From: dave.martin@linaro.org (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/9] ARM: fixup_pv_table bug when CPU_ENDIAN_BE8
Date: Tue, 19 Feb 2013 12:04:11 +0000 [thread overview]
Message-ID: <20130219120411.GC1978@linaro.org> (raw)
In-Reply-To: <1360752927-29331-3-git-send-email-ben.dooks@codethink.co.uk>
On Wed, Feb 13, 2013 at 10:55:20AM +0000, Ben Dooks wrote:
> The fixup_pv_table assumes that the instructions are in the same
> endian configuration as the data, but when the CPU is running in
> BE8 the instructions stay in little-endian format.
>
> Make sure if CONFIG_CPU_ENDIAN_BE8 is set that we do all the
> alterations to the instructions taking in to account the LDR/STR
> will be swapping the data endian-ness.
>
> Since the code is only modifying a byte, we avoid dual-swapping
> the data, and just change the bits we clear and ORR in.
>
> Note, not tested against an actual bug, it looked wrong.
This looks reasonable, but the Thumb case code would need a similar fix.
Should we have LE()/BE8() macros etc. in assembler.h, similar to
ARM()/THUMB()? This would help save on #ifdefs.
Cheers
---Dave
>
> Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
> ---
> arch/arm/kernel/head.S | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index 486a15a..cc15384 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -576,8 +576,14 @@ __fixup_a_pv_table:
> #else
> b 2f
> 1: ldr ip, [r7, r3]
> +#ifdef CONFIG_CPU_ENDIAN_BE8
> + @ in BE8, we load data in BE, but instructions still in LE
> + bic ip, ip, #0xff000000
> + orr ip, ip, r6, lsl#24
> +#else
> bic ip, ip, #0x000000ff
> orr ip, ip, r6 @ mask in offset bits 31-24
> +#endif
> str ip, [r7, r3]
> 2: cmp r4, r5
> ldrcc r7, [r4], #4 @ use branch for delay slot
> --
> 1.7.10.4
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2013-02-19 12:04 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 10:55 [RFC v3] Better BE support for ARM Ben Dooks
2013-02-13 10:55 ` [PATCH 1/9] ARM: fix ARCH_IXP4xx usage of ARCH_SUPPORTS_BIG_ENDIAN Ben Dooks
2013-02-18 19:58 ` Krzysztof Halasa
2013-02-13 10:55 ` [PATCH 2/9] ARM: fixup_pv_table bug when CPU_ENDIAN_BE8 Ben Dooks
2013-02-19 12:04 ` Dave Martin [this message]
2013-02-13 10:55 ` [PATCH 3/9] ARM: asm: Add ARM_BE8() assembly helper Ben Dooks
2013-02-14 4:27 ` Nicolas Pitre
2013-02-19 12:07 ` Dave Martin
2013-02-13 10:55 ` [PATCH 4/9] ARM: set BE8 if LE in head code Ben Dooks
2013-02-14 4:33 ` Nicolas Pitre
2013-02-13 10:55 ` [PATCH 5/9] ARM: pl01x debug code endian fix Ben Dooks
2013-02-19 12:27 ` Dave Martin
2013-02-13 10:55 ` [PATCH 6/9] ARM: twd: data " Ben Dooks
2013-02-13 10:55 ` [PATCH 7/9] ARM: smp_scu: data endian fixes Ben Dooks
2013-02-13 10:55 ` [PATCH 8/9] highbank: enable big-endian Ben Dooks
2013-02-13 10:55 ` [PATCH 9/9] mvebu: support running big-endian Ben Dooks
2013-02-15 11:39 ` [RFC v3] Better BE support for ARM Ben Dooks
2013-02-19 12:00 ` Dave Martin
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