2 files changed, 238 insertions, 83 deletions

diff --git a/include/linux/perf_counter.h b/include/linux/perf_counter.h
index 2b36afe6ae0f..b53f7006cc4e 100644
--- a/include/linux/perf_counter.h
+++ b/include/linux/perf_counter.h
@@ -115,7 +115,7 @@ enum perf_counter_sample_format {
         PERF_SAMPLE_TID                         = 1U << 1,
         PERF_SAMPLE_TIME                        = 1U << 2,
         PERF_SAMPLE_ADDR                        = 1U << 3,
-        PERF_SAMPLE_GROUP                       = 1U << 4,
+        PERF_SAMPLE_READ                        = 1U << 4,
         PERF_SAMPLE_CALLCHAIN                   = 1U << 5,
         PERF_SAMPLE_ID                          = 1U << 6,
         PERF_SAMPLE_CPU                         = 1U << 7,
@@ -127,16 +127,32 @@ enum perf_counter_sample_format {
 };
 
 /*
- * Bits that can be set in attr.read_format to request that
- * reads on the counter should return the indicated quantities,
- * in increasing order of bit value, after the counter value.
+ * The format of the data returned by read() on a perf counter fd,
+ * as specified by attr.read_format:
+ *
+ * struct read_format {
+ *      { u64           value;
+ *        { u64         time_enabled; } && PERF_FORMAT_ENABLED
+ *        { u64         time_running; } && PERF_FORMAT_RUNNING
+ *        { u64         id;           } && PERF_FORMAT_ID
+ *      } && !PERF_FORMAT_GROUP
+ *
+ *      { u64           nr;
+ *        { u64         time_enabled; } && PERF_FORMAT_ENABLED
+ *        { u64         time_running; } && PERF_FORMAT_RUNNING
+ *        { u64         value;
+ *          { u64       id;           } && PERF_FORMAT_ID
+ *        }             cntr[nr];
+ *      } && PERF_FORMAT_GROUP
+ * };
  */
 enum perf_counter_read_format {
         PERF_FORMAT_TOTAL_TIME_ENABLED          = 1U << 0,
         PERF_FORMAT_TOTAL_TIME_RUNNING          = 1U << 1,
         PERF_FORMAT_ID                          = 1U << 2,
+        PERF_FORMAT_GROUP                       = 1U << 3,
 
-        PERF_FORMAT_MAX = 1U << 3,              /* non-ABI */
+        PERF_FORMAT_MAX = 1U << 4,              /* non-ABI */
 };
 
 #define PERF_ATTR_SIZE_VER0     64      /* sizeof first published struct */
@@ -343,10 +359,8 @@ enum perf_event_type {
          * struct {
          *      struct perf_event_header        header;
          *      u32                             pid, tid;
-         *      u64                             value;
-         *      { u64           time_enabled;   } && PERF_FORMAT_ENABLED
-         *      { u64           time_running;   } && PERF_FORMAT_RUNNING
-         *      { u64           parent_id;      } && PERF_FORMAT_ID
+         *
+         *      struct read_format              values;
          * };
          */
         PERF_EVENT_READ                 = 8,
@@ -364,11 +378,22 @@ enum perf_event_type {
          *      { u32                   cpu, res; } && PERF_SAMPLE_CPU
          *      { u64                   period;   } && PERF_SAMPLE_PERIOD
          *
-         *      { u64                   nr;
-         *        { u64 id, val; }      cnt[nr];  } && PERF_SAMPLE_GROUP
+         *      { struct read_format    values;   } && PERF_SAMPLE_READ
          *
          *      { u64                   nr,
          *        u64                   ips[nr];  } && PERF_SAMPLE_CALLCHAIN
+         *
+         *      #
+         *      # The RAW record below is opaque data wrt the ABI
+         *      #
+         *      # That is, the ABI doesn't make any promises wrt to
+         *      # the stability of its content, it may vary depending
+         *      # on event, hardware, kernel version and phase of
+         *      # the moon.
+         *      #
+         *      # In other words, PERF_SAMPLE_RAW contents are not an ABI.
+         *      #
+         *
          *      { u32                   size;
          *        char                  data[size];}&& PERF_SAMPLE_RAW
          * };
diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c
index 3dd4339589a0..b8c6b97a20a3 100644
--- a/kernel/perf_counter.c
+++ b/kernel/perf_counter.c
@@ -1692,7 +1692,32 @@ static int perf_release(struct inode *inode, struct file *file)
         return 0;
 }
 
-static u64 perf_counter_read_tree(struct perf_counter *counter)
+static int perf_counter_read_size(struct perf_counter *counter)
+{
+        int entry = sizeof(u64); /* value */
+        int size = 0;
+        int nr = 1;
+
+        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                size += sizeof(u64);
+
+        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                size += sizeof(u64);
+
+        if (counter->attr.read_format & PERF_FORMAT_ID)
+                entry += sizeof(u64);
+
+        if (counter->attr.read_format & PERF_FORMAT_GROUP) {
+                nr += counter->group_leader->nr_siblings;
+                size += sizeof(u64);
+        }
+
+        size += entry * nr;
+
+        return size;
+}
+
+static u64 perf_counter_read_value(struct perf_counter *counter)
 {
         struct perf_counter *child;
         u64 total = 0;
@@ -1704,14 +1729,96 @@ static u64 perf_counter_read_tree(struct perf_counter *counter)
         return total;
 }
 
+static int perf_counter_read_entry(struct perf_counter *counter,
+                                   u64 read_format, char __user *buf)
+{
+        int n = 0, count = 0;
+        u64 values[2];
+
+        values[n++] = perf_counter_read_value(counter);
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_counter_id(counter);
+
+        count = n * sizeof(u64);
+
+        if (copy_to_user(buf, values, count))
+                return -EFAULT;
+
+        return count;
+}
+
+static int perf_counter_read_group(struct perf_counter *counter,
+                                   u64 read_format, char __user *buf)
+{
+        struct perf_counter *leader = counter->group_leader, *sub;
+        int n = 0, size = 0, err = -EFAULT;
+        u64 values[3];
+
+        values[n++] = 1 + leader->nr_siblings;
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+                values[n++] = leader->total_time_enabled +
+                        atomic64_read(&leader->child_total_time_enabled);
+        }
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+                values[n++] = leader->total_time_running +
+                        atomic64_read(&leader->child_total_time_running);
+        }
+
+        size = n * sizeof(u64);
+
+        if (copy_to_user(buf, values, size))
+                return -EFAULT;
+
+        err = perf_counter_read_entry(leader, read_format, buf + size);
+        if (err < 0)
+                return err;
+
+        size += err;
+
+        list_for_each_entry(sub, &leader->sibling_list, list_entry) {
+                err = perf_counter_read_entry(counter, read_format,
+                                buf + size);
+                if (err < 0)
+                        return err;
+
+                size += err;
+        }
+
+        return size;
+}
+
+static int perf_counter_read_one(struct perf_counter *counter,
+                                 u64 read_format, char __user *buf)
+{
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = perf_counter_read_value(counter);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+                values[n++] = counter->total_time_enabled +
+                        atomic64_read(&counter->child_total_time_enabled);
+        }
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+                values[n++] = counter->total_time_running +
+                        atomic64_read(&counter->child_total_time_running);
+        }
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_counter_id(counter);
+
+        if (copy_to_user(buf, values, n * sizeof(u64)))
+                return -EFAULT;
+
+        return n * sizeof(u64);
+}
+
 /*
  * Read the performance counter - simple non blocking version for now
  */
 static ssize_t
 perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
 {
-        u64 values[4];
-        int n;
+        u64 read_format = counter->attr.read_format;
+        int ret;
 
