Re: [PATCH v2 09/13] powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS

[Miroslav Benes]

On Mon, 20 Dec 2021, Christophe Leroy wrote:

> Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS. It accelerates the call
> of livepatching.
> 
> Also note that powerpc being the last one to convert to
> CONFIG_DYNAMIC_FTRACE_WITH_ARGS, it will now be possible to remove
> klp_arch_set_pc() on all architectures.

Correct. We could replace it ftrace_instruction_pointer_set() and that is 
it. In fact, livepatch.h in both arch/x86/include/asm/ and 
arch/s390/include/asm/ could be removed with that.

On the other hand, there is arm64 live patching support being worked on 
and I am not sure what their plans about DYNAMIC_FTRACE_WITH_ARGS are. The 
above would make it a prerequisite.

Adding CCs... you can find the whole thread at 
https://lore.kernel.org/all/cover.1640017960.git.christophe.leroy@xxxxxxxxxx/

Miroslav