x86/ftrace: Add comment on static function tracing

[firefly-linux-kernel-4.4.55.git] / arch / x86 / kernel / mcount_64.S

diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
index 94ea120fa21ff7a9de85cc123054e9d2133b2305..87e1762e2bca74a3f22004d09d9069d72b41b62b 100644 (file)
--- a/arch/x86/kernel/mcount_64.S
+++ b/arch/x86/kernel/mcount_64.S
@@ -278,6 +278,12 @@ trace:
        /* save_mcount_regs fills in first two parameters */
        save_mcount_regs
 
+       /*
+        * When DYNAMIC_FTRACE is not defined, ARCH_SUPPORTS_FTRACE_OPS is not
+        * set (see include/asm/ftrace.h and include/linux/ftrace.h).  Only the
+        * ip and parent ip are used and the list function is called when
+        * function tracing is enabled.
+        */
        call   *ftrace_trace_function
 
        restore_mcount_regs