Re: Question about config UPROBES and UPROBE_EVENTS

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

On Wed, 11 Sep 2024 14:40:56 +0800
Tiezhu Yang <yangtiezhu@loongson.cn> wrote:

> Hi Masami,
> 
> I am a little confused about config UPROBES and UPROBE_EVENTS.
> Uprobes is the user-space counterpart to kprobes, I want to do
> some small changes:
> 
> (1) since config KPROBES can be selectable, just make config UPROBES
>      selectable too.
> 
> (2) since config KPROBE_EVENTS depends on KPROBES rather than select
>      KPROBES, just make config UPROBE_EVENTS depends on UPROBES rather
>      than select UPROBES.
> 
> Could you please let me know are you OK with the following changes?
> If yes, I will send formal patches later.

Hm, I don't completely reject this idea, but I'm not sure about the benefits
to users and keeping backward compatibility. Especially, the latter one
may hide uprobe_events by default. As you can see, the CONFIG_KPROBES is
enabled by default, thus it does not hide the CONFIG_KPROBE_EVENTS. But
the CONFIG_UPROBES is disabled by default and make CONFIG_UPROBE_EVENTS
depending on it, the uprobe_events menu is hidden. I don't like this.

Thank you,

> 
> -- >8 --
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 975dd22a2dbd..5de2187d3440 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -124,7 +124,8 @@ config KPROBES_ON_FTRACE
>            optimize on top of function tracing.
> 
>   config UPROBES
> -       def_bool n
> +       bool "Uprobes"
> +       default n
>          depends on ARCH_SUPPORTS_UPROBES
>          help
>            Uprobes is the user-space counterpart to kprobes: they
> diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
> index 721c3b221048..7db0462a5d11 100644
> --- a/kernel/trace/Kconfig
> +++ b/kernel/trace/Kconfig
> @@ -732,10 +732,9 @@ config KPROBE_EVENTS_ON_NOTRACE
> 
>   config UPROBE_EVENTS
>          bool "Enable uprobes-based dynamic events"
> -       depends on ARCH_SUPPORTS_UPROBES
> +       depends on UPROBES
>          depends on MMU
>          depends on PERF_EVENTS
> -       select UPROBES
>          select PROBE_EVENTS
>          select DYNAMIC_EVENTS
>          select TRACING
> 
> Thanks,
> Tiezhu
> 
> 


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