linux-kernel - Re: [RESEND PATCH v4 0/6] arm64/mm: Move swapper_pg

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Message-ID: <3748f344-465e-63ee-8a9b-5ac1502163c2@arm.com>
Date:   Fri, 7 Sep 2018 10:57:06 +0100
From:   James Morse <james.morse@....com>
To:     Jun Yao <yaojun8558363@...il.com>
Cc:     linux-arm-kernel@...ts.infradead.org, catalin.marinas@....com,
        will.deacon@....com, linux-kernel@...r.kernel.org
Subject: Re: [RESEND PATCH v4 0/6] arm64/mm: Move swapper_pg_dir to rodata

Hi Jun,

(I'm a bit confused about which version of this series I should be looking at.
I have a v4, and two v4-resends, all of which are different. Please only mark
something as 'resend' if it is exactly the same!)

On 22/08/18 10:54, Jun Yao wrote:
> The set_init_mm_pgd() is reimplemented using assembly in order to
> avoid being instrumented by kasan.

There are some tidier ways of fixing this. The kasan init code is also C code
that is run before kasan is initialized. Kbuild is told not to let KASAN touch
it with 'KASAN_SANITISE_filename.o := n'.

But, in this case you're only calling into C code from pre-kasan head.S so you
can use the same helper to set init_mm.pgd. I don't think this is worth the
effort, we can just do the store in assembly. (more in patch 3).

Thanks,

James