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-rw-r--r--include/linux/perf_counter.h9
-rw-r--r--kernel/perf_counter.c41
2 files changed, 46 insertions, 4 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index c046f7d97cfa..45bdd3b95d3e 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -164,10 +164,11 @@ struct perf_counter_hw_event {
164/* 164/*
165 * Ioctls that can be done on a perf counter fd: 165 * Ioctls that can be done on a perf counter fd:
166 */ 166 */
167#define PERF_COUNTER_IOC_ENABLE _IOW('$', 0, u32) 167#define PERF_COUNTER_IOC_ENABLE _IO ('$', 0)
168#define PERF_COUNTER_IOC_DISABLE _IOW('$', 1, u32) 168#define PERF_COUNTER_IOC_DISABLE _IO ('$', 1)
169#define PERF_COUNTER_IOC_REFRESH _IOW('$', 2, u32) 169#define PERF_COUNTER_IOC_REFRESH _IO ('$', 2)
170#define PERF_COUNTER_IOC_RESET _IOW('$', 3, u32) 170#define PERF_COUNTER_IOC_RESET _IO ('$', 3)
171#define PERF_COUNTER_IOC_PERIOD _IOW('$', 4, u64)
171 172
172enum perf_counter_ioc_flags { 173enum perf_counter_ioc_flags {
173 PERF_IOC_FLAG_GROUP = 1U << 0, 174 PERF_IOC_FLAG_GROUP = 1U << 0,
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 3f11a2bc6c79..abe2f3b6c424 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1604,6 +1604,43 @@ static void perf_counter_for_each(struct perf_counter *counter,
1604 mutex_unlock(&counter->child_mutex); 1604 mutex_unlock(&counter->child_mutex);
1605} 1605}
1606 1606
1607static int perf_counter_period(struct perf_counter *counter, u64 __user *arg)
1608{
1609 struct perf_counter_context *ctx = counter->ctx;
1610 unsigned long size;
1611 int ret = 0;
1612 u64 value;
1613
1614 if (!counter->hw_event.sample_period)
1615 return -EINVAL;
1616
1617 size = copy_from_user(&value, arg, sizeof(value));
1618 if (size != sizeof(value))
1619 return -EFAULT;
1620
1621 if (!value)
1622 return -EINVAL;
1623
1624 spin_lock_irq(&ctx->lock);
1625 if (counter->hw_event.freq) {
1626 if (value > sysctl_perf_counter_limit) {
1627 ret = -EINVAL;
1628 goto unlock;
1629 }
1630
1631 counter->hw_event.sample_freq = value;
1632 } else {
1633 counter->hw_event.sample_period = value;
1634 counter->hw.sample_period = value;
1635
1636 perf_log_period(counter, value);
1637 }
1638unlock:
1639 spin_unlock_irq(&ctx->lock);
1640
1641 return ret;
1642}
1643
1607static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 1644static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1608{ 1645{
1609 struct perf_counter *counter = file->private_data; 1646 struct perf_counter *counter = file->private_data;
@@ -1623,6 +1660,10 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
1623 1660
1624 case PERF_COUNTER_IOC_REFRESH: 1661 case PERF_COUNTER_IOC_REFRESH:
1625 return perf_counter_refresh(counter, arg); 1662 return perf_counter_refresh(counter, arg);
1663
1664 case PERF_COUNTER_IOC_PERIOD:
1665 return perf_counter_period(counter, (u64 __user *)arg);
1666
1626 default: 1667 default:
1627 return -ENOTTY; 1668 return -ENOTTY;
1628 } 1669 }