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Commit 736288ba5016e255869c26296014eeff649971c2

Authored by Oleg Nesterov
1 parent bdf8647c44
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

uprobes/perf: Teach trace_uprobe/perf code to track the active perf_event's 

Introduce "struct trace_uprobe_filter" which records the "active"
perf_event's attached to ftrace_event_call. For the start we simply
use list_head, we can optimize this later if needed. For example, we
do not really need to record an event with ->parent != NULL, we can
rely on parent->child_list. And we can certainly do some optimizations
for the case when 2 events have the same ->tp_target or tp_target->mm.

Change trace_uprobe_register() to process TRACE_REG_PERF_OPEN/CLOSE
and add/del this perf_event to the list.

We can probably avoid any locking, but lets start with the "obvioulsy
correct" trace_uprobe_filter->rwlock which protects everything.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>

Showing 1 changed file with 55 additions and 0 deletions Side-by-side Diff

kernel/trace/trace_uprobe.c
Diff comments   View file @ 736288b
... ... @@ -28,6 +28,12 @@
28 28  
29 29 #define UPROBE_EVENT_SYSTEM "uprobes"
30 30  
  31 +struct trace_uprobe_filter {
  32 + rwlock_t rwlock;
  33 + int nr_systemwide;
  34 + struct list_head perf_events;
  35 +};
  36 +
31 37 /*
32 38 * uprobe event core functions
33 39 */
... ... @@ -35,6 +41,7 @@
35 41 struct list_head list;
36 42 struct ftrace_event_class class;
37 43 struct ftrace_event_call call;
  44 + struct trace_uprobe_filter filter;
38 45 struct uprobe_consumer consumer;
39 46 struct inode *inode;
40 47 char *filename;
... ... @@ -58,6 +65,18 @@
58 65  
59 66 static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
60 67  
  68 +static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
  69 +{
  70 + rwlock_init(&filter->rwlock);
  71 + filter->nr_systemwide = 0;
  72 + INIT_LIST_HEAD(&filter->perf_events);
  73 +}
  74 +
  75 +static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
  76 +{
  77 + return !filter->nr_systemwide && list_empty(&filter->perf_events);
  78 +}
  79 +
61 80 /*
62 81 * Allocate new trace_uprobe and initialize it (including uprobes).
63 82 */
... ... @@ -87,6 +106,7 @@
87 106  
88 107 INIT_LIST_HEAD(&tu->list);
89 108 tu->consumer.handler = uprobe_dispatcher;
  109 + init_trace_uprobe_filter(&tu->filter);
90 110 return tu;
91 111  
92 112 error:
... ... @@ -544,6 +564,8 @@
544 564 if (is_trace_uprobe_enabled(tu))
545 565 return -EINTR;
546 566  
  567 + WARN_ON(!uprobe_filter_is_empty(&tu->filter));
  568 +
547 569 tu->flags |= flag;
548 570 ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
549 571 if (ret)
... ... @@ -557,6 +579,8 @@
557 579 if (!is_trace_uprobe_enabled(tu))
558 580 return;
559 581  
  582 + WARN_ON(!uprobe_filter_is_empty(&tu->filter));
  583 +
560 584 uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
561 585 tu->flags &= ~flag;
562 586 }
... ... @@ -632,6 +656,30 @@
632 656 }
633 657  
634 658 #ifdef CONFIG_PERF_EVENTS
  659 +static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
  660 +{
  661 + write_lock(&tu->filter.rwlock);
  662 + if (event->hw.tp_target)
  663 + list_add(&event->hw.tp_list, &tu->filter.perf_events);
  664 + else
  665 + tu->filter.nr_systemwide++;
  666 + write_unlock(&tu->filter.rwlock);
  667 +
  668 + return 0;
  669 +}
  670 +
  671 +static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
  672 +{
  673 + write_lock(&tu->filter.rwlock);
  674 + if (event->hw.tp_target)
  675 + list_del(&event->hw.tp_list);
  676 + else
  677 + tu->filter.nr_systemwide--;
  678 + write_unlock(&tu->filter.rwlock);
  679 +
  680 + return 0;
  681 +}
  682 +
635 683 /* uprobe profile handler */
636 684 static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
637 685 {
... ... @@ -687,6 +735,13 @@
687 735 case TRACE_REG_PERF_UNREGISTER:
688 736 probe_event_disable(tu, TP_FLAG_PROFILE);
689 737 return 0;
  738 +
  739 + case TRACE_REG_PERF_OPEN:
  740 + return uprobe_perf_open(tu, data);
  741 +
  742 + case TRACE_REG_PERF_CLOSE:
  743 + return uprobe_perf_close(tu, data);
  744 +
690 745 #endif
691 746 default:
692 747 return 0;