function_graph: Enable funcgraph-args and funcgraph-retaddr to work simultaneously

Currently, the funcgraph-args and funcgraph-retaddr features are
mutually exclusive. This patch resolves this limitation by allowing
funcgraph-retaddr to have an args array.

To verify the change, use perf to trace vfs_write with both options
enabled:

Before:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read() { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(); /* <-down_read+0x8b/0x160 */
   }

After:
 # perf ftrace -G vfs_write --graph-opts args,retaddr
   ......
   down_read(sem=0xffff8880100bea78) { /* <-n_tty_write+0xa3/0x540 */
     __cond_resched(); /* <-down_read+0x12/0x160 */
     preempt_count_add(val=1); /* <-down_read+0x3b/0x160 */
     preempt_count_sub(val=1); /* <-down_read+0x8b/0x160 */
   }

Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Xiaoqin Zhang <zhangxiaoqin@xiaomi.com>
Link: https://patch.msgid.link/20251125093425.2563849-1-dolinux.peng@gmail.com
Signed-off-by: pengdonglin <pengdonglin@xiaomi.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 2 insertions, 5 deletions

diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 7ded7df6e9b5..6ca9c6229d93 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -1126,17 +1126,14 @@ static inline void ftrace_init(void) { }
  */
 struct ftrace_graph_ent {
 	unsigned long func; /* Current function */
-	int depth;
+	unsigned long depth;
 } __packed;
 
 /*
  * Structure that defines an entry function trace with retaddr.
- * It's already packed but the attribute "packed" is needed
- * to remove extra padding at the end.
  */
 struct fgraph_retaddr_ent {
-	unsigned long func; /* Current function */
-	int depth;
+	struct ftrace_graph_ent ent;
 	unsigned long retaddr;  /* Return address */
 } __packed;