linux-kernel - Re: [PATCH v2 01/14] kasan: sw_tags: Use arithmetic shift for shadow computation

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Message-ID: <paotjsjnoezcdjj57dsy3ufuneezmlxbc3zk3ebfzuiq722kz2@6vhollkdhul7>
Date: Thu, 27 Feb 2025 13:33:10 +0100
From: Maciej Wieczor-Retman <maciej.wieczor-retman@...el.com>
To: Andrey Konovalov <andreyknvl@...il.com>
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Subject: Re: [PATCH v2 01/14] kasan: sw_tags: Use arithmetic shift for shadow
 computation

On 2025-02-25 at 22:37:58 +0100, Andrey Konovalov wrote:
>On Tue, Feb 25, 2025 at 6:21 PM Maciej Wieczor-Retman
><maciej.wieczor-retman@...el.com> wrote:
>>
>> >> I wanted to have the shadow memory boundries aligned properly, to not waste page
>> >> table entries, so the memory map is more straight forward. This patch helps with
>> >> that, I don't think it would have worked without it.
>> >
>> >Ok, I see - let's add this info into the commit message then.
>>
>> Sure, but if you like the 0xffeffc0000000000 offset I'll just drop this part.
>
>Sure, assuming it works, I like this address :) But to be fair, I like
>any fixed address better than using a runtime const, just to avoid the
>complexity.

Btw just out of curiosity on the topic. If we used a runtime specified kasan
offset, could the gdb script issue (not knowing the offset at compile-time) be
fixed by just exporting the value through sysfs?

I know that in inline mode the compiler would still need to know the offset
value but I was curious if this approach was okay at least in outline mode?

-- 
Kind regards
Maciej Wieczór-Retman