ARM: use arch_extension directive instead of arch argument

The LLVM Target parser currently does not allow to specify the security
extension as part of -march (see also LLVM Bug 40186 [0]). When trying
to use Clang with LLVM's integrated assembler, this leads to build
errors such as this:
  clang-8: error: the clang compiler does not support '-Wa,-march=armv7-a+sec'

Use ".arch_extension sec" to enable the security extension in a more
portable fasion. Also make sure to use ".arch armv7-a" in case a v6/v7
multi-platform kernel is being built.

Note that this is technically not exactly the same as the old code
checked for availabilty of the security extension by calling as-instr.
However, there are already other sites which use ".arch_extension sec"
unconditionally, hence de-facto we need an assembler capable of
".arch_extension sec" already today (arch/arm/mm/proc-v7.S). The
arch extension "sec" is available since binutils 2.21 according to
its documentation [1].

[0] https://bugs.llvm.org/show_bug.cgi?id=40186
[1] https://sourceware.org/binutils/docs-2.21/as/ARM-Options.html

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Mans Rullgard <mans@mansr.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/mach-omap2/Makefile

@@ -41,11 +41,6 @@ obj-$(CONFIG_SOC_OMAP5)			+= $(omap-4-5-common) $(smp-y) sleep44xx.o
 obj-$(CONFIG_SOC_AM43XX)		+= $(omap-4-5-common)
 obj-$(CONFIG_SOC_DRA7XX)		+= $(omap-4-5-common) $(smp-y) sleep44xx.o
 
-plus_sec := $(call as-instr,.arch_extension sec,+sec)
-AFLAGS_omap-headsmp.o			:=-Wa,-march=armv7-a$(plus_sec)
-AFLAGS_omap-smc.o			:=-Wa,-march=armv7-a$(plus_sec)
-AFLAGS_sleep44xx.o			:=-Wa,-march=armv7-a$(plus_sec)
-
 # Functions loaded to SRAM
 obj-$(CONFIG_SOC_OMAP2420)		+= sram242x.o
 obj-$(CONFIG_SOC_OMAP2430)		+= sram243x.o
@@ -95,9 +90,6 @@ obj-$(CONFIG_POWER_AVS_OMAP)		+= sr_device.o
 obj-$(CONFIG_POWER_AVS_OMAP_CLASS3)    += smartreflex-class3.o
 
 AFLAGS_sleep24xx.o			:=-Wa,-march=armv6
-AFLAGS_sleep34xx.o			:=-Wa,-march=armv7-a$(plus_sec)
-AFLAGS_sleep33xx.o			:=-Wa,-march=armv7-a$(plus_sec)
-AFLAGS_sleep43xx.o			:=-Wa,-march=armv7-a$(plus_sec)
 
 endif
 

arch/arm/mach-omap2/omap-headsmp.S

@@ -58,6 +58,8 @@ ENDPROC(omap5_secondary_startup)
  * omap5_secondary_startup if the primary CPU was put into HYP mode by
  * the boot loader.
  */
+	.arch armv7-a
+	.arch_extension sec
 ENTRY(omap5_secondary_hyp_startup)
 wait_2:	ldr	r2, =AUX_CORE_BOOT0_PA	@ read from AuxCoreBoot0
 	ldr	r0, [r2]

arch/arm/mach-omap2/omap-smc.S

@@ -23,7 +23,8 @@
  * link register "lr".
  * Function signature : void omap_smc1(u32 fn, u32 arg)
  */
-
+	.arch armv7-a
+	.arch_extension sec
 ENTRY(omap_smc1)
 	stmfd   sp!, {r2-r12, lr}
 	mov	r12, r0

arch/arm/mach-omap2/sleep33xx.S

@@ -24,6 +24,7 @@
 #define BIT(nr)			(1 << (nr))
 
 	.arm
+	.arch armv7-a
 	.align 3
 
 ENTRY(am33xx_do_wfi)

arch/arm/mach-omap2/sleep34xx.S

@@ -83,6 +83,8 @@ ENDPROC(enable_omap3630_toggle_l2_on_restore)
  *
  * r0 = physical address of the parameters
  */
+	.arch armv7-a
+	.arch_extension sec
 ENTRY(save_secure_ram_context)
 	stmfd	sp!, {r4 - r11, lr}	@ save registers on stack
 	mov	r3, r0			@ physical address of parameters

arch/arm/mach-omap2/sleep43xx.S

@@ -56,6 +56,8 @@
 #define RTC_PMIC_EXT_WAKEUP_EN				BIT(0)
 
 	.arm
+	.arch armv7-a
+	.arch_extension sec
 	.align 3
 
 ENTRY(am43xx_do_wfi)

arch/arm/mach-omap2/sleep44xx.S

@@ -21,8 +21,11 @@
 #include "omap44xx.h"
 #include "omap4-sar-layout.h"
 
+	.arch armv7-a
+
 #if defined(CONFIG_SMP) && defined(CONFIG_PM)
 
+	.arch_extension sec
 .macro	DO_SMC
 	dsb
 	smc	#0