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| author | Masami Hiramatsu (Google) <mhiramat@kernel.org> | 2023-02-01 16:56:55 +0100 |
|---|---|---|
| committer | Steven Rostedt (Google) <rostedt@goodmis.org> | 2023-03-29 00:52:23 +0200 |
| commit | 8be098a9eb2710bc5381ba1ebaac660f8d9b6963 (patch) | |
| tree | 2a27f813fdb345025883310591b9ceb09f525782 /Documentation/trace | |
| parent | lib/test_fprobe: Add a testcase for skipping exit_handler (diff) | |
| download | linux-8be098a9eb2710bc5381ba1ebaac660f8d9b6963.tar.xz linux-8be098a9eb2710bc5381ba1ebaac660f8d9b6963.zip | |
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.rst | 16 |
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 ================================ |