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Diffstat (limited to 'arch/arm64/include/asm/cpufeature.h')
-rw-r--r--arch/arm64/include/asm/cpufeature.h26
1 files changed, 25 insertions, 1 deletions
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index b4989df48670..4ce82ed3e7c3 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;
};
@@ -159,6 +178,11 @@ 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)
{