qemu: Add support for stack canary protection
Allow qemu users to enable stack protection. Since the virt platform
does not provide an RNG, use a basic, timer-based, canary generation,
similarly to FVP.
Increase SRAM size and BL2 size to fit images when stack protection is
enabled.
Notice that stack protection is not enabled by default in qemu.
Fixes ARM-software/tf-issues#568
Signed-off-by: Michalis Pappas <mpappas@fastmail.fm>
diff --git a/plat/qemu/qemu_stack_protector.c b/plat/qemu/qemu_stack_protector.c
new file mode 100644
index 0000000..5b19828
--- /dev/null
+++ b/plat/qemu/qemu_stack_protector.c
@@ -0,0 +1,23 @@
+/*
+ * 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 ((u_register_t) 3288484550995823360ULL)
+
+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.
+ * As the virt platform does not have any random number generator,
+ * this is better than nothing but not necessarily really secure.
+ */
+ return RANDOM_CANARY_VALUE ^ read_cntpct_el0();
+}
+