[PATCH 1/3] riscv/ftrace: add ftrace_graph_func

[Song Shuai]

Here implements ftrace_graph_func as the function graph tracing function
with FTRACE_WITH_REGS defined.

function_graph_func gets the point of the parent IP and the frame pointer
from fregs and call prepare_ftrace_return for function graph tracing.

If FTRACE_WITH_REGS isn't defined, the enable/disable helpers of
ftrace_graph_[regs]_call remain for serving the !FTRACE_WITH_REGS
version ftrace_caller.

Signed-off-by: Song Shuai <suagrfillet at gmail.com>
---
 arch/riscv/include/asm/ftrace.h | 13 +++++++++++--
 arch/riscv/kernel/ftrace.c      | 16 ++++++++++++++++
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 04dad3380041..b33c98070972 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -81,8 +81,17 @@ do {									\
 struct dyn_ftrace;
 int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec);
 #define ftrace_init_nop ftrace_init_nop
-#endif
 
-#endif
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+struct ftrace_ops;
+struct ftrace_regs;
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+			struct ftrace_ops *op, struct ftrace_regs *fregs);
+#define ftrace_graph_func ftrace_graph_func
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_DYNAMIC_FTRACE */
 
 #endif /* _ASM_RISCV_FTRACE_H */
diff --git a/arch/riscv/kernel/ftrace.c b/arch/riscv/kernel/ftrace.c
index 2086f6585773..2d7ce77d4f33 100644
--- a/arch/riscv/kernel/ftrace.c
+++ b/arch/riscv/kernel/ftrace.c
@@ -196,6 +196,20 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr,
 }
 
 #ifdef CONFIG_DYNAMIC_FTRACE
+
+#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
+
+void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
+			struct ftrace_ops *op, struct ftrace_regs *fregs)
+{
+	struct pt_regs *regs = arch_ftrace_get_regs(fregs);
+	unsigned long *parent = (unsigned long *)&(regs->ra);
+
+	prepare_ftrace_return(parent, ip, frame_pointer(regs));
+}
+
+#else /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
 extern void ftrace_graph_call(void);
 extern void ftrace_graph_regs_call(void);
 int ftrace_enable_ftrace_graph_caller(void)
@@ -223,5 +237,7 @@ int ftrace_disable_ftrace_graph_caller(void)
 	return __ftrace_modify_call((unsigned long)&ftrace_graph_regs_call,
 				    (unsigned long)&prepare_ftrace_return, false);
 }
+#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
+
 #endif /* CONFIG_DYNAMIC_FTRACE */
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.20.1