Re: [PATCH v7 3/4] linux-user: Support futex_time64

[Alistair Francis]

On Fri, Mar 13, 2020 at 3:12 PM Alistair Francis <address@hidden> wrote:
>
> On Fri, Mar 13, 2020 at 1:14 AM Laurent Vivier <address@hidden> wrote:
> >
> > Le 12/03/2020 à 23:13, Alistair Francis a écrit :
> > > Add support for host and target futex_time64. If futex_time64 exists on
> > > the host we try that first before falling back to the standard futux
> > > syscall.
> > >
> > > Signed-off-by: Alistair Francis <address@hidden>
> > > ---
> > >  linux-user/syscall.c | 144 +++++++++++++++++++++++++++++++++++++++----
> > >  1 file changed, 131 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> > > index 60fd775d9c..9ae7a05e38 100644
> > > --- a/linux-user/syscall.c
> > > +++ b/linux-user/syscall.c
> > ...
> > > @@ -6890,6 +6905,55 @@ static inline abi_long host_to_target_statx(struct 
> > > target_statx *host_stx,
> > >  }
> > >  #endif
> > >
> > > +static int do_sys_futex(int *uaddr, int op, int val,
> > > +                         const struct timespec *timeout, int *uaddr2,
> > > +                         int val3)
> > > +{
> > > +#if HOST_LONG_BITS == 64
> > > +#if defined(__NR_futex)
> > > +    /* always a 64-bit time_t, it doesn't define _time64 version  */
> > > +    return sys_futex(uaddr, op, val, timeout, uaddr2, val3);
> > > +
> > > +#endif
> > > +#else /* HOST_LONG_BITS == 64 */
> > > +#if defined(__NR_futex_time64)
> > > +    if (sizeof(timeout->tv_sec) == 8) {
> > > +        /* _time64 function on 32bit arch */
> > > +        return sys_futex_time64(uaddr, op, val, timeout, uaddr2, val3);
> > > +    }
> > > +#endif
> > > +#if defined(__NR_futex)
> > > +    /* old function on 32bit arch */
> > > +    return sys_futex(uaddr, op, val, timeout, uaddr2, val3);
> > > +#endif
> > > +#endif /* HOST_LONG_BITS == 64 */
> > > +    return -TARGET_ENOSYS;
> >
> > You cannot return -TARGET_ENOSYS because return value is supposed to be
> > a host value as you have direct value from sys_futex().
> >
> > ...
> >
> > > @@ -7505,7 +7619,7 @@ static abi_long do_syscall1(void *cpu_env, int num, 
> > > abi_long arg1,
> > >              ts = cpu->opaque;
> > >              if (ts->child_tidptr) {
> > >                  put_user_u32(0, ts->child_tidptr);
> > > -                sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,
> > > +                do_sys_futex(g2h(ts->child_tidptr), FUTEX_WAKE, INT_MAX,
> > >                            NULL, NULL, 0);
> >
> > And return value is ignored. Anyway at this point we can't do anything
> > if it doesn't work, but it should not happen. So I think the best to do
> > is to add a g_assert_not_reached() in place of "return -TARGET_ENOSYS"
> > in do_sys_futex() (or "#error" if no futex function is available).
>
> It sounds like you applied this series, so I'm not going to fix this
> up. Let me know if you would like me to.

Ha, I read the wrong cover letter.

I'll send a new version of this.

Alistair

>
> Alistair
>
> >
> > Thanks,
> > Laurent
> >
> >