[PATCH] i386: Utilize performance counter reservation framework in op…

…rofile

Incorporates the new performance counter reservation system in oprofile.
Also cleans up a lot of the initialization code.  The code original zero'd
out every register associated with performance counters regardless if those
registers were used or not.  This causes issues with the nmi watchdog.
Now oprofile tries to reserve registers and gives up if it can't get them.

Cc: levon@movementarian.org
Cc: oprofile-list@lists.sf.net

Signed-off-by:  Don Zickus <dzickus@redhat.com>
Signed-off-by: Andi Kleen <ak@suse.de>

arch/i386/oprofile/nmi_int.c

@@ -98,15 +98,19 @@ static void nmi_cpu_save_registers(struct op_msrs * msrs)
 	unsigned int i;
 
 	for (i = 0; i < nr_ctrs; ++i) {
-		rdmsr(counters[i].addr,
-			counters[i].saved.low,
-			counters[i].saved.high);
+		if (counters[i].addr){
+			rdmsr(counters[i].addr,
+				counters[i].saved.low,
+				counters[i].saved.high);
+		}
 	}
 
 	for (i = 0; i < nr_ctrls; ++i) {
-		rdmsr(controls[i].addr,
-			controls[i].saved.low,
-			controls[i].saved.high);
+		if (controls[i].addr){
+			rdmsr(controls[i].addr,
+				controls[i].saved.low,
+				controls[i].saved.high);
+		}
 	}
 }
 
@@ -205,15 +209,19 @@ static void nmi_restore_registers(struct op_msrs * msrs)
 	unsigned int i;
 
 	for (i = 0; i < nr_ctrls; ++i) {
-		wrmsr(controls[i].addr,
-			controls[i].saved.low,
-			controls[i].saved.high);
+		if (controls[i].addr){
+			wrmsr(controls[i].addr,
+				controls[i].saved.low,
+				controls[i].saved.high);
+		}
 	}
 
 	for (i = 0; i < nr_ctrs; ++i) {
-		wrmsr(counters[i].addr,
-			counters[i].saved.low,
-			counters[i].saved.high);
+		if (counters[i].addr){
+			wrmsr(counters[i].addr,
+				counters[i].saved.low,
+				counters[i].saved.high);
+		}
 	}
 }
 
@@ -234,6 +242,7 @@ static void nmi_cpu_shutdown(void * dummy)
 	apic_write(APIC_LVTPC, saved_lvtpc[cpu]);
 	apic_write(APIC_LVTERR, v);
 	nmi_restore_registers(msrs);
+	model->shutdown(msrs);
 }
 
 
@@ -284,6 +293,14 @@ static int nmi_create_files(struct super_block * sb, struct dentry * root)
 		struct dentry * dir;
 		char buf[4];
 
+ 		/* quick little hack to _not_ expose a counter if it is not
+		 * available for use.  This should protect userspace app.
+		 * NOTE:  assumes 1:1 mapping here (that counters are organized
+		 *        sequentially in their struct assignment).
+		 */
+		if (unlikely(!avail_to_resrv_perfctr_nmi_bit(i)))
+			continue;
+
 		snprintf(buf,  sizeof(buf), "%d", i);
 		dir = oprofilefs_mkdir(sb, root, buf);
 		oprofilefs_create_ulong(sb, dir, "enabled", &counter_config[i].enabled); 

arch/i386/oprofile/op_model_athlon.c

@@ -21,10 +21,12 @@
 #define NUM_COUNTERS 4
 #define NUM_CONTROLS 4
 
+#define CTR_IS_RESERVED(msrs,c) (msrs->counters[(c)].addr ? 1 : 0)
 #define CTR_READ(l,h,msrs,c) do {rdmsr(msrs->counters[(c)].addr, (l), (h));} while (0)
 #define CTR_WRITE(l,msrs,c) do {wrmsr(msrs->counters[(c)].addr, -(unsigned int)(l), -1);} while (0)
 #define CTR_OVERFLOWED(n) (!((n) & (1U<<31)))
 
