linux-kernel - Re: [PATCH v3 1/5] powerpc: Allow flush_icache

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Date:   Thu, 19 Sep 2019 13:48:38 +1000
From:   "Alastair D'Silva" <alastair@....ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     stable@...r.kernel.org,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Christophe Leroy <christophe.leroy@....fr>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Qian Cai <cai@....pw>, Thomas Gleixner <tglx@...utronix.de>,
        Nicholas Piggin <npiggin@...il.com>,
        Allison Randal <allison@...utok.net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        David Hildenbrand <david@...hat.com>,
        Mike Rapoport <rppt@...ux.vnet.ibm.com>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/5] powerpc: Allow flush_icache_range to work across
 ranges >4GB

On Thu, 2019-09-19 at 13:43 +1000, Michael Ellerman wrote:
> "Alastair D'Silva" <alastair@....ibm.com> writes:
> > 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.
> > 
> > __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.
> 

Ok.

> 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@...ilva.org>
> > Cc: stable@...r.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
-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819