Messages in this thread | | | Date | Thu, 1 Feb 2018 16:30:05 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH 4/7] x86,nospec: Annotate indirect calls/jumps |
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On Thu, Feb 01, 2018 at 09:21:34AM -0600, Josh Poimboeuf wrote: > On Thu, Feb 01, 2018 at 04:13:48PM +0100, Peter Zijlstra wrote:
> > arch/x86/entry/.tmp_entry_64.o: warning: objtool: .altinstr_replacement+0x19: indirect jump found in RETPOLINE build > > Right, objtool was recently made smarter, such that it actually decodes > the ignored alternatives.
I think it always did, you just ignored the alternatives for the code flow stuff.
> The check for that warning needs to also check that insn->ignore isn't > set.
So I tried to keep the two annotations independent, thinking the code flow ignore would eventually go away when we got smarter about it. It even has a comment about that:
/* * FIXME: For now, just ignore any alternatives which add retpolines. This is * a temporary hack, as it doesn't allow ORC to unwind from inside a retpoline. * But it at least allows objtool to understand the control flow *around* the * retpoline. */
So I'm not seeing how making retpoline_safe depend on nospec_ignores is a good thing.
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