Re: [PATCH v3 1/4] ARM: use arch_extension directive instead of arch argument

[Stefan Agner <stefan@agner.ch>]

On 11.04.2019 09:54, Stefan Agner wrote:
> 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>

Arnd, Tony,

Patch 3 and 4 got merged by Gregory. I think the other two patches are
ready to be merged too. I think they should go in together to avoid
merge conflicts. Tony, if you agree, can you Ack patch 2 so they can get
merged through arm-soc?

--
Stefan

> ---
> Changes since v1:
> - Explicitly specify assembler architecture as armv7-a to avoid
>   build issues when bulding v6/v7 multi arch kernel.
> 
> Changes since v2:
> - Add armv7-a also in mach-tango
> - Move .arch armv7-a outside of ifdef'ed area in sleep44xx.S
>   to make the kernel compile also without CONFIG_SMP/PM.
> 
>  arch/arm/mach-bcm/Makefile         | 3 ---
>  arch/arm/mach-bcm/bcm_kona_smc.c   | 2 --
>  arch/arm/mach-exynos/Makefile      | 4 ----
>  arch/arm/mach-exynos/exynos-smc.S  | 3 ++-
>  arch/arm/mach-exynos/sleep.S       | 3 ++-
>  arch/arm/mach-highbank/Makefile    | 3 ---
>  arch/arm/mach-highbank/smc.S       | 3 ++-
>  arch/arm/mach-keystone/Makefile    | 3 ---
>  arch/arm/mach-keystone/smc.S       | 1 +
>  arch/arm/mach-omap2/Makefile       | 8 --------
>  arch/arm/mach-omap2/omap-headsmp.S | 2 ++
>  arch/arm/mach-omap2/omap-smc.S     | 3 ++-
>  arch/arm/mach-omap2/sleep33xx.S    | 1 +
>  arch/arm/mach-omap2/sleep34xx.S    | 2 ++
>  arch/arm/mach-omap2/sleep43xx.S    | 2 ++
>  arch/arm/mach-omap2/sleep44xx.S    | 3 +++
>  arch/arm/mach-tango/Makefile       | 3 ---
>  arch/arm/mach-tango/smc.S          | 2 ++
>  18 files changed, 21 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/arm/mach-bcm/Makefile b/arch/arm/mach-bcm/Makefile
> index 8fd23b263c60..b59c813b1af4 100644
> --- a/arch/arm/mach-bcm/Makefile
> +++ b/arch/arm/mach-bcm/Makefile
> @@ -40,9 +40,6 @@ obj-$(CONFIG_ARCH_BCM_MOBILE_L2_CACHE) += kona_l2_cache.o
>  
>  # Support for secure monitor traps
>  obj-$(CONFIG_ARCH_BCM_MOBILE_SMC) += bcm_kona_smc.o
> -ifeq ($(call as-instr,.arch_extension sec,as_has_sec),as_has_sec)
> -CFLAGS_bcm_kona_smc.o		+= -Wa,-march=armv7-a+sec -DREQUIRES_SEC
> -endif
>  
>  # BCM2835
>  obj-$(CONFIG_ARCH_BCM2835)	+= board_bcm2835.o
> diff --git a/arch/arm/mach-bcm/bcm_kona_smc.c b/arch/arm/mach-bcm/bcm_kona_smc.c
> index a55a7ecf146a..541e850a736c 100644
> --- a/arch/arm/mach-bcm/bcm_kona_smc.c
> +++ b/arch/arm/mach-bcm/bcm_kona_smc.c
> @@ -125,9 +125,7 @@ static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
>  		__asmeq("%2", "r4")
>  		__asmeq("%3", "r5")
>  		__asmeq("%4", "r6")
> -#ifdef REQUIRES_SEC
>  		".arch_extension sec\n"
> -#endif
>  		"	smc    #0\n"
>  		: "=r" (ip), "=r" (r0)
>  		: "r" (r4), "r" (r5), "r" (r6)
