From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> Add a notes about the entry argument access at function exit probes for kprobes and fprobe trace event. Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> --- Documentation/trace/fprobetrace.rst | 7 +++++++ Documentation/trace/kprobetrace.rst | 7 +++++++ 2 files changed, 14 insertions(+) diff --git a/Documentation/trace/fprobetrace.rst b/Documentation/trace/fprobetrace.rst index e35e6b18df40..ab71ebf178cb 100644 --- a/Documentation/trace/fprobetrace.rst +++ b/Documentation/trace/fprobetrace.rst @@ -70,6 +70,13 @@ Synopsis of fprobe-events For the details of TYPE, see :ref:`kprobetrace documentation <kprobetrace_types>`. +Function arguments at exit +-------------------------- +Function arguments can be accessed at exit probe 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) + BTF arguments ------------- BTF (BPF Type Format) argument allows user to trace function and tracepoint diff --git a/Documentation/trace/kprobetrace.rst b/Documentation/trace/kprobetrace.rst index bf9cecb69fc9..35a383f95746 100644 --- a/Documentation/trace/kprobetrace.rst +++ b/Documentation/trace/kprobetrace.rst @@ -70,6 +70,13 @@ 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) + .. _kprobetrace_types: Types