         /*
          * Return end-of-file for a read on a counter that is in
@@ -1721,28 +1828,18 @@ perf_read_hw(struct perf_counter *counter, char __user *buf, size_t count)
         if (counter->state == PERF_COUNTER_STATE_ERROR)
                 return 0;
 
+        if (count < perf_counter_read_size(counter))
+                return -ENOSPC;
+
         WARN_ON_ONCE(counter->ctx->parent_ctx);
         mutex_lock(&counter->child_mutex);
-        values[0] = perf_counter_read_tree(counter);
-        n = 1;
-        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
-                values[n++] = counter->total_time_enabled +
-                        atomic64_read(&counter->child_total_time_enabled);
-        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
-                values[n++] = counter->total_time_running +
-                        atomic64_read(&counter->child_total_time_running);
-        if (counter->attr.read_format & PERF_FORMAT_ID)
-                values[n++] = primary_counter_id(counter);
+        if (read_format & PERF_FORMAT_GROUP)
+                ret = perf_counter_read_group(counter, read_format, buf);
+        else
+                ret = perf_counter_read_one(counter, read_format, buf);
         mutex_unlock(&counter->child_mutex);
 
-        if (count < n * sizeof(u64))
-                return -EINVAL;
-        count = n * sizeof(u64);
-
-        if (copy_to_user(buf, values, count))
-                return -EFAULT;
-
-        return count;
+        return ret;
 }
 
 static ssize_t
@@ -2631,6 +2728,79 @@ static u32 perf_counter_tid(struct perf_counter *counter, struct task_struct *p)
         return task_pid_nr_ns(p, counter->ns);
 }
 
+static void perf_output_read_one(struct perf_output_handle *handle,
+                                 struct perf_counter *counter)
+{
+        u64 read_format = counter->attr.read_format;
+        u64 values[4];
+        int n = 0;
+
+        values[n++] = atomic64_read(&counter->count);
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
+                values[n++] = counter->total_time_enabled +
+                        atomic64_read(&counter->child_total_time_enabled);
+        }
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
+                values[n++] = counter->total_time_running +
+                        atomic64_read(&counter->child_total_time_running);
+        }
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_counter_id(counter);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+}
+
+/*
+ * XXX PERF_FORMAT_GROUP vs inherited counters seems difficult.
+ */
+static void perf_output_read_group(struct perf_output_handle *handle,
+                            struct perf_counter *counter)
+{
+        struct perf_counter *leader = counter->group_leader, *sub;
+        u64 read_format = counter->attr.read_format;
+        u64 values[5];
+        int n = 0;
+
+        values[n++] = 1 + leader->nr_siblings;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_ENABLED)
+                values[n++] = leader->total_time_enabled;
+
+        if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING)
+                values[n++] = leader->total_time_running;
+
+        if (leader != counter)
+                leader->pmu->read(leader);
+
+        values[n++] = atomic64_read(&leader->count);
+        if (read_format & PERF_FORMAT_ID)
+                values[n++] = primary_counter_id(leader);
+
+        perf_output_copy(handle, values, n * sizeof(u64));
+
+        list_for_each_entry(sub, &leader->sibling_list, list_entry) {
+                n = 0;
+
+                if (sub != counter)
+                        sub->pmu->read(sub);
+
+                values[n++] = atomic64_read(&sub->count);
+                if (read_format & PERF_FORMAT_ID)
+                        values[n++] = primary_counter_id(sub);
+
+                perf_output_copy(handle, values, n * sizeof(u64));
+        }
+}
+
+static void perf_output_read(struct perf_output_handle *handle,
+                             struct perf_counter *counter)
+{
+        if (counter->attr.read_format & PERF_FORMAT_GROUP)
+                perf_output_read_group(handle, counter);
+        else
+                perf_output_read_one(handle, counter);
+}
+
 void perf_counter_output(struct perf_counter *counter, int nmi,
                                 struct perf_sample_data *data)
 {
@@ -2642,10 +2812,6 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
         struct {
                 u32 pid, tid;
         } tid_entry;
-        struct {
-                u64 id;
-                u64 counter;
-        } group_entry;
         struct perf_callchain_entry *callchain = NULL;
         int callchain_size = 0;
         u64 time;
@@ -2700,10 +2866,8 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
         if (sample_type & PERF_SAMPLE_PERIOD)
                 header.size += sizeof(u64);
 
