On Wed, Oct 02, 2024 at 08:29:28PM +0100, Marc Zyngier wrote: > Mark Brown <broonie@xxxxxxxxxx> wrote: > > They are, though really they should UNDEF if GCS isn't there (which I > > had thought was what you were referencing here). Equally we only have > > traps for a subset of GCS instructions and it's not like there aren't a > > whole bunch of untrappable extensions anyway so it's not clear it's > > worth the effort just for that. > If the encodings UNDEF when GCS is not implemented (i.e. they are not > in the NOP space), then all trapable instructions should absolutely > UNDEF (and yes, it is worth the effort, even if it is only to > demonstrate that the architecture is sub-par). Yes, see DDI0487 K.a C5.9. If you're concerned about being unable to generate UNDEFs there's a rather large set of existing extensions where that's not possible, most of the hwcaps in the hwcap selftest that don't set sigill_reliable but do have a SIGILL generator for a start. > So I expect the next version to handle traps for GCSPUSHX, GCSPOPX, > GCSPUSHM, GCSSTR and GCSSTTR when GCS isn't enabled. OK, I already had that change locally after your first message. > I'm also pretty sure this is missing some form of sanitisation for > PSTATE.EXLOCK, and looking at the pseudocode, you seem to be missing > the handling of that bit on exception injection. Ah, yes - I think I see the missing exception injection handling in enter_exception64(). I'm not seeing what you're referencing with sanitisation though, could you give me some more specific pointers please?
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