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

* Re: [PATCH v2 09/13] powerpc/ftrace: Implement CONFIG_DYNAMIC_FTRACE_WITH_ARGS
       [not found] ` <5831f711a778fcd6eb51eb5898f1faae4378b35b.1640017960.git.christophe.leroy@csgroup.eu>
@ 2021-12-22 14:19   ` Miroslav Benes
  0 siblings, 0 replies; only message in thread
From: Miroslav Benes @ 2021-12-22 14:19 UTC (permalink / raw)
  To: Christophe Leroy
  Cc: Josh Poimboeuf, Jiri Kosina, Petr Mladek, Joe Lawrence,
	Steven Rostedt, Ingo Molnar, Naveen N . Rao, linux-kernel,
	linuxppc-dev, live-patching, linux-arm-kernel, mark.rutland,
	broonie, madvenka

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@csgroup.eu/

Miroslav

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