> diff --git a/arch/arm/mach-exynos/Makefile b/arch/arm/mach-exynos/Makefile
> index cd00c82a1add..44de9f36fd1b 100644
> --- a/arch/arm/mach-exynos/Makefile
> +++ b/arch/arm/mach-exynos/Makefile
> @@ -14,9 +14,5 @@ obj-$(CONFIG_PM_SLEEP)		+= suspend.o
>  
>  obj-$(CONFIG_SMP)		+= platsmp.o headsmp.o
>  
> -plus_sec := $(call as-instr,.arch_extension sec,+sec)
> -AFLAGS_exynos-smc.o		:=-Wa,-march=armv7-a$(plus_sec)
> -AFLAGS_sleep.o			:=-Wa,-march=armv7-a$(plus_sec)
> -
>  obj-$(CONFIG_EXYNOS5420_MCPM)	+= mcpm-exynos.o
>  CFLAGS_mcpm-exynos.o		+= -march=armv7-a
> diff --git a/arch/arm/mach-exynos/exynos-smc.S
> b/arch/arm/mach-exynos/exynos-smc.S
> index d259532ba937..6da31e6a7acb 100644
> --- a/arch/arm/mach-exynos/exynos-smc.S
> +++ b/arch/arm/mach-exynos/exynos-smc.S
> @@ -10,7 +10,8 @@
>  /*
>   * Function signature: void exynos_smc(u32 cmd, u32 arg1, u32 arg2, u32 arg3)
>   */
> -
> +	.arch armv7-a
> +	.arch_extension sec
>  ENTRY(exynos_smc)
>  	stmfd	sp!, {r4-r11, lr}
>  	dsb
> diff --git a/arch/arm/mach-exynos/sleep.S b/arch/arm/mach-exynos/sleep.S
> index 2783c3a0c06a..ed93f91853b8 100644
> --- a/arch/arm/mach-exynos/sleep.S
> +++ b/arch/arm/mach-exynos/sleep.S
> @@ -44,7 +44,8 @@ ENTRY(exynos_cpu_resume)
>  ENDPROC(exynos_cpu_resume)
>  
>  	.align
> -
> +	.arch armv7-a
> +	.arch_extension sec
>  ENTRY(exynos_cpu_resume_ns)
>  	mrc	p15, 0, r0, c0, c0, 0
>  	ldr	r1, =CPU_MASK
> diff --git a/arch/arm/mach-highbank/Makefile b/arch/arm/mach-highbank/Makefile
> index 55840f414d3e..e7741b883d13 100644
> --- a/arch/arm/mach-highbank/Makefile
> +++ b/arch/arm/mach-highbank/Makefile
> @@ -1,6 +1,3 @@
>  obj-y					:= highbank.o system.o smc.o
>  
> -plus_sec := $(call as-instr,.arch_extension sec,+sec)
> -AFLAGS_smc.o				:=-Wa,-march=armv7-a$(plus_sec)
> -
>  obj-$(CONFIG_PM_SLEEP)			+= pm.o
> diff --git a/arch/arm/mach-highbank/smc.S b/arch/arm/mach-highbank/smc.S
> index 407d17baaaa9..860a79135b7b 100644
> --- a/arch/arm/mach-highbank/smc.S
> +++ b/arch/arm/mach-highbank/smc.S
> @@ -16,7 +16,8 @@
>   * the monitor API number.
>   * Function signature : void highbank_smc1(u32 fn, u32 arg)
>   */
> -
> +	.arch armv7-a
> +	.arch_extension sec
>  ENTRY(highbank_smc1)
>  	stmfd   sp!, {r4-r11, lr}
>  	mov	r12, r0
> diff --git a/arch/arm/mach-keystone/Makefile b/arch/arm/mach-keystone/Makefile
> index f8b0dccac8dc..739b38be5696 100644
> --- a/arch/arm/mach-keystone/Makefile
> +++ b/arch/arm/mach-keystone/Makefile
> @@ -1,9 +1,6 @@
>  # SPDX-License-Identifier: GPL-2.0
>  obj-y					:= keystone.o smc.o
>  
> -plus_sec := $(call as-instr,.arch_extension sec,+sec)
> -AFLAGS_smc.o				:=-Wa,-march=armv7-a$(plus_sec)
> -
>  obj-$(CONFIG_SMP)			+= platsmp.o
>  
>  # PM domain driver for Keystone SOCs
> diff --git a/arch/arm/mach-keystone/smc.S b/arch/arm/mach-keystone/smc.S
