Re: [powerpc] ftrace warning kernel/trace/ftrace.c:2068 with code-patching selftests

From: Steven Rostedt <rostedt@goodmis.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>,
	Yinan Liu <yinan@linux.alibaba.com>,
	linuxppc-dev@lists.ozlabs.org,
	Sachin Sant <sachinp@linux.ibm.com>,
	linux-kernel@vger.kernel.org, ardb@kernel.org,
	keescook@chromium.org
Subject: Re: [powerpc] ftrace warning kernel/trace/ftrace.c:2068 with code-patching selftests
Date: Thu, 27 Jan 2022 07:46:01 -0500	[thread overview]
Message-ID: <20220127074601.41a3773d@rorschach.local.home> (raw)
In-Reply-To: <YfKPmFJ2MGsem4VB@FVFF77S0Q05N>

On Thu, 27 Jan 2022 12:27:04 +0000
Mark Rutland <mark.rutland@arm.com> wrote:

> Ah, so those non-ELF relocations for the mcount_loc table just mean "apply the
> KASLR offset here", which is equivalent for all entries.
> 
> That makes sense, thanks!

And this is why we were having such a hard time understanding each other ;-)

I started a new project called "shelf", which is a shell interface to
read ELF files (Shelf on a ELF!).

It uses my ccli library:

   https://github.com/rostedt/libccli

and can be found here:

   https://github.com/rostedt/shelf

Build and install the latest libccli and then build this with just
"make".

  $ shelf vmlinux

and then you can see what is stored in the mcount location:

  shelf> dump symbol __start_mcount_loc - __stop_mcount_loc

I plan on adding more to include the REL and RELA sections and show how
they affect symbols and such.

Feel free to contribute too ;-)

-- Steve