[RFC PATCH v6 23/32] perf record: Enable passing bpf object file to --event

[Wang Nan <wangnan0@huawei.com>]

By introducing new rules in tools/perf/util/parse-events.[ly], this
patch enables 'perf record --event bpf_file.o' to select events by
an eBPF object file. It calls parse_events_load_bpf() to load that
file, which uses bpf__prepare_load() and finally calls
bpf_object__open() for the object files.

Instead of introducing evsel to evlist during parsing, events
selected by eBPF object files are appended separately. The reason
is:

 1. During parsing, the probing points have not been initialized.

 2. Currently we are unable to call add_perf_probe_events() twice,
    therefore we have to wait until all such events are collected,
    then probe all points by one call.

The real probing and selecting is reside in following patches.

'bpf-loader.[ch]' are introduced in this patch. Which will be the
interface between perf and libbpf. bpf__prepare_load() resides in
bpf-loader.c. Dummy functions should be used because bpf-loader.c is
available only when CONFIG_LIBBPF is on.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/util/Build          |  1 +
 tools/perf/util/bpf-loader.c   | 60 ++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/bpf-loader.h   | 24 +++++++++++++++++
 tools/perf/util/debug.c        |  5 ++++
 tools/perf/util/debug.h        |  1 +
 tools/perf/util/parse-events.c | 16 +++++++++++
 tools/perf/util/parse-events.h |  2 ++
 tools/perf/util/parse-events.l |  3 +++
 tools/perf/util/parse-events.y | 18 ++++++++++++-
 9 files changed, 129 insertions(+), 1 deletion(-)
 create mode 100644 tools/perf/util/bpf-loader.c
 create mode 100644 tools/perf/util/bpf-loader.h

diff --git a/tools/perf/util/Build b/tools/perf/util/Build
index e4b676d..1e1025f 100644
--- a/tools/perf/util/Build
+++ b/tools/perf/util/Build
@@ -77,6 +77,7 @@ libperf-y += thread-stack.o
 libperf-$(CONFIG_AUXTRACE) += auxtrace.o
 libperf-y += parse-branch-options.o
 
+libperf-$(CONFIG_LIBBPF) += bpf-loader.o
 libperf-$(CONFIG_LIBELF) += symbol-elf.o
 libperf-$(CONFIG_LIBELF) += probe-event.o
 
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
new file mode 100644
index 0000000..e950baa
--- /dev/null
+++ b/tools/perf/util/bpf-loader.c
@@ -0,0 +1,60 @@
+/*
+ * bpf-loader.c
+ *
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ */
+
+#include <bpf/libbpf.h>
+#include "perf.h"
+#include "debug.h"
+#include "bpf-loader.h"
+
+#define DEFINE_PRINT_FN(name, level) \
+static int libbpf_##name(const char *fmt, ...)	\
+{						\
+	va_list args;				\
+	int ret;				\
+						\
+	va_start(args, fmt);			\
+	ret = veprintf(level, verbose, pr_fmt(fmt), args);\
+	va_end(args);				\
+	return ret;				\
+}
+
+DEFINE_PRINT_FN(warning, 0)
+DEFINE_PRINT_FN(info, 0)
+DEFINE_PRINT_FN(debug, 1)
+
+static bool libbpf_initialized = false;
+
+int bpf__prepare_load(const char *filename)
+{
+	struct bpf_object *obj;
+
+	if (!libbpf_initialized)
+		libbpf_set_print(libbpf_warning,
+				 libbpf_info,
+				 libbpf_debug);
+
+	obj = bpf_object__open(filename);
+	if (!obj) {
+		pr_err("bpf: failed to load %s\n", filename);
+		return -EINVAL;
+	}
+
+	/*
+	 * Throw object pointer away: it will be retrived using
+	 * bpf_objects iterater.
+	 */
+
+	return 0;
+}
+
+void bpf__clear(void)
+{
+	struct bpf_object *obj, *tmp;
+
+	bpf_object__for_each(obj, tmp)
+		bpf_object__close(obj);
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
new file mode 100644
index 0000000..39d8d1a
--- /dev/null
+++ b/tools/perf/util/bpf-loader.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2015, Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015, Huawei Inc.
+ */
+#ifndef __BPF_LOADER_H
+#define __BPF_LOADER_H
+
+#include <linux/compiler.h>
+#include "debug.h"
+
+#ifdef HAVE_LIBBPF_SUPPORT
+int bpf__prepare_load(const char *filename);
+
+void bpf__clear(void);
+#else
+static inline int bpf__prepare_load(const char *filename __maybe_unused)
+{
+	pr_err("ERROR: eBPF object loading is disabled during compiling.\n");
+	return -1;
+}
+
+static inline void bpf__clear(void) { }
+#endif
+#endif
diff --git a/tools/perf/util/debug.c b/tools/perf/util/debug.c
index 2da5581..86d9c73 100644
--- a/tools/perf/util/debug.c
+++ b/tools/perf/util/debug.c
@@ -36,6 +36,11 @@ static int _eprintf(int level, int var, const char *fmt, va_list args)
 	return ret;
 }
 
