On Wed, 31 Oct 2018 14:18:19 +0000
Mark Rutland [off-list ref] wrote:

On Wed, Oct 31, 2018 at 02:19:07PM +0100, Jiri Kosina wrote:

quoted

Other architectures do rely on that. That's exactly for example why
on x86 we use '-pg -mfentry', to make sure we hook the function
*before* prologue.  

Ah, I'd missed -mfentry for x86. I now see that's also the case with
__gnu_mcount_nc on arch/arm, so that covers my confusion.

Yes, fentry used to be the prerequisite, but it's everything but
portable. PPC64 already had the profile-kernel switch, which was
becoming just usable as we got at live patching.

I'm hoping that the patchable-function-entry will become the future
de-facto standard.

	Torsten