MIPS: Unbreak function tracer for 64-bit kernel.

Commit 58b69401c797 [MIPS: Function tracer: Fix broken function tracing]
completely broke the function tracer for 64-bit kernels.  The symptom is
a system hang very early in the boot process.

The fix: Remove/fix $sp adjustments for 64-bit case.

Signed-off-by: David Daney <david.daney@cavium.com>
Cc: linux-mips@linux-mips.org
Cc: Al Cooper <alcooperx@gmail.com>
Cc: viric@viric.name
Cc: stable@vger.kernel.org # 3.8.x
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 7 insertions, 4 deletions

diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index 165867673357..33d067148e61 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -46,10 +46,9 @@
         PTR_L   a5, PT_R9(sp)
         PTR_L   a6, PT_R10(sp)
         PTR_L   a7, PT_R11(sp)
-#else
-        PTR_ADDIU       sp, PT_SIZE
 #endif
-.endm
+        PTR_ADDIU       sp, PT_SIZE
+        .endm
 
         .macro RETURN_BACK
         jr ra
@@ -68,7 +67,11 @@ NESTED(ftrace_caller, PT_SIZE, ra)
         .globl _mcount
 _mcount:
         b       ftrace_stub
-        addiu sp,sp,8
+#ifdef CONFIG_32BIT
+         addiu sp,sp,8
+#else
+         nop
+#endif
 
         /* When tracing is activated, it calls ftrace_caller+8 (aka here) */
         lw      t1, function_trace_stop