Date: Fri, 19 Jun 2015 16:00:51 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Andrey Ryabinin <a.ryabinin@samsung.com>
Cc: Borislav Petkov <bp@alien8.de>, Alexander Popov <alpopov@ptsecurity.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Andrey Konovalov <adech.fo@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Alexander Kuleshov <kuleshovmail@gmail.com>,
        Denys Vlasenko <dvlasenk@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Kees Cook <keescook@chromium.org>, x86@kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 1/1] x86_64: fix KASan shadow region page tables
Message-ID: <20150619140051.GA18930@gmail.com>
References: <1434613012-16046-1-git-send-email-alpopov@ptsecurity.com>
 <20150618090857.GB1385@pd.tnic>
 <5582B801.80705@samsung.com>
 <20150618145510.GC1385@pd.tnic>
 <5582EC30.8080104@samsung.com>
 <20150618163846.GF1385@pd.tnic>
 <558401BF.3040809@samsung.com>
 <20150619120603.GE17826@pd.tnic>
 <55841ACF.50302@samsung.com>
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* Andrey Ryabinin <a.ryabinin@samsung.com> wrote:

> On 06/19/2015 03:06 PM, Borislav Petkov wrote:
> > On Fri, Jun 19, 2015 at 02:49:19PM +0300, Andrey Ryabinin wrote:
> >> I guess that AMD cpus is more strict (unlike Intel) about violation
> >> of reserved/unused bits in page table entries. Please, try with this
> >> patch.
> > 
> > With that the guest boots.
> > 
> 
> Great! Thanks.
> 
> > How do I check whether KASan actually works? I don't see any note in
> > dmesg or some file named "*kasan*" in sysfs...
> > 
> 
> kasan will print report in dmesg whant it will find anything.

It should also printk a one line message at bootup, so that people can be sure 
they are running a KASan-enabled kernel.

> To make sure that it works you could try to load testing module (CONFIG_TEST_KASAN).
> This module has bugs that kasan should catch.

That's a way too obscure mechanism just to determine whether the right kernel 
config was booted. Please add a printk(), ok?

Thanks,

	Ingo
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