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

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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>
This commit is contained in:
Oleg Nesterov 2013-02-03 20:58:35 +01:00
parent bdf8647c44
commit 736288ba50
1 changed files with 55 additions and 0 deletions
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55
kernel/trace/trace_uprobe.c
View file

@ -28,6 +28,12 @@
#define UPROBE_EVENT_SYSTEM "uprobes"
struct trace_uprobe_filter {
rwlock_t rwlock;
int nr_systemwide;
struct list_head perf_events;
};
/*
* uprobe event core functions
*/
@ -35,6 +41,7 @@ struct trace_uprobe {
struct list_head list;
struct ftrace_event_class class;
struct ftrace_event_call call;
struct trace_uprobe_filter filter;
struct uprobe_consumer consumer;
struct inode *inode;
char *filename;
@ -58,6 +65,18 @@ static LIST_HEAD(uprobe_list);
static int uprobe_dispatcher(struct uprobe_consumer *con, struct pt_regs *regs);
static inline void init_trace_uprobe_filter(struct trace_uprobe_filter *filter)
{
rwlock_init(&filter->rwlock);
filter->nr_systemwide = 0;
INIT_LIST_HEAD(&filter->perf_events);
}
static inline bool uprobe_filter_is_empty(struct trace_uprobe_filter *filter)
{
return !filter->nr_systemwide && list_empty(&filter->perf_events);
}
/*
* Allocate new trace_uprobe and initialize it (including uprobes).
*/
@ -87,6 +106,7 @@ alloc_trace_uprobe(const char *group, const char *event, int nargs)
INIT_LIST_HEAD(&tu->list);
tu->consumer.handler = uprobe_dispatcher;
init_trace_uprobe_filter(&tu->filter);
return tu;
error:
@ -544,6 +564,8 @@ static int probe_event_enable(struct trace_uprobe *tu, int flag)
if (is_trace_uprobe_enabled(tu))
return -EINTR;
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
tu->flags |= flag;
ret = uprobe_register(tu->inode, tu->offset, &tu->consumer);
if (ret)
@ -557,6 +579,8 @@ static void probe_event_disable(struct trace_uprobe *tu, int flag)
if (!is_trace_uprobe_enabled(tu))
return;
WARN_ON(!uprobe_filter_is_empty(&tu->filter));
uprobe_unregister(tu->inode, tu->offset, &tu->consumer);
tu->flags &= ~flag;
}
@ -632,6 +656,30 @@ static int set_print_fmt(struct trace_uprobe *tu)
}
#ifdef CONFIG_PERF_EVENTS
static int uprobe_perf_open(struct trace_uprobe *tu, struct perf_event *event)
{
write_lock(&tu->filter.rwlock);
if (event->hw.tp_target)
list_add(&event->hw.tp_list, &tu->filter.perf_events);
else
tu->filter.nr_systemwide++;
write_unlock(&tu->filter.rwlock);
return 0;
}
static int uprobe_perf_close(struct trace_uprobe *tu, struct perf_event *event)
{
write_lock(&tu->filter.rwlock);
if (event->hw.tp_target)
list_del(&event->hw.tp_list);
else
tu->filter.nr_systemwide--;
write_unlock(&tu->filter.rwlock);
return 0;
}
/* uprobe profile handler */
static void uprobe_perf_func(struct trace_uprobe *tu, struct pt_regs *regs)
{
@ -687,6 +735,13 @@ int trace_uprobe_register(struct ftrace_event_call *event, enum trace_reg type,
case TRACE_REG_PERF_UNREGISTER:
probe_event_disable(tu, TP_FLAG_PROFILE);
return 0;
case TRACE_REG_PERF_OPEN:
return uprobe_perf_open(tu, data);
case TRACE_REG_PERF_CLOSE:
return uprobe_perf_close(tu, data);
#endif
default:
return 0;