[Bug bpf/27152] New: Missing tracepoints for for stap --bpf -L 'kernel.trace("*")'

[Bug bpf/27152] New: Missing tracepoints for for stap --bpf -L 'kernel.trace("*")'

[wcohen at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27152

            Bug ID: 27152
           Summary: Missing tracepoints for for stap --bpf -L
                    'kernel.trace("*")'
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: bpf
          Assignee: systemtap at sourceware dot org
          Reporter: wcohen at redhat dot com
  Target Milestone: ---

The expectation is that both the traditional kernel module backend and bpf back
would report the same set of trace points however the following returns no
tracepoints:

 $ ../install/bin/stap --bpf -l 'kernel.trace("*")' |wc
      0       0       0

Include the --compatible=4.1 option and there are many tracepoints reported

$ ../install/bin/stap --compatible=4.1  --bpf -l 'kernel.trace("*")' |wc
   2235   16451  260254

The number of tracepoints reported is not quite as many as the traditional stap
kernel module backend:

$ ../install/bin/stap  -l 'kernel.trace("*")' |wc
   2365   14367  232387

This was observed with locally built systemtap commit
6cb54128e005d1220a7b064ee42b9f72561c28e7 using a Fedora 32
5.9.16-100.fc32.x86_64 kernel.

Looks like the search in collect_raw_tracepoint() from commit
fcdd71babea2435601e5e7f8b6b5faae4a663443 is not finding the various raw
tracepoints.

-- 
You are receiving this mail because:
You are the assignee for the bug.

[Bug bpf/27152] Missing tracepoints for for stap --bpf -L 'kernel.trace("*")'

[wcohen at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27152

--- Comment #1 from William Cohen <wcohen at redhat dot com> ---
Using Serhei's bunsen information found that there was a record of the bpf
tracepoints working with 5.0.0-0.rc6.git1.1.fc30.x86_64 kernel.  Did some
psuedo kernel bisections using the Fedora kernel rpms and found:

kernel-5.7.0-1.fc33.x86_64 bad
kernel-5.6.19-300.fc32.x86_64 good

-- 
You are receiving this mail because:
You are the assignee for the bug.

[Bug bpf/27152] Missing tracepoints for for stap --bpf -L 'kernel.trace("*")'

[wcohen at redhat dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=27152

William Cohen <wcohen at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED

--- Comment #2 from William Cohen <wcohen at redhat dot com> ---
Adjusted the test for BPF raw tracepoint support to accept the new function
name in the following kernel patch in linux 5.7:

commit 70ed506c3bbcfa846d4636b23051ca79fa4781f7
Author: Andrii Nakryiko <andriin@fb.com>  2020-03-02 23:31:57
Committer: Alexei Starovoitov <ast@kernel.org>  2020-03-03 01:06:27
Parent: 775a2be52da1c55fc810a5d151049f86f0fd5362 (selftests/bpf: Declare
bpf_log_buf variables as static)
Child:  c016b68edc7a2adf3db0f11fb649797c1f9216ea (libbpf: Add bpf_link
pinning/unpinning)
Branches: master, remotes/origin/master
Follows: v5.6-rc3
Precedes: v5.7-rc1

    bpf: Introduce pinnable bpf_link abstraction

    Introduce bpf_link abstraction, representing an attachment of BPF program
to
    a BPF hook point (e.g., tracepoint, perf event, etc). bpf_link encapsulates
    ownership of attached BPF program, reference counting of a link itself,
when
    reference from multiple anonymous inodes, as well as ensures that release
    callback will be called from a process context, so that users can safely
take
    mutex locks and sleep.

    Additionally, with a new abstraction it's now possible to generalize
pinning
    of a link object in BPF FS, allowing to explicitly prevent BPF program
    detachment on process exit by pinning it in a BPF FS and let it open from
    independent other process to keep working with it.

    Convert two existing bpf_link-like objects (raw tracepoint and tracing BPF
    program attachments) into utilizing bpf_link framework, making them
pinnable
    in BPF FS. More FD-based bpf_links will be added in follow up patches.

    Signed-off-by: Andrii Nakryiko <andriin@fb.com>
    Signed-off-by: Alexei Starovoitov <ast@kernel.org>
    Link: https://lore.kernel.org/bpf/20200303043159.323675-2-andriin@fb.com

-- 
You are receiving this mail because:
You are the assignee for the bug.