Messages in this thread | | | Date | Thu, 25 Jan 2018 10:56:46 -0600 | From | Josh Poimboeuf <> | Subject | Re: [tip:x86/pti] x86/retpoline: Fill return stack buffer on vmexit |
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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 don't ask me what the long term solution is, I don't even know what I'm having for lunch today.
-- Josh
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