powerpc/pseries: use notrace hcall variant for H_CEDE idle

Rather than special-case H_CEDE in the hcall trace wrappers, make the
idle H_CEDE call use plpar_hcall_norets_notrace().

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210508101455.1578318-4-npiggin@gmail.com

Author: npiggin

arch/powerpc/include/asm/plpar_wrappers.h

@@ -28,7 +28,11 @@ static inline void set_cede_latency_hint(u8 latency_hint)
 
 static inline long cede_processor(void)
 {
-	return plpar_hcall_norets(H_CEDE);
+	/*
+	 * We cannot call tracepoints inside RCU idle regions which
+	 * means we must not trace H_CEDE.
+	 */
+	return plpar_hcall_norets_notrace(H_CEDE);
 }
 
 static inline long extended_cede_processor(unsigned long latency_hint)

arch/powerpc/platforms/pseries/lpar.c

@@ -1840,13 +1840,6 @@ notrace void __trace_hcall_entry(unsigned long opcode, unsigned long *args)
 	unsigned long flags;
 	unsigned int *depth;
 
-	/*
-	 * We cannot call tracepoints inside RCU idle regions which
-	 * means we must not trace H_CEDE.
-	 */
-	if (opcode == H_CEDE)
-		return;
-
 	local_irq_save(flags);
 
 	depth = this_cpu_ptr(&hcall_trace_depth);
@@ -1868,9 +1861,6 @@ notrace void __trace_hcall_exit(long opcode, long retval, unsigned long *retbuf)
 	unsigned long flags;
 	unsigned int *depth;
 
-	if (opcode == H_CEDE)
-		return;
-
 	local_irq_save(flags);
 
 	depth = this_cpu_ptr(&hcall_trace_depth);