s390/perf,oprofile: Share sampling facility

Introduce reserve/release functions to share the sampling facility
between perf and oprofile.
Also improve error handling for the sampling facility support in perf.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 42 insertions, 5 deletions

diff --git a/arch/s390/kernel/perf_cpum_sf.c b/arch/s390/kernel/perf_cpum_sf.c
index 52bf36ee91aa..ae5e0192160d 100644
--- a/arch/s390/kernel/perf_cpum_sf.c
+++ b/arch/s390/kernel/perf_cpum_sf.c
@@ -260,16 +260,12 @@ static int sf_disable(void)
 
 #define PMC_INIT      0
 #define PMC_RELEASE   1
+#define PMC_FAILURE   2
 static void setup_pmc_cpu(void *flags)
 {
 	int err;
 	struct cpu_hw_sf *cpusf = &__get_cpu_var(cpu_hw_sf);
 
-	/* XXX Improve error handling and pass a flag in the *flags
-	 *     variable to indicate failures.  Alternatively, ignore
-	 *     (print) errors here and let the PMU functions fail if
-	 *     the per-cpu PMU_F_RESERVED flag is not.
-	 */
 	err = 0;
 	switch (*((int *) flags)) {
 	case PMC_INIT:
@@ -299,6 +295,8 @@ static void setup_pmc_cpu(void *flags)
 				    "setup_pmc_cpu: released: cpuhw=%p\n", cpusf);
 		break;
 	}
+	if (err)
+		*((int *) flags) |= PMC_FAILURE;
 }
 
 static void release_pmc_hardware(void)
@@ -307,13 +305,22 @@ static void release_pmc_hardware(void)
 
 	irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
 	on_each_cpu(setup_pmc_cpu, &flags, 1);
+	perf_release_sampling();
 }
 
 static int reserve_pmc_hardware(void)
 {
 	int flags = PMC_INIT;
+	int err;
 
+	err = perf_reserve_sampling();
+	if (err)
+		return err;
 	on_each_cpu(setup_pmc_cpu, &flags, 1);
+	if (flags & PMC_FAILURE) {
+		release_pmc_hardware();
+		return -ENODEV;
+	}
 	irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
 
 	return 0;
diff --git a/arch/s390/kernel/perf_event.c b/arch/s390/kernel/perf_event.c
index b9843ba9829f..4edcdfa4894e 100644
--- a/arch/s390/kernel/perf_event.c
+++ b/arch/s390/kernel/perf_event.c
@@ -208,3 +208,33 @@ ssize_t cpumf_events_sysfs_show(struct device *dev,
 	return sprintf(page, "event=0x%04llx,name=%s\n",
 		       pmu_attr->id, attr->attr.name);
 }
+
+/* Reserve/release functions for sharing perf hardware */
+static DEFINE_SPINLOCK(perf_hw_owner_lock);
+static void *perf_sampling_owner;
+
+int perf_reserve_sampling(void)
+{
+	int err;
+
+	err = 0;
+	spin_lock(&perf_hw_owner_lock);
+	if (perf_sampling_owner) {
+		pr_warn("The sampling facility is already reserved by %p\n",
+			perf_sampling_owner);
+		err = -EBUSY;
+	} else
+		perf_sampling_owner = __builtin_return_address(0);
+	spin_unlock(&perf_hw_owner_lock);
+	return err;
+}
+EXPORT_SYMBOL(perf_reserve_sampling);
+
+void perf_release_sampling(void)
+{
+	spin_lock(&perf_hw_owner_lock);
+	WARN_ON(!perf_sampling_owner);
+	perf_sampling_owner = NULL;
+	spin_unlock(&perf_hw_owner_lock);
+}
+EXPORT_SYMBOL(perf_release_sampling);