Re: port-xen/53863: panic: xen_failsafe_handler called! while running 32-bit binary on 64-bit.

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Jan 13, 2019 at 03:15:00AM +0000, marcotte%panix.com@localhost wrote:
> NetBSD/xen 64-bit domU.
> 
> When running an old 32-bit perl binary which loads modules, I sometimes get this:
> 
>   panic: xen_failsafe_handler called!
> 
>   cpu0: Begin traceback...
>   vpanic() at netbsd:vpanic+0x140
>   snprintf() at netbsd:snprintf
>   xpq_flush_queue() at netbsd:xpq_flush_queue
>   failsafe_callback() at netbsd:failsafe_callback+0xa1
>   x86_64_tls_switch() at netbsd:x86_64_tls_switch+0x8a
>   cpu_switchto() at netbsd:cpu_switchto+0x88
>   preempt() at netbsd:preempt+0x4d
>   trap() at netbsd:trap+0x747
>   --- trap (number 3) ---
>   7f7fd860c36a:
>   cpu0: End traceback...
> 
> The binary is an old 32-bit perl which when loading certain modules, changes the text section to read/write. By default this should fail in NetBSD-8 because of mprotect, but it shoudn't panic the kernel. Turning off mprotect allows the program to run, but it sometimes still panics the kernel on startup.
> 
> 
> >How-To-Repeat:
> I wasn't able to make a simple program to cause the panic, but I can reproduce it pretty reliably here.
> 
> >Fix:
> Don't know what the fix is, but I tracked it down to this change:
> 
>   src/sys/arch/amd64/amd64/machdep.c
>   1.255.6.1 -> 1.255.6.2
> 
> That's a pullup of version 1.267.
> 
> When I revert that, I no longer get the panic.

Do you have anything relevant in xl dmesg on the dom0 ? booting with
a xen-debug.gz kernel may be needed to get usefull information

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--