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Subject[PATCH v4 4/6] perf: implement pmu perf_uprobe
Date
This patch adds perf_uprobe support with similar pattern as previous
patch (for kprobe).

Two functions, create_local_trace_uprobe() and
destroy_local_trace_uprobe(), are created so a uprobe can be created
and attached to the file descriptor created by perf_event_open().

Signed-off-by: Song Liu <songliubraving@fb.com>
Reviewed-by: Yonghong Song <yhs@fb.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
---
include/linux/trace_events.h | 4 ++
kernel/events/core.c | 41 ++++++++++++++++++++
kernel/trace/trace_event_perf.c | 54 ++++++++++++++++++++++++++
kernel/trace/trace_probe.h | 4 ++
kernel/trace/trace_uprobe.c | 86 +++++++++++++++++++++++++++++++++++++----
5 files changed, 181 insertions(+), 8 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index e20297f..e0274c7 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -498,6 +498,10 @@ extern void perf_trace_del(struct perf_event *event, int flags);
extern int perf_kprobe_init(struct perf_event *event);
extern void perf_kprobe_destroy(struct perf_event *event);
#endif
+#ifdef CONFIG_UPROBE_EVENTS
+extern int perf_uprobe_init(struct perf_event *event);
+extern void perf_uprobe_destroy(struct perf_event *event);
+#endif
extern int ftrace_profile_set_filter(struct perf_event *event, int event_id,
char *filter_str);
extern void ftrace_profile_free_filter(struct perf_event *event);
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 33d833c..d455635 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8015,6 +8015,40 @@ static int perf_kprobe_event_init(struct perf_event *event)
}
#endif /* CONFIG_KPROBE_EVENTS */

+#ifdef CONFIG_UPROBE_EVENTS
+static int perf_uprobe_event_init(struct perf_event *event);
+static struct pmu perf_uprobe = {
+ .task_ctx_nr = perf_sw_context,
+ .event_init = perf_uprobe_event_init,
+ .add = perf_trace_add,
+ .del = perf_trace_del,
+ .start = perf_swevent_start,
+ .stop = perf_swevent_stop,
+ .read = perf_swevent_read,
+};
+
+static int perf_uprobe_event_init(struct perf_event *event)
+{
+ int err;
+
+ if (event->attr.type != perf_uprobe.type)
+ return -ENOENT;
+ /*
+ * no branch sampling for probe events
+ */
+ if (has_branch_stack(event))
+ return -EOPNOTSUPP;
+
+ err = perf_uprobe_init(event);
+ if (err)
+ return err;
+
+ event->destroy = perf_uprobe_destroy;
+
+ return 0;
+}
+#endif /* CONFIG_UPROBE_EVENTS */
+
/*
* returns true if the event is a tracepoint, or a kprobe/upprobe created
* with perf_event_open()
@@ -8027,6 +8061,10 @@ static inline bool perf_event_is_tracing(struct perf_event *event)
if (event->pmu == &perf_kprobe)
return true;
#endif
+#if CONFIG_UPROBE_EVENTS
+ if (event->pmu == &perf_uprobe)
+ return true;
+#endif
return false;
}

@@ -8036,6 +8074,9 @@ static inline void perf_tp_register(void)
#ifdef CONFIG_KPROBE_EVENTS
perf_pmu_register(&perf_kprobe, "kprobe", -1);
#endif
+#ifdef CONFIG_UPROBE_EVENTS
+ perf_pmu_register(&perf_uprobe, "uprobe", -1);
+#endif
}

static void perf_event_free_filter(struct perf_event *event)
diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index 4de5891..edbbe31 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -287,6 +287,60 @@ void perf_kprobe_destroy(struct perf_event *p_event)
}
#endif /* CONFIG_KPROBE_EVENTS */

