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Subject[PATCH 4/6] perf: implement uprobe support to PERF_TYPE_PROBE
Date
This patch adds uprobe support to perf_probe 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>
---
kernel/trace/trace_event_perf.c | 48 +++++++++++++++++++++-
kernel/trace/trace_probe.h | 4 ++
kernel/trace/trace_uprobe.c | 90 ++++++++++++++++++++++++++++++++++++-----
3 files changed, 131 insertions(+), 11 deletions(-)

diff --git a/kernel/trace/trace_event_perf.c b/kernel/trace/trace_event_perf.c
index bf9b99b..4e4de84 100644
--- a/kernel/trace/trace_event_perf.c
+++ b/kernel/trace/trace_event_perf.c
@@ -256,6 +256,39 @@ static int perf_probe_create_kprobe(struct perf_event *p_event,
}
#endif /* CONFIG_KPROBE_EVENTS */

+#ifdef CONFIG_UPROBE_EVENTS
+static int perf_probe_create_uprobe(struct perf_event *p_event,
+ struct probe_desc *pd, char *name)
+{
+ struct trace_event_call *tp_event;
+ int ret;
+
+ if (!name)
+ return -EINVAL;
+ tp_event = create_local_trace_uprobe(
+ name, pd->offset, p_event->attr.is_return);
+ if (IS_ERR(tp_event))
+ return PTR_ERR(tp_event);
+ /*
+ * 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);
+ return ret;
+}
+#else
+static int perf_probe_create_uprobe(struct perf_event *p_event,
+ struct probe_desc *pd, char *name)
+{
+ return -EOPNOTSUPP;
+}
+#endif /* CONFIG_KPROBE_EVENTS */
+
int perf_probe_init(struct perf_event *p_event)
{
struct probe_desc pd;
@@ -292,7 +325,7 @@ int perf_probe_init(struct perf_event *p_event)
if (!p_event->attr.is_uprobe)
ret = perf_probe_create_kprobe(p_event, &pd, name);
else
- ret = -EOPNOTSUPP;
+ ret = perf_probe_create_uprobe(p_event, &pd, name);
out:
kfree(name);
return ret;
@@ -308,13 +341,26 @@ void perf_trace_destroy(struct perf_event *p_event)

void perf_probe_destroy(struct perf_event *p_event)
{
+ /*
+ * 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.
+ */
+ if (p_event->attr.is_uprobe)
+ mutex_lock(&event_mutex);
perf_trace_event_close(p_event);
perf_trace_event_unreg(p_event);
+ if (p_event->attr.is_uprobe)
+ mutex_unlock(&event_mutex);

if (!p_event->attr.is_uprobe) {
#ifdef CONFIG_KPROBE_EVENTS
destroy_local_trace_kprobe(p_event->tp_event);
#endif
+ } else {
+#ifdef CONFIG_UPROBE_EVENTS
+ destroy_local_trace_uprobe(p_event->tp_event);
+#endif
}
}

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
@@ -31,8 +31,8 @@
#define UPROBE_EVENT_SYSTEM "uprobes"

struct uprobe_trace_entry_head {
- struct trace_entry ent;
- unsigned long vaddr[];
+ struct trace_entry ent;
+ unsigned long vaddr[];
};

#define SIZEOF_TRACE_ENTRY(is_return) \
@@ -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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