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From: Dmitry Vyukov <dvyukov@google.com>
Date: Tue, 13 Dec 2016 10:38:14 +0100
Message-ID: <CACT4Y+Zu9QAYNh3=nnwiRNd6C5sxS1WGR=93ovmZs0hWkucPow@mail.gmail.com>
Subject: Re: [PATCH v2] kasan: Support for r/w instrumentation control
To: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Maninder Singh <maninder1.s@samsung.com>,
        Alexander Potapenko <glider@google.com>,
        Jonathan Corbet <corbet@lwn.net>, Michal Marek <mmarek@suse.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        kasan-dev <kasan-dev@googlegroups.com>, linux-doc@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:KERNEL BUILD + fi..." <linux-kbuild@vger.kernel.org>,
        PANKAJ MISHRA <pankaj.m@samsung.com>,
        Ajeet Kumar Yadav <ajeet.y@samsung.com>,
        Vaneet narang <v.narang@samsung.com>
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On Tue, Dec 13, 2016 at 10:20 AM, Andrey Ryabinin
<aryabinin@virtuozzo.com> wrote:
>
>
> On 12/13/2016 11:58 AM, Dmitry Vyukov wrote:
>
>> --- a/Documentation/dev-tools/kasan.rst
>> +++ b/Documentation/dev-tools/kasan.rst
>> @@ -40,6 +40,14 @@ similar to the following to the respective kernel Makefile:
>>
>>      KASAN_SANITIZE := n
>>
>> +Sometimes it may be useful to disable instrumentation of reads, or writes
>> +or both for the entire kernel. For example, if binary size is a concern,
>> +it may be useful to disable instrumentation of reads to reduce binary size but
>> +still catch more harmful bugs on writes. Or, if one is interested only in
>> +sanitization of a particular module and performance is a concern, she can
>> +disable instrumentation of both reads and writes for kernel code.
>> +Instrumentation can be disabled with CONFIG_KASAN_READS and
>> CONFIG_KASAN_WRITES.
>> +
>
> I don't understand this. How this can be related to modules? Configs are global.
> You can't just disable/enable config per module.


Build everything without instrumentation. Then enable instrumentation
and do "make lib/test_kasan.ko".
Or build everything, copy out bzImage, change config, build everything again.