On 8/8/23 18:39, Warner Losh wrote:
> > +#define __put_user_e(x, hptr, e) \
> > + do { \
> > + PRAGMA_DISABLE_PACKED_WARNING; \
> > + (__builtin_choose_expr(sizeof(*(hptr)) == 1, stb_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 2, stw_##e##_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 4, stl_##e##_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 8, stq_##e##_p, abort)))) \
> > + ((hptr), (x)), (void)0); \
> > + PRAGMA_REENABLE_PACKED_WARNING; \
> > + } while (0)
> > +
> > +#define __get_user_e(x, hptr, e) \
> > + do { \
> > + PRAGMA_DISABLE_PACKED_WARNING; \
> > + ((x) = (typeof(*hptr))( \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 1, ldub_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 2, lduw_##e##_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 4, ldl_##e##_p, \
> > + __builtin_choose_expr(sizeof(*(hptr)) == 8, ldq_##e##_p, abort)))) \
> > + (hptr)), (void)0); \
> > + PRAGMA_REENABLE_PACKED_WARNING; \
> > + } while (0)
>
> Hmm. I guess this works. The typeof cast in __get_user_e being required when
> sizeof(x) >
> sizeof(*hptr) in order to get the correct extension.
>
>
> This code was copied 100% from the current linux-user :)
Ha ha indeed! I should have known.
Yea... It's old-school crazy, and I've done a lot of that in my day, but not
here :)
> Is it clearer with _Generic?
>
> (x) = _Generic(*(hptr),
> int8_t: *(int8_t *)(hptr),
> uint8_t: *(uint8_t *)(hptr),
> int16_t: (int16_t)lduw_##e##_p(hptr),
> uint16_t: lduw_##e##_p(hptr),
> int32_t: (int32_t)ldl_##e##_p(hptr),
> uint32_t: (uint32_t)ldl_##e##_p(hptr),
> int64_t: (int64_t)ldq_##e##_p(hptr),
> uint64_t: ldq_##e##_p(hptr));
>
> In particular I believe the error message will be much prettier.
>
>
> Indeed. That looks cleaner. I'll see if I can test that against the latest bsd-user upstream.
I'll see if we can share this code via common-user.
It seems to work, though I still need the pragmas for clang 16 (see another patch for that).
I tried to implement both get and put in terms of this, but found that it broke the blitz
branch. So why don't we land this as is for bsd-user and then one of us can try to
put it into common-user so as to not create too many waves for our GSoC student Kariim.
There's already enough to fix in this series... Sound fair?
Warner