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| author | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2024-03-04 12:41:15 +0900 |
|---|---|---|
| committer | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2024-03-07 00:27:53 +0900 |
| commit | e8c32f24766a1f22da024e73d1eb8e9c822482ac (patch) | |
| tree | b0d6af06bc60908c19e59510c9f1c351aad7e85a /Documentation/trace/kprobetrace.rst | |
| parent | f6e2253a617c4030b807a18383101b59d6f0f536 (diff) | |
| download | linux-e8c32f24766a1f22da024e73d1eb8e9c822482ac.tar.gz linux-e8c32f24766a1f22da024e73d1eb8e9c822482ac.tar.bz2 linux-e8c32f24766a1f22da024e73d1eb8e9c822482ac.zip | |
Documentation: tracing: Add entry argument access at function exit
Add a notes about the entry argument access at function exit probes for
kprobes and fprobe trace event.
Link: https://lore.kernel.org/all/170952367549.229804.8843506960483577062.stgit@devnote2/
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Diffstat (limited to 'Documentation/trace/kprobetrace.rst')
| -rw-r--r-- | Documentation/trace/kprobetrace.rst | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index bf9cecb69fc9..a49662ccd53c 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -70,6 +70,15 @@ Synopsis of kprobe_events (\*3) this is useful for fetching a field of data structures. (\*4) "u" means user-space dereference. See :ref:`user_mem_access`. +Function arguments at kretprobe +------------------------------- +Function arguments can be accessed at kretprobe using $arg<N> fetcharg. This +is useful to record the function parameter and return value at once, and +trace the difference of structure fields (for debuging a function whether it +correctly updates the given data structure or not). +See the :ref:`sample<fprobetrace_exit_args_sample>` in fprobe event for how +it works. + .. _kprobetrace_types: Types |