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, 3 insertions, 1 deletions

diff --git a/arch/s390/kernel/ftrace.c b/arch/s390/kernel/ftrace.c
index 657c1ab45408..67b80f4412f9 100644
--- a/arch/s390/kernel/ftrace.c
+++ b/arch/s390/kernel/ftrace.c
@@ -198,9 +198,10 @@ int ftrace_disable_ftrace_graph_caller(void)
 
 #ifdef CONFIG_KPROBES_ON_FTRACE
 void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
-		struct ftrace_ops *ops, struct pt_regs *regs)
+		struct ftrace_ops *ops, struct ftrace_regs *fregs)
 {
 	struct kprobe_ctlblk *kcb;
+	struct pt_regs *regs;
 	struct kprobe *p;
 	int bit;
 
@@ -208,6 +209,7 @@ void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
 	if (bit < 0)
 		return;
 
+	regs = ftrace_get_regs(fregs);
 	preempt_disable_notrace();
 	p = get_kprobe((kprobe_opcode_t *)ip);
 	if (unlikely(!p) || kprobe_disabled(p))