[PATCH] Documentation: ftrace-uses: Change pt_regs to ftrace_regs

From: Marcos Paulo de Souza
Date: Sat Jul 27 2024 - 18:46:24 EST


Since commit d19ad0775dcd ("ftrace: Have the callbacks receive a struct
ftrace_regs instead of pt_regs") the callback function receives a
ftrace_regs argument, and not a pt_regs anymore. Change the
documentation to reflect the reality.

Signed-off-by: Marcos Paulo de Souza <mpdesouza@xxxxxxxx>
---
Documentation/trace/ftrace-uses.rst | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/Documentation/trace/ftrace-uses.rst b/Documentation/trace/ftrace-uses.rst
index e198854ace79..05620714d99f 100644
--- a/Documentation/trace/ftrace-uses.rst
+++ b/Documentation/trace/ftrace-uses.rst
@@ -87,7 +87,7 @@ The prototype of the callback function is as follows (as of v4.14):
.. code-block:: c

void callback_func(unsigned long ip, unsigned long parent_ip,
- struct ftrace_ops *op, struct pt_regs *regs);
+ struct ftrace_ops *op, struct ftrace_regs *regs);

@ip
This is the instruction pointer of the function that is being traced.
@@ -104,7 +104,7 @@ The prototype of the callback function is as follows (as of v4.14):
@regs
If the FTRACE_OPS_FL_SAVE_REGS or FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED
flags are set in the ftrace_ops structure, then this will be pointing
- to the pt_regs structure like it would be if an breakpoint was placed
+ to the ftrace_regs structure like it would be if an breakpoint was placed
at the start of the function where ftrace was tracing. Otherwise it
either contains garbage, or NULL.

@@ -169,10 +169,10 @@ Some of the flags are used for internal infrastructure of ftrace, but the
ones that users should be aware of are the following:

FTRACE_OPS_FL_SAVE_REGS
- If the callback requires reading or modifying the pt_regs
+ If the callback requires reading or modifying the ftrace_regs
passed to the callback, then it must set this flag. Registering
a ftrace_ops with this flag set on an architecture that does not
- support passing of pt_regs to the callback will fail.
+ support passing of ftrace_regs to the callback will fail.

FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED
Similar to SAVE_REGS but the registering of a
@@ -199,7 +199,7 @@ FTRACE_OPS_FL_IPMODIFY
Requires FTRACE_OPS_FL_SAVE_REGS set. If the callback is to "hijack"
the traced function (have another function called instead of the
traced function), it requires setting this flag. This is what live
- kernel patches uses. Without this flag the pt_regs->ip can not be
+ kernel patches uses. Without this flag the ftrace_regs->ip can not be
modified.

Note, only one ftrace_ops with FTRACE_OPS_FL_IPMODIFY set may be

---
base-commit: 256abd8e550ce977b728be79a74e1729438b4948
change-id: 20240727-ftrace-docs-cb-args-963ef5676a81

Best regards,
--
Marcos Paulo de Souza <mpdesouza@xxxxxxxx>