Re: NVidia glx stuff dies in sysarch(I386_SET_LDT, ...)

On Fri, 1 Aug 2003, Daniel Eischen wrote:

> On Fri, 1 Aug 2003, Julian Elischer wrote:
> > 
> > Here's my first patch..
> > I'd suggest this (along with man page change) to go in first
> > for a while before we break people's code.
> > 
> > cvs server: Diffing .
> > Index: sys_machdep.c
> > ===================================================================
> > RCS file: /home/ncvs/src/sys/i386/i386/sys_machdep.c,v
> > retrieving revision 1.86
> > diff -u -r1.86 sys_machdep.c
> > --- sys_machdep.c       31 Jul 2003 08:20:24 -0000      1.86
> > +++ sys_machdep.c       1 Aug 2003 23:58:29 -0000
> > _at__at_ -410,6 +410,9 _at__at_
> >         return(error);
> >  }
> >  
> > +static int ldt_warnings;
> > +#define NUM_LDT_WARNINGS 10
> > +
> >  static int
> >  i386_set_ldt(td, args)
> >         struct thread *td;
> > _at__at_ -441,7 +444,7 _at__at_
> >                         uap->start = NLDT;
> >                         uap->num = MAX_LD - NLDT;
> >                 }
> > -               if (uap->start < NLDT || uap->num <= 0)
> > +               if (uap->start <= LUDATA_SEL || uap->num <= 0)
> >                         return (EINVAL);
> >                 mtx_lock_spin(&sched_lock);
> >                 pldt = mdp->md_ldt;
> > _at__at_ -460,10 +463,16 _at__at_
> >         }
> >  
> >         if (!(uap->start == 0 && uap->num == 1)) {
> > +               /* complain a for a while if using old methods */
> > +               if (ldt_warnings++ < NUM_LDT_WARNINGS) {
> > +                       printf("Warning: pid %d used static ldt
> > allocation.\n",
> > +                           td->td_proc->p_pid);
> > +                       printf("See the i386_set_ldt man page for more
> > info\n");
> > +               }
> >                 /* verify range of descriptors to modify */
> >                 largest_ld = uap->start + uap->num;
> > -               if (uap->start < NLDT || uap->start >= MAX_LD ||
> > uap->num < 0 ||
> > -                   largest_ld > MAX_LD) {
> > +               if (uap->start <= LUDATA_SEL || uap->start >= MAX_LD ||
> > +                   uap->num < 0 || largest_ld > MAX_LD) {
> >                         return (EINVAL);
> >                 }
> >         }
> > _at__at_ -562,7 +571,7 _at__at_
> >  again:
> >                 mtx_lock_spin(&sched_lock);
> >                 dp = &((union descriptor *)(pldt->ldt_base))[NLDT];
> > -               for (i = NLDT; i < pldt->ldt_len; ++i) {
> > +               for (i = LUDATA_SEL + 1; i < pldt->ldt_len; ++i) {
> 
> Looks OK, but if we are doing a dynamic allocation, it might be
> better to start at NLDT just to avoid the known problem of someone
> using 6...  Just a thought.

sure.. (though we don't know how many they use.... we just saw the first
one fail).

of course they only link with linux threads.
when they link with us they's use our %gs..

I also noticed that if we disable the 'splat' mode, we'd break sysVR4
binary code as they do that.. (though it's #if 0'd out at the moment)

> 
> -- 
> Dan Eischen
> 
>