Messages in this thread | | | Date | Thu, 26 May 2022 17:21:02 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [RFC PATCH 1/4] objtool: Add --mnop as an option to --mcount |
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Peter Zijlstra wrote: > On Tue, May 24, 2022 at 04:01:48PM +0530, Naveen N. Rao wrote: > >> We need to know for sure either way. Nop'ing out the _mcount locations at >> boot allows us to discover existing long branch trampolines. If we want to >> avoid it, we need to note down those locations during build time. >> >> Do you have a different approach in mind? > > If you put _mcount in a separate section then the compiler cannot tell > where it is and is forced to always emit a long branch trampoline. > > Does that help?
That's an interesting thought. Depending on the type of trampoline the compiler emits, I might be able to use this approach. We will still need objtool on powerpc so that we can note down those trampoline locations.
Thanks, Naveen
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