From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH RFC] ARM: option for loading modules into vmalloc area
Date: Wed, 19 Nov 2014 18:59:12 +0100 [thread overview]
Message-ID: <CAKv+Gu-q7Vdd=Buaz2x=8HASCpeY5D-RsOm-120bkOqmgtUeTw@mail.gmail.com> (raw)
In-Reply-To: <alpine.LFD.2.11.1411191205530.11690@knanqh.ubzr>
On 19 November 2014 18:12, Nicolas Pitre <nicolas.pitre@linaro.org> wrote:
> On Wed, 19 Nov 2014, Russell King - ARM Linux wrote:
>
>> On Wed, Nov 19, 2014 at 11:57:15AM -0500, Nicolas Pitre wrote:
>> > On Wed, 19 Nov 2014, Russell King - ARM Linux wrote:
>> > > I don't think I ever did, because its pretty much impossible to do as I
>> > > explained in a follow up to this thread.
>> > >
>> > > We _used_ to do this with the userspace insmod methods, but since we got
>> > > this kernel-side linker, it's been pretty much impossible to do without
>> > > rewriting the module code. That's not going to happen on account of one
>> > > quirky architecture which Linus doesn't particularly like.
>> >
>> > Still... We could try adding a hook in the generic module linker code
>> > for a pre-relocation pass. Maybe only ARM would use it, but if the need
>> > to load big modules is real then I imagine Linus could be amenable to a
>> > compromise.
>>
>> So, how big a table would you allocate for the trampolines, based upon
>> not knowing anything about the module being loaded? 4K? 8K? 64K?
>
> The idea of a pre-relocation pass is to determine that. That could be
> something similar to calling apply_relocate() twice: once to determine
> the number of trampoline entries, and a second time to perform the
> actual relocation.
>
Well, the veneers shouldn't take more than 3 words each, right?
ldr ip, [pc]
bx ip
.long symbol
and you would need at most one veneer per unique external symbol
referenced by one or more R_ARM_CALL relocations. Is there no way to
just add that to the static mem footprint as padding, and let the
loader populate it as needed at module relocation time?
--
Ard.
next prev parent reply other threads:[~2014-11-19 17:59 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-18 16:21 [PATCH RFC] ARM: option for loading modules into vmalloc area Konstantin Khlebnikov
2014-11-18 17:34 ` Russell King - ARM Linux
2014-11-18 18:13 ` Konstantin Khlebnikov
2014-11-19 13:40 ` Arnd Bergmann
2014-11-19 14:54 ` Ard Biesheuvel
2014-11-19 15:52 ` Konstantin Khlebnikov
2014-11-19 16:02 ` Ard Biesheuvel
2014-11-19 16:07 ` Russell King - ARM Linux
2014-11-19 16:25 ` Ard Biesheuvel
2014-11-19 16:32 ` Konstantin Khlebnikov
2014-11-19 16:38 ` Ard Biesheuvel
2014-11-19 16:55 ` Russell King - ARM Linux
2014-11-19 16:59 ` Nicolas Pitre
2014-11-19 16:41 ` Russell King - ARM Linux
2014-11-19 16:37 ` Nicolas Pitre
2014-11-19 16:41 ` Ard Biesheuvel
2014-11-19 16:49 ` Russell King - ARM Linux
2014-11-19 16:57 ` Nicolas Pitre
2014-11-19 16:59 ` Russell King - ARM Linux
2014-11-19 17:12 ` Nicolas Pitre
2014-11-19 17:59 ` Ard Biesheuvel [this message]
2014-11-19 18:22 ` Nicolas Pitre
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