linux-kernel - Re: [PATCH v6 0/6] KASan for arm

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Date:   Fri, 15 Nov 2019 12:44:16 +0100
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     mark.rutland@....com, alexandre.belloni@...tlin.com,
        mhocko@...e.com, julien.thierry@....com, catalin.marinas@....com,
        christoffer.dall@....com, dhowells@...hat.com,
        yamada.masahiro@...ionext.com, ryabinin.a.a@...il.com,
        glider@...gle.com, kvmarm@...ts.cs.columbia.edu, corbet@....net,
        liuwenliang@...wei.com, daniel.lezcano@...aro.org,
        linux@...linux.org.uk, kasan-dev@...glegroups.com,
        geert@...ux-m68k.org, dvyukov@...gle.com,
        bcm-kernel-feedback-list@...adcom.com, drjones@...hat.com,
        vladimir.murzin@....com, keescook@...omium.org, arnd@...db.de,
        marc.zyngier@....com, andre.przywara@....com, pombredanne@...b.com,
        jinb.park7@...il.com, tglx@...utronix.de, kernel@...gutronix.de,
        linux-arm-kernel@...ts.infradead.org, nico@...xnic.net,
        gregkh@...uxfoundation.org, ard.biesheuvel@...aro.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        rob@...dley.net, philip@....systems, akpm@...ux-foundation.org,
        thgarnie@...gle.com, kirill.shutemov@...ux.intel.com
Subject: Re: [PATCH v6 0/6] KASan for arm

Hi Florian,

On 19-11-15 08:08, Marco Felsch wrote:
> Hi Florian,
> 
> On 19-11-14 15:01, Florian Fainelli wrote:
> > Hello Marco,
> > 
> > On 11/14/19 10:12 AM, Marco Felsch wrote:
> > > Hi Florian,
> > > 
> > > first of all, many thanks for your work on this series =) I picked your
> > > and Arnd patches to make it compilable. Now it's compiling but my imx6q
> > > board didn't boot anymore. I debugged the code and found that the branch
> > > to 'start_kernel' won't be reached
> > > 
> > > 8<------- arch/arm/kernel/head-common.S -------
> > > ....
> > > 
> > > #ifdef CONFIG_KASAN
> > >         bl      kasan_early_init
> > > #endif
> > > 	mov     lr, #0
> > > 	b       start_kernel
> > > ENDPROC(__mmap_switched)
> > > 
> > > ....
> > > 8<----------------------------------------------
> > > 
> > > Now, I found also that 'KASAN_SHADOW_OFFSET' isn't set due to missing
> > > 'CONFIG_KASAN_SHADOW_OFFSET' and so no '-fasan-shadow-offset=xxxxx' is
> > > added. Can that be the reason why my board isn't booted anymore?
> > 
> > The latest that I have is here, though not yet submitted since I needed
> > to solve one issue on a specific platform with a lot of memory:
> > 
> > https://github.com/ffainelli/linux/pull/new/kasan-v7
> 
> Thanks for that hint, I will try this series too :) I read that you
> wanna prepare a v7 but didn't found it ^^
> 
> > Can you share your branch as well? I did not pick all of Arnd's patches
> > since some appeared to be seemingly independent from KASan on ARM. This
> > is the KASAN related options that are set in my configuration:
> 
> Of course I will push it to github and inform you shortly.

Here comes the link:
https://github.com/medude/linux/tree/v5.4/topic/kasan-arm.v7

I just applied Arnds Patche which you didn't added into your v7.

> > grep KASAN build/linux-custom/.config
> > CONFIG_HAVE_ARCH_KASAN=y
> > CONFIG_CC_HAS_KASAN_GENERIC=y
> > CONFIG_KASAN=y
> > CONFIG_KASAN_GENERIC=y
> > CONFIG_KASAN_OUTLINE=y
> > # CONFIG_KASAN_INLINE is not set
> > CONFIG_KASAN_STACK=1
> > CONFIG_TEST_KASAN=m
> 
> My config is:
> 
> CONFIG_HAVE_ARCH_KASAN=y
> CONFIG_CC_HAS_KASAN_GENERIC=y
> CONFIG_KASAN=y
> CONFIG_KASAN_GENERIC=y
> CONFIG_KASAN_OUTLINE=y
> # CONFIG_KASAN_INLINE is not set
> CONFIG_KASAN_STACK=1
> # CONFIG_TEST_KASAN is not set
> 
> > are you using something different by any chance?
> 
> Unfortunately not.

With your v7 it is working on my imx6 but unfortunately I can't run my
gstreamer testcase. My CPU load goes to 100% after starting gstreamer
and nothing happens.. But the test_kasan module works =) So I decided to
check a imx6quadplus but this target did not boot.. I used another
toolchain for the imx6quadplus gcc-9 instead of gcc-8. So it seems that
something went wrong during compilation. Because you didn't changed
something within the logic.

I wonder why we must not define the CONFIG_KASAN_SHADOW_OFFSET for arm.

Regards,
  Marco

> Regards,
>   Marco
> 
> > -- 
> > Florian
> > 
>