From: Jiri Olsa <olsajiri@gmail.com>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: "jordalgo@meta.com" <jordalgo@meta.com>,
"ajor@meta.com" <ajor@meta.com>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@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>,
Stanislav Fomichev <sdf@google.com>, Hao Luo <haoluo@google.com>
Subject: Re: [PATCHv3 bpf-next 05/26] bpf: Add bpf_get_func_ip helper support for uprobe link
Date: Mon, 10 Jul 2023 09:24:26 +0200 [thread overview]
Message-ID: <ZKuyKj8jrEPzWYMM@krava> (raw)
In-Reply-To: <CAEf4BzZ=xLVkG5eurEuvLU79wAMtwho7ReR+XJAgwhFF4M-7Cg@mail.gmail.com>
On Thu, Jul 06, 2023 at 03:29:08PM -0700, Andrii Nakryiko wrote:
> On Fri, Jun 30, 2023 at 1:34 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Adding support for bpf_get_func_ip helper being called from
> > ebpf program attached by uprobe_multi link.
> >
> > It returns the ip of the uprobe.
> >
> > Acked-by: Andrii Nakryiko <andrii@kernel.org>
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > kernel/trace/bpf_trace.c | 33 ++++++++++++++++++++++++++++++---
> > 1 file changed, 30 insertions(+), 3 deletions(-)
> >
>
> A slight aside related to bpf_get_func_ip() support in
> uprobe/uretprobe. We just had a conversation with Alastair and Jordan
> (cc'ed) about bpftrace and using bpf_get_func_ip() there with
> uretprobes, and it seems like it doesn't work.
>
> Is that intentional or we just missed that bpf_get_func_ip() doesn't
> work with uprobes/uretprobes? Do you think it would be hard to add
> support for them for bpf_get_func_ip()? It's a very useful helper,
> would be nice to have it working in all cases where it has meaningful
> behavior (and I think it does for uprobe and uretprobe).
I'm not sure we discussed at the time we added this helper,
but I see same problem as we had with kprobes where we need
to know if the probe is on the start of the symbol
we use KPROBE_FLAG_ON_FUNC_ENTRY flag for that in kprobe's
get_func_ip helper version:
BPF_CALL_1(bpf_get_func_ip_kprobe, struct pt_regs *, regs)
{
struct kprobe *kp = kprobe_running();
if (!kp || !(kp->flags & KPROBE_FLAG_ON_FUNC_ENTRY))
return 0;
return get_entry_ip((uintptr_t)kp->addr);
}
I don't think we can have same flag for uprobe, we don't have
the binary symbol data as we have for kernel
I guess the app needs to store regs->ip and match it against symbol
addresses in user space
jirka
>
> Thanks!
>
> > diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> > index 4ef51fd0497f..f5a41c1604b8 100644
> > --- a/kernel/trace/bpf_trace.c
> > +++ b/kernel/trace/bpf_trace.c
> > @@ -88,6 +88,7 @@ static u64 bpf_kprobe_multi_cookie(struct bpf_run_ctx *ctx);
> > static u64 bpf_kprobe_multi_entry_ip(struct bpf_run_ctx *ctx);
> >
>
> [...]
