From mboxrd@z Thu Jan  1 00:00:00 1970
From: gmate.amit@gmail.com (Kumar amit mehta)
Date: Wed, 20 Mar 2013 00:07:57 -0700
Subject: kernel build error
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To: kernelnewbies@lists.kernelnewbies.org
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On Tue, Mar 19, 2013 at 11:56:44PM -0700, Kumar amit mehta wrote:
> On Tue, Mar 19, 2013 at 09:43:11PM +0700, Mulyadi Santosa wrote:
> > Hi ...
> > 
> > On Tue, Mar 19, 2013 at 12:28 PM, Kumar amit mehta <gmate.amit@gmail.com> wrote:
> > > grep for copy_from_user_overflow gives me this:
> > >
> > > amit at ubuntu:~/linux-next/linux-next$ grep -ri copy_from_user_overflow *
> > > arch/s390/include/asm/uaccess.h:extern void copy_from_user_overflow(void)
> > > arch/s390/include/asm/uaccess.h:                copy_from_user_overflow();
> > > arch/tile/include/asm/uaccess.h:extern void copy_from_user_overflow(void)
> > > arch/tile/include/asm/uaccess.h:                copy_from_user_overflow();
> > > arch/parisc/include/asm/uaccess.h:extern void copy_from_user_overflow(void)
> > > arch/parisc/include/asm/uaccess.h:                copy_from_user_overflow();
> > > arch/x86/include/asm/uaccess_32.h:extern void copy_from_user_overflow(void)
> > > arch/x86/include/asm/uaccess_32.h:              copy_from_user_overflow();
> > > drivers/vfio/pci/vfio_pci_config.c:      * with count of 1/2/4 and hits
> > > copy_from_user_overflow without this.
> > > lib/usercopy.c:void copy_from_user_overflow(void)
> > 
> > 
> > IMHO, I think uaccess_32.h is what you need here.
> > 
> > I draw that conclusion after checking this line:
> > http://lxr.linux.no/#linux+v3.8.3/arch/x86/include/asm/uaccess_32.h#L194
> > 
> > I might be wrong, so feel free to test first
> > 
> Actually the above header file is supposed to get included, based on the 
> architecture only.
> 
> <snip from arch/x86/include/asm/uaccess.h>
> #ifdef CONFIG_X86_32
> # include <asm/uaccess_32.h>
> #else
> # include <asm/uaccess_64.h>
> #endif
> <snip from arch/x86/include/asm/uaccess.h>
> 
> <snip from .config>
> amit at ubuntu:~/linux-next/linux-next$ grep -w CONFIG_X86_32 .config 
> CONFIG_X86_32=y
> <snip from .config>
> 
> CPU arch on my machine: 
> amit at ubuntu:~/linux-next/linux-next$ uname -m
> i686
> 
> Based on this observation, I think, I do not need to include the uaccess_32.h
> in any of those files. 
>

I forgot that 'uname -m' will return me the kernel version and _not_ the CPU
architecture. The CPU on my machine seem to be 64 bit (/proc/cpuinfo|grep flags
shows 'lm'). So my understanding is that I've a 32 bit kernel running on a 64
bit machine.