linux-kernel - [PATCH bpf-next v3 0/4] kprobes: rethook: x86: Replace kretprobe trampoline with rethook

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Date:   Sat, 26 Mar 2022 11:26:49 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Alexei Starovoitov <ast@...nel.org>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>, x86@...nel.org,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        kernel-janitors@...r.kernel.org,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>, bpf@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next v3 0/4] kprobes: rethook: x86: Replace kretprobe trampoline with rethook

Hi,

Here are the 3rd version for generic kretprobe and kretprobe on x86 for
replacing the kretprobe trampoline with rethook. The previous version
is here[1]

[1] https://lore.kernel.org/all/164821817332.2373735.12048266953420821089.stgit@devnote2/T/#u

This version fixed typo and build issues for bpf-next and CONFIG_RETHOOK=y
error. I also add temporary mitigation lines for ANNOTATE_NOENDBR macro
issue for bpf-next tree [2/4].

#ifndef ANNOTATE_NOENDBR
#define ANNOTATE_NOENDBR
#endif

This will be removed after merging kernel IBT series.

Background:

This rethook came from Jiri's request of multiple kprobe for bpf[2].
He tried to solve an issue that starting bpf with multiple kprobe will
take a long time because bpf-kprobe will wait for RCU grace period for
sync rcu events.

Jiri wanted to attach a single bpf handler to multiple kprobes and
he tried to introduce multiple-probe interface to kprobe. So I asked
him to use ftrace and kretprobe-like hook if it is only for the
function entry and exit, instead of adding ad-hoc interface
to kprobes.
For this purpose, I introduced the fprobe (kprobe like interface for
ftrace) with the rethook (this is a generic return hook feature for
fprobe exit handler)[3].

[2] https://lore.kernel.org/all/20220104080943.113249-1-jolsa@kernel.org/T/#u
[3] https://lore.kernel.org/all/164191321766.806991.7930388561276940676.stgit@devnote2/T/#u

The rethook is basically same as the kretprobe trampoline. I just made
it decoupled from kprobes. Eventually, the all arch dependent kretprobe
trampolines will be replaced with the rethook trampoline instead of
cloning and set HAVE_RETHOOK=y.
When I port the rethook for all arch which supports kretprobe, the
legacy kretprobe specific code (which is for CONFIG_KRETPROBE_ON_RETHOOK=n)
will be removed eventually.

Thank you,

---

Masami Hiramatsu (3):
      kprobes: Use rethook for kretprobe if possible
      x86,rethook,kprobes: Replace kretprobe with rethook on x86
      x86,kprobes: Fix optprobe trampoline to generate complete pt_regs

Peter Zijlstra (1):
      x86,rethook: Fix arch_rethook_trampoline() to generate a complete pt_regs

 arch/Kconfig                     |    8 ++
 arch/x86/Kconfig                 |    1 
 arch/x86/include/asm/unwind.h    |   23 +++----
 arch/x86/kernel/Makefile         |    1 
 arch/x86/kernel/kprobes/common.h |    1 
 arch/x86/kernel/kprobes/core.c   |  106 --------------------------------
 arch/x86/kernel/kprobes/opt.c    |   25 +++++--
 arch/x86/kernel/rethook.c        |  127 ++++++++++++++++++++++++++++++++++++++
 arch/x86/kernel/unwind_orc.c     |   10 +--
 include/linux/kprobes.h          |   51 +++++++++++++++
 kernel/Makefile                  |    1 
 kernel/kprobes.c                 |  124 +++++++++++++++++++++++++++++++------
 kernel/trace/trace_kprobe.c      |    4 +
 13 files changed, 325 insertions(+), 157 deletions(-)
 create mode 100644 arch/x86/kernel/rethook.c

--
Masami Hiramatsu (Linaro) <mhiramat@...nel.org>