linux-kernel - Re: [PATCH v2 12/14] x86: Minimal SLAB alignment

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Message-ID: <jjwojlm7ie5f4whsbmhowrxy2upxhrflu3za2sdrnvafyjc746@vhzl7vnvvgh6>
Date: Fri, 21 Feb 2025 08:24:13 +0100
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: Andrey Konovalov <andreyknvl@...il.com>
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Subject: Re: [PATCH v2 12/14] x86: Minimal SLAB alignment

On 2025-02-20 at 00:30:48 +0100, Andrey Konovalov wrote:
>On Tue, Feb 18, 2025 at 9:20 AM Maciej Wieczor-Retman
><maciej.wieczor-retman@...el.com> wrote:
>>
>> Adjust x86 minimal SLAB alignment to match KASAN granularity size. In
>> tag-based mode the size changes to 16 bytes so the value needs to be 4.
>
>This 4 should be 16.

Thanks!

>
>>
>> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
>> ---
>>  arch/x86/include/asm/kasan.h | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/x86/include/asm/kasan.h b/arch/x86/include/asm/kasan.h
>> index 8829337a75fa..a75f0748a4b6 100644
>> --- a/arch/x86/include/asm/kasan.h
>> +++ b/arch/x86/include/asm/kasan.h
>> @@ -36,6 +36,8 @@
>>
>>  #ifdef CONFIG_KASAN_SW_TAGS
>>
>> +#define ARCH_SLAB_MINALIGN (1ULL << KASAN_SHADOW_SCALE_SHIFT)
>
>I believe ARCH_SLAB_MINALIGN needs to be defined in
>include/asm/cache.h: at least other architectures have it there.

Okay, I'll correct it.

>
>
>> +
>>  #define __tag_shifted(tag)             FIELD_PREP(GENMASK_ULL(60, 57), tag)
>>  #define __tag_reset(addr)              (sign_extend64((u64)(addr), 56))
>>  #define __tag_get(addr)                        ((u8)FIELD_GET(GENMASK_ULL(60, 57), (u64)addr))
>> --
>> 2.47.1
>>

-- 
Kind regards
Maciej Wieczór-Retman