Subject: Re: [PATCH] powerpc: module: fix TOC symbol CRC

From: Laurent Dufour <[email-masked]>
Date: Tue, 24 Jun 2014 10:42:20 +0200

On 24/06/2014 06:06, Benjamin Herrenschmidt wrote:
> On Thu, 2014-06-19 at 09:44 +1000, Anton Blanchard wrote:
>> Hi Laurent,
>>
>>> The commit 71ec7c55ed91 introduced the magic symbol ".TOC." for ELFv2
>>> ABI. This symbol is built manually and has no CRC value computed. A
>>> zero value is put in the CRC section to avoid modpost complaining
>>> about a missing CRC. Unfortunately, this breaks the kernel module
>>> loading when the kernel is relocated (kdump case for instance)
>>> because of the relocation applied to the kcrctab values.
>>>
>>> This patch compute a CRC value for the TOC symbol which will match
>>> the one compute by the kernel when it is relocated - aka '0 -
>>> relocate_start' done in maybe_relocated called by check_version
>>> (module.c).
>>
>> Adding Rusty since he maintains the module loader code.
> 
> This patch gives me:
> 
> arch/powerpc/kernel/module_64.c: In function 'dedotify_versions':
> arch/powerpc/kernel/module_64.c:325:33: error: 'reloc_start' undeclared (first use in this function)
> arch/powerpc/kernel/module_64.c:325:33: note: each undeclared identifier is reported only once for each function it appears in

Hi Ben,

My mistake, I forgot to check building the kernel when module version
checking is disabled. I'll send a v2 asap.

Cheers,
Laurent.

> Cheers,
> Ben.