Re: [PATCH -next 3/3] kasan: arm64: Fix pcpu_page_first_chunk crash with KASAN_VMALLOC

Daniel Axtens
2021-07-06T00:05:50Z

> If so, should we put the call inside of vm_area_register_early?
Ah, we already do this. Sorry. My other questions remain.

Kind regards,
Daniel

>
> Kind regards,
> Daniel
>
>>
>>> void __init kasan_init(void)
>>> {
>>> kasan_init_shadow();
>>> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
>>> index 5310e217bd74..79d3895b0240 100644
>>> --- a/include/linux/kasan.h
>>> +++ b/include/linux/kasan.h
>>> @@ -49,6 +49,8 @@ extern p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D];
>>> int kasan_populate_early_shadow(const void *shadow_start,
>>> const void *shadow_end);
>>>
>>> +void kasan_populate_early_vm_area_shadow(void *start, unsigned long size);
>>> +
>>> static inline void *kasan_mem_to_shadow(const void *addr)
>>> {
>>> return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
>>> diff --git a/mm/kasan/init.c b/mm/kasan/init.c
>>> index cc64ed6858c6..d39577d088a1 100644
>>> --- a/mm/kasan/init.c
>>> +++ b/mm/kasan/init.c
>>> @@ -279,6 +279,11 @@ int __ref kasan_populate_early_shadow(const void *shadow_start,
>>> return 0;
>>> }
>>>
>>> +void __init __weak kasan_populate_early_vm_area_shadow(void *start,
>>> + unsigned long size)
>>> +{
>>> +}
>>
>> I'm just wondering if this could be a generic function, perhaps with an
>> appropriate IS_ENABLED() check of a generic Kconfig option
>> (CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK ?) to short-circuit it, if it's
>> not only an arm64 problem.
>>
>> But I haven't looked much further, so would appeal to you to either
>> confirm or reject this idea.
>>
>> Thanks,
>> -- Marco