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authorMasami Hiramatsu (Google) <mhiramat@kernel.org>2023-02-02 00:56:55 +0900
committerSteven Rostedt (Google) <rostedt@goodmis.org>2023-03-28 18:52:23 -0400
commit8be098a9eb2710bc5381ba1ebaac660f8d9b6963 (patch)
tree2a27f813fdb345025883310591b9ceb09f525782 /Documentation/trace
parent87de2163a36b3ffb0d2e0df8e903dc7e30566548 (diff)
docs: tracing: Update fprobe documentation
Update fprobe.rst for - the private entry_data argument - the return value of the entry handler - the nr_rethook_node field. Link: https://lkml.kernel.org/r/167526701579.433354.3057889264263546659.stgit@mhiramat.roam.corp.google.com Cc: Florent Revest <revest@chromium.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Diffstat (limited to 'Documentation/trace')
-rw-r--r--Documentation/trace/fprobe.rst16
1 files changed, 12 insertions, 4 deletions
diff --git a/Documentation/trace/fprobe.rst b/Documentation/trace/fprobe.rst
index b64bec1ce144..40dd2fbce861 100644
--- a/Documentation/trace/fprobe.rst
+++ b/Documentation/trace/fprobe.rst
@@ -87,14 +87,16 @@ returns as same as unregister_ftrace_function().
The fprobe entry/exit handler
=============================
-The prototype of the entry/exit callback function is as follows:
+The prototype of the entry/exit callback function are as follows:
.. code-block:: c
- void callback_func(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs);
+ int entry_callback(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs, void *entry_data);
-Note that both entry and exit callbacks have same ptototype. The @entry_ip is
-saved at function entry and passed to exit handler.
+ void exit_callback(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs, void *entry_data);
+
+Note that the @entry_ip is saved at function entry and passed to exit handler.
+If the entry callback function returns !0, the corresponding exit callback will be cancelled.
@fp
This is the address of `fprobe` data structure related to this handler.
@@ -113,6 +115,12 @@ saved at function entry and passed to exit handler.
to use @entry_ip. On the other hand, in the exit_handler, the instruction
pointer of @regs is set to the currect return address.
+@entry_data
+ This is a local storage to share the data between entry and exit handlers.
+ This storage is NULL by default. If the user specify `exit_handler` field
+ and `entry_data_size` field when registering the fprobe, the storage is
+ allocated and passed to both `entry_handler` and `exit_handler`.
+
Share the callbacks with kprobes
================================