LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support

Allow for arguments to be passed in to ftrace_regs by default. If this
is set, then arguments and stack can be found from the pt_regs.

1. HAVE_DYNAMIC_FTRACE_WITH_ARGS don't need special hook for graph
tracer entry point, but instead we can use graph_ops::func function to
install the return_hooker.

2. Livepatch requires this option in the future.

Signed-off-by: Qing Zhang <zhangqing@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 11 insertions, 0 deletions

diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c
index d6f30918f94f..439ba829b9fd 100644
--- a/arch/loongarch/kernel/ftrace_dyn.c
+++ b/arch/loongarch/kernel/ftrace_dyn.c
@@ -139,6 +139,16 @@ void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
 		*parent = return_hooker;
 }
 
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+		       struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	struct pt_regs *regs = &fregs->regs;
+	unsigned long *parent = (unsigned long *)&regs->regs[1];
+
+	prepare_ftrace_return(ip, (unsigned long *)parent);
+}
+#else
 static int ftrace_modify_graph_caller(bool enable)
 {
 	u32 branch, nop;
@@ -166,4 +176,5 @@ int ftrace_disable_ftrace_graph_caller(void)
 {
 	return ftrace_modify_graph_caller(false);
 }
+#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */