From: Jiri Olsa <jolsa@redhat•com>
To: Alan Maguire <alan.maguire@oracle•com>
Cc: Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <daniel@iogearbox•net>,
Andrii Nakryiko <andriin@fb•com>,
netdev@vger•kernel.org, bpf@vger•kernel.org,
Martin KaFai Lau <kafai@fb•com>, Song Liu <songliubraving@fb•com>,
Yonghong Song <yhs@fb•com>,
John Fastabend <john.fastabend@gmail•com>,
KP Singh <kpsingh@chromium•org>,
Masami Hiramatsu <mhiramat@kernel•org>
Subject: Re: [RFC bpf-next 0/5] bpf, x86: Add bpf_get_func_ip helper
Date: Fri, 2 Jul 2021 10:16:48 +0200 [thread overview]
Message-ID: <YN7LcJu73nCz3Ips@krava> (raw)
In-Reply-To: <alpine.LRH.2.23.451.2107011819160.27594@localhost>
On Thu, Jul 01, 2021 at 06:22:45PM +0100, Alan Maguire wrote:
> On Tue, 29 Jun 2021, 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.
> >
> > 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
> >
> >
>
> This is great Jiri! Feel free to add for the series:
>
> Tested-by: Alan Maguire <alan.maguire@oracle•com>
great, thanks for testing
>
> BTW I also verified that if we extend bpf_program__attach_kprobe() to
> support the function+offset format in the func_name argument for kprobes,
> the following test will pass too:
>
> __u64 test5_result = 0;
> SEC("kprobe/bpf_fentry_test5+0x6")
> int test5(struct pt_regs *ctx)
> {
> __u64 addr = bpf_get_func_ip(ctx);
>
> test5_result = (const void *) addr == (&bpf_fentry_test5 + 0x6);
> return 0;
> }
right, I did not think of this test, I'll add it
thanks,
jirka
prev parent reply other threads:[~2021-07-02 8:17 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-29 19:29 [RFC bpf-next 0/5] bpf, x86: Add bpf_get_func_ip helper Jiri Olsa
2021-06-29 19:29 ` [PATCH bpf-next 1/5] bpf, x86: Store caller's ip in trampoline stack Jiri Olsa
2021-06-29 19:29 ` [PATCH bpf-next 2/5] bpf: Enable BPF_TRAMP_F_IP_ARG for trampolines with call_get_func_ip Jiri Olsa
2021-06-29 19:29 ` [PATCH bpf-next 3/5] bpf: Add bpf_get_func_ip helper for tracing programs Jiri Olsa
2021-06-29 19:29 ` [PATCH bpf-next 4/5] bpf: Add bpf_get_func_ip helper for kprobe programs Jiri Olsa
2021-06-30 17:47 ` Yonghong Song
2021-06-30 23:58 ` Masami Hiramatsu
2021-07-01 1:45 ` Yonghong Song
2021-07-01 2:01 ` Masami Hiramatsu
2021-07-01 8:38 ` Jiri Olsa
2021-07-01 13:10 ` Masami Hiramatsu
2021-07-01 8:34 ` Jiri Olsa
2021-06-29 19:29 ` [PATCH bpf-next 5/5] selftests/bpf: Add test for bpf_get_func_ip helper Jiri Olsa
2021-07-01 17:22 ` [RFC bpf-next 0/5] bpf, x86: Add " Alan Maguire
2021-07-02 8:16 ` Jiri Olsa [this message]
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