linux-kernel - Re: linux-next: Tree for Feb 7 (objtool warning)

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Message-ID: <20200210184514.phyq462bvpxwdiss@treble>
Date:   Mon, 10 Feb 2020 12:45:14 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Linux Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: Tree for Feb 7 (objtool warning)

On Mon, Feb 10, 2020 at 11:26:03AM -0600, Josh Poimboeuf wrote:
> On Mon, Feb 10, 2020 at 11:29:51AM +0100, Peter Zijlstra wrote:
> > On Fri, Feb 07, 2020 at 08:17:25AM -0800, Randy Dunlap wrote:
> > > on x86_64:
> > > 
> > > drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: i915_gem_execbuffer2_ioctl()+0x6c7: call to gen8_canonical_addr() with UACCESS enabled
> > 
> > > CONFIG_CC_OPTIMIZE_FOR_SIZE=y
> > > CONFIG_64BIT=y
> > 
> > That's just really sad, stupid compiler.
> > 
> > Something like so I suppose...
> 
> This looks familiar... here's the approach we decided on before, before
> I subsequently dropped the ball:
> 
>   https://lkml.kernel.org/r/20190923141657.p6kpqro3q4p4umwi@treble

Though that patch looks broken because it masks off the UPDATE bit in
the first loop (via PIN_OFFSET_MASK) before checking UPDATE in the second
loop.

-- 
Josh