Re: [PATCH 0/7] objtool: retpoline validation

From: David Woodhouse
Date: Thu Feb 01 2018 - 10:32:25 EST


On Thu, 2018-02-01 at 09:28 -0600, Josh Poimboeuf wrote:
> On Thu, Feb 01, 2018 at 03:34:21PM +0100, Peter Zijlstra wrote:
> >
> > There are the retpoline validation patches; they work with the
> > __noretpoline
> > thing from David.
> Have you run this through 0-day bot yet?ÂÂA manual awk/sed found
> another
> one, which objtool confirms:
>
> Â drivers/watchdog/.tmp_hpwdt.o: warning: objtool: .text+0x24:
> indirect call found in RETPOLINE build
>
> And my search wasn't exhaustive so it would be good to sic 0-day bot on
> it.

We discussed that one. It's correct; we're calling into firmware so
there's *no* point in retpolining that one. We need to set IBRS before
any runtime calls into firmware, if we want to be safe.

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