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

Naveen N. Rao naveen.n.rao at linux.vnet.ibm.com
Tue May 24 20:15:20 AEST 2022


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



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