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

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Date:   Sun, 03 Nov 2019 19:24:04 +0100
From:   Stefan Agner <stefan@...er.ch>
To:     Russell King - ARM Linux admin <linux@...linux.org.uk>
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

Hi Russell,

On 2019-11-01 23:09, Russell King - ARM Linux admin wrote:
> 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...

I used the form to submit the patch. From what I can tell it worked
fine, patch number is 8929/1.

--
Stefan

> 
> 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
>>
>>