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Diffstat (limited to 'Documentation/trace/fprobe.rst')
| -rw-r--r-- | Documentation/trace/fprobe.rst | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/Documentation/trace/fprobe.rst b/Documentation/trace/fprobe.rst index b64bec1ce144..196f52386aaa 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, unsigned long ret_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, 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. @fp This is the address of `fprobe` data structure related to this handler. @@ -106,12 +108,22 @@ saved at function entry and passed to exit handler. 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 in the entry_handler. If you need traced instruction pointer, you need to use @entry_ip. On the other hand, in the exit_handler, the instruction - pointer of @regs is set to the currect return address. + pointer of @regs is set to the current 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 ================================ |