[MIPS] Oprofile: Fix computation of number of counters.

VSMP kernels will split the available performance counters between the two
processors / cores.  But don't do this when we're not on a VSMP system ...

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 38 insertions, 6 deletions

diff --git a/arch/mips/oprofile/op_model_mipsxx.c b/arch/mips/oprofile/op_model_mipsxx.c
index 423bc2c473df..bdfa07aecd97 100644
--- a/arch/mips/oprofile/op_model_mipsxx.c
+++ b/arch/mips/oprofile/op_model_mipsxx.c
@@ -6,6 +6,7 @@
  * Copyright (C) 2004, 05, 06 by Ralf Baechle
  * Copyright (C) 2005 by MIPS Technologies, Inc.
  */
+#include <linux/cpumask.h>
 #include <linux/oprofile.h>
 #include <linux/interrupt.h>
 #include <linux/smp.h>
@@ -33,11 +34,45 @@
 #ifdef CONFIG_MIPS_MT_SMP
 #define WHAT            (M_TC_EN_VPE | M_PERFCTL_VPEID(smp_processor_id()))
 #define vpe_id()        smp_processor_id()
+
+/*
+ * The number of bits to shift to convert between counters per core and
+ * counters per VPE.  There is no reasonable interface atm to obtain the
+ * number of VPEs used by Linux and in the 34K this number is fixed to two
+ * anyways so we hardcore a few things here for the moment.  The way it's
+ * done here will ensure that oprofile VSMP kernel will run right on a lesser
+ * core like a 24K also or with maxcpus=1.
+ */
+static inline unsigned int vpe_shift(void)
+{
+        if (num_possible_cpus() > 1)
+                return 1;
+
+        return 0;
+}
+
 #else
+
 #define WHAT            0
 #define vpe_id()        0
+
+static inline unsigned int vpe_shift(void)
+{
+        return 0;
+}
+
 #endif
 
+static inline unsigned int counters_total_to_per_cpu(unsigned int counters)
+{
+        return counters >> vpe_shift();
+}
+
+static inline unsigned int counters_per_cpu_to_total(unsigned int counters)
+{
+        return counters << vpe_shift();
+}
+
 #define __define_perf_accessors(r, n, np)                               \
                                                                         \
 static inline unsigned int r_c0_ ## r ## n(void)                        \
@@ -269,9 +304,7 @@ static int __init mipsxx_init(void)
 
         reset_counters(counters);
 
-#ifdef CONFIG_MIPS_MT_SMP
-        counters >>= 1;
-#endif
+        counters = counters_total_to_per_cpu(counters);
 
         op_model_mipsxx_ops.num_counters = counters;
         switch (current_cpu_type()) {
@@ -330,9 +363,8 @@ static int __init mipsxx_init(void)
 static void mipsxx_exit(void)
 {
         int counters = op_model_mipsxx_ops.num_counters;
-#ifdef CONFIG_MIPS_MT_SMP
-        counters <<= 1;
-#endif
+
+        counters = counters_per_cpu_to_total(counters);
         reset_counters(counters);
 
         perf_irq = null_perf_irq;