Enable MTE support

Enable MTE support by adding memory tag option in Makefile
This option is available only when ARMv8.5-MemTag is implemented

MTE options are added in latest clang and armclang compiler which
support below options:
for clang <version 11.0.0>
1. -march=arm8.5-a+memtag
2. -fsanitize=memtag

for armclang <version 6.12>
1. -march=arm8.5-a+memtag
2. -mmemtag-stack

Set the option SUPPORT_STACK_MEMTAG=yes to enable memory stack tagging.

Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
Change-Id: I4e0bbde4e9769ce03ead6f550158e22f32c1c413
diff --git a/Makefile b/Makefile
index ac461a5..e455635 100644
--- a/Makefile
+++ b/Makefile
@@ -187,6 +187,34 @@
+# Memory tagging is supported in architecture Armv8.5-A AArch64 and onwards
+ifeq ($(ARCH), aarch64)
+ifeq ($(shell test $(ARM_ARCH_MAJOR) -gt 8; echo $$?),0)
+mem_tag_arch_support	= 	yes
+else ifeq ($(shell test $(ARM_ARCH_MAJOR) -eq 8 -a $(ARM_ARCH_MINOR) -ge 5; \
+	   echo $$?),0)
+mem_tag_arch_support	= 	yes
+# Enabled required option for memory stack tagging. Currently, these options are
+# enabled only for clang and armclang compiler.
+ifdef mem_tag_arch_support
+ifneq ( ,$(filter $(notdir $(CC)),armclang clang))
+march64-directive       =       -march=armv${ARM_ARCH_MAJOR}.${ARM_ARCH_MINOR}-a+memtag
+ifeq ($(notdir $(CC)),armclang)
+TF_CFLAGS		+=	-mmemtag-stack
+else ifeq ($(notdir $(CC)),clang)
+TF_CFLAGS		+=	-fsanitize=memtag
+$(error "Error: stack memory tagging is not supported for architecture \
 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)
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 69e103d..e1c6c8f 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -667,6 +667,11 @@
    cluster platforms). If this option is enabled, then warm boot path
    enables D-caches immediately after enabling MMU. This option defaults to 0.
+-  ``SUPPORT_STACK_MEMTAG``: This flag determines whether to enable memory
+   tagging for stack or not. It accepts 2 values: ``yes`` and ``no``. The
+   default value of this flag is ``no``. Note this option must be enabled only
+   for ARM architecture greater than Armv8.5-A.
 GICv3 driver options
diff --git a/make_helpers/defaults.mk b/make_helpers/defaults.mk
index 4e968e2..590a800 100644
--- a/make_helpers/defaults.mk
+++ b/make_helpers/defaults.mk
@@ -288,3 +288,8 @@
 # S-EL2 firmware entry/exit. This flag is to be used with SPD=spmd option.
 # Default is 0.
+# Enable Memory tag extension which is supported for architecture greater
+# than Armv8.5-A
+# By default it is set to "no"