On Tue, Aug 8, 2023 at 7:47 PM Richard Henderson <
richard.hender...@linaro.org> wrote:
> 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
