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

Similar to commit a6c30873ee ("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: 1d51c699b9
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>

arch/arm/boot/compressed/Makefile

@@ -164,4 +164,3 @@ $(obj)/piggy_data: $(obj)/../Image FORCE
 $(obj)/piggy.o: $(obj)/piggy_data
 
 CFLAGS_font.o := -Dstatic=
-AFLAGS_hyp-stub.o := -Wa,-march=armv7-a

arch/arm/common/Makefile

@@ -13,7 +13,5 @@ obj-$(CONFIG_SHARP_SCOOP)	+= scoop.o
 obj-$(CONFIG_CPU_V7)		+= secure_cntvoff.o
 obj-$(CONFIG_MCPM)		+= mcpm_head.o mcpm_entry.o mcpm_platsmp.o vlock.o
 CFLAGS_REMOVE_mcpm_entry.o	= -pg
-AFLAGS_mcpm_head.o		:= -march=armv7-a
-AFLAGS_vlock.o			:= -march=armv7-a
 obj-$(CONFIG_BL_SWITCHER)	+= bL_switcher.o
 obj-$(CONFIG_BL_SWITCHER_DUMMY_IF) += bL_switcher_dummy_if.o

arch/arm/common/mcpm_head.S

@@ -15,6 +15,8 @@
 
 #include "vlock.h"
 
+.arch armv7-a
+
 .if MCPM_SYNC_CLUSTER_CPUS
 .error "cpus must be the first member of struct mcpm_sync_struct"
 .endif

arch/arm/common/vlock.S

@@ -12,6 +12,8 @@
 #include <linux/linkage.h>
 #include "vlock.h"
 
+.arch armv7-a
+
 /* Select different code if voting flags  can fit in a single word. */
 #if VLOCK_VOTING_SIZE > 4
 #define FEW(x...)

arch/arm/kernel/Makefile

@@ -71,7 +71,6 @@ obj-$(CONFIG_HAVE_TCM)		+= tcm.o
 obj-$(CONFIG_OF)		+= devtree.o
 obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_SWP_EMULATE)	+= swp_emulate.o
-CFLAGS_swp_emulate.o		:= -Wa,-march=armv7-a
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
 
 obj-$(CONFIG_CPU_XSCALE)	+= xscale-cp0.o
@@ -100,7 +99,6 @@ CFLAGS_head-inflate-data.o := $(call cc-option,-Wframe-larger-than=10240)
 obj-$(CONFIG_XIP_DEFLATED_DATA) += head-inflate-data.o
 
 obj-$(CONFIG_ARM_VIRT_EXT)	+= hyp-stub.o
-AFLAGS_hyp-stub.o		:=-Wa,-march=armv7-a
 ifeq ($(CONFIG_ARM_PSCI),y)
 obj-$(CONFIG_SMP)		+= psci_smp.o
 endif

arch/arm/kernel/hyp-stub.S

@@ -9,6 +9,8 @@
 #include <asm/assembler.h>
 #include <asm/virt.h>
 
+.arch armv7-a
+
 #ifndef ZIMAGE
 /*
  * For the kernel proper, we need to find out the CPU boot mode long after

arch/arm/kernel/swp_emulate.c

@@ -34,6 +34,7 @@
  */
 #define __user_swpX_asm(data, addr, res, temp, B)		\
 	__asm__ __volatile__(					\
+	".arch armv7-a\n"					\
 	"0:	ldrex"B"	%2, [%3]\n"			\
 	"1:	strex"B"	%0, %1, [%3]\n"			\
 	"	cmp		%0, #0\n"			\

arch/arm/lib/Makefile

@@ -36,10 +36,6 @@ else
   lib-y	+= io-readsw-armv4.o io-writesw-armv4.o
 endif
 
-ifeq ($(CONFIG_ARCH_RPC),y)
-  AFLAGS_delay-loop.o		+= -march=armv4
-endif
-
 $(obj)/csumpartialcopy.o:	$(obj)/csumpartialcopygeneric.S
 $(obj)/csumpartialcopyuser.o:	$(obj)/csumpartialcopygeneric.S
 

arch/arm/lib/delay-loop.S

@@ -8,6 +8,10 @@
 #include <asm/assembler.h>
 #include <asm/delay.h>
 
+#ifdef CONFIG_ARCH_RPC
+		.arch	armv4
+#endif
+
 		.text
 
 .LC0:		.word	loops_per_jiffy

arch/arm/mach-at91/Makefile

@@ -14,9 +14,6 @@ obj-$(CONFIG_SOC_SAMV7)		+= samv7.o
 # Power Management
 obj-$(CONFIG_ATMEL_PM)		+= pm.o pm_suspend.o
 
-ifeq ($(CONFIG_CPU_V7),y)
-AFLAGS_pm_suspend.o := -march=armv7-a
-endif
 ifeq ($(CONFIG_PM_DEBUG),y)
 CFLAGS_pm.o += -DDEBUG
 endif

arch/arm/mach-at91/pm_suspend.S

@@ -12,6 +12,10 @@
 #include "pm.h"
 #include "pm_data-offsets.h"
 
+#ifdef CONFIG_CPU_V7
+.arch armv7-a
+#endif
+
 #define	SRAMC_SELF_FRESH_ACTIVE		0x01
 #define	SRAMC_SELF_FRESH_EXIT		0x00
 

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

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 - .
 

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

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 ====================
  *

arch/arm/mach-mvebu/Makefile

@@ -1,9 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/arch/arm/plat-orion/include
 
-AFLAGS_coherency_ll.o		:= -Wa,-march=armv7-a
-CFLAGS_pmsu.o			:= -march=armv7-a
-
 obj-$(CONFIG_MACH_MVEBU_ANY)	 += system-controller.o mvebu-soc-id.o
 
 ifeq ($(CONFIG_MACH_MVEBU_V7),y)

arch/arm/mach-mvebu/coherency_ll.S

@@ -20,6 +20,7 @@
 #include <asm/assembler.h>
 #include <asm/cp15.h>
 
+	.arch armv7-a
 	.text
 /*
  * Returns the coherency base address in r1 (r0 is untouched), or 0 if

arch/arm/mach-mvebu/pmsu.c

@@ -291,6 +291,7 @@ int armada_370_xp_pmsu_idle_enter(unsigned long deepidle)
 
 	/* Test the CR_C bit and set it if it was cleared */
 	asm volatile(
+	".arch	armv7-a\n\t"
 	"mrc	p15, 0, r0, c1, c0, 0 \n\t"
 	"tst	r0, %0 \n\t"
 	"orreq	r0, r0, #(1 << 2) \n\t"

arch/arm/mach-npcm/Makefile

@@ -1,6 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
-AFLAGS_headsmp.o		+= -march=armv7-a
-
 obj-$(CONFIG_ARCH_WPCM450)	+= wpcm450.o
 obj-$(CONFIG_ARCH_NPCM7XX)	+= npcm7xx.o
 obj-$(CONFIG_SMP)		+= platsmp.o headsmp.o

arch/arm/mach-npcm/headsmp.S

@@ -6,6 +6,8 @@
 #include <linux/init.h>
 #include <asm/assembler.h>
 
+.arch armv7-a
+
 /*
  * The boot ROM does not start secondary CPUs in SVC mode, so we need to do that
  * here.