2 files changed, 66 insertions, 5 deletions

diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
index 39d8860b2684..165287fd2cc4 100644
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -804,12 +804,18 @@ struct perf_event {
 #endif /* CONFIG_PERF_EVENTS */
 };
 
+enum perf_event_context_type {
+        task_context,
+        cpu_context,
+};
+
 /**
  * struct perf_event_context - event context structure
  *
  * Used as a container for task events and CPU events as well:
  */
 struct perf_event_context {
+        enum perf_event_context_type    type;
         struct pmu                      *pmu;
         /*
          * Protect the states of the events in the list,
diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index ce95617f5d2c..6d7eef5f3c41 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -5184,6 +5184,7 @@ int perf_pmu_register(struct pmu *pmu)
 
                 cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
                 __perf_event_init_context(&cpuctx->ctx);
+                cpuctx->ctx.type = cpu_context;
                 cpuctx->ctx.pmu = pmu;
                 cpuctx->timer_interval = TICK_NSEC;
                 hrtimer_init(&cpuctx->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
@@ -5517,7 +5518,8 @@ SYSCALL_DEFINE5(perf_event_open,
                 struct perf_event_attr __user *, attr_uptr,
                 pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
 {
-        struct perf_event *event, *group_leader = NULL, *output_event = NULL;
+        struct perf_event *group_leader = NULL, *output_event = NULL;
+        struct perf_event *event, *sibling;
         struct perf_event_attr attr;
         struct perf_event_context *ctx;
         struct file *event_file = NULL;
@@ -5525,6 +5527,7 @@ SYSCALL_DEFINE5(perf_event_open,
         struct task_struct *task = NULL;
         struct pmu *pmu;
         int event_fd;
+        int move_group = 0;
         int fput_needed = 0;
         int err;
 
@@ -5574,8 +5577,29 @@ SYSCALL_DEFINE5(perf_event_open,
          * any hardware group.
          */
         pmu = event->pmu;
-        if ((pmu->task_ctx_nr == perf_sw_context) && group_leader)
-                pmu = group_leader->pmu;
+
+        if (group_leader &&
+            (is_software_event(event) != is_software_event(group_leader))) {
+                if (is_software_event(event)) {
+                        /*
+                         * If event and group_leader are not both a software
+                         * event, and event is, then group leader is not.
+                         *
+                         * Allow the addition of software events to !software
+                         * groups, this is safe because software events never
+                         * fail to schedule.
+                         */
+                        pmu = group_leader->pmu;
+                } else if (is_software_event(group_leader) &&
+                           (group_leader->group_flags & PERF_GROUP_SOFTWARE)) {
+                        /*
+                         * In case the group is a pure software group, and we
+                         * try to add a hardware event, move the whole group to
+                         * the hardware context.
+                         */
+                        move_group = 1;
+                }
+        }
 
         if (pid != -1)
                 task = find_lively_task_by_vpid(pid);
@@ -5605,8 +5629,14 @@ SYSCALL_DEFINE5(perf_event_open,
                  * Do not allow to attach to a group in a different
                  * task or CPU context:
                  */
-                if (group_leader->ctx != ctx)
-                        goto err_context;
+                if (move_group) {
+                        if (group_leader->ctx->type != ctx->type)
+                                goto err_context;
+                } else {
+                        if (group_leader->ctx != ctx)
+                                goto err_context;
+                }
+
                 /*
                  * Only a group leader can be exclusive or pinned
                  */
@@ -5626,9 +5656,34 @@ SYSCALL_DEFINE5(perf_event_open,
                 goto err_context;
         }
 
+        if (move_group) {
+                struct perf_event_context *gctx = group_leader->ctx;
+
+                mutex_lock(&gctx->mutex);
+                perf_event_remove_from_context(group_leader);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_event_remove_from_context(sibling);
+                        put_ctx(gctx);
+                }
+                mutex_unlock(&gctx->mutex);
+                put_ctx(gctx);
+        }
+
         event->filp = event_file;
         WARN_ON_ONCE(ctx->parent_ctx);
         mutex_lock(&ctx->mutex);
+
+        if (move_group) {
+                perf_install_in_context(ctx, group_leader, cpu);
+                get_ctx(ctx);
+                list_for_each_entry(sibling, &group_leader->sibling_list,
+                                    group_entry) {
+                        perf_install_in_context(ctx, sibling, cpu);
+                        get_ctx(ctx);
+                }
+        }
+
         perf_install_in_context(ctx, event, cpu);
         ++ctx->generation;
         mutex_unlock(&ctx->mutex);