Allow setting compiler's target architecture

Change-Id: I56ea088f415bdb9077c385bd3450ff4b2cfa2eac
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>

Makefile

@@ -147,26 +147,34 @@ target32-directive	= 	-target arm-none-eabi
 # Will set march32-directive from platform configuration
 else
 target32-directive	= 	-target armv8a-none-eabi
+
+# Set the compiler's target architecture profile based on ARM_ARCH_MINOR option
+ifeq (${ARM_ARCH_MINOR},0)
 march32-directive	= 	-march=armv8-a
+march64-directive	= 	-march=armv8-a
+else
+march32-directive	= 	-march=armv8.${ARM_ARCH_MINOR}-a
+march64-directive	= 	-march=armv8.${ARM_ARCH_MINOR}-a
+endif
 endif
 
 ifneq ($(findstring armclang,$(notdir $(CC))),)
 TF_CFLAGS_aarch32	=	-target arm-arm-none-eabi $(march32-directive)
-TF_CFLAGS_aarch64	=	-target aarch64-arm-none-eabi -march=armv8-a
+TF_CFLAGS_aarch64	=	-target aarch64-arm-none-eabi $(march64-directive)
 LD			=	$(LINKER)
 AS			=	$(CC) -c -x assembler-with-cpp $(TF_CFLAGS_$(ARCH))
 CPP			=	$(CC) -E $(TF_CFLAGS_$(ARCH))
 PP			=	$(CC) -E $(TF_CFLAGS_$(ARCH))
 else ifneq ($(findstring clang,$(notdir $(CC))),)
 TF_CFLAGS_aarch32	=	$(target32-directive) $(march32-directive)
-TF_CFLAGS_aarch64	=	-target aarch64-elf
+TF_CFLAGS_aarch64	=	-target aarch64-elf $(march64-directive)
 LD			=	$(LINKER)
 AS			=	$(CC) -c -x assembler-with-cpp $(TF_CFLAGS_$(ARCH))
 CPP			=	$(CC) -E
 PP			=	$(CC) -E
 else
 TF_CFLAGS_aarch32	=	$(march32-directive)
-TF_CFLAGS_aarch64	=	-march=armv8-a
+TF_CFLAGS_aarch64	=	$(march64-directive)
 LD			=	$(LINKER)
 endif
 
@@ -182,15 +190,7 @@ TF_CFLAGS_aarch32	+=	-mno-unaligned-access
 TF_CFLAGS_aarch64	+=	-mgeneral-regs-only -mstrict-align
 
 ASFLAGS_aarch32		=	$(march32-directive)
-ASFLAGS_aarch64		=	-march=armv8-a
-
-# Set the compiler to ARMv8.3 mode so that it uses all the ARMv8.3-PAuth
-# instructions. Keeping it in 8.0 would make the compiler emit
-# backwards-compatible hint instructions, which needs more space.
-ifeq (${ENABLE_PAUTH},1)
-TF_CFLAGS_aarch64	+=	-march=armv8.3-a
-ASFLAGS_aarch64		+=	-march=armv8.3-a
-endif
+ASFLAGS_aarch64		=	$(march64-directive)
 
 WARNING1 := -Wextra
 WARNING1 += -Wunused -Wno-unused-parameter

docs/firmware-design.rst

@@ -2521,7 +2521,7 @@ section lists the usage of Architecture Extensions, and build flags
 controlling them.
 
 In general, and unless individually mentioned, the build options
-``ARM_ARCH_MAJOR`` and ``ARM_ARCH_MINOR`` selects the Architecture Extension to
+``ARM_ARCH_MAJOR`` and ``ARM_ARCH_MINOR`` select the Architecture Extension to
 target when building TF-A. Subsequent Arm Architecture Extensions are backward
 compatible with previous versions.
 
@@ -2570,6 +2570,10 @@ Armv8.3-A
    ``CTX_INCLUDE_PAUTH_REGS`` to 1. This enables pointer authentication in BL1,
    BL2, BL31, and the TSP if it is used.
 
+   If ``ARM_ARCH_MAJOR == 8`` and ``ARM_ARCH_MINOR >= 3`` the code footprint of
+   enabling PAuth is lower because the compiler will use the optimized
+   PAuth instructions rather than the backwards-compatible ones.
+
 Armv7-A
 ~~~~~~~