Re: [PATCH 12/27] asm-generic: add a NOMMU uaccess.h

Michal Simek
2009-05-01T12:38:40Z

Arnd Bergmann wrote:
> On Friday 01 May 2009, Michal Simek wrote:
>>> +#ifndef __put_user
>>> +#define __put_user(x, ptr) \
>>> +({ \
>>> + int __pu_err = 0; \
>>> + typeof(*(ptr)) __pu_val = (x); \
>>> + switch (sizeof (*(ptr))) { \
>>> + case 1: \
>>> + case 2: \
>>> + case 4: \
>>> + *(ptr) = (__pu_val); \
>>> + break; \
>>> + case 8: \
>>> + memcpy(ptr, &__pu_val, sizeof (*(ptr)));\
>>
>> potential cast problem
>
> Yes, I'm looking into this already, probably will do something
> based on the s390 code, which seems to do this correctly.
>
>>> +#define put_user(x, ptr) ( \
>>> + access_ok(VERIFY_WRITE, ptr, sizeof (*ptr)) ? \
>>> + __put_user(x, ptr) : \
>>> + -EFAULT)
>>
>> IMHO write it as inline function with type checking.
>
> Unfortunately, this doesn't work because of the callin
> conventions: __put_user needs to know the type of ptr,
> so it has to be a macro.

yes, I am looking on it too.

Michal

>
> Arnd <><

--
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854