From: Michael Ellerman <mpe@ellerman.id.au>
To: Kees Cook <keescook@chromium.org>
Cc: "kernel-hardening\@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
"David S. Miller" <davem@davemloft.net>,
Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
Jiri Slaby <jslaby@suse.cz>, Guenter Roeck <linux@roeck-us.net>,
LKML <linux-kernel@vger.kernel.org>,
"linuxppc-dev\@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
Anton Blanchard <anton@samba.org>, Alan Modra <amodra@gmail.com>
Subject: Re: [kernel-hardening] Re: Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section)
Date: Wed, 03 Aug 2016 14:46:49 +1000 [thread overview]
Message-ID: <87lh0elarq.fsf@concordia.ellerman.id.au> (raw)
In-Reply-To: <CAGXu5j+tc8Q9NkDi7Wf_JV=D65WC=v=y4ormng9nJ6avDKCMZQ@mail.gmail.com>
Kees Cook <keescook@chromium.org> writes:
> On Mon, Aug 1, 2016 at 8:12 PM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>> Kees Cook <keescook@chromium.org> writes:
>>> On Mon, Aug 1, 2016 at 5:37 AM, Michael Ellerman <mpe@ellerman.id.au> wrote:
>>>>
>>>> scripts/link-vmlinux.sh: line 52: 36260 Segmentation fault (core dumped) ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>>>>
>>>> Haven't had a chance to debug it further.
...
>> Interestingly I *can't* reproduce with the Ubuntu x86->ppc cross
>> (5.4.0-6ubuntu1~16.04.1).
>
> Oh, weird. Well, that does explains my lack of hitting the problem,
> though: that's the cross compiler I was using. :P
Actually that was a false negative.
The trick is you have to have LKDTM=y *and* FUNCTION_TRACER=y.
It is a linker bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=20428
Which Alan has already fixed.
But we need to workaround existing linkers that are out there.
We can do that by marking lkdtm_rodata_do_nothing() notrace, which I
think makes sense for all arches actually.
So I'll send you a patch to do that.
cheers
next prev parent reply other threads:[~2016-08-03 4:54 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 21:57 [PATCH 0/5] lkdtm: add usercopy and rodata, fix atomic Kees Cook
2016-06-07 21:57 ` [PATCH 1/5] lkdtm: split build into multiple source files Kees Cook
2016-06-07 21:57 ` [PATCH 2/5] lkdtm: clean up after rename Kees Cook
2016-06-07 21:57 ` [PATCH 3/5] lkdtm: add function for testing .rodata section Kees Cook
2016-06-08 1:02 ` Laura Abbott
2016-06-08 15:46 ` Kees Cook
2016-06-08 16:15 ` Laura Abbott
2016-06-08 21:26 ` Kees Cook
2016-06-10 1:14 ` Laura Abbott
[not found] ` <87h9b4oebf.fsf@concordia.ellerman.id.au>
2016-08-01 19:45 ` Linker segfault on powerpc when CONFIG_LKDTM=y (was Re: [kernel-hardening] [PATCH 3/5] lkdtm: add function for testing .rodata section) Kees Cook
2016-08-02 3:12 ` [kernel-hardening] " Michael Ellerman
2016-08-02 19:12 ` Kees Cook
2016-08-03 4:46 ` Michael Ellerman [this message]
2016-06-07 21:57 ` [PATCH 4/5] lkdtm: add usercopy tests Kees Cook
2016-06-07 23:36 ` kbuild test robot
2016-06-08 0:07 ` kbuild test robot
2016-06-07 21:57 ` [PATCH 5/5] lkdtm: split atomic test into over and underflow Kees Cook
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