From: Simon Horman <horms@verge.net.au>
To: Scott Wood <scottwood@freescale.com>
Cc: linuxppc-dev@lists.ozlabs.org, kexec@lists.infradead.org,
Samuel Mendoza-Jonas <sam.mj@au1.ibm.com>,
Michael Ellerman <mpe@ellerman.id.au>
Subject: Re: [PATCH v2 2/3] ppc64: Avoid rfid if no need to clear MSR_LE
Date: Fri, 16 Oct 2015 10:48:03 +0900 [thread overview]
Message-ID: <20151016014803.GF20667@verge.net.au> (raw)
In-Reply-To: <1444172150-29493-2-git-send-email-scottwood@freescale.com>
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
Could I get a review of this from at lest one ppc person?
> 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
>
>
> _______________________________________________
> kexec mailing list
> kexec@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/kexec
>
next prev parent reply other threads:[~2015-10-16 1:54 UTC|newest]
Thread overview: 13+ 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 ` [PATCH v2 2/3] ppc64: Avoid rfid if no need to clear MSR_LE Scott Wood
2015-10-16 1:48 ` Simon Horman [this message]
2015-10-30 0:16 ` Scott Wood
2015-11-01 22:55 ` Sam Mendoza-Jonas
2015-11-02 0:21 ` Sam Mendoza-Jonas
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
2015-10-16 1:48 ` Simon Horman
2015-12-07 20:42 ` Scott Wood
2015-12-08 3:46 ` Michael Ellerman
2015-12-08 6:01 ` Simon Horman
2015-10-16 1:47 ` [PATCH v2 1/3] ppc64: Fix warnings Simon Horman
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