arm64: use preempt_disable_notrace in _percpu_read/write

When debug preempt or preempt tracer is enabled, preempt_count_add/sub()
can be traced by function and function graph tracing, and
preempt_disable/enable() would call preempt_count_add/sub(), so in Ftrace
subsystem we should use preempt_disable/enable_notrace instead.

In the commit 345ddcc8 ("ftrace: Have set_ftrace_pid use the bitmap
like events do") the function this_cpu_read() was added to
trace_graph_entry(), and if this_cpu_read() calls preempt_disable(), graph
tracer will go into a recursive loop, even if the tracing_on is
disabled.

So this patch change to use preempt_enable/disable_notrace instead in
this_cpu_read().

Since Yonghui Yang helped a lot to find the root cause of this problem,
so also add his SOB.
Signed-off-by: Yonghui Yang <mark.yang@spreadtrum.com>
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/percpu.h

@@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val,
 #define _percpu_read(pcp)						\
 ({									\
 	typeof(pcp) __retval;						\
-	preempt_disable();						\
+	preempt_disable_notrace();					\
 	__retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), 	\
 					      sizeof(pcp));		\
-	preempt_enable();						\
+	preempt_enable_notrace();					\
 	__retval;							\
 })
 
 #define _percpu_write(pcp, val)						\
 do {									\
-	preempt_disable();						\
+	preempt_disable_notrace();					\
 	__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), 	\
 				sizeof(pcp));				\
-	preempt_enable();						\
+	preempt_enable_notrace();					\
 } while(0)								\
 
 #define _pcp_protect(operation, pcp, val)			\