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[v2,12/14] x86: Minimal SLAB alignment

Message ID 7492f65cd21a898e2f2608fb51642b7b0c05ef21.1739866028.git.maciej.wieczor-retman@intel.com (mailing list archive)
State New
Headers show
Series [v2,01/14] kasan: sw_tags: Use arithmetic shift for shadow computation | expand

Commit Message

Maciej Wieczor-Retman Feb. 18, 2025, 8:15 a.m. UTC 
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.

Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
---
 arch/x86/include/asm/kasan.h | 2 ++
 1 file changed, 2 insertions(+)

Comments

Andrey Konovalov Feb. 19, 2025, 11:30 p.m. UTC | #1 
On Tue, Feb 18, 2025 at 9:20 AM Maciej Wieczor-Retman
<maciej.wieczor-retman@intel.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.

>
> Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.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.


> +
>  #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
>
Maciej Wieczor-Retman Feb. 21, 2025, 7:24 a.m. UTC | #2 
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@intel.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@intel.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
>>
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Patch

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)
+
 #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))