From 2a86ac30a6687e47436e547deadae3bf0fc28697 Mon Sep 17 00:00:00 2001
From: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Date: Sun, 24 Sep 2023 22:36:11 +0900
Subject: [PATCH] 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: cb16330d1274 ("fprobe: Pass return address to the handlers")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Florent Revest <revest@chromium.org>
---
Documentation/trace/fprobe.rst | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/Documentation/trace/fprobe.rst b/Documentation/trace/fprobe.rst
index 7a895514b5379..196f52386aaa8 100644
--- a/Documentation/trace/fprobe.rst
+++ b/Documentation/trace/fprobe.rst
@@ -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
--
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