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>
diff --git a/arch/x86/oprofile/op_model_ppro.c b/arch/x86/oprofile/op_model_ppro.c
index 8eb0587..c344525 100644
--- a/arch/x86/oprofile/op_model_ppro.c
+++ b/arch/x86/oprofile/op_model_ppro.c
@@ -82,9 +82,18 @@
 
 	/* 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);
 	}