Re: [PATCH] parisc: fix module loading failure of large kernel modules (take 4)

Helge Deller
2008-12-31T17:40:06Z

Linus Torvalds wrote:
>
> On Wed, 31 Dec 2008, Helge Deller wrote:
>> [PATCH 1/2] module.c: fix module loading failure of large kernel modules
>>
>> When creating the final layout of a kernel module in memory, allow the
>> module loader to reserve some additional memory in front of a given section.
>> This is currently only needed for the parisc port which needs to put the
>> stub entries there to fulfill the 17/22bit PCREL relocations with large
>> kernel modules like xfs.
>>
>> Differences of this patch to previous versions:
>> - added weak funtion arch_module_section_size()
>
> This doesn't work.
>
> We've had this bug several times now, and one of them just very recently.
>
> Some gcc versions will inline weak functions if they are in scope - even
> if there is a non-weak function somewhere else. So you MUST NOT have the
> weak definition in the same file (or indirectly called through some inline
> functions in a header file) as the call. Because if you do, then any user
> with the wrong version of gcc will get the weak function semantics, even
> if it was meant to be overridden by something else.

Ok, that might explain why I saw some strange things in the unwind tables
after that I switched to using the weak function (hppa-crosscompiler, gcc-3.3.4).

>> +/* Additional bytes needed by arch in front of individual sections */
>> +unsigned int __attribute__ ((weak)) arch_module_section_size(
>> + struct module *mod, unsigned int section)
>
> We don't write out that whole "__attribute__" crud. We use
>
> unsigned in __weak arch_module_section_size(struct module *mod, unsigned int section)
>
> instead.

Ok.

> But as mentioned, it needs to be in another compilation unit.

Understood.

Rusty, back to you for an advise on how to continue ;-)
(I assume Rusty is just right now celebrating new-year)

Helge