Re: [PATCH 2/5 v16] ARM: Replace string mem* functions for KASan

From: Nathan Chancellor <natechancellor@gmail.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>,
	Florian Fainelli <f.fainelli@gmail.com>,
	Ahmad Fatoum <a.fatoum@pengutronix.de>,
	Arnd Bergmann <arnd@arndb.de>,
	Abbott Liu <liuwenliang@huawei.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Russell King - ARM Linux admin <linux@armlinux.org.uk>,
	kasan-dev <kasan-dev@googlegroups.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	Linux-Next Mailing List <linux-next@vger.kernel.org>,
	Alexander Potapenko <glider@google.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Naresh Kamboju <naresh.kamboju@linaro.org>,
	Dmitry Vyukov <dvyukov@google.com>
Subject: Re: [PATCH 2/5 v16] ARM: Replace string mem* functions for KASan
Date: Thu, 12 Nov 2020 10:52:16 -0700	[thread overview]
Message-ID: <20201112175216.GB934563@ubuntu-m3-large-x86> (raw)
In-Reply-To: <CAMj1kXGXPnC8k2MRxVzCtGu4X=nZ8yHg7F3NUM8S_9xMxreA9Q@mail.gmail.com>

On Thu, Nov 12, 2020 at 04:05:52PM +0100, Ard Biesheuvel wrote:
> On Thu, 12 Nov 2020 at 14:51, Linus Walleij <linus.walleij@linaro.org> wrote:
> >
> > On Tue, Nov 10, 2020 at 1:05 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> > > On Mon, 9 Nov 2020 at 17:07, Russell King - ARM Linux admin
> > > <linux@armlinux.org.uk> wrote:
> > > >
> > > > On Mon, Nov 09, 2020 at 05:02:09PM +0100, Linus Walleij wrote:
> > > > > On Fri, Nov 6, 2020 at 4:16 PM Russell King - ARM Linux admin
> > > > > <linux@armlinux.org.uk> wrote:
> > > > > > On Fri, Nov 06, 2020 at 02:37:21PM +0100, Linus Walleij wrote:
> > > > >
> > > > > > > Aha. So shall we submit this to Russell? I figure that his git will not
> > > > > > > build *without* the changes from mmotm?
> > > > > > >
> > > > > > > That tree isn't using git either is it?
> > > > > > >
> > > > > > > Is this one of those cases where we should ask Stephen R
> > > > > > > to carry this patch on top of -next until the merge window?
> > > > > >
> > > > > > Another solution would be to drop 9017/2 ("Enable KASan for ARM")
> > > > > > until the following merge window, and queue up the non-conflicing
> > > > > > ARM KASan fixes in my "misc" branch along with the rest of KASan,
> > > > > > and the conflicting patches along with 9017/2 in the following
> > > > > > merge window.
> > > > > >
> > > > > > That means delaying KASan enablement another three months or so,
> > > > > > but should result in less headaches about how to avoid build
> > > > > > breakage with different bits going through different trees.
> > > > > >
> > > > > > Comments?
> > > > >
> > > > > I suppose I would survive deferring it. Or we could merge the
> > > > > smaller enablement patch towards the end of the merge
> > > > > window once the MM changes are in.
> > > > >
> > > > > If it is just *one* patch in the MM tree I suppose we could also
> > > > > just apply that one patch also to the ARM tree, and then this
> > > > > fixup on top. It does look a bit convoluted in the git history with
> > > > > two hashes and the same patch twice, but it's what I've done
> > > > > at times when there was no other choice that doing that or
> > > > > deferring development. It works as long as the patches are
> > > > > textually identical: git will cope.
> > > >
> > > > I thought there was a problem that if I applied the fix then my tree
> > > > no longer builds without the changes in -mm?
> > > >
> > >
> > > Indeed. Someone is changing the __alias() wrappers [for no good reason
> > > afaict] in a way that does not allow for new users of those wrappers
> > > to come in concurrently.
> > >
> > > Hency my suggestion to switch to the raw __attribute__((alias("..")))
> > > notation for the time being, and switch back to __alias() somewhere
> > > after v5.11-rc1.
> > >
> > > Or we might add this to the file in question
> > >
> > > #undef __alias
> > > #define __alias(symbol) __attribute__((__alias__(symbol)))
> > >
> > > and switch to the quoted versions of the identifier. Then we can just
> > > drop these two lines again later, after v5.11-rc1
> >
> > I was under the impression that there was some "post-next"
> > trick that mmot apply this patch after -next has been merged
> > so it's solved now?
> >
> 
> Yes, it appears that [0] has been picked up, I guess we weren't cc'ed
> on the version that was sent to akpm [which is fine btw, although a
> followup reply here that things are all good now would have been
> appreciated]
> 
> 
> https://lore.kernel.org/linux-arm-kernel/20201109001712.3384097-1-natechancellor@gmail.com/

Hi Ard,

Odd, you were on the list of people to receive that patch and you acked
it but it seems that Andrew did not CC you when he actually applied the
patch:

https://lore.kernel.org/mm-commits/20201110212436.yGYhesom8%25akpm@linux-foundation.org/

My apologies for not following up, we appear to be all good now for the
time being (aside from the futex issue that I reported earlier).

Cheers,
Nathan

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