[PATCH 2/9] tracing: MIPS: mcount.S: cleanup the arguments of prepare_ftrace_return

[Wu Zhangjin <wuzhangjin@gmail.com>]

From: Wu Zhangjin <wuzhangjin@gmail.com>

The old arguments handling for prepare_ftrace_return is awlful, this
patch cleans it up.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
---
 arch/mips/kernel/mcount.S |   36 ++++++++++++++++++++++--------------
 1 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index e256bf9..d4a00d2 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -132,28 +132,34 @@ ftrace_stub:
 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 
 NESTED(ftrace_graph_caller, PT_SIZE, ra)
-#ifdef CONFIG_DYNAMIC_FTRACE
-       PTR_L   a1, PT_R31(sp)  /* load the original ra from the stack */
-#ifdef KBUILD_MCOUNT_RA_ADDRESS
-       PTR_L   t0, PT_R12(sp)  /* load the original t0 from the stack */
-#endif
-#else
+#ifndef CONFIG_DYNAMIC_FTRACE
        MCOUNT_SAVE_REGS
-       move    a1, ra          /* arg2: next ip, selfaddr */
 #endif
 
+       /* arg1: Get the location of the parent's return address */
 #ifdef KBUILD_MCOUNT_RA_ADDRESS
-       bnez    t0, 1f          /* non-leaf func: t0 saved the location of the 
return address */
+#ifdef CONFIG_DYNAMIC_FTRACE
+       PTR_L   a0, PT_R12(sp)
+#else
+       move    a0, t0
+#endif
+       bnez    a0, 1f          /* non-leaf func: stored in t0 */
         nop
-       PTR_LA  t0, PT_R1(sp)   /* leaf func: get the location of at(old ra) 
from our own stack */
-1:     move    a0, t0          /* arg1: the location of the return address */
+#endif
+       PTR_LA  a0, PT_R1(sp)   /* leaf func: the location in current stack */
+1:
+
+       /* arg2: Get self return address */
+#ifdef CONFIG_DYNAMIC_FTRACE
+       PTR_L   a1, PT_R31(sp)
 #else
-       PTR_LA  a0, PT_R1(sp)   /* arg1: &AT -> a0 */
+       move    a1, ra
 #endif
-       jal     prepare_ftrace_return
+
+       /* arg3: Get frame pointer of current stack */
 #ifdef CONFIG_FRAME_POINTER
-        move   a2, fp          /* arg3: frame pointer */
-#else
+        move   a2, fp
+#else /* ! CONFIG_FRAME_POINTER */
 #ifdef CONFIG_64BIT
         PTR_LA a2, PT_SIZE(sp)
 #else
@@ -161,6 +167,8 @@ NESTED(ftrace_graph_caller, PT_SIZE, ra)
 #endif
 #endif
 
+       jal     prepare_ftrace_return
+        nop
        MCOUNT_RESTORE_REGS
        RETURN_BACK
        END(ftrace_graph_caller)
-- 
1.7.0.4