hi,
this patchset is adding support for session uprobe attachment and
using it through bpf link for bpf programs.

The session means that the uprobe consumer is executed on entry
and return of probed function with additional control:
  - entry callback can control execution of the return callback
  - entry and return callbacks can share data/cookie

On more details please see patch #2.

The patchset is based on Peter's perf/core [1] tree merged in bpf-next/master.

There's an proposal from Andrii how to get this merged in [2]:

> I think uprobe parts should stay in tip/perf/core (if that's where all
> uprobe code goes in), as we have a bunch of ongoing work that all will
> conflict a bit with each other, if it lands across multiple trees.
> 
> So that means that patches #1 and #2 ideally land in tip/perf/core.
> But you have a lot of BPF-specific things that would be inconvenient
> to route through tip, so I'd say those should go through bpf-next.
> 
> What we can do, if Ingo and Peter are OK with that, is to create a
> stable (non-rebaseable) branch off of your first two patches (applied
> in tip/perf/core), which we'll merge into bpf-next/master and land the
> rest of your patch set there. We've done that with recent struct fd
> changes, and there were few other similar cases in the past, and that
> all worked well.
> 
> Peter, Ingo, are you guys OK with that approach?


v6 changes:
  - added acks [Andrii, Oleg]
  - added missing Fixes tags
  - added fix to force uprobe bpf program to always return 0 [Andrii]
  - separated kprobe session verifier check for return value check
    and squashed similar uprobe session fix in patch 5 [Andrii]
  - move session return handler check for cookie data to handle_uretprobe_chain [Andrii]
  - added threads the session test to speed it up
  - several smaller fixes [Andrii]

thanks,
jirka


[1] git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git perf/core
[2] https://lore.kernel.org/bpf/CAEf4BzY8tGCstcD4BVBLPd0V92p--b_vUmQyWydObRJHZPgCLA@mail.gmail.com/
---
Jiri Olsa (16):
      uprobe: Add data pointer to consumer handlers
      uprobe: Add support for session consumer
      bpf: Allow return values 0 and 1 for kprobe session
      bpf: Force uprobe bpf program to always return 0
      bpf: Add support for uprobe multi session attach
      bpf: Add support for uprobe multi session context
      libbpf: Add support for uprobe multi session attach
      selftests/bpf: Add uprobe session test
      selftests/bpf: Add uprobe session cookie test
      selftests/bpf: Add uprobe session recursive test
      selftests/bpf: Add uprobe session verifier test for return value
      selftests/bpf: Add kprobe session verifier test for return value
      selftests/bpf: Add uprobe session single consumer test
      selftests/bpf: Scale down uprobe multi consumer test
      selftests/bpf: Add uprobe sessions to consumer test
      selftests/bpf: Add threads to consumer test

 include/linux/uprobes.h                                            |  25 ++++++-
 include/uapi/linux/bpf.h                                           |   1 +
 kernel/bpf/syscall.c                                               |   9 ++-
 kernel/bpf/verifier.c                                              |  10 +++
 kernel/events/uprobes.c                                            | 148 +++++++++++++++++++++++++++++--------
 kernel/trace/bpf_trace.c                                           |  63 +++++++++++-----
 kernel/trace/trace_uprobe.c                                        |  12 ++-
 tools/include/uapi/linux/bpf.h                                     |   1 +
 tools/lib/bpf/bpf.c                                                |   1 +
 tools/lib/bpf/libbpf.c                                             |  19 ++++-
 tools/lib/bpf/libbpf.h                                             |   4 +-
 tools/testing/selftests/bpf/bpf_testmod/bpf_testmod.c              |   2 +-
 tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c         |   2 +
 tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c         | 336 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----------
 tools/testing/selftests/bpf/progs/kprobe_multi_verifier.c          |  31 ++++++++
 tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c         |   6 +-
 tools/testing/selftests/bpf/progs/uprobe_multi_session.c           |  71 ++++++++++++++++++
 tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c    |  48 ++++++++++++
 tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c |  44 +++++++++++
 tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c    |  44 +++++++++++
 tools/testing/selftests/bpf/progs/uprobe_multi_verifier.c          |  31 ++++++++
 21 files changed, 808 insertions(+), 100 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/progs/kprobe_multi_verifier.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session_cookie.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session_recursive.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_session_single.c
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_verifier.c