TF-A: Add ARMv8.5 'bti' build option

This patch adds BRANCH_PROTECTION = 4 'bti' build option
which turns on branch target identification mechanism.

Change-Id: I32464a6b51726a100519f449a95aea5331f0e82d
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index bc5604be2..160cd44cc 100644
--- a/Makefile
+++ b/Makefile
@@ -121,6 +121,10 @@ else ifeq (${BRANCH_PROTECTION},3)
 	# Extend the signing to include leaf functions
 	BP_OPTION := pac-ret+leaf
 	ENABLE_PAUTH := 1
+else ifeq (${BRANCH_PROTECTION},4)
+	# Turn on branch target identification mechanism
+	BP_OPTION := bti
+	ENABLE_BTI := 1
 else
         $(error Unknown BRANCH_PROTECTION value ${BRANCH_PROTECTION})
 endif