[PATCH 3/8] powerpc/ftrace: Remove redundant saving of LR in ftrace[_graph]_caller

[Naveen N. Rao]

For -mprofile-kernel, there is no need to save LR into the ABI save
location on entry into ftrace_caller(). It is sufficient to have the
(possibly updated) return address in LR (and r0?). On return from
ftrace, this value is stored in the ABI save location if necessary.

Furthermore, we can also remove the redundant saving of LR in
ftrace_graph_caller() for similar reasons. It is sufficient to ensure
LR and r0 point to the new return address.

Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
---
 arch/powerpc/kernel/trace/ftrace_64_mprofile.S | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
index fa0921410fa4..d8d75f4eb853 100644
--- a/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
+++ b/arch/powerpc/kernel/trace/ftrace_64_mprofile.S
@@ -38,9 +38,6 @@
  * and then arrange for the ftrace function to be called.
  */
 _GLOBAL(ftrace_caller)
-	/* Save the original return address in A's stack frame */
-	std	r0,LRSAVE(r1)
-
 	/* Create our stack frame + pt_regs */
 	stdu	r1,-SWITCH_FRAME_SIZE(r1)
 
@@ -271,6 +268,5 @@ _GLOBAL(ftrace_graph_caller)
 
 	addi	r1, r1, 112
 	mflr	r0
-	std	r0, LRSAVE(r1)
 	bctr
 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
-- 
2.12.2