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SubjectRe: [PATCH V3 01/13] perf/core, x86: Add PERF_SAMPLE_DATA_PAGE_SIZE
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On 2/8/2019 5:39 AM, Thomas Gleixner wrote:
> On Thu, 31 Jan 2019, Liang, Kan wrote:
>>>> +u64 perf_get_page_size(u64 virt)
>>>> +{
>>>> + unsigned long flags;
>>>> + unsigned int level;
>>>> + pte_t *pte;
>>>> +
>>>> + if (!virt)
>>>> + return 0;
>>>> +
>>>> + /*
>>>> + * Interrupts are disabled, so it prevents any tear down
>>>> + * of the page tables.
>>>> + * See the comment near struct mmu_table_batch.
>>>> + */
>>>> + local_irq_save(flags);
>>>> + if (virt >= TASK_SIZE)
>>>> + pte = lookup_address(virt, &level);
>>>> + else {
>>>> + if (current->mm)
>>>> + pte = lookup_address_in_pgd(pgd_offset(current->mm,
>>>> virt),
>>>> + virt, &level);
>>>
>>> Aside from all the missin {}, I'm fairly sure this is broken since this
>>> happens from NMI context. This can interrupt switch_mm() and things like
>>> use_temporary_mm().
>>>
>>> Also; why does this live in the x86 code and not in the generic code?
>>>
>>
>> This is x86 implementation.
>> In generic code, there is a __weak function. I'll make it clear in the change
>> log in v4.
>
> No, instead of hiding it in the changelog, split the patch into two:
>
> #1 Adding the core stuff including the weak function
>
> #2 Adding the x86 implementation.
>

Thanks for the comments. I will do it in V5.

Thanks,
Kan

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