Re: [PATCH v19 12/19] fprobe: Rewrite fprobe on function-graph tracer

[Heiko Carstens]

On Mon, Nov 11, 2024 at 12:51:09AM +0900, Masami Hiramatsu (Google) wrote:
> From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> 
> Rewrite fprobe implementation on function-graph tracer.
> Major API changes are:
>  -  'nr_maxactive' field is deprecated.
>  -  This depends on CONFIG_DYNAMIC_FTRACE_WITH_ARGS or
>     !CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS, and
>     CONFIG_HAVE_FUNCTION_GRAPH_FREGS. So currently works only
>     on x86_64.
>  -  Currently the entry size is limited in 15 * sizeof(long).
>  -  If there is too many fprobe exit handler set on the same
>     function, it will fail to probe.
> 
> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> ---
>  arch/arm64/include/asm/ftrace.h     |    6 
>  arch/loongarch/include/asm/ftrace.h |    6 
>  arch/powerpc/include/asm/ftrace.h   |    6 
>  arch/riscv/include/asm/ftrace.h     |    5 
>  arch/s390/include/asm/ftrace.h      |    6 
>  arch/x86/include/asm/ftrace.h       |    6 
>  include/linux/fprobe.h              |   58 ++-
>  kernel/trace/Kconfig                |   10 -
>  kernel/trace/fprobe.c               |  637 +++++++++++++++++++++++++----------
>  lib/test_fprobe.c                   |   45 --
>  10 files changed, 539 insertions(+), 246 deletions(-)
...
> diff --git a/arch/s390/include/asm/ftrace.h b/arch/s390/include/asm/ftrace.h
> index fd3f0fe9f7b3..a3b73a4f626e 100644
> --- a/arch/s390/include/asm/ftrace.h
> +++ b/arch/s390/include/asm/ftrace.h
> @@ -77,6 +77,12 @@ ftrace_regs_get_frame_pointer(struct ftrace_regs *fregs)
>  	return ftrace_regs_get_stack_pointer(fregs);
>  }
>  
> +static __always_inline unsigned long
> +ftrace_regs_get_return_address(const struct ftrace_regs *fregs)
> +{
> +	return arch_ftrace_regs(fregs)->regs.gprs[14];
> +}
> +

Acked-by: Heiko Carstens <hca@xxxxxxxxxxxxx> # s390