[PATCH v10-mte 7/7] arm64: mte: implement CONFIG_ARM64_MTE_SWAP_STATS

[Yury Norov]

On Thu, Dec 14, 2023 at 12:06:39PM +0100, Alexander Potapenko wrote:
> Provide a config to collect the usage statistics for ARM MTE tag
> compression. This patch introduces allocation/deallocation counters
> for buffers that were stored uncompressed (and thus occupy 128 bytes of
> heap plus the Xarray overhead to store a pointer) and those that were
> compressed into 8-byte pointers (effectively using 0 bytes of heap in
> addition to the Xarray overhead).
> 
> The counters are exposed to the userspace via
> /sys/kernel/debug/mteswap/stats:
> 
>   # cat /sys/kernel/debug/mteswap/stats
>   8 bytes:      102496 allocations,     67302 deallocations
>   128 bytes:    212234 allocations,     178278 deallocations
>   uncompressed tag storage size:        8851200
>   compressed tag storage size:  4346368
> 
> Suggested-by: Yury Norov <yury.norov at gmail.com>
> Signed-off-by: Alexander Potapenko <glider at google.com>
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>

Reviewed-by: Yury Norov <yury.norov at gmail.com>