Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
References: <20180402095033.nfzcrmxvpm46dhbl@gmail.com> <CA+55aFzV8L-uv9706ryJ2mP9VGBuzqFVPu1cgYY+sZAtDAroqg@mail.gmail.com>
 <20180403085904.GY4082@hirez.programming.kicks-ass.net> <20180403095118.rpf7tj577dppvx7d@gmail.com>
 <20180403180658.GE87376@google.com> <CAKwvOdkaBNTyNjackJcWYkdfwyR2wjAruMFqN8LuYqC8V0ii_A@mail.gmail.com>
 <20180404093823.GC25996@kroah.com> <CAKwvOdmk-e5NCkyMT_LX2i5F1X+xGP+ZxAjaJasjgE6FaXKi6w@mail.gmail.com>
 <20180404193247.lsoxe3xjcidwtlgv@treble>
In-Reply-To: <20180404193247.lsoxe3xjcidwtlgv@treble>
From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Thu, 7 Jun 2018 12:23:31 -0700
Message-ID: <CAKwvOdmFVO=SUxazTR+WGgrTtKyfqgEup-aY_P3LrQBZqrL84Q@mail.gmail.com>
Subject: Re: [GIT PULL] x86/build changes for v4.17
To:     Josh Poimboeuf <jpoimboe@redhat.com>
Cc:     Greg KH <gregkh@linuxfoundation.org>,
        Matthias Kaehlcke <mka@chromium.org>,
        Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        James Y Knight <jyknight@google.com>,
        Chandler Carruth <chandlerc@google.com>,
        Stephen Hines <srhines@google.com>,
        Kees Cook <keescook@google.com>, groeck@chromium.org,
        Greg Hackmann <ghackmann@google.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Apr 4, 2018 at 12:32 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
>
> On Wed, Apr 04, 2018 at 04:53:52PM +0000, Nick Desaulniers wrote:
> > (re-sending as plain text)
> >
> > On Wed, Apr 4, 2018 at 2:38 AM Greg KH <gregkh@linuxfoundation.org> wrote:
> > > There are known-bugs with building a kernel with clang right now (I
> > > pointed one out a few days ago about NULL checks being deleted from the
> > > clang output for no good reason, which really is scary for obvious
> > > reasons).
> >
> > Is this the thread you are referring to?
> > https://lkml.org/lkml/2018/3/27/1286
> >
> > It's definitely something curious that I'll need to sit down and
> > investigate more.  If there are other known instances, it would be good to
> > let me know.
>
> As Matthias mentioned elsewhere, it sounds like they're planning to
> implement -fno-delete-null-pointer-checks, which would presumably fix
> the above issue.

Just to follow this up, -fno-delete-null-pointer-checks is being added
to clang in:
https://reviews.llvm.org/D47894
https://reviews.llvm.org/D47895

-- 
Thanks,
~Nick Desaulniers