-        if (sample_type & PERF_SAMPLE_GROUP) {
-                header.size += sizeof(u64) +
-                        counter->nr_siblings * sizeof(group_entry);
-        }
+        if (sample_type & PERF_SAMPLE_READ)
+                header.size += perf_counter_read_size(counter);
 
         if (sample_type & PERF_SAMPLE_CALLCHAIN) {
                 callchain = perf_callchain(data->regs);
@@ -2760,26 +2924,8 @@ void perf_counter_output(struct perf_counter *counter, int nmi,
         if (sample_type & PERF_SAMPLE_PERIOD)
                 perf_output_put(&handle, data->period);
 
-        /*
-         * XXX PERF_SAMPLE_GROUP vs inherited counters seems difficult.
-         */
-        if (sample_type & PERF_SAMPLE_GROUP) {
-                struct perf_counter *leader, *sub;
-                u64 nr = counter->nr_siblings;
-
-                perf_output_put(&handle, nr);
-
-                leader = counter->group_leader;
-                list_for_each_entry(sub, &leader->sibling_list, list_entry) {
-                        if (sub != counter)
-                                sub->pmu->read(sub);
-
-                        group_entry.id = primary_counter_id(sub);
-                        group_entry.counter = atomic64_read(&sub->count);
-
-                        perf_output_put(&handle, group_entry);
-                }
-        }
+        if (sample_type & PERF_SAMPLE_READ)
+                perf_output_read(&handle, counter);
 
         if (sample_type & PERF_SAMPLE_CALLCHAIN) {
                 if (callchain)
@@ -2818,8 +2964,6 @@ struct perf_read_event {
 
         u32                             pid;
         u32                             tid;
-        u64                             value;
-        u64                             format[3];
 };
 
 static void
@@ -2831,34 +2975,20 @@ perf_counter_read_event(struct perf_counter *counter,
                 .header = {
                         .type = PERF_EVENT_READ,
                         .misc = 0,
-                        .size = sizeof(event) - sizeof(event.format),
+                        .size = sizeof(event) + perf_counter_read_size(counter),
                 },
                 .pid = perf_counter_pid(counter, task),
                 .tid = perf_counter_tid(counter, task),
-                .value = atomic64_read(&counter->count),
         };
-        int ret, i = 0;
-
-        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_ENABLED) {
-                event.header.size += sizeof(u64);
-                event.format[i++] = counter->total_time_enabled;
-        }
-
-        if (counter->attr.read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) {
-                event.header.size += sizeof(u64);
-                event.format[i++] = counter->total_time_running;
-        }
-
-        if (counter->attr.read_format & PERF_FORMAT_ID) {
-                event.header.size += sizeof(u64);
-                event.format[i++] = primary_counter_id(counter);
-        }
+        int ret;
 
         ret = perf_output_begin(&handle, counter, event.header.size, 0, 0);
         if (ret)
                 return;
 
-        perf_output_copy(&handle, &event, event.header.size);
+        perf_output_put(&handle, event);
+        perf_output_read(&handle, counter);
+
         perf_output_end(&handle);
 }
 
@@ -3921,9 +4051,9 @@ perf_counter_alloc(struct perf_counter_attr *attr,
         atomic64_set(&hwc->period_left, hwc->sample_period);
 
         /*
-         * we currently do not support PERF_SAMPLE_GROUP on inherited counters
+         * we currently do not support PERF_FORMAT_GROUP on inherited counters
          */
-        if (attr->inherit && (attr->sample_type & PERF_SAMPLE_GROUP))
+        if (attr->inherit && (attr->read_format & PERF_FORMAT_GROUP))
                 goto done;
 
         switch (attr->type) {