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

[Nick Desaulniers]

On Tue, Aug 6, 2019 at 5:59 AM Josh Poimboeuf <jpoimboe@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxx> wrote:
> > >
> > > On Fri, Jul 26, 2019 at 9:30 PM Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> > > > > > > > Reported-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
> > > > > > > > Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > > > > > > > Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> > > > > > > > Tested-by: Sedat Dilek <sedat.dilek@xxxxxxxxx>
> > > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/617
> > > > > > > > Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > > > > > >
> > > > > > > Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > > > > >
> > > > > > 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@xxxxxxxxxxxxxxxxxx>
> > >
> > > 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.

tglx just picked up 2 other patches of mine, bumping just in case he's
not picking up patches while on vacation. ;)
-- 
Thanks,
~Nick Desaulniers