linux-kernel - Re: [Patch 4/5] module: trim exception table in module

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Message-ID: <4A2C695B.2060505@redhat.com>
Date:	Mon, 08 Jun 2009 09:28:59 +0800
From:	Amerigo Wang <amwang@...hat.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	linux-kernel@...r.kernel.org, jdike@...toit.com, hch@...radead.org,
	mingo@...e.hu, akpm@...ux-foundation.org,
	David Miller <davem@...emloft.net>, sparclinux@...r.kernel.org,
	linux-alpha@...r.kernel.org, linux-ia64@...r.kernel.org
Subject: Re: [Patch 4/5] module: trim exception table in module_free()

Rusty Russell wrote:
> On Thu, 4 Jun 2009 06:27:06 pm Amerigo Wang wrote:
>   
>> Rusty Russell wrote:
>>     
>>> I've taken this one to make it more generic.  I'll leave the x86
>>> maintainers to apply the rest.
>>>       
>> Thank you. But this one depends on the previous, I don't think you can
>> apply this without the previous ones.
>>     
>
> Here's what I ended up with: I need to rig up a test and make sure it goes to
> all the maintainers and linux-next.
>
> Subject: module: trim exception table on init free.
>
> It's theoretically possible that there are exception table entries
> which point into the (freed) init text of modules.  These could cause
> future problems if other modules get loaded into that memory and cause
> an exception as we'd see the wrong fixup.
>
> Amerigo fixed this long-standing FIXME in the x86 version, but this
> patch is more general.
>
> This implements trim_init_extable(); most archs are simple since they
> use the standard lib/extable.c sort code.  Alpha and IA64 use relative
> addresses in their fixups, so thier trimming is a slight variation.
>
> Sparc32 is unique; it doesn't seem to define ARCH_HAS_SORT_EXTABLE,
> yet it defines its own sort_extable() which overrides the one in lib.
> It doesn't sort, so we have to mark deleted entries instead of
> actually trimming them.
>
> Inspired-by: Amerigo Wang <amwang@...hat.com>
> Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
>   

Very nice!
The generic part of this patch looks good for me, of course. :)

Thank you, Rusty!


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