MIPS: Tracing: Enable HAVE_FUNCTION_TRACE_MCOUNT_TEST for MIPS

There is an exisiting common ftrace_test_stop_func() in
kernel/trace/ftrace.c, which is used to check the global variable
ftrace_trace_stop to determine whether stop the function tracing.

This patch implepment the MIPS specific one to speedup the procedure.

Thanks goes to Zhang Le for Cleaning it up.

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nicholas Mc Guire <der.herr@hofr.at>
Cc: zhangfx@lemote.com
Cc: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: http://patchwork.linux-mips.org/patch/673/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 4 insertions, 0 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 632dba2ac300..d203dbfa8037 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -6,6 +6,7 @@ config MIPS
         select HAVE_OPROFILE
         select HAVE_ARCH_KGDB
         select HAVE_FUNCTION_TRACER
+        select HAVE_FUNCTION_TRACE_MCOUNT_TEST
         # Horrible source of confusion.  Die, die, die ...
         select EMBEDDED
         select RTC_LIB if !MACH_LOONGSON
diff --git a/arch/mips/kernel/mcount.S b/arch/mips/kernel/mcount.S
index cebcc3c11305..cbb45edad464 100644
--- a/arch/mips/kernel/mcount.S
+++ b/arch/mips/kernel/mcount.S
@@ -59,6 +59,9 @@
         .endm
 
 NESTED(_mcount, PT_SIZE, ra)
+        lw      t0, function_trace_stop
+        bnez    t0, ftrace_stub
+         nop
         PTR_LA  t0, ftrace_stub
         PTR_L   t1, ftrace_trace_function /* Prepare t1 for (1) */
         bne     t0, t1, static_trace