On Thu, Jan 25, 2018 at 05:00:39PM +0000, David Woodhouse wrote: > On Thu, 2018-01-25 at 10:56 -0600, Josh Poimboeuf wrote: > > On Thu, Jan 25, 2018 at 04:03:18PM +0000, David Woodhouse wrote: > > > On Thu, 2018-01-25 at 16:51 +0100, Borislav Petkov wrote: > > > > > > > > > And the seg fault is objtool's way of telling you you need a > > > > > ANNOTATE_NOSPEC_ALTERNATIVE above the alternative ;-) > > > > > > > > Except that it blew up when I did this which doesn't have ALTERNATIVE > > > > (it's the diff I saved :-)) > > > > > > Yeah, ANNOTATE_NOSPEC_ALTERNATIVE just tells objtool "don't look at the > > > alternative; you're not going to like it". > > > > > > If you start putting a __fill_rsb() function out of line somewhere and > > > only *calling* it from alternatives, then objtool is going to shit > > > itself when it sees that function, regardless. > > > > Right, if you *really* want it always inline, the short term solution is > > to just patch it in with X86_FEATURE_ALWAYS. > > And the whole problem here is that patching it in with alternatives is > painful on kernels < 4.1 because back then, we didn't cope with > oldinstr and altinstr being different lengths. We just manually added the nops for the in-line path, that should be good enough. -- Josh -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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