Introduce STMicroelectronics STM32MP1 platform

STM32MP1 is a microprocessor designed by STMicroelectronics,
based on a dual Arm Cortex-A7.
It is an Armv7-A platform, using dedicated code from TF-A.

STM32MP1 uses BL2 compiled with BL2_AT_EL3.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Mathieu Belou <mathieu.belou@st.com>
Signed-off-by: Etienne Carriere <etienne.carriere@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Signed-off-by: Pascal Paillet <p.paillet@st.com>
diff --git a/plat/st/stm32mp1/stm32mp1_stack_protector.c b/plat/st/stm32mp1/stm32mp1_stack_protector.c
new file mode 100644
index 0000000..c681300
--- /dev/null
+++ b/plat/st/stm32mp1/stm32mp1_stack_protector.c
@@ -0,0 +1,21 @@
+/*
+ * Copyright (c) 2018, ARM Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <arch_helpers.h>
+#include <platform.h>
+#include <stdint.h>
+
+#define RANDOM_CANARY_VALUE	2144346116U
+
+u_register_t plat_get_stack_protector_canary(void)
+{
+	/*
+	 * Ideally, a random number should be returned instead of the
+	 * combination of a timer's value and a compile-time constant.
+	 */
+	return RANDOM_CANARY_VALUE ^ (u_register_t)read_cntpct_el0();
+}
+