linux-kernel - Re: [PATCH 1/2] powerpc: Allow flush_icache

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Date:   Fri, 9 Aug 2019 10:59:01 +0200
From:   Christophe Leroy <christophe.leroy@....fr>
To:     Alastair D'Silva <alastair@....ibm.com>, alastair@...ilva.org
Cc:     stable@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] powerpc: Allow flush_icache_range to work across
 ranges >4GB



Le 09/08/2019 à 02:45, Alastair D'Silva a écrit :
> From: Alastair D'Silva <alastair@...ilva.org>
> 
> When calling flush_icache_range with a size >4GB, we were masking
> off the upper 32 bits, so we would incorrectly flush a range smaller
> than intended.
> 
> This patch replaces the 32 bit shifts with 64 bit ones, so that
> the full size is accounted for.
> 
> Heads-up for backporters: the old version of flush_dcache_range is
> subject to a similar bug (this has since been replaced with a C
> implementation).

Can you submit a patch to stable, explaining this ?

> 
> Signed-off-by: Alastair D'Silva <alastair@...ilva.org>

Reviewed-by: Christophe Leroy <christophe.leroy@....fr>

Should add:

Cc: stable@...r.kernel.org

Christophe

> ---
>   arch/powerpc/kernel/misc_64.S | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
> index b55a7b4cb543..9bc0aa9aeb65 100644
> --- a/arch/powerpc/kernel/misc_64.S
> +++ b/arch/powerpc/kernel/misc_64.S
> @@ -82,7 +82,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
>   	subf	r8,r6,r4		/* compute length */
>   	add	r8,r8,r5		/* ensure we get enough */
>   	lwz	r9,DCACHEL1LOGBLOCKSIZE(r10)	/* Get log-2 of cache block size */
> -	srw.	r8,r8,r9		/* compute line count */
> +	srd.	r8,r8,r9		/* compute line count */
>   	beqlr				/* nothing to do? */
>   	mtctr	r8
>   1:	dcbst	0,r6
> @@ -98,7 +98,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_COHERENT_ICACHE)
>   	subf	r8,r6,r4		/* compute length */
>   	add	r8,r8,r5
>   	lwz	r9,ICACHEL1LOGBLOCKSIZE(r10)	/* Get log-2 of Icache block size */
> -	srw.	r8,r8,r9		/* compute line count */
> +	srd.	r8,r8,r9		/* compute line count */
>   	beqlr				/* nothing to do? */
>   	mtctr	r8
>   2:	icbi	0,r6
>