Re: [PATCH v3 1/5] docs: tracing: fprobe: document list filters and :entry/:exit

On Sun, 5 Oct 2025 08:46:55 +0900 Ryan Chung seokwoo.chung130@gmail.com wrote:

Signed-off-by: Ryan Chung seokwoo.chung130@gmail.com

Documentation/trace/fprobetrace.rst | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/Documentation/trace/fprobetrace.rst b/Documentation/trace/fprobetrace.rst index b4c2ca3d02c1..629e2d7402bd 100644 --- a/Documentation/trace/fprobetrace.rst +++ b/Documentation/trace/fprobetrace.rst @@ -25,21 +25,36 @@ Synopsis of fprobe-events

---

::

• f[:[GRP1/][EVENT1]] SYM [FETCHARGS] : Probe on function entry
• f[MAXACTIVE][:[GRP1/][EVENT1]] SYM%return [FETCHARGS] : Probe on function exit
• t[:[GRP2/][EVENT2]] TRACEPOINT [FETCHARGS] : Probe on tracepoint

• # fprobe (function entry/exit)
• f[:[GRP1/][EVENT1]] SYM_OR_LIST[:entry|:exit] [FETCHARGS]
• # legacy single-symbol exit
• f[MAXACTIVE][:[GRP1/][EVENT1]] SYM%return [FETCHARGS]
• # Probe on tracepoint
• t[:[GRP2/][EVENT2]] TRACEPOINT [FETCHARGS]

GRP1 : Group name for fprobe. If omitted, use "fprobes" for it. GRP2 : Group name for tprobe. If omitted, use "tracepoints" for it.

• EVENT1 : Event name for fprobe. If omitted, the event name is

•              "SYM__entry" or "SYM__exit".
  

• EVENT1 : Event name for fprobe. If omitted,

•              - For a single literal symbol, the event name is
  

•                "SYM__entry" or "SYM__exit".
  

•              - For a *list or any wildcard*, an explicit [GRP1/][EVENT1]
  

•                is required; otherwise the parser rejects it.
  

  EVENT2 : Event name for tprobe. If omitted, the event name is the same as "TRACEPOINT", but if the "TRACEPOINT" starts with a digit character, "_TRACEPOINT" is used. MAXACTIVE : Maximum number of instances of the specified function that can be probed simultaneously, or 0 for the default value as defined in Documentation/trace/fprobe.rst

• SYM_OR_LIST : Either a single symbol, or a comma-separated list of

•              include/exclude patterns:
  

•              - Tokens are matched as symbols; wildcards may be used.
  

•              - Tokens prefixed with '!' are exclusions.
  

•              - Examples:
  

•                    foo             # single literal (entry)
  

•                    foo:exit        # single literal exit
  

•                    foo%return      # legacy single-symbol exit
  

So you can explain it in syntax formats:

Single function (including wildcard):

f[:[GRP1/][EVENT1]] SYM[%return] [FETCHARGS]

Multiple functions:

f[:[GRP1/]EVENT3 SYM[,[!]SYM[,...]][:entry|:exit] [FETCHARGS]

Where, - SYM prefixed with '!' are exclusions. - ":entry" suffix means it probes entry of given symbols. (default) - ":exit" suffix means it probes exit of given symbols. - "%return" suffix means it probes exit of SYM (single symbol).

Thank you,

FETCHARGS : Arguments. Each probe can have up to 128 args. ARG : Fetch "ARG" function argument using BTF (only for function entry or tracepoint.) (*1) -- 2.43.0