Re: [PATCH v8 08/14] x86/kasan: KASAN raw shadow memory PTE init

[Andrey Ryabinin]

On 1/12/26 6:28 PM, Maciej Wieczor-Retman wrote:
> From: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
> 
> In KASAN's generic mode the default value in shadow memory is zero.
> During initialization of shadow memory pages they are allocated and
> zeroed.
> 
> In KASAN's tag-based mode the default tag for the arm64 architecture is
> 0xFE which corresponds to any memory that should not be accessed. On x86
> (where tags are 4-bit wide instead of 8-bit wide) that tag is 0xE so
> during the initializations all the bytes in shadow memory pages should
> be filled with it.
> 
> Use memblock_alloc_try_nid_raw() instead of memblock_alloc_try_nid() to
> avoid zeroing out the memory so it can be set with the KASAN invalid
> tag.
> 
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@xxxxxxxxx>
> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
> ---

Reviewed-by: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>