From mboxrd@z Thu Jan 1 00:00:00 1970 From: dave.martin@linaro.org (Dave Martin) Date: Tue, 19 Feb 2013 12:04:11 +0000 Subject: [PATCH 2/9] ARM: fixup_pv_table bug when CPU_ENDIAN_BE8 In-Reply-To: <1360752927-29331-3-git-send-email-ben.dooks@codethink.co.uk> References: <1360752927-29331-1-git-send-email-ben.dooks@codethink.co.uk> <1360752927-29331-3-git-send-email-ben.dooks@codethink.co.uk> Message-ID: <20130219120411.GC1978@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 > --- > 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