[PATCH tracing 0/3] tracing: support > 8 byte filter predicates

From: Alan Maguire
Date: Tue Apr 25 2023 - 05:16:54 EST


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.

Patch 1 provides the support for > 8 byte fields via a memcmp()-style
predicate. Patch 2 adds tests for filter predicates, and patch 3
documents the fact that for > 8 bytes. only == and != are supported.

Changes since RFC [1]:

- originally a fix was intermixed with the new functionality as
patch 1 in series [1]; the fix landed separately
- small tweaks to how filter predicates are defined via fn_num as
opposed to via fn directly

[1] https://lore.kernel.org/lkml/1659910883-18223-1-git-send-email-alan.maguire@xxxxxxxxxx/

Alan Maguire (3):
tracing: support > 8 byte array filter predicates
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 | 55 +++++++++++++++-
.../selftests/ftrace/test.d/event/filter.tc | 62 +++++++++++++++++++
3 files changed, 125 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/ftrace/test.d/event/filter.tc

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2.31.1