[PATCH] ftrace/x86: Remove jumps to ftrace_epilogue

[Steven Rostedt (Google)]

The jumps to ftrace_epilogue were done as a way to make sure all the
function tracing trampolines ended at the function graph trampoline, as
the ftrace_epilogue was the location that it would handle that.

With the advent of function graph tracer now being just one of the
callbacks of the function tracer there is no more requirement that all
trampolines go to a single location.

Remove the jumps to the ftrace_epilogue and replace them with return
statements.

Note, the ftrace_epilogue can probably be renamed to ftrace_stub and the
weak logic for that could probably be removed. But lets leave that as a
separate change.

Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
 arch/x86/kernel/ftrace_64.S | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S
index dfeb227de561..8f225fafa5fb 100644
--- a/arch/x86/kernel/ftrace_64.S
+++ b/arch/x86/kernel/ftrace_64.S
@@ -173,7 +173,9 @@ SYM_INNER_LABEL(ftrace_call, SYM_L_GLOBAL)
 SYM_INNER_LABEL(ftrace_caller_end, SYM_L_GLOBAL)
 	ANNOTATE_NOENDBR
 
-	jmp ftrace_epilogue
+	UNWIND_HINT_FUNC
+	ENDBR
+	RET
 SYM_FUNC_END(ftrace_caller);
 STACK_FRAME_NON_STANDARD_FP(ftrace_caller)
 
@@ -261,15 +263,9 @@ SYM_INNER_LABEL(ftrace_regs_caller_jmp, SYM_L_GLOBAL)
 	/* Restore flags */
 	popfq
 
-	/*
-	 * As this jmp to ftrace_epilogue can be a short jump
-	 * it must not be copied into the trampoline.
-	 * The trampoline will add the code to jump
-	 * to the return.
-	 */
 SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
 	ANNOTATE_NOENDBR
-	jmp ftrace_epilogue
+	jmp 2f
 
 	/* Swap the flags with orig_rax */
 1:	movq MCOUNT_REG_SIZE(%rsp), %rdi
@@ -279,8 +275,10 @@ SYM_INNER_LABEL(ftrace_regs_caller_end, SYM_L_GLOBAL)
 	restore_mcount_regs 8
 	/* Restore flags */
 	popfq
+2:
 	UNWIND_HINT_FUNC
-	jmp	ftrace_epilogue
+	ENDBR
+	RET
 
 SYM_FUNC_END(ftrace_regs_caller)
 STACK_FRAME_NON_STANDARD_FP(ftrace_regs_caller)
-- 
2.35.1