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Subject: Re: [PATCH v2 3/5] signal: Add unsafe_copy_siginfo_to_user()
To:     Christoph Hellwig <hch@infradead.org>
Cc:     Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
References: <fd7938d94008711d441551c06b25a033669a0618.1629732940.git.christophe.leroy@csgroup.eu>
 <a94be61f008ab29c231b805e1a97e9dab35cb0cc.1629732940.git.christophe.leroy@csgroup.eu>
 <YTB1F7o15FrxmmP1@infradead.org>
From:   Christophe Leroy <christophe.leroy@csgroup.eu>
Message-ID: <a98f9e92-f304-9f69-c5b2-eed628846e4c@csgroup.eu>
Date:   Mon, 13 Sep 2021 14:59:00 +0200
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Le 02/09/2021 à 08:54, Christoph Hellwig a écrit :
> On Mon, Aug 23, 2021 at 03:35:53PM +0000, Christophe Leroy wrote:
>> In the same spirit as commit fb05121fd6a2 ("signal: Add
>> unsafe_get_compat_sigset()"), implement an 'unsafe' version of
>> copy_siginfo_to_user() in order to use it within user access blocks.
>>
>> For that, also add an 'unsafe' version of clear_user().
> 
> I'm a little worried about all these unsafe helper in powerpc and the
> ever increasing scope of the unsafe sections.  Can you at least at
> powerpc support to objtool to verify them?  objtool verifications has
> helped to find quite a few bugs in unsafe sections on x86.

Ok, I've started looking at it, I have not found any work at all on 
objtool for powerpc. I'll see if I can draft something from the ARM64 
tentatives.

Christophe