ARM: 9263/1: use .arch directives instead of assembler command line flags

Similar to commit a6c30873ee4a ("ARM: 8989/1: use .fpu assembler
directives instead of assembler arguments").

GCC and GNU binutils support setting the "sub arch" via -march=,
-Wa,-march, target function attribute, and .arch assembler directive.

Clang was missing support for -Wa,-march=, but this was implemented in
clang-13.

The behavior of both GCC and Clang is to
prefer -Wa,-march= over -march= for assembler and assembler-with-cpp
sources, but Clang will warn about the -march= being unused.

clang: warning: argument unused during compilation: '-march=armv6k'
[-Wunused-command-line-argument]

Since most assembler is non-conditionally assembled with one sub arch
(modulo arch/arm/delay-loop.S which conditionally is assembled as armv4
based on CONFIG_ARCH_RPC, and arch/arm/mach-at91/pm-suspend.S which is
conditionally assembled as armv7-a based on CONFIG_CPU_V7), prefer the
.arch assembler directive.

Add a few more instances found in compile testing as found by Arnd and
Nathan.

Link: https://github.com/llvm/llvm-project/commit/1d51c699b9e2ebc5bcfdbe85c74cc871426333d4
Link: https://bugs.llvm.org/show_bug.cgi?id=48894
Link: https://github.com/ClangBuiltLinux/linux/issues/1195
Link: https://github.com/ClangBuiltLinux/linux/issues/1315

Suggested-by: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

4 files changed, 6 insertions, 3 deletions

diff --git a/arch/arm/mach-imx/Makefile b/arch/arm/mach-imx/Makefile
index 6fb3965b9ae6..5c650bf40e02 100644
--- a/arch/arm/mach-imx/Makefile
+++ b/arch/arm/mach-imx/Makefile
@@ -34,7 +34,6 @@ obj-$(CONFIG_HAVE_IMX_GPC) += gpc.o
 obj-$(CONFIG_HAVE_IMX_MMDC) += mmdc.o
 obj-$(CONFIG_HAVE_IMX_SRC) += src.o
 ifneq ($(CONFIG_SOC_IMX6)$(CONFIG_SOC_IMX7D_CA7)$(CONFIG_SOC_LS1021A),)
-AFLAGS_headsmp.o :=-Wa,-march=armv7-a
 obj-$(CONFIG_SMP) += headsmp.o platsmp.o
 obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
 endif
@@ -48,12 +47,10 @@ obj-$(CONFIG_SOC_IMX7D_CM4) += mach-imx7d-cm4.o
 obj-$(CONFIG_SOC_IMX7ULP) += mach-imx7ulp.o pm-imx7ulp.o
 
 ifeq ($(CONFIG_SUSPEND),y)
-AFLAGS_suspend-imx6.o :=-Wa,-march=armv7-a
 obj-$(CONFIG_SOC_IMX6) += suspend-imx6.o
 obj-$(CONFIG_SOC_IMX53) += suspend-imx53.o
 endif
 ifeq ($(CONFIG_ARM_CPU_SUSPEND),y)
-AFLAGS_resume-imx6.o :=-Wa,-march=armv7-a
 obj-$(CONFIG_SOC_IMX6) += resume-imx6.o
 endif
 obj-$(CONFIG_SOC_IMX6) += pm-imx6.o
diff --git a/arch/arm/mach-imx/headsmp.S b/arch/arm/mach-imx/headsmp.S
index fcba58be8e79..5f9c7b48ae80 100644
--- a/arch/arm/mach-imx/headsmp.S
+++ b/arch/arm/mach-imx/headsmp.S
@@ -8,6 +8,8 @@
 #include <linux/init.h>
 #include <asm/assembler.h>
 
+.arch armv7-a
+
 diag_reg_offset:
 	.word	g_diag_reg - .
 
diff --git a/arch/arm/mach-imx/resume-imx6.S b/arch/arm/mach-imx/resume-imx6.S
index 5bd1ba7ef15b..2c0c5c771251 100644
--- a/arch/arm/mach-imx/resume-imx6.S
+++ b/arch/arm/mach-imx/resume-imx6.S
@@ -9,6 +9,8 @@
 #include <asm/hardware/cache-l2x0.h>
 #include "hardware.h"
 
+.arch armv7-a
+
 /*
  * The following code must assume it is running from physical address
  * where absolute virtual addresses to the data section have to be
diff --git a/arch/arm/mach-imx/suspend-imx6.S b/arch/arm/mach-imx/suspend-imx6.S
index e06f946b75b9..63ccc2d0e920 100644
--- a/arch/arm/mach-imx/suspend-imx6.S
+++ b/arch/arm/mach-imx/suspend-imx6.S
@@ -9,6 +9,8 @@
 #include <asm/hardware/cache-l2x0.h>
 #include "hardware.h"
 
+.arch armv7-a
+
 /*
  * ==================== low level suspend ====================
  *