[PATCH 03/26] tracing, perf: Implement BPF programs attached to uprobes

[Arnaldo Carvalho de Melo <acme@kernel.org>]

From: Wang Nan <wangnan0@huawei.com>

By copying BPF related operation to uprobe processing path, this patch
allow users attach BPF programs to uprobes like what they are already
doing on kprobes.

After this patch, users are allowed to use PERF_EVENT_IOC_SET_BPF on a
uprobe perf event. Which make it possible to profile user space programs
and kernel events together using BPF.

Because of this patch, CONFIG_BPF_EVENTS should be selected by
CONFIG_UPROBE_EVENT to ensure trace_call_bpf() is compiled even if
KPROBE_EVENT is not set.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: David Ahern <dsahern@gmail.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kaixu Xia <xiakaixu@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1435716878-189507-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 include/linux/trace_events.h | 5 +++++
 kernel/events/core.c         | 4 ++--
 kernel/trace/Kconfig         | 2 +-
 kernel/trace/trace_uprobe.c  | 5 +++++
 4 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/include/linux/trace_events.h b/include/linux/trace_events.h
index 180dbf8720f9..ed27917cabc9 100644
--- a/include/linux/trace_events.h
+++ b/include/linux/trace_events.h
@@ -243,6 +243,7 @@ enum {
 	TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
 	TRACE_EVENT_FL_TRACEPOINT_BIT,
 	TRACE_EVENT_FL_KPROBE_BIT,
+	TRACE_EVENT_FL_UPROBE_BIT,
 };
 
 /*
@@ -257,6 +258,7 @@ enum {
  *  USE_CALL_FILTER - For trace internal events, don't use file filter
  *  TRACEPOINT    - Event is a tracepoint
  *  KPROBE        - Event is a kprobe
+ *  UPROBE        - Event is a uprobe
  */
 enum {
 	TRACE_EVENT_FL_FILTERED		= (1 << TRACE_EVENT_FL_FILTERED_BIT),
@@ -267,8 +269,11 @@ enum {
 	TRACE_EVENT_FL_USE_CALL_FILTER	= (1 << TRACE_EVENT_FL_USE_CALL_FILTER_BIT),
 	TRACE_EVENT_FL_TRACEPOINT	= (1 << TRACE_EVENT_FL_TRACEPOINT_BIT),
 	TRACE_EVENT_FL_KPROBE		= (1 << TRACE_EVENT_FL_KPROBE_BIT),
+	TRACE_EVENT_FL_UPROBE		= (1 << TRACE_EVENT_FL_UPROBE_BIT),
 };
 
+#define TRACE_EVENT_FL_UKPROBE (TRACE_EVENT_FL_KPROBE | TRACE_EVENT_FL_UPROBE)
+
 struct trace_event_call {
 	struct list_head	list;
 	struct trace_event_class *class;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index bdea12924b11..77f9e5d0e2d1 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6846,8 +6846,8 @@ static int perf_event_set_bpf_prog(struct perf_event *event, u32 prog_fd)
 	if (event->tp_event->prog)
 		return -EEXIST;
 
-	if (!(event->tp_event->flags & TRACE_EVENT_FL_KPROBE))
-		/* bpf programs can only be attached to kprobes */
+	if (!(event->tp_event->flags & TRACE_EVENT_FL_UKPROBE))
+		/* bpf programs can only be attached to u/kprobes */
 		return -EINVAL;
 
 	prog = bpf_prog_get(prog_fd);
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index 3b9a48ae153a..1153c43428f3 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -434,7 +434,7 @@ config UPROBE_EVENT
 
 config BPF_EVENTS
 	depends on BPF_SYSCALL
-	depends on KPROBE_EVENT
+	depends on KPROBE_EVENT || UPROBE_EVENT
 	bool
 	default y
 	help
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index aa1ea7b36fa8..f97479f1ce35 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -1095,11 +1095,15 @@ static void __uprobe_perf_func(struct trace_uprobe *tu,
 {
 	struct trace_event_call *call = &tu->tp.call;
 	struct uprobe_trace_entry_head *entry;
+	struct bpf_prog *prog = call->prog;
 	struct hlist_head *head;
 	void *data;
 	int size, esize;
 	int rctx;
 
+	if (prog && !trace_call_bpf(prog, regs))
+		return;
+
 	esize = SIZEOF_TRACE_ENTRY(is_ret_probe(tu));
 
 	size = esize + tu->tp.size + dsize;
@@ -1289,6 +1293,7 @@ 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);
-- 
2.1.0