diff options
| -rw-r--r-- | include/linux/perf_counter.h | 5 | ||||
| -rw-r--r-- | kernel/perf_counter.c | 83 |
2 files changed, 85 insertions, 3 deletions
diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h index b53f7006cc4..e022b847c90 100644 --- a/include/linux/perf_counter.h +++ b/include/linux/perf_counter.h @@ -216,6 +216,7 @@ struct perf_counter_attr { #define PERF_COUNTER_IOC_REFRESH _IO ('$', 2) #define PERF_COUNTER_IOC_RESET _IO ('$', 3) #define PERF_COUNTER_IOC_PERIOD _IOW('$', 4, u64) +#define PERF_COUNTER_IOC_SET_OUTPUT _IO ('$', 5) enum perf_counter_ioc_flags { PERF_IOC_FLAG_GROUP = 1U << 0, @@ -415,6 +416,9 @@ enum perf_callchain_context { PERF_CONTEXT_MAX = (__u64)-4095, }; +#define PERF_FLAG_FD_NO_GROUP (1U << 0) +#define PERF_FLAG_FD_OUTPUT (1U << 1) + #ifdef __KERNEL__ /* * Kernel-internal data types and definitions: @@ -536,6 +540,7 @@ struct perf_counter { struct list_head sibling_list; int nr_siblings; struct perf_counter *group_leader; + struct perf_counter *output; const struct pmu *pmu; enum perf_counter_active_state state; diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index 06bf6a4f260..53abcbefa0b 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1692,6 +1692,11 @@ static void free_counter(struct perf_counter *counter) atomic_dec(&nr_task_counters); } + if (counter->output) { + fput(counter->output->filp); + counter->output = NULL; + } + if (counter->destroy) counter->destroy(counter); @@ -1977,6 +1982,8 @@ unlock: return ret; } +int perf_counter_set_output(struct perf_counter *counter, int output_fd); + static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { struct perf_counter *counter = file->private_data; @@ -2000,6 +2007,9 @@ static long perf_ioctl(struct file *file, unsigned int cmd, unsigned long arg) case PERF_COUNTER_IOC_PERIOD: return perf_counter_period(counter, (u64 __user *)arg); + case PERF_COUNTER_IOC_SET_OUTPUT: + return perf_counter_set_output(counter, arg); + default: return -ENOTTY; } @@ -2270,6 +2280,11 @@ static int perf_mmap(struct file *file, struct vm_area_struct *vma) WARN_ON_ONCE(counter->ctx->parent_ctx); mutex_lock(&counter->mmap_mutex); + if (counter->output) { + ret = -EINVAL; + goto unlock; + } + if (atomic_inc_not_zero(&counter->mmap_count)) { if (nr_pages != counter->data->nr_pages) ret = -EINVAL; @@ -2655,6 +2670,7 @@ static int perf_output_begin(struct perf_output_handle *handle, struct perf_counter *counter, unsigned int size, int nmi, int sample) { + struct perf_counter *output_counter; struct perf_mmap_data *data; unsigned int offset, head; int have_lost; @@ -2664,13 +2680,17 @@ static int perf_output_begin(struct perf_output_handle *handle, u64 lost; } lost_event; + rcu_read_lock(); /* * For inherited counters we send all the output towards the parent. */ if (counter->parent) counter = counter->parent; - rcu_read_lock(); + output_counter = rcu_dereference(counter->output); + if (output_counter) + counter = output_counter; + data = rcu_dereference(counter->data); if (!data) goto out; @@ -4218,6 +4238,57 @@ err_size: goto out; } +int perf_counter_set_output(struct perf_counter *counter, int output_fd) +{ + struct perf_counter *output_counter = NULL; + struct file *output_file = NULL; + struct perf_counter *old_output; + int fput_needed = 0; + int ret = -EINVAL; + + if (!output_fd) + goto set; + + output_file = fget_light(output_fd, &fput_needed); + if (!output_file) + return -EBADF; + + if (output_file->f_op != &perf_fops) + goto out; + + output_counter = output_file->private_data; + + /* Don't chain output fds */ + if (output_counter->output) + goto out; + + /* Don't set an output fd when we already have an output channel */ + if (counter->data) + goto out; + + atomic_long_inc(&output_file->f_count); + +set: + mutex_lock(&counter->mmap_mutex); + old_output = counter->output; + rcu_assign_pointer(counter->output, output_counter); + mutex_unlock(&counter->mmap_mutex); + + if (old_output) { + /* + * we need to make sure no existing perf_output_*() + * is still referencing this counter. + */ + synchronize_rcu(); + fput(old_output->filp); + } + + ret = 0; +out: + fput_light(output_file, fput_needed); + return ret; +} + /** * sys_perf_counter_open - open a performance counter, associate it to a task/cpu * @@ -4240,7 +4311,7 @@ SYSCALL_DEFINE5(perf_counter_open, int ret; /* for future expandability... */ - if (flags) + if (flags & ~(PERF_FLAG_FD_NO_GROUP | PERF_FLAG_FD_OUTPUT)) return -EINVAL; ret = perf_copy_attr(attr_uptr, &attr); @@ -4268,7 +4339,7 @@ SYSCALL_DEFINE5(perf_counter_open, * Look up the group leader (we will attach this counter to it): */ group_leader = NULL; - if (group_fd != -1) { + if (group_fd != -1 && !(flags & PERF_FLAG_FD_NO_GROUP)) { ret = -EINVAL; group_file = fget_light(group_fd, &fput_needed); if (!group_file) @@ -4310,6 +4381,12 @@ SYSCALL_DEFINE5(perf_counter_open, if (!counter_file) goto err_free_put_context; + if (flags & PERF_FLAG_FD_OUTPUT) { + ret = perf_counter_set_output(counter, group_fd); + if (ret) + goto err_free_put_context; + } + counter->filp = counter_file; WARN_ON_ONCE(ctx->parent_ctx); mutex_lock(&ctx->mutex); |