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>

5 files changed, 73 insertions, 8 deletions

diff --git a/arch/s390/include/asm/perf_event.h b/arch/s390/include/asm/perf_event.h
index b4eea25f379e..23d2dfa8201d 100644
--- a/arch/s390/include/asm/perf_event.h
+++ b/arch/s390/include/asm/perf_event.h
@@ -52,5 +52,9 @@ extern unsigned long perf_misc_flags(struct pt_regs *regs);
 #define TEAR_REG(hwc)           ((hwc)->last_tag)
 #define SAMPL_RATE(hwc)         ((hwc)->event_base)
 
+/* Perf hardware reserve and release functions */
+int perf_reserve_sampling(void);
+void perf_release_sampling(void);
+
 #endif /* CONFIG_64BIT */
 #endif /* _ASM_S390_PERF_EVENT_H */
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);
diff --git a/arch/s390/oprofile/hwsampler.c b/arch/s390/oprofile/hwsampler.c
index bbca76ad6e1b..eb095874540d 100644
--- a/arch/s390/oprofile/hwsampler.c
+++ b/arch/s390/oprofile/hwsampler.c
@@ -41,6 +41,7 @@ static DEFINE_MUTEX(hws_sem_oom);
 
 static unsigned char hws_flush_all;
 static unsigned int hws_oom;
+static unsigned int hws_alert;
 static struct workqueue_struct *hws_wq;
 
 static unsigned int hws_state;
@@ -182,6 +183,9 @@ static void hws_ext_handler(struct ext_code ext_code,
         if (!(param32 & CPU_MF_INT_SF_MASK))
                 return;
 
+        if (!hws_alert)
+                return;
+
         inc_irq_stat(IRQEXT_CMS);
         atomic_xchg(&cb->ext_params, atomic_read(&cb->ext_params) | param32);
 
@@ -941,6 +945,7 @@ int hwsampler_deallocate(void)
                 goto deallocate_exit;
 
         irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
+        hws_alert = 0;
         deallocate_sdbt();
 
         hws_state = HWS_DEALLOCATED;
@@ -1055,6 +1060,7 @@ int hwsampler_shutdown(void)
 
                 if (hws_state == HWS_STOPPED) {
                         irq_subclass_unregister(IRQ_SUBCLASS_MEASUREMENT_ALERT);
+                        hws_alert = 0;
                         deallocate_sdbt();
                 }
                 if (hws_wq) {
@@ -1129,6 +1135,7 @@ start_all_exit:
         hws_oom = 1;
         hws_flush_all = 0;
         /* now let them in, 1407 CPUMF external interrupts */
+        hws_alert = 1;
         irq_subclass_register(IRQ_SUBCLASS_MEASUREMENT_ALERT);
 
         return 0;
diff --git a/arch/s390/oprofile/init.c b/arch/s390/oprofile/init.c
index 04e1b6a85362..9ffe645d5989 100644
--- a/arch/s390/oprofile/init.c
+++ b/arch/s390/oprofile/init.c
@@ -10,6 +10,7 @@
  */
 
 #include <linux/oprofile.h>
+#include <linux/perf_event.h>
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/fs.h>
@@ -67,6 +68,21 @@ module_param_call(cpu_type, set_cpu_type, NULL, NULL, 0);
 MODULE_PARM_DESC(cpu_type, "Force legacy basic mode sampling"
                            "(report cpu_type \"timer\"");
 
+static int __oprofile_hwsampler_start(void)
+{
+        int retval;
+
+        retval = hwsampler_allocate(oprofile_sdbt_blocks, oprofile_sdb_blocks);
+        if (retval)
+                return retval;
+
+        retval = hwsampler_start_all(oprofile_hw_interval);
+        if (retval)
+                hwsampler_deallocate();
+
+        return retval;
+}
+
 static int oprofile_hwsampler_start(void)
 {
         int retval;
@@ -76,13 +92,13 @@ static int oprofile_hwsampler_start(void)
         if (!hwsampler_running)
                 return timer_ops.start();
 
-        retval = hwsampler_allocate(oprofile_sdbt_blocks, oprofile_sdb_blocks);
+        retval = perf_reserve_sampling();
         if (retval)
                 return retval;
 
-        retval = hwsampler_start_all(oprofile_hw_interval);
+        retval = __oprofile_hwsampler_start();
         if (retval)
-                hwsampler_deallocate();
+                perf_release_sampling();
 
         return retval;
 }
@@ -96,6 +112,7 @@ static void oprofile_hwsampler_stop(void)
 
         hwsampler_stop_all();
         hwsampler_deallocate();
+        perf_release_sampling();
         return;
 }