[RFA][PATCH 2/2] ftrace/x86: Have function graph tracer use its own trampoline

[Steven Rostedt]

From: "Steven Rostedt (Red Hat)" <rostedt@xxxxxxxxxxx>

The function graph trampoline is called from the function trampoline
and both do a save and restore of registers. The save of registers
done by the function trampoline when only the function graph tracer
is running is a waste of CPU cycles.

As the function graph tracer trampoline in x86 is dependent from
the function trampoline, we can call it directly when a function
is only being traced by the function graph trampoline.

Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
 arch/x86/include/asm/ftrace.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 0525a8bdf65d..e1f7fecaa7d6 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -68,6 +68,8 @@ struct dyn_arch_ftrace {
 
 int ftrace_int3_handler(struct pt_regs *regs);
 
+#define FTRACE_GRAPH_TRAMP_ADDR FTRACE_GRAPH_ADDR
+
 #endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
-- 
2.0.0


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