[RFC PATCH v7 34/37] perf tools: Add bpf_fd field to evsel and config it

[Wang Nan]

This patch adds a bpf_fd field to 'struct evsel' then introduces method
to config it. In bpf-loader, a bpf__for_each_program() function is added.
Which calls the callback function for each eBPF programs with their event
structure and file descriptors. In evlist.c, perf_evlist__add_bpf()
is added to add all bpf events into evlist. The event names are found
from probe_trace_event structure. 'perf record' calls
perf_evlist__add_bpf().

Since bpf-loader.c will not be built if libbpf is turned off, an empty
bpf__for_each_program() is defined in bpf-loader.h to avoid compiling
error.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
---
 tools/perf/builtin-record.c  |  6 ++++++
 tools/perf/util/bpf-loader.c | 36 +++++++++++++++++++++++++++++++
 tools/perf/util/bpf-loader.h | 13 +++++++++++
 tools/perf/util/evlist.c     | 51 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/evlist.h     |  1 +
 tools/perf/util/evsel.c      |  1 +
 tools/perf/util/evsel.h      |  1 +
 7 files changed, 109 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 7fcce98..c15865f 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1135,6 +1135,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 		goto out_symbol_exit;
 	}
 
+	err = perf_evlist__add_bpf(rec->evlist);
+	if (err < 0) {
+		pr_err("Failed to add events from BPF object(s)\n");
+		goto out_symbol_exit;
+	}
+
 	symbol__init(NULL);
 
 	if (symbol_conf.kptr_restrict)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 54bda7e..00fb94f 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -258,3 +258,39 @@ errout:
 		bpf_object__unload(obj);
 	return err;
 }
+
+int
+bpf__for_each_program(bpf_prog_iter_callback_t func,
+		      void *arg)
+{
+	struct bpf_object *obj, *tmp;
+	struct bpf_program *prog;
+	int err;
+
+	bpf_object__for_each(obj, tmp) {
+		bpf_object__for_each_program(prog, obj) {
+			struct bpf_prog_priv *priv;
+			int fd;
+
+			err = bpf_program__get_private(prog,
+						       (void **)&priv);
+			if (err || !priv) {
+				pr_err("bpf: failed to get private field\n");
+				return -EINVAL;
+			}
+			err = bpf_program__get_fd(prog, &fd);
+			if (err || fd < 0) {
+				pr_err("bpf: failed to get file descriptor\n");
+				return -EINVAL;
+			}
+
+			err = func(priv->pev, fd, arg);
+			if (err) {
+				pr_err("bpf: call back failed, stop iterate\n");
+				return err;
+			}
+		}
+	}
+
+	return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index ae0dc9b..da03e12 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -6,10 +6,14 @@
 #define __BPF_LOADER_H
 
 #include <linux/compiler.h>
+#include "probe-event.h"
 #include "debug.h"
 
 #define PERF_BPF_PROBE_GROUP "perf_bpf_probe"
 
+typedef int (*bpf_prog_iter_callback_t)(struct perf_probe_event *pev,
+					int fd, void *arg);
+
 #ifdef HAVE_LIBBPF_SUPPORT
 int bpf__prepare_load(const char *filename, bool source);
 int bpf__probe(void);
@@ -17,6 +21,8 @@ int bpf__unprobe(void);
 int bpf__load(void);
 
 void bpf__clear(void);
+
+int bpf__for_each_program(bpf_prog_iter_callback_t func, void *arg);
 #else
 static inline int bpf__prepare_load(const char *filename __maybe_unused,
 				    bool source __maybe_unused)
@@ -29,5 +35,12 @@ static inline int bpf__probe(void) { return 0; }
 static inline int bpf__unprobe(void) { return 0; }
 static inline int bpf__load(void) { return 0; }
 static inline void bpf__clear(void) { }
+
+static inline int
+bpf__for_each_program(bpf_prog_iter_callback_t func __maybe_unused,
+		      void *arg __maybe_unused)
+{
+	return 0;
+}
 #endif
 #endif
diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index dc1dc2c..08863b6 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -14,6 +14,7 @@
 #include "target.h"
 #include "evlist.h"
 #include "evsel.h"
+#include "bpf-loader.h"
 #include "debug.h"
 #include <unistd.h>
 
@@ -194,6 +195,56 @@ error:
 	return -ENOMEM;
 }
 
+static int add_bpf_event(struct perf_probe_event *pev, int fd,
+			 void *arg)
+{
+	struct perf_evlist *evlist = arg;
+	struct perf_evsel *pos;
+	struct list_head list;
+	int err, idx, entries, i;
+
+	if (!pev || !pev->ntevs) {
+		pr_err("Internal error: add bpf event before probing\n");
+		return -EINVAL;
+	}
+
+	pr_debug("add bpf event %s:%s and attach bpf program %d\n",
+		 pev->group, pev->event, fd);
+	INIT_LIST_HEAD(&list);
+	idx = evlist->nr_entries;
+
+	for (i = 0; i < pev->ntevs; i++) {
+		struct probe_trace_event *tev = &pev->tevs[i];
+
+		pr_debug("adding %s:%s\n", tev->group, tev->event);
+		err = parse_events_add_tracepoint(&list, &idx,
+						  tev->group,
+						  tev->event);
+		if (err) {
+			struct perf_evsel *evsel, *tmp;
+
+			pr_err("Failed to add BPF event %s:%s\n",
+			       tev->group, tev->event);
+			list_for_each_entry_safe(evsel, tmp, &list, node) {
+				list_del(&evsel->node);
+				perf_evsel__delete(evsel);
+			}
+			return -EINVAL;
+		}
+	}
+
+	list_for_each_entry(pos, &list, node)
+		pos->bpf_fd = fd;
+	entries = idx - evlist->nr_entries;
+	perf_evlist__splice_list_tail(evlist, &list, entries);
+	return 0;
+}
+
+int perf_evlist__add_bpf(struct perf_evlist *evlist)
+{
+	return bpf__for_each_program(add_bpf_event, evlist);
+}
+
 static int perf_evlist__add_attrs(struct perf_evlist *evlist,
 				  struct perf_event_attr *attrs, size_t nr_attrs)
 {
diff --git a/tools/perf/util/evlist.h b/tools/perf/util/evlist.h
index 955bf31..773e8e9 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -71,6 +71,7 @@ void perf_evlist__delete(struct perf_evlist *evlist);
 
 void perf_evlist__add(struct perf_evlist *evlist, struct perf_evsel *entry);
 int perf_evlist__add_default(struct perf_evlist *evlist);
+int perf_evlist__add_bpf(struct perf_evlist *evlist);
 int __perf_evlist__add_default_attrs(struct perf_evlist *evlist,
 				     struct perf_event_attr *attrs, size_t nr_attrs);
 
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index a3e36fc..e5cbfcd 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -205,6 +205,7 @@ void perf_evsel__init(struct perf_evsel *evsel,
 	evsel->leader	   = evsel;
 	evsel->unit	   = "";
 	evsel->scale	   = 1.0;
+	evsel->bpf_fd	   = -1;
 	INIT_LIST_HEAD(&evsel->node);
 	perf_evsel__object.init(evsel);
 	evsel->sample_size = __perf_evsel__sample_size(attr->sample_type);
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 21ec082..261de76 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -100,6 +100,7 @@ struct perf_evsel {
 	unsigned long		*per_pkg_mask;
 	struct perf_evsel	*leader;
 	char			*group_name;
+	int			bpf_fd;
 };
 
 union u64_swap {
-- 
1.8.3.4

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