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Subject[PATCH v3 1/5] powerpc: ftrace: minor cleanup
Date
Move the stack setup and teardown code to the ftrace_graph_caller().
This way, we don't incur the cost of setting it up unless function graph
is enabled for this function.

Also, remove the extraneous LR restore code after the function graph
stub. LR has previously been restored and neither livepatch_handler()
nor ftrace_graph_caller() return back here.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
---
arch/powerpc/kernel/entry_64.S | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index 6432d4bf08c8..8fd8718722a1 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -1313,16 +1313,12 @@ ftrace_call:
#endif

#ifdef CONFIG_FUNCTION_GRAPH_TRACER
- stdu r1, -112(r1)
.globl ftrace_graph_call
ftrace_graph_call:
b ftrace_graph_stub
_GLOBAL(ftrace_graph_stub)
- addi r1, r1, 112
#endif

- ld r0,LRSAVE(r1) /* restore callee's lr at _mcount site */
- mtlr r0
bctr /* jump after _mcount site */
#endif /* CC_USING_MPROFILE_KERNEL */

@@ -1446,6 +1442,7 @@ _GLOBAL(ftrace_stub)
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
#ifndef CC_USING_MPROFILE_KERNEL
_GLOBAL(ftrace_graph_caller)
+ stdu r1, -112(r1)
/* load r4 with local address */
ld r4, 128(r1)
subi r4, r4, MCOUNT_INSN_SIZE
@@ -1471,6 +1468,7 @@ _GLOBAL(ftrace_graph_caller)

#else /* CC_USING_MPROFILE_KERNEL */
_GLOBAL(ftrace_graph_caller)
+ stdu r1, -112(r1)
/* with -mprofile-kernel, parameter regs are still alive at _mcount */
std r10, 104(r1)
std r9, 96(r1)
--
2.12.1
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