ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs

In preparation to have arguments of a function passed to callbacks attached
to functions as default, change the default callback prototype to receive a
struct ftrace_regs as the forth parameter instead of a pt_regs.

For callbacks that set the FL_SAVE_REGS flag in their ftrace_ops flags, they
will now need to get the pt_regs via a ftrace_get_regs() helper call. If
this is called by a callback that their ftrace_ops did not have a
FL_SAVE_REGS flag set, it that helper function will return NULL.

This will allow the ftrace_regs to hold enough just to get the parameters
and stack pointer, but without the worry that callbacks may have a pt_regs
that is not completely filled.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
index 875c5dbbdd33..f89f9e7e9b07 100644
--- a/kernel/livepatch/patch.c
+++ b/kernel/livepatch/patch.c
@@ -40,8 +40,9 @@ struct klp_ops *klp_find_ops(void *old_func)
 static void notrace klp_ftrace_handler(unsigned long ip,
 				       unsigned long parent_ip,
 				       struct ftrace_ops *fops,
-				       struct pt_regs *regs)
+				       struct ftrace_regs *fregs)
 {
+	struct pt_regs *regs = ftrace_get_regs(fregs);
 	struct klp_ops *ops;
 	struct klp_func *func;
 	int patch_state;