Messages in this thread Patch in this message | | | Date | Wed, 25 Mar 2020 00:00:10 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation |
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On Tue, Mar 24, 2020 at 11:11:09PM +0100, Peter Zijlstra wrote: > On Tue, Mar 24, 2020 at 04:40:06PM -0500, Josh Poimboeuf wrote: > > On Tue, Mar 24, 2020 at 04:31:31PM +0100, Peter Zijlstra wrote: > > > > + if (!save_insn->visited) { > > > + /* > > > + * Oops, no state to copy yet. > > > + * Hopefully we can reach this > > > + * instruction from another branch > > > + * after the save insn has been > > > + * visited. > > > + */ > > > + if (insn == first) > > > + return 0; // XXX > > > > Yeah, moving this code out to apply_insn_hint() seems like a nice idea, > > but it wouldn't be worth it if it breaks this case. TBH I don't > > remember if this check was for a real-world case. Might be worth > > looking at... If this case doesn't exist in reality then we could just > > remove this check altogether. > > I'll go run a bunch of builds with a print on it, that should tell us I > suppose.
I can a bunch of builds, including an allmodconfig with the below on top and it 'works'.
So I suppose we can remove this special case.
--- --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2134,11 +2134,13 @@ static int apply_insn_hint(struct objtoo * after the save insn has been * visited. */ - if (insn == first) - return 0; // XXX
WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", sec, insn->offset); + + if (insn == first) + return -1; + return 1; }
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