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

Makefile

@@ -242,6 +242,9 @@ endif
 $(info Arm Architecture Features specified: $(subst +, ,$(arch-features)))
 endif	# arch-features
 
+# Determine if FEAT_RNG is supported
+ENABLE_FEAT_RNG		=	$(if $(findstring rng,${arch-features}),1,0)
+
 ifneq ($(findstring armclang,$(notdir $(CC))),)
 TF_CFLAGS_aarch32	=	-target arm-arm-none-eabi $(march32-directive)
 TF_CFLAGS_aarch64	=	-target aarch64-arm-none-eabi $(march64-directive)
@@ -940,6 +943,7 @@ $(eval $(call assert_booleans,\
         RAS_TRAP_LOWER_EL_ERR_ACCESS \
         COT_DESC_IN_DTB \
         USE_SP804_TIMER \
+        ENABLE_FEAT_RNG \
 )))
 
 $(eval $(call assert_numerics,\
@@ -1030,6 +1034,7 @@ $(eval $(call add_defines,\
         RAS_TRAP_LOWER_EL_ERR_ACCESS \
         COT_DESC_IN_DTB \
         USE_SP804_TIMER \
+        ENABLE_FEAT_RNG \
 )))
 
 ifeq (${SANITIZE_UB},trap)

include/arch/aarch64/arch.h

@@ -193,6 +193,10 @@
 #define ID_AA64DFR0_MTPMU_MASK		ULL(0xf)
 #define ID_AA64DFR0_MTPMU_SUPPORTED	ULL(1)
 
+/* ID_AA64ISAR0_EL1 definitions */
+#define ID_AA64ISAR0_RNDR_SHIFT U(60)
+#define ID_AA64ISAR0_RNDR_MASK  ULL(0xf)
+
 /* ID_AA64ISAR1_EL1 definitions */
 #define ID_AA64ISAR1_EL1	S3_0_C0_C6_1
 #define ID_AA64ISAR1_GPI_SHIFT	U(28)

include/arch/aarch64/arch_features.h

@@ -76,6 +76,12 @@ static inline unsigned long int get_armv8_6_ecv_support(void)
 		ID_AA64MMFR0_EL1_ECV_MASK);
 }
 
+static inline bool is_armv8_5_rng_present(void)
+{
+	return ((read_id_aa64isar0_el1() >> ID_AA64ISAR0_RNDR_SHIFT) &
+		ID_AA64ISAR0_RNDR_MASK);
+}
+
 /*
  * Return MPAM version:
  *

include/arch/aarch64/arch_helpers.h

@@ -245,6 +245,7 @@ void disable_mmu_icache_el3(void);
 
 DEFINE_SYSREG_RW_FUNCS(par_el1)
 DEFINE_SYSREG_READ_FUNC(id_pfr1_el1)
+DEFINE_SYSREG_READ_FUNC(id_aa64isar0_el1)
 DEFINE_SYSREG_READ_FUNC(id_aa64isar1_el1)
 DEFINE_SYSREG_READ_FUNC(id_aa64pfr0_el1)
 DEFINE_SYSREG_READ_FUNC(id_aa64pfr1_el1)
@@ -522,6 +523,10 @@ DEFINE_RENAME_SYSREG_RW_FUNCS(tfsr_el1, TFSR_EL1)
 DEFINE_RENAME_SYSREG_RW_FUNCS(rgsr_el1, RGSR_EL1)
 DEFINE_RENAME_SYSREG_RW_FUNCS(gcr_el1, GCR_EL1)
 
+/* Armv8.5 FEAT_RNG Registers */
+DEFINE_SYSREG_READ_FUNC(rndr)
+DEFINE_SYSREG_READ_FUNC(rndrrs)
+
 /* DynamIQ Shared Unit power management */
 DEFINE_RENAME_SYSREG_RW_FUNCS(clusterpwrdn_el1, CLUSTERPWRDN_EL1)
 

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();
 }