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From: Sam Mendoza-Jonas <sam.mj@au1.ibm.com>
To: Scott Wood <scottwood@freescale.com>
Cc: kexec@lists.infradead.org, Simon Horman <horms@verge.net.au>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2 2/3] ppc64: Avoid rfid if no need to clear MSR_LE
Date: Mon, 2 Nov 2015 11:21:43 +1100	[thread overview]
Message-ID: <20151102002143.GA7053@localhost.localdomain> (raw)
In-Reply-To: <20151101225553.GA1995@localhost.localdomain>

On Mon, Nov 02, 2015 at 09:55:53AM +1100, Sam Mendoza-Jonas wrote:
> On Tue, Oct 06, 2015 at 05:55:49PM -0500, Scott Wood wrote:
> > Commit a304e2d82a8c3 ("ppc64: purgatory: Reset primary cpu endian to
> > big-endian) changed bctr to rfid.  rfid is book3s-only and will cause a
> > fatal exception on book3e.
> > 
> > Purgatory is an isolated environment which makes importing information
> > about the subarch awkward, so instead rely on the fact that MSR_LE
> > should never be set on book3e, and the rfid is only needed if MSR_LE is
> > set (and thus needs to be cleared).  In theory that MSR bit is reserved
> > on book3e, rather than zero, but in practice I have not seen it set.
> > 
> > Signed-off-by: Scott Wood <scottwood@freescale.com>
> > Cc: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> > ---
> > v2: new patch
> 
> Looks good to me, thanks for catching this!
> I'll ping Michael too if you'd like his reviewed-by.
> 
> Reviewed-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

Following up, also add my

Tested-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

> 
> > 
> >  purgatory/arch/ppc64/v2wrap.S | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/purgatory/arch/ppc64/v2wrap.S b/purgatory/arch/ppc64/v2wrap.S
> > index 179ade9..3534080 100644
> > --- a/purgatory/arch/ppc64/v2wrap.S
> > +++ b/purgatory/arch/ppc64/v2wrap.S
> > @@ -116,9 +116,17 @@ master:
> >  	stw	7,0x5c(4)	# and patch it into the kernel
> >  	mr      3,16            # restore dt address
> >  
> > +	mfmsr	5
> > +	andi.	10,5,1		# test MSR_LE
> > +	bne	little_endian
> > +
> > +	li	5,0		# r5 will be 0 for kernel
> > +	mtctr	4		# prepare branch to
> > +	bctr			# start kernel
> > +	
> > +little_endian:			# book3s-only
> >  	mtsrr0	4		# prepare branch to
> >  
> > -	mfmsr	5
> >  	clrrdi	5,5,1		# clear MSR_LE
> >  	mtsrr1	5
> >  
> > -- 
> > 2.1.4
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev


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WARNING: multiple messages have this Message-ID (diff)
From: Sam Mendoza-Jonas <sam.mj@au1.ibm.com>
To: Scott Wood <scottwood@freescale.com>
Cc: linuxppc-dev@lists.ozlabs.org, Simon Horman <horms@verge.net.au>,
	kexec@lists.infradead.org
Subject: Re: [PATCH v2 2/3] ppc64: Avoid rfid if no need to clear MSR_LE
Date: Mon, 2 Nov 2015 11:21:43 +1100	[thread overview]
Message-ID: <20151102002143.GA7053@localhost.localdomain> (raw)
In-Reply-To: <20151101225553.GA1995@localhost.localdomain>

On Mon, Nov 02, 2015 at 09:55:53AM +1100, Sam Mendoza-Jonas wrote:
> On Tue, Oct 06, 2015 at 05:55:49PM -0500, Scott Wood wrote:
> > Commit a304e2d82a8c3 ("ppc64: purgatory: Reset primary cpu endian to
> > big-endian) changed bctr to rfid.  rfid is book3s-only and will cause a
> > fatal exception on book3e.
> > 
> > Purgatory is an isolated environment which makes importing information
> > about the subarch awkward, so instead rely on the fact that MSR_LE
> > should never be set on book3e, and the rfid is only needed if MSR_LE is
> > set (and thus needs to be cleared).  In theory that MSR bit is reserved
> > on book3e, rather than zero, but in practice I have not seen it set.
> > 
> > Signed-off-by: Scott Wood <scottwood@freescale.com>
> > Cc: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>
> > ---
> > v2: new patch
> 
> Looks good to me, thanks for catching this!
> I'll ping Michael too if you'd like his reviewed-by.
> 
> Reviewed-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

Following up, also add my

Tested-by: Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>

> 
> > 
> >  purgatory/arch/ppc64/v2wrap.S | 10 +++++++++-
> >  1 file changed, 9 insertions(+), 1 deletion(-)
> > 
> > diff --git a/purgatory/arch/ppc64/v2wrap.S b/purgatory/arch/ppc64/v2wrap.S
> > index 179ade9..3534080 100644
> > --- a/purgatory/arch/ppc64/v2wrap.S
> > +++ b/purgatory/arch/ppc64/v2wrap.S
> > @@ -116,9 +116,17 @@ master:
> >  	stw	7,0x5c(4)	# and patch it into the kernel
> >  	mr      3,16            # restore dt address
> >  
> > +	mfmsr	5
> > +	andi.	10,5,1		# test MSR_LE
> > +	bne	little_endian
> > +
> > +	li	5,0		# r5 will be 0 for kernel
> > +	mtctr	4		# prepare branch to
> > +	bctr			# start kernel
> > +	
> > +little_endian:			# book3s-only
> >  	mtsrr0	4		# prepare branch to
> >  
> > -	mfmsr	5
> >  	clrrdi	5,5,1		# clear MSR_LE
> >  	mtsrr1	5
> >  
> > -- 
> > 2.1.4
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

  reply	other threads:[~2015-11-02  0:23 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-06 22:55 [PATCH v2 1/3] ppc64: Fix warnings Scott Wood
2015-10-06 22:55 ` Scott Wood
2015-10-06 22:55 ` [PATCH v2 2/3] ppc64: Avoid rfid if no need to clear MSR_LE Scott Wood
2015-10-06 22:55   ` Scott Wood
2015-10-16  1:48   ` Simon Horman
2015-10-16  1:48     ` Simon Horman
2015-10-30  0:16     ` Scott Wood
2015-10-30  0:16       ` Scott Wood
2015-11-01 22:55   ` Sam Mendoza-Jonas
2015-11-01 22:55     ` Sam Mendoza-Jonas
2015-11-02  0:21     ` Sam Mendoza-Jonas [this message]
2015-11-02  0:21       ` Sam Mendoza-Jonas
2015-11-02  2:06       ` Simon Horman
2015-11-02  2:06         ` Simon Horman
2015-10-06 22:55 ` [PATCH v2 3/3] ppc64: Add a flag to tell the kernel it's booting from kexec Scott Wood
2015-10-06 22:55   ` Scott Wood
2015-10-16  1:48   ` Simon Horman
2015-10-16  1:48     ` Simon Horman
2015-12-07 20:42   ` Scott Wood
2015-12-07 20:42     ` Scott Wood
2015-12-08  3:46     ` Michael Ellerman
2015-12-08  3:46       ` Michael Ellerman
2015-12-08  6:01       ` Simon Horman
2015-12-08  6:01         ` Simon Horman
2015-10-16  1:47 ` [PATCH v2 1/3] ppc64: Fix warnings Simon Horman
2015-10-16  1:47   ` Simon Horman

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