netdev - Re: [PATCHv2 bpf-next 0/7] bpf, x86: Add bpf_get_func

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Date:   Wed, 7 Jul 2021 21:49:57 +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>,
        Alan Maguire <alan.maguire@...cle.com>,
        Masami Hiramatsu <mhiramat@...nel.org>
Subject: Re: [PATCHv2 bpf-next 0/7] bpf, x86: Add bpf_get_func_ip helper

ugh forgot to cc Masami.. sorry, I can resend if needed

jirka

On Wed, Jul 07, 2021 at 09:46:12PM +0200, Jiri Olsa wrote:
> 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.
> 
> Also available at:
>   https://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
>   bpf/get_func_ip
> 
> v2 changes:
>   - use kprobe_running to get kprobe instead of cpu var [Masami]
>   - added support to add kprobe on function+offset
>     and test for that [Alan]
> 
> thanks,
> jirka
> 
> 
> ---
> Alan Maguire (1):
>       libbpf: allow specification of "kprobe/function+offset"
> 
> Jiri Olsa (6):
>       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
>       selftests/bpf: Add test for bpf_get_func_ip in kprobe+offset probe
> 
>  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                                  | 32 ++++++++++++++++++++++++++++++++
>  tools/include/uapi/linux/bpf.h                            |  7 +++++++
>  tools/lib/bpf/libbpf.c                                    | 20 +++++++++++++++++---
>  tools/testing/selftests/bpf/prog_tests/get_func_ip_test.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  tools/testing/selftests/bpf/progs/get_func_ip_test.c      | 75 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  11 files changed, 270 insertions(+), 7 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