linux-kernel - Re: [PATCH] drm/i915: Remove redundant user_access_end() from __copy_from

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Message-ID: <CA+icZUXwBFS-6e+Qp4e3PhnRzEHvwdzWtS6OfVsgy85R5YNGOg@mail.gmail.com>
Date:   Wed, 31 Jul 2019 14:25:16 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org,
        Peter Zijlstra <peterz@...radead.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH] drm/i915: Remove redundant user_access_end() from
 __copy_from_user() error path

On Fri, Jul 26, 2019 at 9:30 PM Chris Wilson <chris@...is-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@...utronix.de>
> > > > > Reported-by: Sedat Dilek <sedat.dilek@...il.com>
> > > > > Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> > > > > Tested-by: Nick Desaulniers <ndesaulniers@...gle.com>
> > > > > Tested-by: Sedat Dilek <sedat.dilek@...il.com>
> > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/617
> > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
> > > >
> > > > Reviewed-by: Thomas Gleixner <tglx@...utronix.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@...is-wilson.co.uk>

Thomas did you take this through tip tree after Chris' ACK?

- Sedat -