Re: [RFC PATCH 1/4] objtool: Add --mnop as an option to --mcount

From: Naveen N. Rao
Date: Tue May 24 2022 - 06:16:02 EST


Christophe Leroy wrote:


Le 23/05/2022 à 19:55, Sathvika Vasireddy a écrit :
Architectures can select HAVE_NOP_MCOUNT if they choose
to nop out mcount call sites. If that config option is
selected, then --mnop is passed as an option to objtool,
along with --mcount.


Is there a reason not to nop out mcount call sites on powerpc as well ?

Yes, if there are functions that are out of range of _mcount(), then the linker would have inserted long branch trampolines. We detect such cases during boot. But, if we nop out the _mcount call sites during build time, we will need some other way to identify these.

- Naveen