linux-kernel - Re: [PATCH] ARM: use APSR_nzcv instead of r15 as mrc operand

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Date:   Fri, 1 Nov 2019 22:09:39 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Stefan Agner <stefan@...er.ch>
Cc:     ndesaulniers@...gle.com, nico@...xnic.net, rfranz@...vell.com,
        linus.walleij@...aro.org, ard.biesheuvel@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] ARM: use APSR_nzcv instead of r15 as mrc operand

On Fri, Nov 01, 2019 at 10:47:58PM +0100, Stefan Agner wrote:
> LLVM's integrated assembler does not accept r15 as mrc operand.
>   arch/arm/boot/compressed/head.S:1267:16: error: operand must be a register in range [r0, r14] or apsr_nzcv
>   1: mrc p15, 0, r15, c7, c14, 3 @ test,clean,invalidate D cache
>                  ^
> 
> Use APSR_nzcv instead of r15. The GNU assembler supports this
> syntax since binutils 2.21 [0].
> 
> [0] https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=commit;h=db472d6ff0f438a21b357249a9b48e4b74498076
> 
> Signed-off-by: Stefan Agner <stefan@...er.ch>

Looks fine, please put it in the patch system; however, please note
that I've been tweaking the patch system over the last week (mainly
with the database, which has impacted almost everything) so there
may be issues that I've not yet found...

Thanks.

> ---
>  arch/arm/boot/compressed/head.S | 2 +-
>  arch/arm/mm/proc-arm1026.S      | 4 ++--
>  arch/arm/mm/proc-arm926.S       | 4 ++--
>  3 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 15ecad944847..ead21e5f2b80 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -1273,7 +1273,7 @@ iflush:
>  __armv5tej_mmu_cache_flush:
>  		tst	r4, #1
>  		movne	pc, lr
> -1:		mrc	p15, 0, r15, c7, c14, 3	@ test,clean,invalidate D cache
> +1:		mrc	p15, 0, APSR_nzcv, c7, c14, 3	@ test,clean,invalidate D cache
>  		bne	1b
>  		mcr	p15, 0, r0, c7, c5, 0	@ flush I cache
>  		mcr	p15, 0, r0, c7, c10, 4	@ drain WB
> diff --git a/arch/arm/mm/proc-arm1026.S b/arch/arm/mm/proc-arm1026.S
> index 10e21012380b..0bdf25a95b10 100644
> --- a/arch/arm/mm/proc-arm1026.S
> +++ b/arch/arm/mm/proc-arm1026.S
> @@ -138,7 +138,7 @@ ENTRY(arm1026_flush_kern_cache_all)
>  	mov	ip, #0
>  __flush_whole_cache:
>  #ifndef CONFIG_CPU_DCACHE_DISABLE
> -1:	mrc	p15, 0, r15, c7, c14, 3		@ test, clean, invalidate
> +1:	mrc	p15, 0, APSR_nzcv, c7, c14, 3		@ test, clean, invalidate
>  	bne	1b
>  #endif
>  	tst	r2, #VM_EXEC
> @@ -363,7 +363,7 @@ ENTRY(cpu_arm1026_switch_mm)
>  #ifdef CONFIG_MMU
>  	mov	r1, #0
>  #ifndef CONFIG_CPU_DCACHE_DISABLE
> -1:	mrc	p15, 0, r15, c7, c14, 3		@ test, clean, invalidate
> +1:	mrc	p15, 0, APSR_nzcv, c7, c14, 3		@ test, clean, invalidate
>  	bne	1b
>  #endif
>  #ifndef CONFIG_CPU_ICACHE_DISABLE
> diff --git a/arch/arm/mm/proc-arm926.S b/arch/arm/mm/proc-arm926.S
> index 3188ab2bac61..1ba253c2bce1 100644
> --- a/arch/arm/mm/proc-arm926.S
> +++ b/arch/arm/mm/proc-arm926.S
> @@ -131,7 +131,7 @@ __flush_whole_cache:
>  #ifdef CONFIG_CPU_DCACHE_WRITETHROUGH
>  	mcr	p15, 0, ip, c7, c6, 0		@ invalidate D cache
>  #else
> -1:	mrc	p15, 0, r15, c7, c14, 3 	@ test,clean,invalidate
> +1:	mrc	p15, 0, APSR_nzcv, c7, c14, 3 	@ test,clean,invalidate
>  	bne	1b
>  #endif
>  	tst	r2, #VM_EXEC
> @@ -358,7 +358,7 @@ ENTRY(cpu_arm926_switch_mm)
>  	mcr	p15, 0, ip, c7, c6, 0		@ invalidate D cache
>  #else
>  @ && 'Clean & Invalidate whole DCache'
> -1:	mrc	p15, 0, r15, c7, c14, 3 	@ test,clean,invalidate
> +1:	mrc	p15, 0, APSR_nzcv, c7, c14, 3 	@ test,clean,invalidate
>  	bne	1b
>  #endif
>  	mcr	p15, 0, ip, c7, c5, 0		@ invalidate I cache
> -- 
> 2.23.0
> 
> 

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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