On 19/06/2017 19:30, Konrad Rzeszutek Wilk wrote: > On Wed, Jun 14, 2017 at 12:49:21PM -0600, Jan Beulich wrote: >>>>> Andrew Cooper <andrew.coop...@citrix.com> 06/14/17 8:34 PM >>> >>> Well - I've got a livepatch with such a relocation. It is probably a >>> livepatch build tools issue, but the question is whether Xen should ever >>> accept such a livepatch or not (irrespective of whether this exact >>> relocation is permitted within the ELF spec). >> Since the spec explicitly mentions that case, I think we'd better support it. >> But it wouldn't be the end of the world if we didn't, as presumably there >> aren't that many use cases for it. > OK. In that case: > > Acked-by: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> > > > Andrew, > > Do you think it would be possible to generate an test-case for this > in arch/test/livepatch?
I can trivially cause this situation to occur with the current build tools, but we are currently presuming a build tools bug to be the underlying issue behind getting a STN_UNDEF relocation in the livepatch. Given that a STN_UNDEF relocation (appears to) mean a NULL dereference once the relocations are evaluated, I am not happy with supporting such a case. Therefore, I'm going to insist that we take a concrete decision as to what to do in the hypervisor code, before adding a test case, and advocate for excluding it outright rather than tolerating it in the (certain?) knowledge that Xen will subsequently crash. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
