MIPS: Add perf counter feature

Add CPU feature for standard MIPS r2 performance counters, as determined
by the Config1.PC bit. Both perf_events and oprofile probe this bit, so
lets combine the probing and change both to use cpu_has_perf.

This will also be used for VZ support in KVM to know whether performance
counters exist which can be exposed to guests.

[ralf@linux-mips.org: resolve conflict.]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Robert Richter <rric@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: oprofile-list@lists.sf.net
Patchwork: https://patchwork.linux-mips.org/patch/13226/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/cpu-features.h

@@ -454,4 +454,8 @@
 # define cpu_has_contextconfig	(cpu_data[0].options & MIPS_CPU_CTXTC)
 #endif
 
+#ifndef cpu_has_perf
+# define cpu_has_perf		(cpu_data[0].options & MIPS_CPU_PERF)
+#endif
+
 #endif /* __ASM_CPU_FEATURES_H */

arch/mips/include/asm/cpu.h

@@ -408,6 +408,7 @@ enum cpu_type_enum {
 #define MIPS_CPU_BADINSTR	MBIT_ULL(44)	/* CPU has BadInstr register */
 #define MIPS_CPU_BADINSTRP	MBIT_ULL(45)	/* CPU has BadInstrP register */
 #define MIPS_CPU_CTXTC		MBIT_ULL(46)	/* CPU has [X]ConfigContext registers */
+#define MIPS_CPU_PERF		MBIT_ULL(47)	/* CPU has MIPS performance counters */
 
 /*
  * CPU ASE encodings

arch/mips/kernel/cpu-probe.c

@@ -648,6 +648,8 @@ static inline unsigned int decode_config1(struct cpuinfo_mips *c)
 
 	if (config1 & MIPS_CONF1_MD)
 		c->ases |= MIPS_ASE_MDMX;
+	if (config1 & MIPS_CONF1_PC)
+		c->options |= MIPS_CPU_PERF;
 	if (config1 & MIPS_CONF1_WR)
 		c->options |= MIPS_CPU_WATCH;
 	if (config1 & MIPS_CONF1_CA)

arch/mips/kernel/perf_event_mipsxx.c

@@ -101,8 +101,6 @@ struct mips_pmu {
 
 static struct mips_pmu mipspmu;
 
-#define M_CONFIG1_PC	(1 << 4)
-
 #define M_PERFCTL_EXL			(1	<<  0)
 #define M_PERFCTL_KERNEL		(1	<<  1)
 #define M_PERFCTL_SUPERVISOR		(1	<<  2)
@@ -754,7 +752,7 @@ static void handle_associated_event(struct cpu_hw_events *cpuc,
 
 static int __n_counters(void)
 {
-	if (!(read_c0_config1() & M_CONFIG1_PC))
+	if (!cpu_has_perf)
 		return 0;
 	if (!(read_c0_perfctrl0() & M_PERFCTL_MORE))
 		return 1;

arch/mips/oprofile/op_model_mipsxx.c

@@ -269,11 +269,9 @@ static int mipsxx_perfcount_handler(void)
 	return handled;
 }
 
-#define M_CONFIG1_PC	(1 << 4)
-
 static inline int __n_counters(void)
 {
-	if (!(read_c0_config1() & M_CONFIG1_PC))
+	if (!cpu_has_perf)
 		return 0;
 	if (!(read_c0_perfctrl0() & M_PERFCTL_MORE))
 		return 1;