Re: [PATCH v2 1/9] kasan: sw_tags: Use arithmetic shift for shadow computation

From: Andrey Konovalov <andreyknvl@gmail.com>
To: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
Cc: Samuel Holland <samuel.holland@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	 linux-riscv@lists.infradead.org,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	 Alexander Potapenko <glider@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	 Vincenzo Frascino <vincenzo.frascino@arm.com>,
	kasan-dev@googlegroups.com,  llvm@lists.linux.dev,
	Catalin Marinas <catalin.marinas@arm.com>,
	 linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	 Alexandre Ghiti <alexghiti@rivosinc.com>,
	Will Deacon <will@kernel.org>,
	 Evgenii Stepanov <eugenis@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	 linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 1/9] kasan: sw_tags: Use arithmetic shift for shadow computation
Date: Mon, 17 Feb 2025 20:00:10 +0100	[thread overview]
Message-ID: <CA+fCnZfBsQd=nJVu7QOX09w6uR5LK1Gc5UqiHS8aCxzhDJsssA@mail.gmail.com> (raw)
In-Reply-To: <kmibbbrtlwds6td64hloau7pf3smqth4wff33soebvujohsvli@kni5dtvpwsxf>

On Mon, Feb 17, 2025 at 7:38 PM Maciej Wieczor-Retman
<maciej.wieczor-retman@intel.com> wrote:
>
> >I'm a bit lost with these calculations at this point. Please send the
> >full patch, including the new values for KASAN_SHADOW_OFFSET (do I
> >understand correctly that you want to change them?). It'll be easier
> >to look at the code.
>
> Sorry, this thread became a little bit confusing. No, I think the
> KASAN_SHADOW_OFFSET values are fine. I just wanted to embrace the idea of
> overflow for the purpose of the check in kasan_non_canonical_hook().
>
> But I'll put down my train of thought about the overflow + calculations in the
> patch message.
>
> >
> >Feel free to send this patch separately from the rest of the series,
> >so that we can finalize it first.
>
> I have the x86 tag-based series basically ready (just need to re-read it) so I
> think I can send it as whole with this patch and 3 others from this series.

Sounds good!