KSE/ia64: NULL thread pointer in _thr_sig_add()

[Daniel Eischen]

On Mon, 11 Aug 2003, Marcel Moolenaar wrote:

> On Mon, Aug 11, 2003 at 10:22:50AM -0400, Daniel Eischen wrote:
> 
> > > The fault is given on the last instruction if the disassembly
> > > given above (the thread pointer is r13):
> > > 
> > > (gdb) info register r13
> > > r13            0x0      0
> > > (gdb) info register r14
> > > r14            0xffffffffffffffe0       -32
> > 
> > Right, that's what I was guessing.
> > 
> > > Q: Shouldn't we call _tcb_set() somewhere in the code stream to make
> > > sure we have a valid thread pointer?
> > 
> > Once its set, it should always be set, right?  The kernel doesn't
> > change it, right?  I think that's the idea anyways.  If you look at
> > the beginning of _thr_sched_multi(), we handle first time initialization:
> 
> The kernel creates a new context by virtue of the upcall. Since
> we established earlier that the thread pointer itself is not part
> of the context, you cannot assume that the thread pointer is not
> destroyed.

OK, that's different than x86/amd64 then.

> > 	if ((curkse->k_flags & KF_INITIALIZED) == 0) {
> > 		/* Setup this KSEs specific data. */
> > 		_kcb_set(curkse->k_kcb);
> > 
> > 		/* Set this before grabbing the context. */
> > 		curkse->k_flags |= KF_INITIALIZED;
> > 	}
> > 
> > That should set it up so that we always have TP set to something
> > (in this case, it's the fake tcb).  But from then on, we rely
> > on the kernel not to touch it.  Are you sure the kernel doesn't
> > destroy it somehow?
> 
> I'm positive that the kernel *does* clear _tp. It's by design.

Try David's patch.  It sets the current thread in the upcall
handler.

-- 
Dan Eischen