x86: Unify copy_to_user() and add size checking to it

Similarly to copy_from_user(), where the range check is to
protect against kernel memory corruption, copy_to_user() can
benefit from such checking too: Here it protects against kernel
information leaks.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Cc: <arjan@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/5265059502000078000FC4F6@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>

arch/x86/include/asm/uaccess_32.h

@@ -184,7 +184,4 @@ __copy_from_user_inatomic_nocache(void *to, const void __user *from,
        return __copy_from_user_ll_nocache_nozero(to, from, n);
 }
 
-unsigned long __must_check copy_to_user(void __user *to,
-					const void *from, unsigned long n);
-
 #endif /* _ASM_X86_UACCESS_32_H */