Commit 2a86ac30 authored by Masami Hiramatsu (Google)'s avatar Masami Hiramatsu (Google)
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Documentation: probes: Add a new ret_ip callback parameter 

Add a new ret_ip callback parameter description.

Link: https://lore.kernel.org/all/169556257133.146934.13560704846459957726.stgit@devnote2/



Fixes: cb16330d ("fprobe: Pass return address to the handlers")
Signed-off-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: default avatarFlorent Revest <revest@chromium.org>
parent 58720809

Documentation/trace/fprobe.rst

+6 −2
Original line number Diff line number Diff line
@@ -91,9 +91,9 @@ The prototype of the entry/exit callback function are as follows: 


.. code-block:: c



 int entry_callback(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs, void *entry_data);

 int entry_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_ip, struct pt_regs *regs, void *entry_data);



 void exit_callback(struct fprobe *fp, unsigned long entry_ip, struct pt_regs *regs, void *entry_data);

 void exit_callback(struct fprobe *fp, unsigned long entry_ip, unsigned long ret_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.
@@ -108,6 +108,10 @@ If the entry callback function returns !0, the corresponding exit callback will 
        Note that this may not be the actual entry address of the function but

        the address where the ftrace is instrumented.



@ret_ip

        This is the return address that the traced function will return to,

        somewhere in the caller. This can be used at both entry and exit.



@regs

        This is the `pt_regs` data structure at the entry and exit. Note that

        the instruction pointer of @regs may be different from the @entry_ip