linux-kernel - Re: [PATCH] ARM: map_init_section flushes incorrect pmd

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Message-ID: <51A4B938.7080708@ti.com>
Date:	Tue, 28 May 2013 19:33:36 +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 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 ?

Regards,
 Sricharan
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