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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Alastair D'Silva <alastair@au1.ibm.com>, alastair@d-silva.org
Cc:     stable@vger.kernel.org,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Christophe Leroy <christophe.leroy@c-s.fr>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Qian Cai <cai@lca.pw>, Thomas Gleixner <tglx@linutronix.de>,
        Nicholas Piggin <npiggin@gmail.com>,
        Allison Randal <allison@lohutok.net>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>,
        David Hildenbrand <david@redhat.com>,
        Mike Rapoport <rppt@linux.vnet.ibm.com>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 1/5] powerpc: Allow flush_icache_range to work across ranges >4GB
In-Reply-To: <20190918052106.14113-2-alastair@au1.ibm.com>
References: <20190918052106.14113-1-alastair@au1.ibm.com> <20190918052106.14113-2-alastair@au1.ibm.com>
Date:   Thu, 19 Sep 2019 13:43:43 +1000
Message-ID: <87imppuf0w.fsf@mpe.ellerman.id.au>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
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"Alastair D'Silva" <alastair@au1.ibm.com> writes:
> From: Alastair D'Silva <alastair@d-silva.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.
>
> __kernel_sync_dicache in the 64 bit VDSO has the same bug.

Please fix that in a separate patch.

Your subject doesn't mention __kernel_sync_dicache(), and also the two
changes backport differently, so it's better if they're done as separate
patches.

cheers

> This patch replaces the 32 bit shifts with 64 bit ones, so that
> the full size is accounted for.
>
> Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
> Cc: stable@vger.kernel.org
> ---
>  arch/powerpc/kernel/misc_64.S           | 4 ++--
>  arch/powerpc/kernel/vdso64/cacheflush.S | 4 ++--
>  2 files changed, 4 insertions(+), 4 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
> diff --git a/arch/powerpc/kernel/vdso64/cacheflush.S b/arch/powerpc/kernel/vdso64/cacheflush.S
> index 3f92561a64c4..526f5ba2593e 100644
> --- a/arch/powerpc/kernel/vdso64/cacheflush.S
> +++ b/arch/powerpc/kernel/vdso64/cacheflush.S
> @@ -35,7 +35,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
>  	subf	r8,r6,r4		/* compute length */
>  	add	r8,r8,r5		/* ensure we get enough */
>  	lwz	r9,CFG_DCACHE_LOGBLOCKSZ(r10)
> -	srw.	r8,r8,r9		/* compute line count */
> +	srd.	r8,r8,r9		/* compute line count */
>  	crclr	cr0*4+so
>  	beqlr				/* nothing to do? */
>  	mtctr	r8
> @@ -52,7 +52,7 @@ V_FUNCTION_BEGIN(__kernel_sync_dicache)
>  	subf	r8,r6,r4		/* compute length */
>  	add	r8,r8,r5
>  	lwz	r9,CFG_ICACHE_LOGBLOCKSZ(r10)
> -	srw.	r8,r8,r9		/* compute line count */
> +	srd.	r8,r8,r9		/* compute line count */
>  	crclr	cr0*4+so
>  	beqlr				/* nothing to do? */
>  	mtctr	r8
> -- 
> 2.21.0