From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Masahiro Yamada <masahiroy@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Michal Marek <michal.lkml@markovi.net>,
linux-hardening@vger.kernel.org,
Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Justin Forbes <jforbes@redhat.com>,
Ondrej Mosnacek <omosnace@redhat.com>,
Frank Eigler <fche@redhat.com>, Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules
Date: Thu, 4 Mar 2021 09:08:12 -0600 [thread overview]
Message-ID: <20210304150812.rzya7ewmerwhe4m4@treble> (raw)
In-Reply-To: <CAK7LNAQaAgg+mVSw_U3_FuuqcqJNnonyhVD1M-ezv71Y+dyAww@mail.gmail.com>
On Thu, Mar 04, 2021 at 09:27:28PM +0900, Masahiro Yamada wrote:
> I agree with rebuilding GCC plugins when the compiler is upgraded
> for *in-tree* building.
> Linus had reported it a couple of months before,
> and I just submitted a very easy fix.
Hm? So does that mean that a GCC version change won't trigger a
tree-wide rebuild? So you're asserting that a GCC mismatch is ok for
in-tree code, but not for external modules??? That seems backwards.
For in-tree, why not just rebuild the entire tree? Some kernel features
are dependent on compiler version or capability, so not rebuilding the
tree could introduce silent breakage.
For external modules, a tree-wide rebuild isn't an option so the risk is
assumed by the user. I posted a patch earlier [1] which prints a
warning if the compiler major/minor version changes with an external
module build.
[1] https://lkml.kernel.org/r/20210201211322.t2rxmvnrystc2ky7@treble
> Rebuilding plugins for external modules is not easy;
> plugins are placed in the read-only directory,
> /usr/src/linux-headers-$(uname -r)/scripts/gcc-plugins/.
>
> The external modules must not (cannot) update in-tree
> build artifacts. "Rebuild" means creating copies in a different
> writable directory.
> Doing that requires a lot of design changes.
Ok. So it sounds like the best/easiest option is the original patch in
this thread: when building an external module with a GCC mismatch, just
disable the GCC plugin, with a warning (or an error for randstruct).
--
Josh
next prev parent reply other threads:[~2021-03-04 15:10 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 20:42 [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules Josh Poimboeuf
2021-01-25 21:16 ` Masahiro Yamada
2021-01-25 21:27 ` Josh Poimboeuf
2021-01-25 21:44 ` Masahiro Yamada
2021-01-25 22:07 ` Josh Poimboeuf
2021-01-26 8:13 ` Greg KH
2021-01-26 12:44 ` Justin Forbes
2021-01-26 13:51 ` Greg KH
2021-01-26 14:51 ` Josh Poimboeuf
2021-01-26 15:00 ` Greg KH
2021-01-26 15:15 ` Peter Zijlstra
2021-01-26 15:46 ` Josh Poimboeuf
2021-01-26 16:05 ` Peter Zijlstra
2021-01-26 16:15 ` Justin Forbes
2021-01-26 16:19 ` Josh Poimboeuf
2021-01-26 17:06 ` Greg KH
2021-01-26 17:47 ` Justin Forbes
2021-01-26 16:22 ` David Laight
2021-01-27 18:03 ` Christoph Hellwig
2021-01-26 8:12 ` Greg KH
2021-01-25 22:03 ` Kees Cook
2021-01-25 22:19 ` Josh Poimboeuf
2021-01-26 17:56 ` Kees Cook
2021-01-26 18:43 ` Josh Poimboeuf
2021-01-26 22:59 ` Kees Cook
2021-01-26 23:32 ` Josh Poimboeuf
2021-01-26 1:53 ` Masahiro Yamada
2021-01-26 12:16 ` David Laight
2021-01-27 18:02 ` Christoph Hellwig
2021-01-27 18:38 ` Josh Poimboeuf
2021-01-27 18:43 ` Christoph Hellwig
2021-01-27 18:51 ` Josh Poimboeuf
2021-01-27 22:09 ` David Laight
2021-01-28 14:29 ` Christoph Hellwig
2021-01-28 15:45 ` Josh Poimboeuf
2021-03-02 23:26 ` Josh Poimboeuf
2021-03-03 18:49 ` Masahiro Yamada
2021-03-03 19:15 ` Josh Poimboeuf
2021-03-03 19:25 ` Linus Torvalds
2021-03-03 19:38 ` Josh Poimboeuf
2021-03-03 19:57 ` Linus Torvalds
2021-03-03 20:24 ` Josh Poimboeuf
2021-03-03 20:31 ` Josh Poimboeuf
2021-03-03 20:56 ` Linus Torvalds
2021-03-03 21:45 ` Josh Poimboeuf
2021-03-04 12:27 ` Masahiro Yamada
2021-03-04 15:08 ` Josh Poimboeuf [this message]
2021-03-04 15:35 ` Masahiro Yamada
2021-03-04 19:12 ` Linus Torvalds
2021-03-05 2:41 ` Josh Poimboeuf
2021-03-05 2:49 ` Linus Torvalds
2021-03-05 16:03 ` Masahiro Yamada
2021-03-05 19:18 ` Josh Poimboeuf
2021-03-08 9:39 ` David Laight
2021-03-05 15:31 ` Masahiro Yamada
2021-03-03 21:52 ` Kees Cook
2021-03-04 12:26 ` Masahiro Yamada
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