linux-kernel - Re: [PATCH] objtool: fix CONFIG_STACK_VALIDATION warning for out-of-tree modules

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Message-ID: <20170215185548.zhjunwvzbdjsfsd6@merlins.org>
Date:   Wed, 15 Feb 2017 10:55:48 -0800
From:   Marc MERLIN <marc@...lins.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
        Jessica Yu <jeyu@...hat.com>, Michal Marek <mmarek@...e.com>
Subject: Re: [PATCH] objtool: fix CONFIG_STACK_VALIDATION warning for
 out-of-tree modules

On Wed, Feb 15, 2017 at 12:21:17PM -0600, Josh Poimboeuf wrote:
> When building a CONFIG_STACK_VALIDATION enabled kernel without the
> libelf devel package installed, the Makefile prints a warning:
> 
>   "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel"
> 
> But when building an out-of-tree module, the warning doesn't show.
> Instead it tries to use objtool, and the build fails with:
> 
>   /bin/sh: ./tools/objtool/objtool: No such file or directory
> 
> Make sure the warning and the disabling of objtool occur in all cases,
> by moving the CONFIG_STACK_VALIDATION checks outside the 'ifeq
> ($(KBUILD_EXTMOD),)' block in the Makefile.
> 
> Reported-by: Marc MERLIN <marc@...lins.org>
> Suggested-by: Jessica Yu <jeyu@...hat.com>
> Fixes: 3b27a0c85d70 ("objtool: Detect and warn if libelf is missing and don't break the build")
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

Tested-By: Marc MERLIN <marc@...lins.org>

saruman:/usr/src/linux-block# dpkg --remove libelf-dev
saruman:/usr/src/linux-block/tools/objtool# make clean
saruman:/usr/src/linux-block# dkms install  bbswitch/0.8

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area...
make -j8 KERNELRELEASE=4.10.0-rc7-mm3kb1+ KVERSION=4.10.0-rc7-mm3kb1+...(bad exit status: 2)
Error! Bad return status for module build on kernel: 4.10.0-rc7-mm3kb1+ (x86_64)

saruman:/usr/src/linux-block# patch -p1 -s < objtool.patch 

saruman:/usr/src/linux-block# dkms install  bbswitch/0.8

Kernel preparation unnecessary for this kernel.  Skipping...

Building module:
cleaning build area...
make -j8 KERNELRELEASE=4.10.0-rc7-mm3kb1+ KVERSION=4.10.0-rc7-mm3kb1+...
cleaning build area...

DKMS: build completed.

bbswitch.ko:
Running module version sanity check.
 - Original module
   - No original module exists within this kernel
 - Installation
   - Installing to /lib/modules/4.10.0-rc7-mm3kb1+/updates/dkms/

depmod...

DKMS: install completed.


All good, thank you.

Marc
-- 
"A mouse is a device used to point at the xterm you want to type in" - A.S.R.
Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/                         | PGP 1024R/763BE901