caps[i].matches(&caps[i]))
continue;
if (!cpus_have_cap(caps[i].capability))
pr_info("%s %s\n", info, caps[i].desc);
cpus_set_cap(caps[i].capability);
}
/* second pass allows enable() to consider interacting capabilities */
for (i = 0; caps[i].desc; i++) {
if (cpus_have_cap(caps[i].capability) && caps[i].enable)
caps[i].enable();
}
}
void check_local_cpu_features(void)
{
check_cpu_capabilities(arm64_features, "detected feature:");
}
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