Messages in this thread | | | Date | Thu, 29 Nov 2018 12:37:12 -0600 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64 |
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On Thu, Nov 29, 2018 at 06:15:39PM +0100, Peter Zijlstra wrote: > On Thu, Nov 29, 2018 at 08:59:31AM -0800, Andy Lutomirski wrote: > > > If you make it conditional on CPL, do it for 32-bit as well, add > > comments, > > > and convince yourself that there isn’t a better solution > > (like pointing IP at a stub that retpolines to the target by reading > > the function pointer, a la the unoptimizable version), then okay, I > > guess, with only a small amount of grumbling. > > Right; so we _could_ grow the trampoline with a retpoline indirect call > and ret. It just makes the trampoline a whole lot bigger, but it could > work.
I'm trying to envision how this would work. How would the function (or stub) know how to return back to the call site?
-- Josh
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