[RFC,tracing,0/4] tracing: support > 8 byte filter predicates

Message

Alan Maguire Aug. 7, 2022, 10:21 p.m. UTC

For cases like IPv6 addresses, having a means to supply tracing
predicates for fields with more than 8 bytes would be convenient.
This series provides a simple way to support this by allowing
simple ==, != memory comparison with the predicate supplied when
the size of the field exceeds 8 bytes.  For example, to trace
::1, the predicate

	"dst == 0x00000000000000000000000000000001"

..could be used.

When investigating this initially, I stumbled upon a kernel
crash when specifying a predicate for a non-string field that is
not 1, 2, 4, or 8 bytes in size. Patch 1 fixes it.  Patch 2
provides the support for > 8 byte fields via a memcmp()-style
predicate.  Patch 3 adds tests for filter predicates, and patch 4
documents the fact that for > 8 bytes. only == and != are
supported.

Alan Maguire (2):
  tracing: predicate matching trigger crashes for > 8-byte arrays
  tracing: support > 8 byte array filter predicates

Oracle Public Cloud User (2):
  selftests/ftrace: add test coverage for filter predicates
  tracing: document > 8 byte numeric filtering support

 Documentation/trace/events.rst                |  9 +++
 kernel/trace/trace_events_filter.c            | 59 +++++++++++++++++-
 .../selftests/ftrace/test.d/event/filter.tc   | 62 +++++++++++++++++++
 3 files changed, 129 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/event/filter.tc