+int veprintf(int level, int var, const char *fmt, va_list args)
+{
+	return _eprintf(level, var, fmt, args);
+}
+
 int eprintf(int level, int var, const char *fmt, ...)
 {
 	va_list args;
diff --git a/tools/perf/util/debug.h b/tools/perf/util/debug.h
index caac2fd..8b9a088 100644
--- a/tools/perf/util/debug.h
+++ b/tools/perf/util/debug.h
@@ -50,6 +50,7 @@ void pr_stat(const char *fmt, ...);
 
 int eprintf(int level, int var, const char *fmt, ...) __attribute__((format(printf, 3, 4)));
 int eprintf_time(int level, int var, u64 t, const char *fmt, ...) __attribute__((format(printf, 4, 5)));
+int veprintf(int level, int var, const char *fmt, va_list args);
 
 int perf_debug_option(const char *str);
 
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 2a4d1ec..6f7a7b1 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -18,6 +18,7 @@
 #include "pmu.h"
 #include "thread_map.h"
 #include "asm/bug.h"
+#include "bpf-loader.h"
 
 #define MAX_NAME_LEN 100
 
@@ -472,6 +473,21 @@ int parse_events_add_tracepoint(struct list_head *list, int *idx,
 		return add_tracepoint_event(list, idx, sys, event);
 }
 
+int parse_events_load_bpf(struct list_head *list __maybe_unused,
+			  int *idx __maybe_unused,
+			  char *bpf_file_name)
+{
+	/*
+	 * Currently don't link any event to list. BPF object files
+	 * should be saved to a seprated list and processed together.
+	 *
+	 * Things could be changed if we solve perf probe reentering
+	 * problem. After that probe events file by file is possible.
+	 * However, probing cost is still need to be considered.
+	 */
+	return bpf__prepare_load(bpf_file_name);
+}
+
 static int
 parse_breakpoint_type(const char *type, struct perf_event_attr *attr)
 {
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 131f29b..41b962a 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -114,6 +114,8 @@ int parse_events__modifier_group(struct list_head *list, char *event_mod);
 int parse_events_name(struct list_head *list, char *name);
 int parse_events_add_tracepoint(struct list_head *list, int *idx,
 				char *sys, char *event);
+int parse_events_load_bpf(struct list_head *list, int *idx,
+			  char *bpf_file_name);
 int parse_events_add_numeric(struct parse_events_evlist *data,
 			     struct list_head *list,
 			     u32 type, u64 config,
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index 09e738f..4acea38 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -115,6 +115,7 @@ do {							\
 group		[^,{}/]*[{][^}]*[}][^,{}/]*
 event_pmu	[^,{}/]+[/][^/]*[/][^,{}/]*
 event		[^,{}/]+
+bpf_object	.*\.(o|bpf)
 
 num_dec		[0-9]+
 num_hex		0x[a-fA-F0-9]+
@@ -159,6 +160,7 @@ modifier_bp	[rwx]{1,3}
 		}
 
 {event_pmu}	|
+{bpf_object}	|
 {event}		{
 			BEGIN(INITIAL);
 			REWIND(1);
@@ -262,6 +264,7 @@ r{num_raw_hex}		{ return raw(yyscanner); }
 
 {modifier_event}	{ return str(yyscanner, PE_MODIFIER_EVENT); }
 {name}			{ return pmu_str_check(yyscanner); }
+{bpf_object}		{ return str(yyscanner, PE_BPF_OBJECT); }
 "/"			{ BEGIN(config); return '/'; }
 -			{ return '-'; }
 ,			{ BEGIN(event); return ','; }
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 591905a..481f3cd 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -42,6 +42,7 @@ static inc_group_count(struct list_head *list,
 %token PE_VALUE PE_VALUE_SYM_HW PE_VALUE_SYM_SW PE_RAW PE_TERM
 %token PE_EVENT_NAME
 %token PE_NAME
+%token PE_BPF_OBJECT
 %token PE_MODIFIER_EVENT PE_MODIFIER_BP
 %token PE_NAME_CACHE_TYPE PE_NAME_CACHE_OP_RESULT
 %token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
@@ -53,6 +54,7 @@ static inc_group_count(struct list_head *list,
 %type <num> PE_RAW
 %type <num> PE_TERM
 %type <str> PE_NAME
+%type <str> PE_BPF_OBJECT
 %type <str> PE_NAME_CACHE_TYPE
 %type <str> PE_NAME_CACHE_OP_RESULT
 %type <str> PE_MODIFIER_EVENT
@@ -69,6 +71,7 @@ static inc_group_count(struct list_head *list,
 %type <head> event_legacy_tracepoint
 %type <head> event_legacy_numeric
 %type <head> event_legacy_raw
+%type <head> event_bpf_file
 %type <head> event_def
 %type <head> event_mod
 %type <head> event_name
@@ -198,7 +201,8 @@ event_def: event_pmu |
 	   event_legacy_mem |
 	   event_legacy_tracepoint sep_dc |
 	   event_legacy_numeric sep_dc |
-	   event_legacy_raw sep_dc
+	   event_legacy_raw sep_dc |
+	   event_bpf_file
 
 event_pmu:
 PE_NAME '/' event_config '/'
@@ -420,6 +424,18 @@ PE_RAW
 	$$ = list;
 }
 
+event_bpf_file:
+PE_BPF_OBJECT
+{
+	struct parse_events_evlist *data = _data;
+	struct list_head *list;
+
+	ALLOC_LIST(list);
+	ABORT_ON(parse_events_load_bpf(list, &data->idx, $1));
+	$$ = list;
+}
+
+
 start_terms: event_config
 {
 	struct parse_events_terms *data = _data;
-- 
1.8.3.4