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    SubjectRe: [RFC/PATCH -next 00/21] Address sanitizer for kernel (kasan) - dynamic memory error detector.
    From
    2014-07-12 4:59 GMT+04:00 H. Peter Anvin <hpa@zytor.com>:
    > 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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