+#define CTRL_IS_RESERVED(msrs,c) (msrs->controls[(c)].addr ? 1 : 0)
 #define CTRL_READ(l,h,msrs,c) do {rdmsr(msrs->controls[(c)].addr, (l), (h));} while (0)
 #define CTRL_WRITE(l,h,msrs,c) do {wrmsr(msrs->controls[(c)].addr, (l), (h));} while (0)
 #define CTRL_SET_ACTIVE(n) (n |= (1<<22))
@@ -40,15 +42,21 @@ static unsigned long reset_value[NUM_COUNTERS];
 
 static void athlon_fill_in_addresses(struct op_msrs * const msrs)
 {
-	msrs->counters[0].addr = MSR_K7_PERFCTR0;
-	msrs->counters[1].addr = MSR_K7_PERFCTR1;
-	msrs->counters[2].addr = MSR_K7_PERFCTR2;
-	msrs->counters[3].addr = MSR_K7_PERFCTR3;
-
-	msrs->controls[0].addr = MSR_K7_EVNTSEL0;
-	msrs->controls[1].addr = MSR_K7_EVNTSEL1;
-	msrs->controls[2].addr = MSR_K7_EVNTSEL2;
-	msrs->controls[3].addr = MSR_K7_EVNTSEL3;
+	int i;
+
+	for (i=0; i < NUM_COUNTERS; i++) {
+		if (reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i))
+			msrs->counters[i].addr = MSR_K7_PERFCTR0 + i;
+		else
+			msrs->counters[i].addr = 0;
+	}
+
+	for (i=0; i < NUM_CONTROLS; i++) {
+		if (reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i))
+			msrs->controls[i].addr = MSR_K7_EVNTSEL0 + i;
+		else
+			msrs->controls[i].addr = 0;
+	}
 }
 
 
@@ -59,19 +67,23 @@ static void athlon_setup_ctrs(struct op_msrs const * const msrs)
 
 	/* clear all counters */
 	for (i = 0 ; i < NUM_CONTROLS; ++i) {
+		if (unlikely(!CTRL_IS_RESERVED(msrs,i)))
+			continue;
 		CTRL_READ(low, high, msrs, i);
 		CTRL_CLEAR(low);
 		CTRL_WRITE(low, high, msrs, i);
 	}
-	
+
 	/* avoid a false detection of ctr overflows in NMI handler */
 	for (i = 0; i < NUM_COUNTERS; ++i) {
+		if (unlikely(!CTR_IS_RESERVED(msrs,i)))
+			continue;
 		CTR_WRITE(1, msrs, i);
 	}
 
 	/* enable active counters */
 	for (i = 0; i < NUM_COUNTERS; ++i) {
-		if (counter_config[i].enabled) {
+		if ((counter_config[i].enabled) && (CTR_IS_RESERVED(msrs,i))) {
 			reset_value[i] = counter_config[i].count;
 
 			CTR_WRITE(counter_config[i].count, msrs, i);
@@ -98,6 +110,8 @@ static int athlon_check_ctrs(struct pt_regs * const regs,
 	int i;
 
 	for (i = 0 ; i < NUM_COUNTERS; ++i) {
+		if (!reset_value[i])
+			continue;
 		CTR_READ(low, high, msrs, i);
 		if (CTR_OVERFLOWED(low)) {
 			oprofile_add_sample(regs, i);
@@ -132,12 +146,27 @@ static void athlon_stop(struct op_msrs const * const msrs)
 	/* Subtle: stop on all counters to avoid race with
 	 * setting our pm callback */
 	for (i = 0 ; i < NUM_COUNTERS ; ++i) {
+		if (!reset_value[i])
+			continue;
 		CTRL_READ(low, high, msrs, i);
 		CTRL_SET_INACTIVE(low);
 		CTRL_WRITE(low, high, msrs, i);
 	}
 }
 
+static void athlon_shutdown(struct op_msrs const * const msrs)
+{
+	int i;
+
+	for (i = 0 ; i < NUM_COUNTERS ; ++i) {
+		if (CTR_IS_RESERVED(msrs,i))
+			release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
+	}
+	for (i = 0 ; i < NUM_CONTROLS ; ++i) {
+		if (CTRL_IS_RESERVED(msrs,i))
+			release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
+	}
+}
 
 struct op_x86_model_spec const op_athlon_spec = {
 	.num_counters = NUM_COUNTERS,
@@ -146,5 +175,6 @@ struct op_x86_model_spec const op_athlon_spec = {
 	.setup_ctrs = &athlon_setup_ctrs,
 	.check_ctrs = &athlon_check_ctrs,
 	.start = &athlon_start,
-	.stop = &athlon_stop
+	.stop = &athlon_stop,
+	.shutdown = &athlon_shutdown
 };