> index d15de8179fab..ec03dc499270 100644
> --- a/arch/arm/mach-keystone/smc.S
> +++ b/arch/arm/mach-keystone/smc.S
> @@ -21,6 +21,7 @@
>   *
>   * Return: Non zero value on failure
>   */
> +	.arch_extension sec
>  ENTRY(keystone_cpu_smc)
>  	stmfd   sp!, {r4-r11, lr}
>  	smc	#0
> diff --git a/arch/arm/mach-omap2/Makefile b/arch/arm/mach-omap2/Makefile
> index 85d1b13c9215..f1d283995b31 100644
> --- a/arch/arm/mach-omap2/Makefile
> +++ b/arch/arm/mach-omap2/Makefile
> @@ -41,11 +41,6 @@ obj-$(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
>  
> diff --git a/arch/arm/mach-omap2/omap-headsmp.S
> b/arch/arm/mach-omap2/omap-headsmp.S
> index 4c6f14cf92a8..b26c0daaa3c1 100644
> --- a/arch/arm/mach-omap2/omap-headsmp.S
> +++ b/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]
> diff --git a/arch/arm/mach-omap2/omap-smc.S b/arch/arm/mach-omap2/omap-smc.S
> index 72506e6cf9e7..a14aee5e81d1 100644
> --- a/arch/arm/mach-omap2/omap-smc.S
> +++ b/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
> diff --git a/arch/arm/mach-omap2/sleep33xx.S b/arch/arm/mach-omap2/sleep33xx.S
> index 47a816468cdb..68fee339d3f1 100644
> --- a/arch/arm/mach-omap2/sleep33xx.S
> +++ b/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)
> diff --git a/arch/arm/mach-omap2/sleep34xx.S b/arch/arm/mach-omap2/sleep34xx.S
> index 22daf4efed68..4927304b5902 100644
> --- a/arch/arm/mach-omap2/sleep34xx.S
> +++ b/arch/arm/mach-omap2/sleep34xx.S
> @@ -97,6 +97,8 @@ 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
> diff --git a/arch/arm/mach-omap2/sleep43xx.S b/arch/arm/mach-omap2/sleep43xx.S
> index 5b9343b58fc7..31dda92d9d03 100644
> --- a/arch/arm/mach-omap2/sleep43xx.S
> +++ b/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)
> diff --git a/arch/arm/mach-omap2/sleep44xx.S b/arch/arm/mach-omap2/sleep44xx.S
> index 0cae3b070208..fb559d3de1f2 100644
> --- a/arch/arm/mach-omap2/sleep44xx.S
> +++ b/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
> diff --git a/arch/arm/mach-tango/Makefile b/arch/arm/mach-tango/Makefile
> index da6c633d3cc0..97cd04508fa1 100644
> --- a/arch/arm/mach-tango/Makefile
> +++ b/arch/arm/mach-tango/Makefile
> @@ -1,7 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0
> -plus_sec := $(call as-instr,.arch_extension sec,+sec)
> -AFLAGS_smc.o := -Wa,-march=armv7-a$(plus_sec)
> -
>  obj-y += setup.o smc.o
>  obj-$(CONFIG_SMP) += platsmp.o
>  obj-$(CONFIG_SUSPEND) += pm.o
> diff --git a/arch/arm/mach-tango/smc.S b/arch/arm/mach-tango/smc.S
> index 361a8dc89804..b1752aaa72bc 100644
> --- a/arch/arm/mach-tango/smc.S
> +++ b/arch/arm/mach-tango/smc.S
> @@ -1,6 +1,8 @@
>  /* SPDX-License-Identifier: GPL-2.0 */
>  #include <linux/linkage.h>
>  
> +	.arch armv7-a
> +	.arch_extension sec
>  ENTRY(tango_smc)
>  	push	{lr}
>  	mov	ip, r1