[PATCH v8 2/3] arm64: random: Add data to pool from setup_arch()

@@ -59,9 +59,33 @@ static inline bool __must_check arch_get_random_seed_int(unsigned int *v)
 	return ok;
 }
 
+/*
+ * Our ARCH_RANDOM implementation does not function until relatively
+ * late in the boot when cpufeature has detertmined system
+ * capabilities so the core code can't use arch_get_random*() to
+ * initialize, instead we call this function to inject data from
+ * setup_arch() if the boot CPU supports v8.5-RNG.
+ */
+static inline void arm64_add_early_rndr_entropy(void)
+{
+	unsigned long val;
+	int i;
+
+	/* Open code as we run prior to the first call to cpufeature. */
+	val = read_sysreg_s(SYS_ID_AA64ISAR0_EL1);
+	if (!((val >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf))
+		return;
+
+	/* Add multiple values to mirror the generic code. */
+	for (i = 0; i < 16; i++)
+		if (__arm64_rndr(&val))
+			add_device_randomness(&val, sizeof(val));
+}
+
 #else
 
 static inline bool __arm64_rndr(unsigned long *v) { return false; }
+static inline void arm64_add_early_rndr_entropy(void) { }
 
 #endif /* CONFIG_ARCH_RANDOM */
 #endif /* _ASM_ARCHRANDOM_H */

@@ -344,6 +344,8 @@ void __init setup_arch(char **cmdline_p)
 	/* Init percpu seeds for random tags after cpus are set up. */
 	kasan_init_tags();
 
+	arm64_add_early_rndr_entropy();
+
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
 	/*
 	 * Make sure init_thread_info.ttbr0 always generates translation