From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Nick Desaulniers <ndesaulniers@google.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>
Subject: Re: [GIT PULL] x86/build changes for v4.17
Date: Wed, 4 Apr 2018 14:32:47 -0500 [thread overview]
Message-ID: <20180404193247.lsoxe3xjcidwtlgv@treble> (raw)
In-Reply-To: <CAKwvOdmk-e5NCkyMT_LX2i5F1X+xGP+ZxAjaJasjgE6FaXKi6w@mail.gmail.com>
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.
Aside from the above-mentioned debugfs NULL checks, there was also
another (seemingly valid) objtool warning:
arch/x86/mm/pti.o: warning: objtool: pti_init() falls through to next function pti_user_pagetable_walk_pmd()
I don't know if that one was also caused by removed NULL checks, but
it's worth investigating.
More details (and the .o file) here:
https://lkml.kernel.org/r/20180319232255.GF37438@google.com
--
Josh
next prev parent reply other threads:[~2018-04-04 19:32 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-02 9:50 [GIT PULL] x86/build changes for v4.17 Ingo Molnar
2018-04-02 21:44 ` Linus Torvalds
2018-04-02 22:38 ` Matthias Kaehlcke
2018-04-03 1:26 ` Matthias Kaehlcke
2018-04-03 8:59 ` Peter Zijlstra
2018-04-03 9:51 ` Ingo Molnar
2018-04-03 12:09 ` Peter Zijlstra
2018-04-03 18:06 ` Matthias Kaehlcke
2018-04-03 21:58 ` Nick Desaulniers
2018-04-04 9:19 ` Peter Zijlstra
2018-04-04 9:38 ` Greg KH
2018-04-04 16:49 ` Nick Desaulniers
2018-04-04 17:13 ` Linus Torvalds
2018-04-04 17:46 ` Nick Desaulniers
2018-04-04 23:10 ` Nick Desaulniers
2018-04-04 16:53 ` Nick Desaulniers
2018-04-04 16:59 ` Greg KH
2018-04-04 19:26 ` James Y Knight
2018-04-04 19:42 ` Linus Torvalds
2018-04-04 22:21 ` James Y Knight
2018-04-04 22:29 ` Linus Torvalds
2018-04-05 7:08 ` Peter Zijlstra
2018-04-05 16:21 ` James Y Knight
2018-04-04 19:32 ` Josh Poimboeuf [this message]
2018-06-07 19:23 ` Nick Desaulniers
2018-06-07 20:11 ` Greg KH
2018-04-04 9:30 ` Peter Zijlstra
2018-04-04 19:17 ` Matthias Kaehlcke
2018-04-04 20:33 ` Arnd Bergmann
2018-04-04 20:58 ` Matthias Kaehlcke
2018-04-04 21:11 ` Arnd Bergmann
2018-04-04 21:46 ` Matthias Kaehlcke
2018-04-04 21:59 ` Linus Torvalds
2018-04-04 22:17 ` Matthias Kaehlcke
2018-04-04 22:39 ` Linus Torvalds
2018-04-04 23:31 ` Matthias Kaehlcke
2018-04-05 0:05 ` Linus Torvalds
2018-04-05 0:20 ` Kees Cook
2018-04-05 7:24 ` Peter Zijlstra
2018-04-05 8:04 ` Ingo Molnar
2018-04-05 8:24 ` Peter Zijlstra
2018-04-05 16:43 ` Linus Torvalds
2018-04-05 7:20 ` Peter Zijlstra
2018-04-05 17:46 ` James Y Knight
2018-04-05 18:06 ` Linus Torvalds
2018-04-05 20:51 ` James Y Knight
2018-04-05 21:13 ` Linus Torvalds
2018-04-05 22:51 ` James Y Knight
2018-04-06 2:02 ` Linus Torvalds
2018-04-05 17:47 ` James Y Knight
2018-04-04 23:04 ` Nick Desaulniers
2018-04-03 17:36 ` Linus Torvalds
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