ftrace: use code patching for ftrace graph tracer

Impact: more efficient code for ftrace graph tracer

This patch uses the dynamic patching, when available, to patch
the function graph code into the kernel.

This patch will ease the way for letting both function tracing
and function graph tracing run together.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index 7def9fd5c1e6..958af86186c4 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -1174,6 +1174,11 @@ ftrace_call:
         popl %edx
         popl %ecx
         popl %eax
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+.globl ftrace_graph_call
+ftrace_graph_call:
+        jmp ftrace_stub
+#endif
 
 .globl ftrace_stub
 ftrace_stub: