linux-kernel - Re: [PATCHv6 bpf-next 9/9] bpf,x86: Use single ftrace

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Message-ID: <CAEf4Bzay1q2oMYSDfdQi8LXt7HjFVXF+C+=+jLurp_GixWbD8Q@mail.gmail.com>
Date: Fri, 9 Jan 2026 16:36:45 -0800
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Jiri Olsa <jolsa@...nel.org>
Cc: Steven Rostedt <rostedt@...nel.org>, Florent Revest <revest@...gle.com>, 
	Mark Rutland <mark.rutland@....com>, bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-trace-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	Alexei Starovoitov <ast@...nel.org>, Daniel Borkmann <daniel@...earbox.net>, 
	Andrii Nakryiko <andrii@...nel.org>, Menglong Dong <menglong8.dong@...il.com>, Song Liu <song@...nel.org>
Subject: Re: [PATCHv6 bpf-next 9/9] bpf,x86: Use single ftrace_ops for direct calls

On Tue, Dec 30, 2025 at 6:51 AM Jiri Olsa <jolsa@...nel.org> wrote:
>
> Using single ftrace_ops for direct calls update instead of allocating
> ftrace_ops object for each trampoline.
>
> With single ftrace_ops object we can use update_ftrace_direct_* api
> that allows multiple ip sites updates on single ftrace_ops object.
>
> Adding HAVE_SINGLE_FTRACE_DIRECT_OPS config option to be enabled on
> each arch that supports this.
>
> At the moment we can enable this only on x86 arch, because arm relies
> on ftrace_ops object representing just single trampoline image (stored
> in ftrace_ops::direct_call). Archs that do not support this will continue
> to use *_ftrace_direct api.
>
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  arch/x86/Kconfig        |   1 +
>  kernel/bpf/trampoline.c | 220 ++++++++++++++++++++++++++++++++++------
>  kernel/trace/Kconfig    |   3 +
>  kernel/trace/ftrace.c   |   7 +-
>  4 files changed, 200 insertions(+), 31 deletions(-)
>

As far as I can follow, everything looks reasonable

Acked-by: Andrii Nakryiko <andrii@...nel.org>


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