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SubjectRe: [PATCH] powerpc/32s: Don't flush all TLBs when flushing one page
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Le 01/02/2020 à 15:06, Segher Boessenkool a écrit :
> On Sat, Feb 01, 2020 at 08:27:03AM +0100, Christophe Leroy wrote:
>> Le 31/01/2020 à 20:38, Segher Boessenkool a écrit :
>>> On Fri, Jan 31, 2020 at 05:15:20PM +0100, Christophe Leroy wrote:
>>>> Le 31/01/2020 à 16:51, Segher Boessenkool a écrit :
>>>>> On Fri, Jan 31, 2020 at 03:37:34PM +0000, Christophe Leroy wrote:
>>>>>> When the range is a single page, do a page flush instead.
>>>>>
>>>>>> + start &= PAGE_MASK;
>>>>>> + end = (end - 1) | ~PAGE_MASK;
>>>>>> if (!Hash) {
>>>>>> - _tlbia();
>>>>>> + if (end - start == PAGE_SIZE)
>>>>>> + _tlbie(start);
>>>>>> + else
>>>>>> + _tlbia();
>>>>>> return;
>>>>>> }
>>>>>
>>>>> For just one page, you get end - start == 0 actually?
>>>>
>>>> Oops, good catch.
>>>>
>>>> Indeed you don't get PAGE_SIZE but (PAGE_SIZE - 1) for just one page.
>>>
>>> You have all low bits masked off in both start and end, so you get zero.
>>> You could make the condion read "if (start == end)?
>>
>> No, in end the low bits are set, that's a BIT OR with ~PAGE_MASK, so it
>> sets all low bits to 1.
>
> Oh, wow, yes, I cannot read apparently.
>
> Maybe there are some ROUND_DOWN and ROUND_UP macros you could use?
>

Yes but my intention was to modify the existing code as less as possible.
What do you think about version v2 of the patch ?

Christophe

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