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From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Greg KH <greg@kroah.com>, Justin Forbes <jforbes@redhat.com>,
	Masahiro Yamada <masahiroy@kernel.org>,
	Kees Cook <keescook@chromium.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>,
	Ondrej Mosnacek <omosnace@redhat.com>
Subject: Re: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules
Date: Tue, 26 Jan 2021 09:46:51 -0600	[thread overview]
Message-ID: <20210126154651.itfrnhwfistia3ss@treble> (raw)
In-Reply-To: <YBAyGU7H8E98xKng@hirez.programming.kicks-ass.net>

On Tue, Jan 26, 2021 at 04:15:37PM +0100, Peter Zijlstra wrote:
> On Tue, Jan 26, 2021 at 08:51:55AM -0600, Josh Poimboeuf wrote:
> > User space mixes compiler versions all the time.  The C ABI is stable.
> > 
> > What specifically is the harder issue you're referring to?
> 
> I don't think the C ABI captures nearly enough. Imagine trying to mix a
> compiler with and without asm-goto support (ok, we fail to build without
> by now, but just imagine).
> 
> No C ABI violated, but having that GCC extention vs not having it
> radically changes the kernel ABI.
> 
> I think I'm with Greg here, just don't do it.

Ok, thank you for an actual example.  asm goto is a good one.

But it's not a cut-and-dry issue.  Otherwise how could modversions
possibly work?

So yes, we should enforce GCC versions, but I still haven't seen a
reason it should be more than just "same compiler and *major* version".

-- 
Josh


  reply	other threads:[~2021-01-26 15:49 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 [this message]
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
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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