[PATCH 1/2] powerpc: Allow flush_icache_range to work across ranges >4GB

[PATCH 1/2] powerpc: Allow flush_icache_range to work across ranges >4GB

[Alastair D'Silva]

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.

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).

Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
---
 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
-- 
2.21.0

Re: [PATCH 1/2] powerpc: Allow flush_icache_range to work across ranges >4GB

[Christophe Leroy]

Le 09/08/2019 à 02:45, Alastair D'Silva a écrit :
> 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.
> 
> 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@d-silva.org>

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

Should add:

Cc: stable@vger.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
> 

Re: [PATCH 1/2] powerpc: Allow flush_icache_range to work across ranges >4GB

[Alastair D'Silva]

On Fri, 2019-08-09 at 10:59 +0200, Christophe Leroy wrote:
> 
> Le 09/08/2019 à 02:45, Alastair D'Silva a écrit :
> > 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.
> > 
> > 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 ?
> 

This patch was sent to stable too - or did you mean send another patch
for the stable asm version of flush_dcache_range?

-- 
Alastair D'Silva
Open Source Developer
Linux Technology Centre, IBM Australia
mob: 0423 762 819

Re: [PATCH 1/2] powerpc: Allow flush_icache_range to work across ranges >4GB

[Christophe Leroy]

Le 12/08/2019 à 03:19, Alastair D'Silva a écrit :
> On Fri, 2019-08-09 at 10:59 +0200, Christophe Leroy wrote:
>>
>> Le 09/08/2019 à 02:45, Alastair D'Silva a écrit :
>>> 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.
>>>
>>> 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 ?
>>
> 
> This patch was sent to stable too - or did you mean send another patch
> for the stable asm version of flush_dcache_range?
> 

Yes I meant a patch for your 'heads-up', in extenso a patch for fixing 
flush_dcache_range().

And for this patch, you put stable is copy of the mail, but for it to be 
taken into account it needs to also explicitely include a Cc: 
stable@vger.kernel.org in the commit message. I guess Michael will add 
it for this time.

Christophe