1 files changed, 35 insertions, 5 deletions

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index b4989df48670..05310ad8c5ab 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -29,7 +29,20 @@
 #include <linux/jump_label.h>
 #include <linux/kernel.h>
 
-/* CPU feature register tracking */
+/*
+ * CPU feature register tracking
+ *
+ * The safe value of a CPUID feature field is dependent on the implications
+ * of the values assigned to it by the architecture. Based on the relationship
+ * between the values, the features are classified into 3 types - LOWER_SAFE,
+ * HIGHER_SAFE and EXACT.
+ *
+ * The lowest value of all the CPUs is chosen for LOWER_SAFE and highest
+ * for HIGHER_SAFE. It is expected that all CPUs have the same value for
+ * a field when EXACT is specified, failing which, the safe value specified
+ * in the table is chosen.
+ */
+
 enum ftr_type {
 	FTR_EXACT,	/* Use a predefined safe value */
 	FTR_LOWER_SAFE,	/* Smaller value is safe */
@@ -42,8 +55,12 @@ enum ftr_type {
 #define FTR_SIGNED	true	/* Value should be treated as signed */
 #define FTR_UNSIGNED	false	/* Value should be treated as unsigned */
 
+#define FTR_VISIBLE	true	/* Feature visible to the user space */
+#define FTR_HIDDEN	false	/* Feature is hidden from the user */
+
 struct arm64_ftr_bits {
 	bool		sign;	/* Value is signed ? */
+	bool		visible;
 	bool		strict;	/* CPU Sanity check: strict matching required ? */
 	enum ftr_type	type;
 	u8		shift;
@@ -59,7 +76,9 @@ struct arm64_ftr_bits {
 struct arm64_ftr_reg {
 	const char			*name;
 	u64				strict_mask;
+	u64				user_mask;
 	u64				sys_val;
+	u64				user_val;
 	const struct arm64_ftr_bits	*ftr_bits;
 };
 
@@ -159,17 +178,28 @@ static inline u64 arm64_ftr_mask(const struct arm64_ftr_bits *ftrp)
 	return (u64)GENMASK(ftrp->shift + ftrp->width - 1, ftrp->shift);
 }
 
+static inline u64 arm64_ftr_reg_user_value(const struct arm64_ftr_reg *reg)
+{
+	return (reg->user_val | (reg->sys_val & reg->user_mask));
+}
+
 static inline int __attribute_const__
-cpuid_feature_extract_field(u64 features, int field, bool sign)
+cpuid_feature_extract_field_width(u64 features, int field, int width, bool sign)
 {
 	return (sign) ?
-		cpuid_feature_extract_signed_field(features, field) :
-		cpuid_feature_extract_unsigned_field(features, field);
+		cpuid_feature_extract_signed_field_width(features, field, width) :
+		cpuid_feature_extract_unsigned_field_width(features, field, width);
+}
+
+static inline int __attribute_const__
+cpuid_feature_extract_field(u64 features, int field, bool sign)
+{
+	return cpuid_feature_extract_field_width(features, field, 4, sign);
 }
 
 static inline s64 arm64_ftr_value(const struct arm64_ftr_bits *ftrp, u64 val)
 {
-	return (s64)cpuid_feature_extract_field(val, ftrp->shift, ftrp->sign);
+	return (s64)cpuid_feature_extract_field_width(val, ftrp->shift, ftrp->width, ftrp->sign);
 }
 
 static inline bool id_aa64mmfr0_mixed_endian_el0(u64 mmfr0)