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@@ -1243,11 +1243,7 @@ static inline void perf_event__state_init(struct perf_event *event)
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PERF_EVENT_STATE_INACTIVE;
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}
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-/*
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- * Called at perf_event creation and when events are attached/detached from a
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- * group.
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- */
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-static void perf_event__read_size(struct perf_event *event)
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+static void __perf_event_read_size(struct perf_event *event, int nr_siblings)
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{
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int entry = sizeof(u64); /* value */
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int size = 0;
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@@ -1263,7 +1259,7 @@ static void perf_event__read_size(struct perf_event *event)
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entry += sizeof(u64);
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if (event->attr.read_format & PERF_FORMAT_GROUP) {
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- nr += event->group_leader->nr_siblings;
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+ nr += nr_siblings;
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size += sizeof(u64);
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}
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@@ -1271,14 +1267,11 @@ static void perf_event__read_size(struct perf_event *event)
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event->read_size = size;
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}
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-static void perf_event__header_size(struct perf_event *event)
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+static void __perf_event_header_size(struct perf_event *event, u64 sample_type)
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{
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struct perf_sample_data *data;
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- u64 sample_type = event->attr.sample_type;
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u16 size = 0;
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- perf_event__read_size(event);
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-
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if (sample_type & PERF_SAMPLE_IP)
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size += sizeof(data->ip);
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@@ -1303,6 +1296,17 @@ static void perf_event__header_size(struct perf_event *event)
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event->header_size = size;
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}
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+/*
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+ * Called at perf_event creation and when events are attached/detached from a
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+ * group.
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+ */
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+static void perf_event__header_size(struct perf_event *event)
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+{
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+ __perf_event_read_size(event,
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+ event->group_leader->nr_siblings);
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+ __perf_event_header_size(event, event->attr.sample_type);
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+}
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+
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static void perf_event__id_header_size(struct perf_event *event)
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{
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struct perf_sample_data *data;
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@@ -1330,6 +1334,27 @@ static void perf_event__id_header_size(struct perf_event *event)
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event->id_header_size = size;
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}
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+static bool perf_event_validate_size(struct perf_event *event)
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+{
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+ /*
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+ * The values computed here will be over-written when we actually
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+ * attach the event.
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+ */
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+ __perf_event_read_size(event, event->group_leader->nr_siblings + 1);
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+ __perf_event_header_size(event, event->attr.sample_type & ~PERF_SAMPLE_READ);
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+ perf_event__id_header_size(event);
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+
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+ /*
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+ * Sum the lot; should not exceed the 64k limit we have on records.
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+ * Conservative limit to allow for callchains and other variable fields.
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+ */
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+ if (event->read_size + event->header_size +
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+ event->id_header_size + sizeof(struct perf_event_header) >= 16*1024)
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+ return false;
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+
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+ return true;
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+}
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+
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static void perf_group_attach(struct perf_event *event)
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{
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struct perf_event *group_leader = event->group_leader, *pos;
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@@ -8297,13 +8322,35 @@ SYSCALL_DEFINE5(perf_event_open,
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if (move_group) {
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gctx = group_leader->ctx;
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+ mutex_lock_double(&gctx->mutex, &ctx->mutex);
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+ } else {
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+ mutex_lock(&ctx->mutex);
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+ }
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+ if (!perf_event_validate_size(event)) {
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+ err = -E2BIG;
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+ goto err_locked;
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+ }
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+
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+ /*
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+ * Must be under the same ctx::mutex as perf_install_in_context(),
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+ * because we need to serialize with concurrent event creation.
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+ */
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+ if (!exclusive_event_installable(event, ctx)) {
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+ /* exclusive and group stuff are assumed mutually exclusive */
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+ WARN_ON_ONCE(move_group);
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+
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+ err = -EBUSY;
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+ goto err_locked;
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+ }
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+
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+ WARN_ON_ONCE(ctx->parent_ctx);
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+
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+ if (move_group) {
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/*
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* See perf_event_ctx_lock() for comments on the details
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* of swizzling perf_event::ctx.
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*/
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- mutex_lock_double(&gctx->mutex, &ctx->mutex);
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-
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perf_remove_from_context(group_leader, false);
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list_for_each_entry(sibling, &group_leader->sibling_list,
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@@ -8311,13 +8358,7 @@ SYSCALL_DEFINE5(perf_event_open,
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perf_remove_from_context(sibling, false);
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put_ctx(gctx);
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}
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- } else {
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- mutex_lock(&ctx->mutex);
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- }
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- WARN_ON_ONCE(ctx->parent_ctx);
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-
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- if (move_group) {
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/*
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* Wait for everybody to stop referencing the events through
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* the old lists, before installing it on new lists.
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@@ -8349,22 +8390,29 @@ SYSCALL_DEFINE5(perf_event_open,
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perf_event__state_init(group_leader);
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perf_install_in_context(ctx, group_leader, group_leader->cpu);
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get_ctx(ctx);
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- }
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- if (!exclusive_event_installable(event, ctx)) {
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- err = -EBUSY;
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- mutex_unlock(&ctx->mutex);
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- fput(event_file);
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- goto err_context;
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+ /*
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+ * Now that all events are installed in @ctx, nothing
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+ * references @gctx anymore, so drop the last reference we have
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+ * on it.
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+ */
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+ put_ctx(gctx);
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}
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+ /*
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+ * Precalculate sample_data sizes; do while holding ctx::mutex such
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+ * that we're serialized against further additions and before
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+ * perf_install_in_context() which is the point the event is active and
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+ * can use these values.
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+ */
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+ perf_event__header_size(event);
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+ perf_event__id_header_size(event);
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+
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perf_install_in_context(ctx, event, event->cpu);
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perf_unpin_context(ctx);
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- if (move_group) {
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+ if (move_group)
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mutex_unlock(&gctx->mutex);
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- put_ctx(gctx);
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- }
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mutex_unlock(&ctx->mutex);
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put_online_cpus();
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@@ -8375,12 +8423,6 @@ SYSCALL_DEFINE5(perf_event_open,
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list_add_tail(&event->owner_entry, ¤t->perf_event_list);
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mutex_unlock(¤t->perf_event_mutex);
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- /*
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- * Precalculate sample_data sizes
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- */
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- perf_event__header_size(event);
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- perf_event__id_header_size(event);
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-
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/*
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* Drop the reference on the group_event after placing the
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* new event on the sibling_list. This ensures destruction
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@@ -8391,6 +8433,12 @@ SYSCALL_DEFINE5(perf_event_open,
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fd_install(event_fd, event_file);
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return event_fd;
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+err_locked:
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+ if (move_group)
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+ mutex_unlock(&gctx->mutex);
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+ mutex_unlock(&ctx->mutex);
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+/* err_file: */
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+ fput(event_file);
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err_context:
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perf_unpin_context(ctx);
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put_ctx(ctx);
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