Juno: Initialize stack protector canary from the trusted entropy source

Change-Id: I7f3e4bfd46613c6311ba4015d56705414fd6feab
Signed-off-by: dp-arm <dimitris.papastamos@arm.com>

plat/arm/board/juno/juno_def.h

@@ -83,6 +83,7 @@
 #define TRNG_INTMASK	0x14
 #define TRNG_CONFIG	0x18
 #define TRNG_CONTROL	0x1C
+#define TRNG_NBYTES	16	/* Number of bytes generated per round. */
 
 /*******************************************************************************
  * MMU-401 related constants

plat/arm/board/juno/juno_stack_protector.c

+/*
+ * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * Redistributions of source code must retain the above copyright notice, this
+ * list of conditions and the following disclaimer.
+ *
+ * Redistributions in binary form must reproduce the above copyright notice,
+ * this list of conditions and the following disclaimer in the documentation
+ * and/or other materials provided with the distribution.
+ *
+ * Neither the name of ARM nor the names of its contributors may be used
+ * to endorse or promote products derived from this software without specific
+ * prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <arch_helpers.h>
+#include <debug.h>
+#include <utils.h>
+#include "juno_decl.h"
+#include "juno_def.h"
+
+u_register_t plat_get_stack_protector_canary(void)
+{
+	u_register_t c[TRNG_NBYTES / sizeof(u_register_t)];
+	u_register_t ret = 0;
+	size_t i;
+
+	if (juno_getentropy(c, sizeof(c)) != 0) {
+		ERROR("Not enough entropy to initialize canary value\n");
+		panic();
+	}
+
+	/*
+	 * On Juno we get 128-bits of entropy in one round.
+	 * Fuse the values together to form the canary.
+	 */
+	for (i = 0; i < ARRAY_SIZE(c); i++)
+		ret ^= c[i];
+	return ret;
+}

plat/arm/board/juno/platform.mk

@@ -42,6 +42,9 @@ JUNO_SECURITY_SOURCES	:=	drivers/arm/tzc/tzc400.c		\
 				plat/arm/board/juno/juno_trng.c		\
 				plat/arm/common/arm_tzc400.c
 
+ifneq (${ENABLE_STACK_PROTECTOR}, 0)
+JUNO_SECURITY_SOURCES	+=	plat/arm/board/juno/juno_stack_protector.c
+endif
 
 PLAT_INCLUDES		:=	-Iplat/arm/board/juno/include
 
@@ -52,7 +55,8 @@ BL1_SOURCES		+=	lib/cpus/aarch64/cortex_a53.S		\
 				lib/cpus/aarch64/cortex_a72.S		\
 				plat/arm/board/juno/juno_bl1_setup.c	\
 				plat/arm/board/juno/juno_err.c		\
-				${JUNO_INTERCONNECT_SOURCES}
+				${JUNO_INTERCONNECT_SOURCES}		\
+				${JUNO_SECURITY_SOURCES}
 
 BL2_SOURCES		+=	plat/arm/board/juno/juno_err.c		\
 				${JUNO_SECURITY_SOURCES}