Re: [RFC][PATCH] ftrace/x86: Remove mcount support

[Linus Torvalds]

On Thu, May 9, 2019 at 12:49 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h
> index ed80003ce3e2..2f2bdf0662f8 100644
> --- a/arch/x86/include/asm/livepatch.h
> +++ b/arch/x86/include/asm/livepatch.h
> @@ -26,9 +26,6 @@
>
>  static inline int klp_check_compiler_support(void)
>  {
> -#ifndef CC_USING_FENTRY
> -       return 1;
> -#endif
>         return 0;
>  }

Please remove this entirely.

There are now three copies of klp_check_compiler_support(), and all
three are now trivial "return 0" functions.

Remove the whole thing, and remove the single use in kernel/livepatch/core.c.

The only reason for this function existing was literally "mcount isn't
good enough", so with mcount removed, the function should be removed
too.

                     Linus