oprofile/x86: warn user if a counter is already active

This patch generates a warning if a counter is already active.

Implemented for AMD and P6 models. P4 is not supported.

Cc: Naga Chumbalkar <nagananda.chumbalkar@hp.com>
Cc: Shashi Belur <shashi-kiran.belur@hp.com>
Cc: Tony Jones <tonyj@suse.de>
Signed-off-by: Robert Richter <robert.richter@amd.com>

3 files changed, 31 insertions, 2 deletions

diff --git a/arch/x86/oprofile/op_model_amd.c b/arch/x86/oprofile/op_model_amd.c
index a9d194734a8e..ef9d735dea35 100644
--- a/arch/x86/oprofile/op_model_amd.c
+++ b/arch/x86/oprofile/op_model_amd.c
@@ -194,9 +194,18 @@ static void op_amd_setup_ctrs(struct op_x86_model_spec const *model,
 
         /* clear all counters */
         for (i = 0; i < NUM_CONTROLS; ++i) {
-                if (unlikely(!msrs->controls[i].addr))
+                if (unlikely(!msrs->controls[i].addr)) {
+                        if (counter_config[i].enabled && !smp_processor_id())
+                                /*
+                                 * counter is reserved, this is on all
+                                 * cpus, so report only for cpu #0
+                                 */
+                                op_x86_warn_reserved(i);
                         continue;
+                }
                 rdmsrl(msrs->controls[i].addr, val);
+                if (val & ARCH_PERFMON_EVENTSEL0_ENABLE)
+                        op_x86_warn_in_use(i);
                 val &= model->reserved;
                 wrmsrl(msrs->controls[i].addr, val);
         }
diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
index 8eb05878554c..c344525ebb55 100644
--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -82,9 +82,18 @@ static void ppro_setup_ctrs(struct op_x86_model_spec const *model,
 
         /* clear all counters */
         for (i = 0; i < num_counters; ++i) {
-                if (unlikely(!msrs->controls[i].addr))
+                if (unlikely(!msrs->controls[i].addr)) {
+                        if (counter_config[i].enabled && !smp_processor_id())
+                                /*
+                                 * counter is reserved, this is on all
+                                 * cpus, so report only for cpu #0
+                                 */
+                                op_x86_warn_reserved(i);
                         continue;
+                }
                 rdmsrl(msrs->controls[i].addr, val);
+                if (val & ARCH_PERFMON_EVENTSEL0_ENABLE)
+                        op_x86_warn_in_use(i);
                 val &= model->reserved;
                 wrmsrl(msrs->controls[i].addr, val);
         }
diff --git a/arch/x86/oprofile/op_x86_model.h b/arch/x86/oprofile/op_x86_model.h
index 7b8e75d16081..59fa2bdb0da3 100644
--- a/arch/x86/oprofile/op_x86_model.h
+++ b/arch/x86/oprofile/op_x86_model.h
@@ -57,6 +57,17 @@ struct op_x86_model_spec {
 
 struct op_counter_config;
 
+static inline void op_x86_warn_in_use(int counter)
+{
+        pr_warning("oprofile: counter #%d on cpu #%d may already be used\n",
+                   counter, smp_processor_id());
+}
+
+static inline void op_x86_warn_reserved(int counter)
+{
+        pr_warning("oprofile: counter #%d is already reserved\n", counter);
+}
+
 extern u64 op_x86_get_ctrl(struct op_x86_model_spec const *model,
                            struct op_counter_config *counter_config);
 extern int op_x86_phys_to_virt(int phys);