Re: [PATCH v16 04/18] function_graph: Replace fgraph_ret_regs with ftrace_regs

Masami Hiramatsu
2024-10-21T04:22:31Z

On Wed, 16 Oct 2024 10:33:23 +0200
Heiko Carstens <hca@linux.ibm.com> wrote:

> On Wed, Oct 16, 2024 at 08:47:20AM +0900, Masami Hiramatsu wrote:
> > On Tue, 15 Oct 2024 20:39:06 +0200
> > Heiko Carstens <hca@linux.ibm.com> wrote:
> >
> > > That would make things much simpler... e.g. your new patch is also
> > > writing r3 to fregs, why?
> >
> > BTW, according to the document [1], r3 is for "return value 1", isn't it
> > used usually?
> >
> > [1] https://www.kernel.org/doc/Documentation/s390/Debugging390.txt
>
> That is true for the 32 bit ABI, but not for the 64 bit ABI which we
> care about. Besides other this is also the reason why I removed the
> above file five years ago: f62f7dcbf023 ("Documentation/s390: remove
> outdated debugging390 documentation").
>
> If you really want to understand the 64 bit s390 ABI then you need to
> look at https://github.com/IBM/s390x-abi .
>
> A PDF file of the latest release is available at
> https://github.com/IBM/s390x-abi/releases/download/v1.6.1/lzsabi_s390x.pdf
>
> See section "1.2.5. Return Values" for return value handling.

Ah, these are the info what I searched!

>
> All of that said, I would appreciate if you would just merge the
> provided patch, unless there is a reason for not doing that. Chances
> are that I missed something with all the recent fregs vs ptregs
> changes.

OK

Thanks!

--
Masami Hiramatsu (Google) <mhiramat@kernel.org>