1 files changed, 97 insertions, 0 deletions
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
new file mode 100644
index 000000000000..978fa169d3c3
--- /dev/null
+++ b/arch/arm64/kernel/cpufeature.c
@@ -0,0 +1,97 @@
+/*
+ * 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>
+
+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;
+}
+
+static bool
+has_id_aa64pfr0_feature(const struct arm64_cpu_capabilities *entry)
+{
+	u64 val;
+
+	val = read_cpuid(id_aa64pfr0_el1);
+	return feature_matches(val, entry);
+}
+
+static bool __maybe_unused
+has_id_aa64mmfr1_feature(const struct arm64_cpu_capabilities *entry)
+{
+	u64 val;
+
+	val = read_cpuid(id_aa64mmfr1_el1);
+	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,
+		.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 */
+	{},
+};
+
+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");
+}