Re: [PATCH] filldir write data missing size

From: Yoshinori Sato
Date: Mon Jul 21 2008 - 11:48:56 EST


At Sun, 20 Jul 2008 05:11:29 +0900,
OGAWA Hirofumi wrote:
>
> Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx> writes:
>
> >> > - if (__put_user(offset, &dirent->d_off))
> >> > + if (__put_user((unsigned long)offset, &dirent->d_off))
> >>
> >> Um.. __put_user() should be already doing it automatically..
> >
> > I'm mistake.
> >
> > I checked object, and found bad code.
> > This problem fix __put_user.
>
> Um.. Could you explain the detail of problem? Is this a workaround or
> something for the bug of some compiler? If so, shouldn't we fix
> __put_user() instead of caller?
>
> E.g. the following or something fixes it? (btw, this is for x86)
>
> #define __put_user(x, ptr) ({ \
> /* Since some compiler generates wrong code, we need __v.?? */ \
> __typeof__(*(ptr)) __v = (x); \
> __put_user_nocheck(__v, (ptr), sizeof(*(ptr))); \
> })
> --
> OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>

This problem is sh-linux-gcc v4.1.2 and target sh2(a)-bigendian.

"__put_user(s64, u32_ptr)" compiled.

Correct code.
*u32_ptr = s64 & 0xffffffff;

Bad code.
*u32_ptr = s64 >> 32;

I'm add cast put_user 4byte case.

--
Yoshinori Sato
<ysato@xxxxxxxxxxxxxxxxxxxx>
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