[RFC PATCH 12/13] perf record: Add UBPF hooks at beginning and end of perf record

[Wang Nan]

Like tracepoint in kernel code, UBPF hooks can be added in perf code and
trigger UBPF programs passed by BPF scripts. The first two UBPF hooks
added are record start/end. UBPF scripts can initial BPF maps in
record start, and report result when record finished.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Li Zefan <lizefan@xxxxxxxxxx>
---
 tools/perf/builtin-record.c       |  4 ++
 tools/perf/util/Build             |  2 +-
 tools/perf/util/ubpf-hooks-list.h | 10 +++++
 tools/perf/util/ubpf-hooks.c      | 81 +++++++++++++++++++++++++++++++++++++++
 tools/perf/util/ubpf-hooks.h      | 35 +++++++++++++++++
 5 files changed, 131 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/util/ubpf-hooks-list.h
 create mode 100644 tools/perf/util/ubpf-hooks.c
 create mode 100644 tools/perf/util/ubpf-hooks.h

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c7f92cc..0c49249 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -35,6 +35,7 @@
 #include "util/llvm-utils.h"
 #include "util/bpf-loader.h"
 #include "util/trigger.h"
+#include "util/ubpf-hooks.h"
 #include "asm/bug.h"
 
 #include <unistd.h>
@@ -824,6 +825,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 
 	auxtrace_snapshot_ready();
 	switch_output_ready();
+	ubpf_hook_perf_record_start(0);
 	for (;;) {
 		unsigned long long hits = rec->samples;
 
@@ -888,6 +890,8 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
 			disabled = true;
 		}
 	}
+	ubpf_hook_perf_record_end(0, rec->samples);
+
 	auxtrace_snapshot_off();
 	switch_output_off();
 
diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index e193e6b..c3b8763 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -87,7 +87,7 @@ libperf-y += mem-events.o
 
 libperf-$(CONFIG_LIBBPF) += bpf-loader.o
 libperf-$(CONFIG_BPF_PROLOGUE) += bpf-prologue.o
-libperf-$(CONFIG_UBPF) += ubpf-helpers.o
+libperf-$(CONFIG_UBPF) += ubpf-helpers.o ubpf-hooks.o
 libperf-$(CONFIG_LIBELF) += symbol-elf.o
 libperf-$(CONFIG_LIBELF) += probe-file.o
 libperf-$(CONFIG_LIBELF) += probe-event.o
diff --git a/tools/perf/util/ubpf-hooks-list.h b/tools/perf/util/ubpf-hooks-list.h
new file mode 100644
index 0000000..626d18a
--- /dev/null
+++ b/tools/perf/util/ubpf-hooks-list.h
@@ -0,0 +1,10 @@
+UBPF_HOOK(perf_record_start,,)
+
+UBPF_HOOK(perf_record_end,
+		__UBPF_HOOK_ARG(
+			__arg(int, samples)
+		),
+		__UBPF_HOOK_ASSIGN(
+			__entry.samples = samples;
+		)
+	)
diff --git a/tools/perf/util/ubpf-hooks.c b/tools/perf/util/ubpf-hooks.c
new file mode 100644
index 0000000..9a53f7c
--- /dev/null
+++ b/tools/perf/util/ubpf-hooks.c
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2016, Wang Nan <wangnan0@xxxxxxxxxx>
+ * Copyright (C) 2016, Huawei Inc.
+ */
+
+#include <bpf/libbpf.h>
+#include <asm/bug.h>
+#include <ubpf.h>
+#include "ubpf-hooks.h"
+#include "debug.h"
+
+static int run_ubpf_program(struct bpf_program *prog, void *mem, size_t len)
+{
+	struct ubpf_vm *vm;
+	int ret;
+
+	vm = bpf_program__vm(prog);
+	if (!vm) {
+		WARN_ONCE(!vm, "Unable to fetch vm from UBPF program\n");
+		return -EINVAL;
+	}
+
+	ret = ubpf_exec(vm, mem, len);
+	pr_debug("program %s returns %d\n",
+		 bpf_program__title(prog, false), ret);
+	return ret;
+}
+
+static int
+run_ubpf_programs(unsigned long flags, const char *expect_title,
+		  void *mem, size_t len)
+{
+
+	struct bpf_object *obj, *tmp;
+	struct bpf_program *prog;
+	const char *title;
+	int err;
+
+	if (!len)
+		mem = NULL;
+
+	bpf_object__for_each_safe(obj, tmp) {
+		bpf_object__for_each_program(prog, obj) {
+			if (bpf_program__is_ubpf(prog)) {
+				title = bpf_program__title(prog, false);
+				if (!title)
+					continue;
+				if (strcmp(title, expect_title) != 0)
+					continue;
+				err = run_ubpf_program(prog, mem, len);
+				if (err && (flags & UBPF_HOOK_BREAKABLE))
+					return err;
+			}
+		}
+	}
+
+	return 0;
+}
+
+#define __arg(t, n) t n;
+#define __UBPF_HOOK_ARG(args) args
+#define UBPF_HOOK(n, args, assign) struct ubpf_hook_##n##_proto {args};
+#include "ubpf-hooks-list.h"
+#undef UBPF_HOOK
+#undef __UBPF_HOOK_ARG
+#undef __arg
+
+#define __arg(t, n) , t n
+#define __UBPF_HOOK_ASSIGN(code) do {code;} while(0)
+#define __UBPF_HOOK_ARG(args) args
+#define UBPF_HOOK(n, a, assign) 		\
+int ubpf_hook_##n(unsigned long flags a) {	\
+	struct ubpf_hook_##n##_proto __entry;	\
+	assign;					\
+	return run_ubpf_programs(flags, "UBPF;"#n, &__entry, sizeof(__entry));\
+}
+#include "ubpf-hooks-list.h"
+#undef UBPF_HOOK
+#undef __UBPF_HOOK_ARG
+#undef __UBPF_HOOK_ASSIGN
+#undef __arg
diff --git a/tools/perf/util/ubpf-hooks.h b/tools/perf/util/ubpf-hooks.h
new file mode 100644
index 0000000..165f52d
--- /dev/null
+++ b/tools/perf/util/ubpf-hooks.h
@@ -0,0 +1,35 @@
+/*
+ * Copyright (C) 2016, Wang Nan <wangnan0@xxxxxxxxxx>
+ * Copyright (C) 2016, Huawei Inc.
+ */
+#ifndef __PERF_UBPF_HOOKS_H
+#define __PERF_UBPF_HOOKS_H
+
+#include <linux/compiler.h>
+
+#define UBPF_HOOK_BREAKABLE	1
+
+#ifdef HAVE_UBPF_SUPPORT
+
+#define __arg(t, n) , t n
+#define __UBPF_HOOK_ARG(args) args
+#define UBPF_HOOK(n, args, assign) int ubpf_hook_##n(unsigned long flags args);
+#include "ubpf-hooks-list.h"
+#undef UBPF_HOOK
+#undef __UBPF_HOOK_ARG
+#undef __arg
+
+#else
+
+#define __arg(t, n) , t n __maybe_unused
+#define __UBPF_HOOK_ARG(args) args
+#define UBPF_HOOK(n, args, assign) \
+static inline int ubpf_hook_##n(unsigned long flags __maybe_unused args) {return 0;};
+#include "ubpf-hooks-list.h"
+#undef UBPF_HOOK
+#undef __UBPF_HOOK_ARG
+#undef __arg
+
+#endif
+
+#endif
-- 
1.8.3.4