[PATCH v2 0/6] perf: Introduce extended syscall error reporting

[Alexander Shishkin]

Hi Peter and Ingo and everybody,

Here's an update of my extended error reporting patchset, addressing
review comments and adding a few more error messages to PT and BTS
drivers.

Changes since v1:
  * addressed Peter's comments,
  * added perf_err() annotation to intel_pt and intel_bts drivers;
  especially the former is rich in EINVALs in event validation path,
  so it should be immediately useful;
  * changed the error code to EINVAL for the case when perf_err() is
  supplied a non-constart error code;
  * dropped RFC, added sign-offs.

This time around, I employed a linker trick to convert the structures
containing extended error information into integers, which are then
made to look just like normal error codes so that IS_ERR_VALUE() and
friends would still work correctly on them. So no extra pointers in
the struct perf_event or anywhere else; the extended error codes are
passed around like normal error codes. They only need to be converted
in syscalls' topmost return statements. This is done in 1/6.

Then, 2/6 illustrates how error sites can be extended to include more
information such as file names and line numbers [1]. Side note, it can
be dropped without impact on other patches.

The other patches add perf_err() annotation to a few semi-randomly
picked places in perf core (3/6), x86 bits (4/6), intel_pt (5/6) and
intel_bts (6/6).

[1] http://marc.info/?l=linux-kernel&m=141471816115946

Alexander Shishkin (6):
  perf: Introduce extended syscall error reporting
  perf: Add file name and line number to perf extended error reports
  perf: Annotate some of the error codes with perf_err()
  perf/x86: Annotate some of the error codes with perf_err()
  perf/x86/intel/pt: Use extended error reporting in event
    initialization
  perf/x86/intel/bts: Use extended error reporting in event
    initialization

 arch/x86/kernel/cpu/perf_event.c           |   8 +-
 arch/x86/kernel/cpu/perf_event_intel_bts.c |   4 +-
 arch/x86/kernel/cpu/perf_event_intel_lbr.c |   2 +-
 arch/x86/kernel/cpu/perf_event_intel_pt.c  |  29 +++++---
 include/linux/perf_event.h                 |  82 +++++++++++++++++++++
 include/uapi/linux/perf_event.h            |   8 +-
 kernel/events/core.c                       | 113 +++++++++++++++++++++++++----
 7 files changed, 215 insertions(+), 31 deletions(-)

-- 
2.5.0

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