linux-kernel - Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm

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Message-ID: <CA+55aFxOGw57Gm-QiNs13kfy5k=aRrn3+98415V0g73eGc66mg@mail.gmail.com>
Date:   Tue, 29 Nov 2016 08:17:35 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Michal Marek <mmarek@...e.com>
Cc:     Adam Borowski <kilobyte@...band.pl>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Ben Hutchings <ben@...adent.org.uk>,
        Debian kernel maintainers <debian-kernel@...ts.debian.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>, Ingo Molnar <mingo@...nel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/kbuild: enable modversions for symbols exported from asm

On Tue, Nov 29, 2016 at 8:03 AM, Michal Marek <mmarek@...e.com> wrote:
>
> The original and easily observable bug is that were are not generating
> symbol checksums for the asm-exported symbols, so they default to 0.
> This can be seen e.g. in the Module.symvers file. This seemed like a
> minor issue, because with the functions written in asm, the type
> checking is rather weak (this has been the case even before Al's
> patches). However, there is another bug that with _some_ toolchains /
> architectures, the checksums do not default to 0, but they are simply
> missing in the ___kcrctab* sections and the module loader complains. We
> can of course research into the details of the second bug, but we
> already know that we are not generating the checksums while we should be.

So let's just say that "toolchain is buggy" and make a missing kcrctab
entry mean zero (or mean "matches anything"). And just shut up the
warning.

I do *not* want to add random bandaids for something like a broken
toolchain issue when I'd really rather just delete the feature.

                     Linus