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List:       uclibc
Subject:    [RFC 1/1] Fix varargs in prctl syscall
From:       hans-christian.egtvedt () atmel ! com (Hans-Christian Egtvedt)
Date:       2009-07-28 14:07:38
Message-ID: 20090728160738.266f92f4 () hcegtvedt ! norway ! atmel ! com
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On Tue, 28 Jul 2009 09:43:21 -0400
Mike Frysinger <vapier at gentoo.org> wrote:

> On Tuesday 28 July 2009 02:25:03 Hans-Christian Egtvedt wrote:
> > On Mon, 27 Jul 2009 13:24:25 -0400 Mike Frysinger wrote:
> > > i'm guessing your syscall.S is doing something similar.  how
> > > exactly does your code know how many things have been passed ?
> > > or does it blindly assume 6 args have been specified ?
> >
> > The patch I sent grabs the number of arguments depending on what
> > prctl call was made.
> 
> i'm talking about syscall() now, not prctl()
>

The kernel syscall defines 5 arguments for prctl, AFAICT it does not
expect the arguments to be filled, unless the specific prctl call
requires an argument.

AFAIK all architectures will behave like that, given how prctl is
defined in kernel/sys.c?

For syscalls with 6 arguments the AVR32 arch will grab the 6th argument
from the stack and put it into r3. Handled by
arch/avr32/kernel/syscall-stubs.S.

Did I come even close to giving an explanation? (-:

-- 
Best regards,
Hans-Christian Egtvedt

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