Re: [RFC/PATCH -next 00/21] Address sanitizer for kernel (kasan) - dynamic memory error detector.

[Andrey Ryabinin]

2014-07-12 4:59 GMT+04:00 H. Peter Anvin <hpa@xxxxxxxxx>:
> On 07/09/2014 04:00 AM, Andrey Ryabinin wrote:
>>
>> Address sanitizer dedicates 1/8 of the low memory to the shadow memory and uses direct
>> mapping with a scale and offset to translate a memory address to its corresponding
>> shadow address.
>>
>> Here is function to translate address to corresponding shadow address:
>>
>>      unsigned long kasan_mem_to_shadow(unsigned long addr)
>>      {
>>               return ((addr) >> KASAN_SHADOW_SCALE_SHIFT)
>>                            + kasan_shadow_start - (PAGE_OFFSET >> KASAN_SHADOW_SCALE_SHIFT);
>>      }
>>
>> where KASAN_SHADOW_SCALE_SHIFT = 3.
>>
>
> How does that work when memory is sparsely populated?
>

Sparsemem configurations currently may not work with kasan.
I suppose I will have to move shadow area to vmalloc address space and
make it (shadow) sparse too if needed.

>         -hpa
>
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-- 
Best regards,
Andrey Ryabinin
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