Merge changes from topic "tp-feat-rng" into integration

* changes:
  plat/qemu: Use RNDR in stack protector
  Makefile: Add FEAT_RNG support define
  Define registers for FEAT_RNG support

1 files changed, 12 insertions, 4 deletions

diff --git a/plat/qemu/common/qemu_stack_protector.c b/plat/qemu/common/qemu_stack_protector.c
index c226158ad6..15ce3d6d2c 100644
--- a/plat/qemu/common/qemu_stack_protector.c
+++ b/plat/qemu/common/qemu_stack_protector.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2021, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -7,17 +7,25 @@
 #include <stdint.h>
 
 #include <arch_helpers.h>
+#include <arch_features.h>
 #include <plat/common/platform.h>
 
 #define RANDOM_CANARY_VALUE ((u_register_t) 3288484550995823360ULL)
 
 u_register_t plat_get_stack_protector_canary(void)
 {
+#if ENABLE_FEAT_RNG
+	/* Use the RNDR instruction if the CPU supports it */
+	if (is_armv8_5_rng_present()) {
+		return read_rndr();
+	}
+#endif
+
 	/*
-	 * Ideally, a random number should be returned instead of the
+	 * Ideally, a random number should be returned above. If a random
+	 * number generator is not supported, return instead a
 	 * combination of a timer's value and a compile-time constant.
-	 * As the virt platform does not have any random number generator,
-	 * this is better than nothing but not necessarily really secure.
+	 * This is better than nothing but not necessarily really secure.
 	 */
 	return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
 }