Messages in this thread | | | Date | Mon, 2 Mar 2020 09:52:40 -0600 | From | Josh Poimboeuf <> | Subject | Re: x86 entry perf unwinding failure (missing IRET_REGS annotation on stack switch?) |
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On Mon, Mar 02, 2020 at 09:18:29AM -0600, Josh Poimboeuf wrote: > > So I think on machines without X86_FEATURE_SMAP, trying to unwind from > > the two NOPs at f41 and f42 will cause the unwinder to report an > > error? Looking at unwind_next_frame(), "sp:(und)" without the "end:1" > > marker seems to be reserved for errors.
I think we can blame this one on Peter ;-)
764eef4b109a ("objtool: Rewrite alt->skip_orig")
With X86_FEATURE_SMAP, alt->skip_orig gets set, which tells objtool to skip validation of the NOPs. That has the side effect of not propagating the ORC state to the NOPs as well.
-- Josh
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