Commit 8be098a9 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google) Committed by Steven Rostedt (Google)
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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: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 87de2163

Documentation/trace/fprobe.rst

+12 −4
Original line number Diff line number Diff line
@@ -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

================================