+#ifdef CONFIG_UPROBE_EVENTS
+int perf_uprobe_init(struct perf_event *p_event)
+{
+ int ret;
+ char *path = NULL;
+ struct trace_event_call *tp_event;
+
+ if (!p_event->attr.uprobe_path)
+ return -EINVAL;
+ path = kzalloc(PATH_MAX, GFP_KERNEL);
+ if (!path)
+ return -ENOMEM;
+ ret = strncpy_from_user(
+ path, u64_to_user_ptr(p_event->attr.uprobe_path), PATH_MAX);
+ if (ret < 0)
+ goto out;
+ if (path[0] == '\0') {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ tp_event = create_local_trace_uprobe(
+ path, p_event->attr.probe_offset,
+ p_event->attr.config & PERF_PROBE_CONFIG_IS_RETPROBE);
+ if (IS_ERR(tp_event)) {
+ ret = PTR_ERR(tp_event);
+ goto out;
+ }
+
+ /*
+ * local trace_uprobe need to hold event_mutex to call
+ * uprobe_buffer_enable() and uprobe_buffer_disable().
+ * event_mutex is not required for local trace_kprobes.
+ */
+ mutex_lock(&event_mutex);
+ ret = perf_trace_event_init(tp_event, p_event);
+ if (ret)
+ destroy_local_trace_uprobe(tp_event);
+ mutex_unlock(&event_mutex);
+out:
+ kfree(path);
+ return ret;
+}
+
+void perf_uprobe_destroy(struct perf_event *p_event)
+{
+ mutex_lock(&event_mutex);
+ perf_trace_event_close(p_event);
+ perf_trace_event_unreg(p_event);
+ mutex_unlock(&event_mutex);
+ destroy_local_trace_uprobe(p_event->tp_event);
+}
+#endif /* CONFIG_UPROBE_EVENTS */
+
int perf_trace_add(struct perf_event *p_event, int flags)
{
struct trace_event_call *tp_event = p_event->tp_event;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index 910ae1b..86b5925 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -417,4 +417,8 @@ extern struct trace_event_call *
create_local_trace_kprobe(char *func, void *addr, unsigned long offs,
bool is_return);
extern void destroy_local_trace_kprobe(struct trace_event_call *event_call);
+
+extern struct trace_event_call *
+create_local_trace_uprobe(char *name, unsigned long offs, bool is_return);
+extern void destroy_local_trace_uprobe(struct trace_event_call *event_call);
#endif
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index 4525e02..4d805d2 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -1293,16 +1293,25 @@ static struct trace_event_functions uprobe_funcs = {
.trace = print_uprobe_event
};

-static int register_uprobe_event(struct trace_uprobe *tu)
+static inline void init_trace_event_call(struct trace_uprobe *tu,
+ struct trace_event_call *call)
{
- struct trace_event_call *call = &tu->tp.call;
- int ret;
-
- /* Initialize trace_event_call */
INIT_LIST_HEAD(&call->class->fields);
call->event.funcs = &uprobe_funcs;
call->class->define_fields = uprobe_event_define_fields;

+ call->flags = TRACE_EVENT_FL_UPROBE;
+ call->class->reg = trace_uprobe_register;
+ call->data = tu;
+}
+
+static int register_uprobe_event(struct trace_uprobe *tu)
+{
+ struct trace_event_call *call = &tu->tp.call;
+ int ret = 0;
+
+ init_trace_event_call(tu, call);
+
if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0)
return -ENOMEM;

@@ -1312,9 +1321,6 @@ static int register_uprobe_event(struct trace_uprobe *tu)
return -ENODEV;
}

- call->flags = TRACE_EVENT_FL_UPROBE;
- call->class->reg = trace_uprobe_register;
- call->data = tu;
ret = trace_add_event_call(call);

if (ret) {
@@ -1340,6 +1346,70 @@ static int unregister_uprobe_event(struct trace_uprobe *tu)
return 0;
}

+#ifdef CONFIG_PERF_EVENTS
+struct trace_event_call *
+create_local_trace_uprobe(char *name, unsigned long offs, bool is_return)
+{
+ struct trace_uprobe *tu;
+ struct inode *inode;
+ struct path path;
+ int ret;
+
+ ret = kern_path(name, LOOKUP_FOLLOW, &path);
+ if (ret)
+ return ERR_PTR(ret);
+
+ inode = igrab(d_inode(path.dentry));
+ path_put(&path);
+
+ if (!inode || !S_ISREG(inode->i_mode)) {
+ iput(inode);
+ return ERR_PTR(-EINVAL);
+ }
+
+ /*
+ * local trace_kprobes are not added to probe_list, so they are never
+ * searched in find_trace_kprobe(). Therefore, there is no concern of
+ * duplicated name "DUMMY_EVENT" here.
+ */
+ tu = alloc_trace_uprobe(UPROBE_EVENT_SYSTEM, "DUMMY_EVENT", 0,
+ is_return);
+
+ if (IS_ERR(tu)) {
+ pr_info("Failed to allocate trace_uprobe.(%d)\n",
+ (int)PTR_ERR(tu));
+ return ERR_CAST(tu);
+ }
+
+ tu->offset = offs;
+ tu->inode = inode;
+ tu->filename = kstrdup(name, GFP_KERNEL);
+ init_trace_event_call(tu, &tu->tp.call);
+
+ if (set_print_fmt(&tu->tp, is_ret_probe(tu)) < 0) {
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ return &tu->tp.call;
+error:
+ free_trace_uprobe(tu);
+ return ERR_PTR(ret);
+}
+
+void destroy_local_trace_uprobe(struct trace_event_call *event_call)
+{
+ struct trace_uprobe *tu;
+
+ tu = container_of(event_call, struct trace_uprobe, tp.call);
+
+ kfree(tu->tp.call.print_fmt);
+ tu->tp.call.print_fmt = NULL;
+
+ free_trace_uprobe(tu);
+}
+#endif /* CONFIG_PERF_EVENTS */
+
/* Make a trace interface for controling probe points */
static __init int init_uprobe_trace(void)
{
--
2.9.5
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