[PATCH v2 1/2] ftrace: Make ftrace_regs abstract from direct use

[Heiko Carstens]

On Tue, Oct 08, 2024 at 07:05:28PM -0400, Steven Rostedt wrote:
> From: Steven Rostedt <rostedt at goodmis.org>
> 
> ftrace_regs was created to hold registers that store information to save
> function parameters, return value and stack. Since it is a subset of
> pt_regs, it should only be used by its accessor functions. But because
> pt_regs can easily be taken from ftrace_regs (on most archs), it is
> tempting to use it directly. But when running on other architectures, it
> may fail to build or worse, build but crash the kernel!
> 
> Instead, make struct ftrace_regs an empty structure and have the
> architectures define __arch_ftrace_regs and all the accessor functions
> will typecast to it to get to the actual fields. This will help avoid
> usage of ftrace_regs directly.
> 
> Link: https://lore.kernel.org/all/20241007171027.629bdafd@gandalf.local.home/
> 
> Acked-by: Catalin Marinas <catalin.marinas at arm.com>
> Signed-off-by: Steven Rostedt (Google) <rostedt at goodmis.org>
> ---
...
>  arch/s390/include/asm/ftrace.h           | 23 ++++++++++---------
>  arch/s390/kernel/asm-offsets.c           |  4 ++--
>  arch/s390/kernel/ftrace.c                |  2 +-
>  arch/s390/lib/test_unwind.c              |  4 ++--

Acked-by: Heiko Carstens <hca at linux.ibm.com> # s390