Re: copy_from_user broken on i386 since 2.5.57

[Andrew Morton <akpm@digeo.com>]

Brice Goglin <bgoglin@ens-lyon.fr> wrote:
>
> Hi,
> 
> Trying to compile a very very simple module for 2.5,
> I got an error from gcc saying that assembly code
> is incorrect.
> This problem appeared in 2.5.57 and is still here
> in 2.5.59.
> I only tried on i386.
> 
> Here's a very simple example code :
> 
> #define __KERNEL__
> #define MODULE
> #include "linux/module.h"
> #include "asm/uaccess.h"
> 
> int func(void *to, const void *from) {
>   return __copy_from_user(to, from, 1);
> }
> 
> 
> Here's gcc report :
> 
> mp760:~/tmp% gcc user.c -c -o user.o -Ipath_to_2.5.57/include
> /tmp/cceAbcRd.s: Assembler messages:
> /tmp/cceAbcRd.s:120: Error: `%al' not allowed with `movl'
> /tmp/cceAbcRd.s:124: Error: `%al' not allowed with `xorl'
> /tmp/cceAbcRd.s:209: Warning: using `%eax' instead of `%ax' due to `l' suffix
> /tmp/cceAbcRd.s:213: Warning: using `%eax' instead of `%ax' due to `l' suffix
> /tmp/cceAbcRd.s:213: Warning: using `%eax' instead of `%ax' due to `l' suffix

Add `-O2' to the compiler switches.

No, I don't know either ;)