Messages in this thread | | | Date | Tue, 24 Mar 2020 23:11:09 +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 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.
> > + > > + WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo", > > + sec, insn->offset); > > + return 1; > > + } > > + > > + insn->state = save_insn->state; > > + } > > + > > + *state = insn->state; > > This would have been easier to review if apply_insn_hint() were added in > a separate patch.
27 it will be!
> > + > > + /* restore !CFI state */ > > + state->df = old.df; > > + state->uaccess = old.uaccess; > > + state->uaccess_stack = old.uaccess_stack; > > Maybe we should just move the CFI stuff into a state->cfi substruct. > That would remove the need for these bits and probably also the comment > above the insn_state declaration.
Indeed!
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