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Date: Wed, 29 May 2013 00:18:40 +0530 From: Sricharan R <r.sricharan@...com> To: Will Deacon <will.deacon@....com> CC: Po-Yu Chuang <ratbert.chuang@...il.com>, "linux@....linux.org.uk" <linux@....linux.org.uk>, "nico@...aro.org" <nico@...aro.org>, Catalin Marinas <Catalin.Marinas@....com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "rob.herring@...xeda.com" <rob.herring@...xeda.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org> Subject: Re: [PATCH] ARM: map_init_section flushes incorrect pmd On Tuesday 28 May 2013 07:37 PM, Will Deacon wrote: > On Tue, May 28, 2013 at 03:03:36PM +0100, Sricharan R wrote: >> On Tuesday 28 May 2013 06:35 PM, Will Deacon wrote: >>> On Tue, May 28, 2013 at 11:48:20AM +0100, Po-Yu Chuang wrote: >>>> This bug was introduced in commit e651eab0. >>>> Some v4/v5 platforms failed to boot due to this. >>>> >>>> Signed-off-by: Po-Yu Chuang <ratbert.chuang@...il.com> >>>> --- >>>> arch/arm/mm/mmu.c | 4 +++- >>>> 1 file changed, 3 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c >>>> index e0d8565..19a43f8 100644 >>>> --- a/arch/arm/mm/mmu.c >>>> +++ b/arch/arm/mm/mmu.c >>>> @@ -620,6 +620,8 @@ static void __init map_init_section(pmd_t *pmd, unsigned long addr, >>>> unsigned long end, phys_addr_t phys, >>>> const struct mem_type *type) >>>> { >>>> + pmd_t *p = pmd; >>>> + >>>> #ifndef CONFIG_ARM_LPAE >>>> /* >>>> * In classic MMU format, puds and pmds are folded in to >>>> @@ -638,7 +640,7 @@ static void __init map_init_section(pmd_t *pmd, unsigned long addr, >>>> phys += SECTION_SIZE; >>>> } while (pmd++, addr += SECTION_SIZE, addr != end); >>>> >>>> - flush_pmd_entry(pmd); >>>> + flush_pmd_entry(p); >>> Wait, shouldn't this flush be *inside* the loop anyway? Otherwise we just >>> flush the cacheline containing the first pmd. The flushing code could also >>> flush to PoU instead of PoC for UP ARMv7, but that's an unrelated optimisation. >> I think in LPAE this loop iterates once and non LPAE twice. >> So both the entries should be contained in same cache line right ? > Dunno, are there any guarantees about alignment of the starting pmd? Even > so, the function takes the range as parameters, so I don't think we > should tailor it to the caller. It may explain why this hasn't come up > sooner though. > > Will This function is not exposed outside. And the ranges passed to this is going to not more than 2 entries in any case. If we put the flush inside the loop, then we will end up doing an extra flush for the same line. Regarding the alignment, I think if the pgd base is aligned, then rest should be fine. Will have to check this. Regards, Sricharan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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