linux-kernel - Re: [PATCH v3 0/3] modversions: Fix CRC mangling under CONFIG

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Date:   Fri, 25 Nov 2016 22:12:33 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc:     "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel\@lists.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>, jeyu@...hat.com,
        Will Deacon <will.deacon@....com>,
        Rusty Russell <rusty@...tcorp.com.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        "paulus\@samba.org" <paulus@...ba.org>
Subject: Re: [PATCH v3 0/3] modversions: Fix CRC mangling under CONFIG_RELOCATABLE=y

Ard Biesheuvel <ard.biesheuvel@...aro.org> writes:

> On 15 November 2016 at 09:13, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
>> On 10 November 2016 at 05:22, Michael Ellerman <mpe@...erman.id.au> wrote:
>>> Ard Biesheuvel <ard.biesheuvel@...aro.org> writes:
>>>
>>>> On 27 October 2016 at 17:27, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
>>>>> This series is a followup to the single patch 'modversions: treat symbol
>>>>> CRCs as 32 bit quantities on 64 bit archs', of which two versions have
>>>>> been sent out so far [0][1]
>>>>>
>>>>> As pointed out by Michael, GNU ld behaves a bit differently between arm64
>>>>> and PowerPC64, and where the former gets rid of all runtime relocations
>>>>> related to CRCs, the latter is not as easily convinced.
>>>>>
>>>>> Patch #1 fixes the issue where CRCs are corrupted by the runtime relocation
>>>>> routines for 32-bit PowerPC, for which the original fix was effectively
>>>>> reverted by commit 0e0ed6406e61 ("powerpc/modules: Module CRC relocation fix
>>>>> causes perf issues")
>>>>>
>>>>> Patch #2 adds handling of R_PPC64_ADDR32 relocations against the NULL .dynsym
>>>>> symbol entry to the PPC64 runtime relocation routines, so it is prepared to
>>>>> deal with CRCs being emitted as 32-bit quantities.
>>>>>
>>>>> Patch #3 is the original patch from the v1 and v2 submissions.
>>>>>
>>>>> Changes since v2:
>>>>> - added #1 and #2
>>>>> - updated #3 to deal with CRC entries being emitted from assembler
>>>>> - added Rusty's ack (#3)
>>>>>
>>>>> Branch can be found here:
>>>>> https://git.kernel.org/cgit/linux/kernel/git/ardb/linux.git/log/?h=kcrctab-reloc
>>>>>
>>>>> [0] http://marc.info/?l=linux-kernel&m=147652300207369&w=2
>>>>> [1] http://marc.info/?l=linux-kernel&m=147695629614409&w=2
>>>>
>>>> Ping?
>>>
>>> Sorry, you didn't cc linuxppc-dev, so it's not in my patchwork list
>>> which tends to mean I miss it.
>>
>> Ah, my mistake. Apologies.
>>
>>> Will try and test and get back to you.
>
> Ping?

Sorry :/

I tried testing it last week or so but it was interacting badly with the
other modversion CRC problems we were having (fixed recently in my fixes
branch).

I'll rebase on top of those fixes and try again.

cheers