From: Mark Rutland <mark.rutland@arm.com>
Date: Mon, 10 Feb 2020 13:00:14 +0000
Subject: arm64: add credited/trusted RNG support
Git-commit: ead5084cdf5af51445d219800c2ac8b01eb85f2f
Patch-mainline: v5.7-rc1
References: jsc#SLE-16574 jsc#SLE-13718

Currently arm64 doesn't initialize the primary CRNG in a (potentially)
trusted manner as we only detect the presence of the RNG once secondary
CPUs are up.

Now that the core RNG code distinguishes the early initialization of the
primary CRNG, we can implement arch_get_random_seed_long_early() to
support this.

This patch does so.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200210130015.17664-4-mark.rutland@arm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Matthias Brugger <mbrugger@suse.com>
---
 arch/arm64/include/asm/archrandom.h | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/arch/arm64/include/asm/archrandom.h b/arch/arm64/include/asm/archrandom.h
index 3fe02da70004..fc1594a0710e 100644
--- a/arch/arm64/include/asm/archrandom.h
+++ b/arch/arm64/include/asm/archrandom.h
@@ -4,6 +4,8 @@
 
 #ifdef CONFIG_ARCH_RANDOM
 
+#include <linux/bug.h>
+#include <linux/kernel.h>
 #include <linux/random.h>
 #include <asm/cpufeature.h>
 
@@ -66,6 +68,18 @@ static inline bool __init __early_cpu_has_rndr(void)
 	return (ftr >> ID_AA64ISAR0_RNDR_SHIFT) & 0xf;
 }
 
+static inline bool __init __must_check
+arch_get_random_seed_long_early(unsigned long *v)
+{
+	WARN_ON(system_state != SYSTEM_BOOTING);
+
+	if (!__early_cpu_has_rndr())
+		return false;
+
+	return __arm64_rndr(v);
+}
+#define arch_get_random_seed_long_early arch_get_random_seed_long_early
+
 #else
 
 static inline bool __arm64_rndr(unsigned long *v) { return false; }
-- 
2.29.2