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

Alexander Shishkin
2015-08-24T14:33:18Z

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(-)

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2.5.0