@@ -117,6 +117,8 @@ infrastructure:
      +------------------------------+---------+---------+
      | Name                         |  bits   | visible |
      +------------------------------+---------+---------+
+     | RNDR                         | [63-60] |    y    |
+     +------------------------------+---------+---------+
      | TS                           | [55-52] |    y    |
      +------------------------------+---------+---------+
      | FHM                          | [51-48] |    y    |

@@ -1484,6 +1484,18 @@ config ARM64_PTR_AUTH
 
 endmenu
 
+menu "ARMv8.5 architectural features"
+
+config ARCH_RANDOM
+	bool "Enable support for random number generation"
+	default y
+	help
+	  Random number generation (part of the ARMv8.5 Extensions)
+	  provides a high bandwidth, cryptographically secure
+	  hardware random number generator.
+
+endmenu
+
 config ARM64_SVE
 	bool "ARM Scalable Vector Extension support"
 	default y

@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_ARCHRANDOM_H
+#define _ASM_ARCHRANDOM_H
+
+#ifdef CONFIG_ARCH_RANDOM
+
+#include <linux/random.h>
+#include <asm/cpufeature.h>
+
+static inline bool __arm64_rndr(unsigned long *v)
+{
+	bool ok;
+
+	/*
+	 * Reads of RNDR set PSTATE.NZCV to 0b0000 on success,
+	 * and set PSTATE.NZCV to 0b0100 otherwise.
+	 */
+	asm volatile(
+		__mrs_s("%0", SYS_RNDR_EL0) "\n"
+	"	cset %w1, ne\n"
+	: "=r"(*v), "=r"(ok)
+	:
+	: "cc");
+
+	return ok;
+}
+
+static inline bool __must_check arch_get_random_long(unsigned long *v)
+{
+	return false;
+}
+
+static inline bool __must_check arch_get_random_int(unsigned int *v)
+{
+	return false;
+}
+
+static inline bool __must_check arch_get_random_seed_long(unsigned long *v)
+{
+	/*
+	 * Only support the generic interface after we have detected
+	 * the system wide capability, avoiding complexity with the
+	 * cpufeature code and with potential scheduling between CPUs
+	 * with and without the feature.
+	 */
+	if (!cpus_have_const_cap(ARM64_HAS_RNG))
+		return false;
+
+	return __arm64_rndr(v);
+}
+
+
+static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
+{
+	unsigned long val;
+	bool ok = arch_get_random_seed_long(&val);
+
+	*v = val;
+	return ok;
+}
+
+#else
+
+static inline bool __arm64_rndr(unsigned long *v) { return false; }
+
+#endif /* CONFIG_ARCH_RANDOM */
+#endif /* _ASM_ARCHRANDOM_H */

@@ -56,7 +56,8 @@
 #define ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM	46
 #define ARM64_WORKAROUND_1542419		47
 #define ARM64_WORKAROUND_1319367		48
+#define ARM64_HAS_RNG				49
 
-#define ARM64_NCAPS				49
+#define ARM64_NCAPS				50
 
 #endif /* __ASM_CPUCAPS_H */

@@ -365,6 +365,9 @@
 #define SYS_CTR_EL0			sys_reg(3, 3, 0, 0, 1)
 #define SYS_DCZID_EL0			sys_reg(3, 3, 0, 0, 7)
 
+#define SYS_RNDR_EL0			sys_reg(3, 3, 2, 4, 0)
+#define SYS_RNDRRS_EL0			sys_reg(3, 3, 2, 4, 1)
+
 #define SYS_PMCR_EL0			sys_reg(3, 3, 9, 12, 0)
 #define SYS_PMCNTENSET_EL0		sys_reg(3, 3, 9, 12, 1)
 #define SYS_PMCNTENCLR_EL0		sys_reg(3, 3, 9, 12, 2)

@@ -539,6 +542,7 @@
 			 ENDIAN_SET_EL1 | SCTLR_EL1_UCI  | SCTLR_EL1_RES1)
 
 /* id_aa64isar0 */
+#define ID_AA64ISAR0_RNDR_SHIFT		60
 #define ID_AA64ISAR0_TS_SHIFT		52
 #define ID_AA64ISAR0_FHM_SHIFT		48
 #define ID_AA64ISAR0_DP_SHIFT		44

@@ -119,6 +119,7 @@ static void cpu_enable_cnp(struct arm64_cpu_capabilities const *cap);
  * sync with the documentation of the CPU feature register ABI.
  */
 static const struct arm64_ftr_bits ftr_id_aa64isar0[] = {
+	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_RNDR_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_TS_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_FHM_SHIFT, 4, 0),
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64ISAR0_DP_SHIFT, 4, 0),

@@ -1566,6 +1567,18 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.sign = FTR_UNSIGNED,
 		.min_field_value = 1,
 	},
+#endif
+#ifdef CONFIG_ARCH_RANDOM
+	{
+		.desc = "Random Number Generator",
+		.capability = ARM64_HAS_RNG,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_cpuid_feature,
+		.sys_reg = SYS_ID_AA64ISAR0_EL1,
+		.field_pos = ID_AA64ISAR0_RNDR_SHIFT,
+		.sign = FTR_UNSIGNED,
+		.min_field_value = 1,
+	},
 #endif
 	{},
 };