3 files changed, 193 insertions, 13 deletions

diff --git a/drivers/oprofile/nmi_timer_int.c b/drivers/oprofile/nmi_timer_int.c
new file mode 100644
index 000000000000..76f1c9357f39
--- /dev/null
+++ b/drivers/oprofile/nmi_timer_int.c
@@ -0,0 +1,173 @@
+/**
+ * @file nmi_timer_int.c
+ *
+ * @remark Copyright 2011 Advanced Micro Devices, Inc.
+ *
+ * @author Robert Richter <robert.richter@amd.com>
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/errno.h>
+#include <linux/oprofile.h>
+#include <linux/perf_event.h>
+
+#ifdef CONFIG_OPROFILE_NMI_TIMER
+
+static DEFINE_PER_CPU(struct perf_event *, nmi_timer_events);
+static int ctr_running;
+
+static struct perf_event_attr nmi_timer_attr = {
+        .type           = PERF_TYPE_HARDWARE,
+        .config         = PERF_COUNT_HW_CPU_CYCLES,
+        .size           = sizeof(struct perf_event_attr),
+        .pinned         = 1,
+        .disabled       = 1,
+};
+
+static void nmi_timer_callback(struct perf_event *event,
+                               struct perf_sample_data *data,
+                               struct pt_regs *regs)
+{
+        event->hw.interrupts = 0;       /* don't throttle interrupts */
+        oprofile_add_sample(regs, 0);
+}
+
+static int nmi_timer_start_cpu(int cpu)
+{
+        struct perf_event *event = per_cpu(nmi_timer_events, cpu);
+
+        if (!event) {
+                event = perf_event_create_kernel_counter(&nmi_timer_attr, cpu, NULL,
+                                                         nmi_timer_callback, NULL);
+                if (IS_ERR(event))
+                        return PTR_ERR(event);
+                per_cpu(nmi_timer_events, cpu) = event;
+        }
+
+        if (event && ctr_running)
+                perf_event_enable(event);
+
+        return 0;
+}
+
+static void nmi_timer_stop_cpu(int cpu)
+{
+        struct perf_event *event = per_cpu(nmi_timer_events, cpu);
+
+        if (event && ctr_running)
+                perf_event_disable(event);
+}
+
+static int nmi_timer_cpu_notifier(struct notifier_block *b, unsigned long action,
+                                  void *data)
+{
+        int cpu = (unsigned long)data;
+        switch (action) {
+        case CPU_DOWN_FAILED:
+        case CPU_ONLINE:
+                nmi_timer_start_cpu(cpu);
+                break;
+        case CPU_DOWN_PREPARE:
+                nmi_timer_stop_cpu(cpu);
+                break;
+        }
+        return NOTIFY_DONE;
+}
+
+static struct notifier_block nmi_timer_cpu_nb = {
+        .notifier_call = nmi_timer_cpu_notifier
+};
+
+static int nmi_timer_start(void)
+{
+        int cpu;
+
+        get_online_cpus();
+        ctr_running = 1;
+        for_each_online_cpu(cpu)
+                nmi_timer_start_cpu(cpu);
+        put_online_cpus();
+
+        return 0;
+}
+
+static void nmi_timer_stop(void)
+{
+        int cpu;
+
+        get_online_cpus();
+        for_each_online_cpu(cpu)
+                nmi_timer_stop_cpu(cpu);
+        ctr_running = 0;
+        put_online_cpus();
+}
+
+static void nmi_timer_shutdown(void)
+{
+        struct perf_event *event;
+        int cpu;
+
+        get_online_cpus();
+        unregister_cpu_notifier(&nmi_timer_cpu_nb);
+        for_each_possible_cpu(cpu) {
+                event = per_cpu(nmi_timer_events, cpu);
+                if (!event)
+                        continue;
+                perf_event_disable(event);
+                per_cpu(nmi_timer_events, cpu) = NULL;
+                perf_event_release_kernel(event);
+        }
+
+        put_online_cpus();
+}
+
+static int nmi_timer_setup(void)
+{
+        int cpu, err;
+        u64 period;
+
+        /* clock cycles per tick: */
+        period = (u64)cpu_khz * 1000;
+        do_div(period, HZ);
+        nmi_timer_attr.sample_period = period;
+
+        get_online_cpus();
+        err = register_cpu_notifier(&nmi_timer_cpu_nb);
+        if (err)
+                goto out;
+        /* can't attach events to offline cpus: */
+        for_each_online_cpu(cpu) {
+                err = nmi_timer_start_cpu(cpu);
+                if (err)
+                        break;
+        }
+        if (err)
+                nmi_timer_shutdown();
+out:
+        put_online_cpus();
+        return err;
+}
+
+int __init op_nmi_timer_init(struct oprofile_operations *ops)
+{
+        int err = 0;
+
+        err = nmi_timer_setup();
+        if (err)
+                return err;
+        nmi_timer_shutdown();           /* only check, don't alloc */
+
+        ops->create_files       = NULL;
+        ops->setup              = nmi_timer_setup;
+        ops->shutdown           = nmi_timer_shutdown;
+        ops->start              = nmi_timer_start;
+        ops->stop               = nmi_timer_stop;
+        ops->cpu_type           = "timer";
+
+        printk(KERN_INFO "oprofile: using NMI timer interrupt.\n");
+
+        return 0;
+}
+
+#endif
diff --git a/drivers/oprofile/oprof.c b/drivers/oprofile/oprof.c
index f7cd06967aed..ed2c3ec07024 100644
--- a/drivers/oprofile/oprof.c
+++ b/drivers/oprofile/oprof.c
@@ -246,26 +246,24 @@ static int __init oprofile_init(void)
         int err;
 
         /* always init architecture to setup backtrace support */
+        timer_mode = 0;
         err = oprofile_arch_init(&oprofile_ops);
+        if (!err) {
+                if (!timer && !oprofilefs_register())
+                        return 0;
+                oprofile_arch_exit();
+        }
 
-        timer_mode = err || timer;      /* fall back to timer mode on errors */
-        if (timer_mode) {
-                if (!err)
-                        oprofile_arch_exit();
+        /* setup timer mode: */
+        timer_mode = 1;
+        /* no nmi timer mode if oprofile.timer is set */
+        if (timer || op_nmi_timer_init(&oprofile_ops)) {
                 err = oprofile_timer_init(&oprofile_ops);
                 if (err)
                         return err;
         }
 
-        err = oprofilefs_register();
-        if (!err)
-                return 0;
-
-        /* failed */
-        if (!timer_mode)
-                oprofile_arch_exit();
-
-        return err;
+        return oprofilefs_register();
 }
 
 
diff --git a/drivers/oprofile/oprof.h b/drivers/oprofile/oprof.h
index 177b73de5e5f..769fb0fcac44 100644
--- a/drivers/oprofile/oprof.h
+++ b/drivers/oprofile/oprof.h
@@ -36,6 +36,15 @@ struct dentry;
 void oprofile_create_files(struct super_block *sb, struct dentry *root);
 int oprofile_timer_init(struct oprofile_operations *ops);
 void oprofile_timer_exit(void);
+#ifdef CONFIG_OPROFILE_NMI_TIMER
+int op_nmi_timer_init(struct oprofile_operations *ops);
+#else
+static inline int op_nmi_timer_init(struct oprofile_operations *ops)
+{
+        return -ENODEV;
+}
+#endif
+
 
 int oprofile_set_ulong(unsigned long *addr, unsigned long val);
 int oprofile_set_timeout(unsigned long time);