Re: [PATCH] drm/i915: Remove redundant user_access_end() from __copy_from_user() error path

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>,
	Thomas Gleixner <tglx@linutronix.de>,
	intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org,
	Peter Zijlstra <peterz@infradead.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Nathan Chancellor <natechancellor@gmail.com>,
	Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH] drm/i915: Remove redundant user_access_end() from __copy_from_user() error path
Date: Tue, 6 Aug 2019 07:59:31 -0500	[thread overview]
Message-ID: <20190806125931.oqeqateyzqikusku@treble> (raw)
In-Reply-To: <CA+icZUWA6e0Zsio6sthRUC=Ehb2-mw_9U76UnvwGc_tOnOqt7w@mail.gmail.com>

On Mon, Aug 05, 2019 at 09:29:53PM +0200, Sedat Dilek wrote:
> On Wed, Jul 31, 2019 at 2:25 PM Sedat Dilek <sedat.dilek@gmail.com> wrote:
> >
> > On Fri, Jul 26, 2019 at 9:30 PM Chris Wilson <chris@chris-wilson.co.uk> wrote:
> > >
> > > Quoting Thomas Gleixner (2019-07-26 20:18:32)
> > > > On Fri, 26 Jul 2019, Chris Wilson wrote:
> > > > > Quoting Thomas Gleixner (2019-07-25 22:55:45)
> > > > > > On Thu, 25 Jul 2019, Josh Poimboeuf wrote:
> > > > > >
> > > > > > > Objtool reports:
> > > > > > >
> > > > > > >   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x36: redundant UACCESS disable
> > > > > > >
> > > > > > > __copy_from_user() already does both STAC and CLAC, so the
> > > > > > > user_access_end() in its error path adds an extra unnecessary CLAC.
> > > > > > >
> > > > > > > Fixes: 0b2c8f8b6b0c ("i915: fix missing user_access_end() in page fault exception case")
> > > > > > > Reported-by: Thomas Gleixner <tglx@linutronix.de>
> > > > > > > Reported-by: Sedat Dilek <sedat.dilek@gmail.com>
> > > > > > > Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> > > > > > > Tested-by: Nick Desaulniers <ndesaulniers@google.com>
> > > > > > > Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
> > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/617
> > > > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> > > > > >
> > > > > > Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
> > > > >
> > > > > Which tree do you plan to apply it to? I can put in drm-intel, and with
> > > > > the fixes tag it will percolate through to 5.3 and beyond, but if you
> > > > > want to apply it directly to squash the build warnings, feel free.
> > > >
> > > > It would be nice to get it into 5.3. I can route it linuxwards if you give
> > > > an Acked-by, but I'm happy to hand it to you :)
> > >
> > > Acked-by: Chris Wilson <chris@chris-wilson.co.uk>
> >
> > Thomas did you take this through tip tree after Chris' ACK?
> >
> 
> Hi,
> 
> Gentle ping...
> Thomas and Chris: Will someone of you pick this up?
> As "objtool: Improve UACCESS coverage" [1] went trough tip tree I
> highly appreciate to do so with this one.

I think Thomas has gone on holiday, so hopefully Chris can pick it up
after all.

-- 
Josh