dom0 PV looping on search_pre_exception_table()

[Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>]

Hello,
for the first time I tried to boot a xen kernel from devel with
a NetBSD PV dom0. The kernel boots, but when the first userland prcess
is launched, it seems to enter a loop involving search_pre_exception_table()
(I see an endless stream from the dprintk() at arch/x86/extable.c:202)

With xen 4.13 I see it, but exactly once:
(XEN) extable.c:202: Pre-exception: ffff82d08038c304 -> ffff82d08038c8c8

with devel:
(XEN) extable.c:202: Pre-exception: ffff82d040393309 -> ffff82d0403938c8        
(XEN) extable.c:202: Pre-exception: ffff82d040393309 -> ffff82d0403938c8        
(XEN) extable.c:202: Pre-exception: ffff82d040393309 -> ffff82d0403938c8        
(XEN) extable.c:202: Pre-exception: ffff82d040393309 -> ffff82d0403938c8        
(XEN) extable.c:202: Pre-exception: ffff82d040393309 -> ffff82d0403938c8        
[...]

the dom0 kernel is the same.

At first glance it looks like a fault in the guest is not handled at it should,
and the userland process keeps faulting on the same address.

Any idea what to look at ?

-- 
Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
     NetBSD: 26 ans d'experience feront toujours la difference
--