next prev parent reply other threads:[~2023-07-10 7:24 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-30 8:33 [PATCHv3 bpf-next 00/26] bpf: Add multi uprobe link Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 01/26] bpf: Add attach_type checks under bpf_prog_attach_check_attach_type Jiri Olsa
2023-07-06 22:34 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 02/26] bpf: Add multi uprobe link Jiri Olsa
2023-07-06 22:34 ` Andrii Nakryiko
2023-07-11 9:00 ` Jiri Olsa
2023-07-07 4:22 ` Andrii Nakryiko
2023-07-11 9:01 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 03/26] bpf: Add cookies support for uprobe_multi link Jiri Olsa
2023-07-01 3:40 ` Yafang Shao
2023-07-01 8:54 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 04/26] bpf: Add pid filter " Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 05/26] bpf: Add bpf_get_func_ip helper support for uprobe link Jiri Olsa
2023-07-06 22:29 ` Andrii Nakryiko
2023-07-10 7:24 ` Jiri Olsa [this message]
2023-07-10 17:55 ` Andrii Nakryiko
2023-07-11 8:28 ` Jiri Olsa
2023-07-11 16:57 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 06/26] libbpf: Add uprobe_multi attach type and link names Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 07/26] libbpf: Move elf_find_func_offset* functions to elf object Jiri Olsa
2023-07-06 23:02 ` Andrii Nakryiko
2023-07-11 9:05 ` Jiri Olsa
2023-07-11 17:01 ` Andrii Nakryiko
2023-07-06 23:03 ` Andrii Nakryiko
2023-07-11 9:05 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 08/26] libbpf: Add elf_open/elf_close functions Jiri Olsa
2023-07-06 23:09 ` Andrii Nakryiko
2023-07-11 9:01 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 09/26] libbpf: Add elf symbol iterator Jiri Olsa
2023-07-06 23:24 ` Andrii Nakryiko
2023-07-11 9:03 ` Jiri Olsa
2023-07-11 16:59 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 10/26] libbpf: Add elf_resolve_syms_offsets function Jiri Olsa
2023-07-07 3:48 ` Andrii Nakryiko
2023-07-11 9:04 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 11/26] libbpf: Add elf_resolve_pattern_offsets function Jiri Olsa
2023-07-07 3:52 ` Andrii Nakryiko
2023-07-11 9:04 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 12/26] libbpf: Add bpf_link_create support for multi uprobes Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 13/26] libbpf: Add bpf_program__attach_uprobe_multi function Jiri Olsa
2023-07-07 4:05 ` Andrii Nakryiko
2023-07-11 9:05 ` Jiri Olsa
2023-07-11 17:02 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 14/26] libbpf: Add support for u[ret]probe.multi[.s] program sections Jiri Olsa
2023-07-07 4:07 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 15/26] libbpf: Add uprobe multi link detection Jiri Olsa
2023-07-07 4:20 ` Andrii Nakryiko
2023-07-11 9:03 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 16/26] libbpf: Add uprobe multi link support to bpf_program__attach_usdt Jiri Olsa
2023-07-07 4:29 ` Andrii Nakryiko
2023-07-11 9:04 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 17/26] selftests/bpf: Add uprobe_multi skel test Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 18/26] selftests/bpf: Add uprobe_multi api test Jiri Olsa
2023-07-07 4:32 ` Andrii Nakryiko
2023-07-11 9:06 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 19/26] selftests/bpf: Add uprobe_multi link test Jiri Olsa
2023-07-07 4:33 ` Andrii Nakryiko
2023-07-11 9:06 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 20/26] selftests/bpf: Add uprobe_multi test program Jiri Olsa
2023-07-07 4:35 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 21/26] selftests/bpf: Add uprobe_multi bench test Jiri Olsa
2023-07-07 4:38 ` Andrii Nakryiko
2023-07-11 9:07 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 22/26] selftests/bpf: Add usdt_multi test program Jiri Olsa
2023-07-07 4:39 ` Andrii Nakryiko
2023-06-30 8:33 ` [PATCHv3 bpf-next 23/26] selftests/bpf: Add usdt_multi bench test Jiri Olsa
2023-07-07 4:42 ` Andrii Nakryiko
2023-07-11 9:07 ` Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 24/26] selftests/bpf: Add uprobe_multi cookie test Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 25/26] selftests/bpf: Add uprobe_multi pid filter tests Jiri Olsa
2023-06-30 8:33 ` [PATCHv3 bpf-next 26/26] selftests/bpf: Add extra link to uprobe_multi tests Jiri Olsa
2023-07-05 12:45 ` [PATCHv3 bpf-next 00/26] bpf: Add multi uprobe link Daniel Borkmann
2023-07-05 19:10 ` Jiri Olsa
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