Re: [PATCH for-4.10 2/2] ubsan: disable unaligned access checks

["Roger Pau Monné" <roger.pau@citrix.com>]

On Tue, Oct 17, 2017 at 01:56:18PM +0100, Wei Liu wrote:
> On Tue, Oct 17, 2017 at 12:36:44PM +0100, Roger Pau Monne wrote:
> > Currently there are many offenders of the unaligned access checks,
> > which makes booting with the unaligned check a PVH Dom0 impossible.
> > 
> > The main offenders seem to be the ACPI code, the VMX code and
> > specially the intremap code (set_ire_sid).
> > 
> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> > ---
> > Cc: Andrew Cooper <andrew.cooper3@citrix.com>
> > Cc: George Dunlap <George.Dunlap@eu.citrix.com>
> > Cc: Ian Jackson <ian.jackson@eu.citrix.com>
> > Cc: Jan Beulich <jbeulich@suse.com>
> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> > Cc: Stefano Stabellini <sstabellini@kernel.org>
> > Cc: Tim Deegan <tim@xen.org>
> > Cc: Wei Liu <wei.liu2@citrix.com>
> > Cc: Julien Grall <julien.grall@arm.com>
> > ---
> > I'm not sure whether we prefer to fix the offenders, or just disable
> > the alignment wholesale. In any case if we decide to disable the
> > check, the patch should have vary low impact, and hence should be
> > committed to 4.10 on the base that it only affects ubsan, which is not
> > enabled by default and not to be used on production systems.
> 
> I would very much like to fix the offenders but if the fixes turn out to
> be cumbersome, so be it.
> 
> What is wrong to leave this enabled? Each location is reported once,
> right?

With clang it's reported every time it's hit AFAICT (certainly more
than once).

Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
https://lists.xen.org/xen-devel