Subject: Re: [PATCH 07/12] powerpc/ftrace: FTRACE_WITH_REGS implementation for ppc64le

From: Torsten Duwe <[email-masked]>
Date: Thu, 25 Feb 2016 16:11:13 +0100

On Thu, Feb 25, 2016 at 11:48:59AM +1100, Balbir Singh wrote:
> > @@ -608,6 +621,9 @@ int apply_relocate_add(Elf64_Shdr *sechdrs,
> >  					return -ENOENT;
> >  				if (!restore_r2((u32 *)location + 1, me))
> >  					return -ENOEXEC;
> > +				/* Squash the TOC saver for profiler calls */
> > +				if (!strcmp("_mcount", strtab+sym->st_name))
> > +					SQUASH_TOC_SAVE_INSN(value);
> I don't think we need this anymore, do we?

I'm not sure. Once a module is loaded, are all the "bl _mcount"s NOPed out
before any of its functions are run? If not, the _mcount trampoline will
be used, and it must not save R2!

	Torsten