netdev - [RFC bpf-next 0/5] bpf, x86: Add bpf_get_func

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Date:   Tue, 29 Jun 2021 21:29:40 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Andrii Nakryiko <andriin@...com>
Cc:     netdev@...r.kernel.org, bpf@...r.kernel.org,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: [RFC bpf-next 0/5] bpf, x86: Add bpf_get_func_ip helper

hi,
adding bpf_get_func_ip helper that returns IP address of the
caller function for trampoline and krobe programs.

There're 2 specific implementation of the bpf_get_func_ip
helper, one for trampoline progs and one for kprobe/kretprobe
progs.

The trampoline helper call is replaced/inlined by verifier
with simple move instruction. The kprobe/kretprobe is actual
helper call that returns prepared caller address.

The trampoline extra 3 instructions for storing IP address
is now optional, which I'm not completely sure is necessary,
so I plan to do some benchmarks, if it's noticeable, hence
the RFC. I'm also not completely sure about the kprobe/kretprobe
implementation.

Also available at:
  https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
  bpf/get_func_ip

thanks,
jirka


---
Jiri Olsa (5):
      bpf, x86: Store caller's ip in trampoline stack
      bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip
      bpf: Add bpf_get_func_ip helper for tracing programs
      bpf: Add bpf_get_func_ip helper for kprobe programs
      selftests/bpf: Add test for bpf_get_func_ip helper

 arch/x86/net/bpf_jit_comp.c                               | 19 +++++++++++++++++++
 include/linux/bpf.h                                       |  5 +++++
 include/linux/filter.h                                    |  3 ++-
 include/uapi/linux/bpf.h                                  |  7 +++++++
 kernel/bpf/trampoline.c                                   | 12 +++++++++---
 kernel/bpf/verifier.c                                     | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 kernel/trace/bpf_trace.c                                  | 29 +++++++++++++++++++++++++++++
 kernel/trace/trace_kprobe.c                               | 20 ++++++++++++++++++--
 kernel/trace/trace_probe.h                                |  5 +++++
 tools/include/uapi/linux/bpf.h                            |  7 +++++++
 tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 tools/testing/selftests/bpf/progs/get_func_ip_test.c      | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 12 files changed, 260 insertions(+), 6 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c
 create mode 100644 tools/testing/selftests/bpf/progs/get_func_ip_test.c