LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Seth Forshee <seth.forshee@canonical.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>,
	kbuild-all@01.org,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	kbuild test robot <lkp@intel.com>
Subject: Re: [kbuild:kbuild 5/19] drivers/atm/eni.o: warning: objtool: eni_init_one()+0xe42: indirect call found in RETPOLINE build
Date: Tue, 16 Jul 2019 11:20:14 -0500	[thread overview]
Message-ID: <20190716162014.iu47g6o7ralxhcf5@treble> (raw)
In-Reply-To: <20190716124249.GP5418@ubuntu-xps13>

On Tue, Jul 16, 2019 at 07:42:49AM -0500, Seth Forshee wrote:
> On Tue, Jul 16, 2019 at 03:57:24PM +0900, Masahiro Yamada wrote:
> > (+ Josh Poimboeuf)
> > 
> > On Tue, Jul 16, 2019 at 8:44 AM kbuild test robot <lkp@intel.com> wrote:
> > >
> > > tree:   https://kernel.googlesource.com/pub/scm/linux/kernel/git/masahiroy/linux-kbuild.git kbuild
> > > head:   0ff0c3753e06c0420c80dac1b0187a442b372acb
> > > commit: 2eaf4e87ba258cc3f27e486cdf32d5ba76303c6f [5/19] kbuild: add -fcf-protection=none to retpoline flags
> > > config: x86_64-randconfig-s2-07160214 (attached as .config)
> > > compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
> > > reproduce:
> > >         git checkout 2eaf4e87ba258cc3f27e486cdf32d5ba76303c6f
> > >         # save the attached .config to linux build tree
> > >         make ARCH=x86_64
> > 
> > 0-day bot reports objtool warnings with the following applied:
> > https://patchwork.kernel.org/patch/11037379/
> > 
> > I have no idea about objtool.
> > 
> > Is it better to drop this patch for now?
> 
> I'm surprised that the change would have any impact on a build with
> gcc-4.9, since -fcf-protection seems to have been introduced in gcc-8. I
> guess there's no full build log that would let us see the actual flags
> passed to the compiler.
> 
> I'll try to reproduce this result. If you think the patch should be
> dropped in the meantime, that's fine.

The problem with this patch is that it's breaking the following check in
arch/x86/Makefile.  GCC 4.9 doesn't support retpolines, so it's supposed
to fail with the below error.

ifdef CONFIG_RETPOLINE
ifeq ($(RETPOLINE_CFLAGS),)
	@echo "You are building kernel with non-retpoline compiler." >&2
	@echo "Please update your compiler." >&2
	@false
endif
endif

Maybe the flags should be placed in another variable other than
RETPOLINE_CFLAGS.

-- 
Josh

  parent reply	other threads:[~2019-07-16 16:20 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <201907160706.9xUSQ36X%lkp@intel.com>
2019-07-16  6:57 ` Masahiro Yamada
2019-07-16 12:42   ` Seth Forshee
2019-07-16 13:59     ` Masahiro Yamada
2019-07-16 16:20     ` Josh Poimboeuf [this message]
2019-07-17  2:52       ` Masahiro Yamada
2019-07-17 14:44         ` Seth Forshee

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190716162014.iu47g6o7ralxhcf5@treble \
    --to=jpoimboe@redhat.com \
    --cc=kbuild-all@01.org \
    --cc=linux-kbuild@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=lkp@intel.com \
    --cc=seth.forshee@canonical.com \
    --cc=yamada.masahiro@socionext.com \
    --subject='Re: [kbuild:kbuild 5/19] drivers/atm/eni.o: warning: objtool: eni_init_one()+0xe42: indirect call found in RETPOLINE build' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).