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List:       linux-mips
Subject:    Re: [PATCH] MIPS: tlbex: fix a missing statement for HUGETLB
From:       Huacai Chen <chenhc () lemote ! com>
Date:       2014-08-05 7:09:04
Message-ID: CAAhV-H56MhaMvjX1T4uj=DhC9vgibVvAOa+-u5n_s1cwP4EHzw () mail ! gmail ! com
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Now what should we do? My original patch is not perfect, but it has
already merged into Ralf's tree (but hasn't merged in Linus's tree).
Let me send Ralf a new version of this patch? Or let David send
another patch on top of my original one?

Huacai

On Mon, Aug 4, 2014 at 9:10 PM, James Hogan <james.hogan@imgtec.com> wrote:
> On 04/08/14 14:05, Aurelien Jarno wrote:
>> On Mon, Aug 04, 2014 at 11:08:50AM +0100, James Hogan wrote:
>>> Hi Aurelien,
>>>
>>> On 02/08/14 22:35, Aurelien Jarno wrote:
>>>> On Thu, Jul 31, 2014 at 10:33:55AM -0700, David Daney wrote:
>>>>> diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
>>>>> index f99ec587..341add1 100644
>>>>> --- a/arch/mips/mm/tlbex.c
>>>>> +++ b/arch/mips/mm/tlbex.c
>>>>> @@ -1299,6 +1299,8 @@ static void build_r4000_tlb_refill_handler(void)
>>>>>         }
>>>>>  #ifdef CONFIG_MIPS_HUGE_TLB_SUPPORT
>>>>>         uasm_l_tlb_huge_update(&l, p);
>>>>> +       if (!use_bbit_insns())
>>>>> +               UASM_i_LW(&p, K0, 0, K1);
>>>>>         build_huge_update_entries(&p, htlb_info.huge_pte, K1);
>>>>>         build_huge_tlb_write_entry(&p, &l, &r, K0, tlb_random,
>>>>>                                    htlb_info.restore_scratch);
>>>>
>>>> This patch fixes the issue, thanks. That said it doesn't look fully
>>>> correct. The test should be done the same way as for
>>>> build_fast_tlb_refill_handler. For example the fast handler is not
>>>> called on a 32-bit machine with bbit instructions, so it would need
>>>> to reload K0.
>>>
>>> In the non fast case build_is_huge_pte() will still use bbit1 if
>>> available after restoring K0, and I don't think the bbit1 would clobber
>>> K0 when the branch is taken, so I think the test for !use_bbit_insns()
>>> is correct.
>>>
>> Oh you are right! Therefore this second patch is:
>>
>> Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
>
> Likewise:
>
> Reviewed-by: James Hogan <james.hogan@imgtec.com>
>
> Cheers
> James
>
>> Tested-by: Aurelien Jarno <aurelien@aurel32.net>
>>
>
>

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