linux-kernel - Re: [PATCH v12 1/6] kasan: allow an architecture to disable inline instrumentation

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Message-ID: <87im2ev2wl.fsf@dja-thinkpad.axtens.net>
Date:   Wed, 16 Jun 2021 14:39:38 +1000
From:   Daniel Axtens <dja@...ens.net>
To:     Marco Elver <elver@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        linuxppc-dev@...ts.ozlabs.org,
        kasan-dev <kasan-dev@...glegroups.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        aneesh.kumar@...ux.ibm.com, Balbir Singh <bsingharora@...il.com>
Subject: Re: [PATCH v12 1/6] kasan: allow an architecture to disable inline
 instrumentation

Hi Marco,

@@ -12,6 +12,15 @@ config HAVE_ARCH_KASAN_HW_TAGS
>>  config HAVE_ARCH_KASAN_VMALLOC
>>         bool
>>
>> +# Sometimes an architecture might not be able to support inline instrumentation
>> +# but might be able to support outline instrumentation. This option allows an
>> +# arch to prevent inline and stack instrumentation from being enabled.
>
> This comment could be moved into 'help' of this new config option.

It could. I did wonder if that made sense given that this is not a user
selectable option so I'm not sure if the help will ever be visible, but
I see that we do this sort of thing in Kconfig.kcsan and Kconfig.kgdb.
I've changed it over.

>> +# ppc64 turns on virtual memory late in boot, after calling into generic code
>> +# like the device-tree parser, so it uses this in conjuntion with a hook in
>> +# outline mode to avoid invalid access early in boot.
>
> I think the ppc64-related comment isn't necessary and can be moved to
> arch/ppc64 somewhere, if there isn't one already.

Fair enough. I'll pull it out of this file and look for a good place to
put the information in arch/powerpc in a later patch/series.

Kind regards,
Daniel