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[RFC PATCH v10 02/50] tracing, perf: Implement BPF programs attached to uprobes

From Wang Nan <wangnan0@huawei.com>
Newsgroups linux.kernel
Subject [RFC PATCH v10 02/50] tracing, perf: Implement BPF programs attached to uprobes
Date 2015-07-01 04:20 +0200
Message-ID <pHfMZ-3Uy-19@gated-at.bofh.it> (permalink)
References <pHfMZ-3Uy-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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>
---
 include/linux/ftrace_event.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/ftrace_event.h b/include/linux/ftrace_event.h
index ec48c92..98cb3d6 100644
--- a/include/linux/ftrace_event.h
+++ b/include/linux/ftrace_event.h
@@ -254,6 +254,7 @@ enum {
 	TRACE_EVENT_FL_USE_CALL_FILTER_BIT,
 	TRACE_EVENT_FL_TRACEPOINT_BIT,
 	TRACE_EVENT_FL_KPROBE_BIT,
+	TRACE_EVENT_FL_UPROBE_BIT,
 };
 
 /*
@@ -268,6 +269,7 @@ enum {
  *  USE_CALL_FILTER - For ftrace 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),
@@ -278,8 +280,11 @@ 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 ftrace_event_call {
 	struct list_head	list;
 	struct ftrace_event_class *class;
diff --git a/kernel/events/core.c b/kernel/events/core.c
index 8e13f3e..a8f75bf 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -6751,8 +6751,8 @@ 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 3b9a48a..1153c43 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 6dd022c..0b580bd 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 ftrace_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);
-- 
1.8.3.4

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Thread

[RFC PATCH v10 00/50] perf tools: filtering events using eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 18/50] bpf tools: Introduce bpf_load_program() to bpf.c Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 07/50] bpf tools: Check endianness and make libbpf fail early Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 25/50] perf tools: Call clang to compile C source to object code Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 02/50] tracing, perf: Implement BPF programs attached to uprobes Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 05/50] bpf tools: Open eBPF object file and do basic validation Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 22/50] bpf tools: Link all bpf objects onto a list Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 27/50] perf tools: Auto detecting kernel build directory Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 06/50] bpf tools: Read eBPF object from buffer Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 13/50] bpf tools: Collect relocation sections from SHT_REL sections Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 01/50] bpf: Use correct #ifdef controller for trace_call_bpf() Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 16/50] bpf tools: Create eBPF maps defined in an object file Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  [RFC PATCH v10 17/50] bpf tools: Relocate eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-07-01 04:20 +0200
  Re: [RFC PATCH v10 23/50] perf tools: Make perf depend on libbpf Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-07-08 15:10 +0200
  Re: [RFC PATCH v10 23/50] perf tools: Make perf depend on libbpf Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-07-08 15:10 +0200

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