[RFC PATCH v3 36/37] 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 found eBPF program with
their names and file descriptors. In evlist.c, perf_evlist__add_bpf()
is added to add all bpf events into evlist. 'perf record' calls
perf_evlist__add_bpf() if it is wrapped by perf bpf.

Since bpf-loader.c will not built if libelf not found, 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 | 30 ++++++++++++++++++++++++++++++
 tools/perf/util/bpf-loader.h | 18 ++++++++++++++++++
 tools/perf/util/evlist.c     | 34 ++++++++++++++++++++++++++++++++++
 tools/perf/util/evlist.h     |  1 +
 tools/perf/util/evsel.c      |  1 +
 tools/perf/util/evsel.h      |  1 +
 7 files changed, 91 insertions(+)

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index c3efdfb..21f3dcb 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -978,6 +978,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
 		goto out_symbol_exit;
 	}
 
+	if (bpf_wrapper &&
+	    perf_evlist__add_bpf(rec->evlist) < 0) {
+		pr_err("Failed to add events from bpf object\n");
+		goto out_symbol_exit;
+	}
+
 	if (rec->opts.target.tid && !rec->opts.no_inherit_set)
 		rec->opts.no_inherit = true;
 
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 7295a3b..b793c69 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -230,3 +230,33 @@ int bpf_load(void)
 
 	return 0;
 }
+
+int bpf_for_each_program(bpf_prog_iter_callback_t func, void *arg)
+{
+	int i;
+	
+	if (!func)
+		return -EINVAL;
+
+	for (i = 0; i < (int)params.nr_progs; i++) {
+		int err, fd;
+		const char *group, *event;
+		struct bpf_prog_handler *prog =
+			params.progs[i].prog;
+		struct perf_probe_event *pevent =
+			params.progs[i].pevent;
+
+		group = pevent->group;
+		event = pevent->event;
+		err = bpf_prog_get_fd(prog, &fd);
+		if (err) {
+			pr_err("Unable to get program fd\n");
+			return -EINVAL;
+		}
+
+		err = func(group, event, fd, arg);
+		if (err)
+			return err;
+	}
+	return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 1ccebdf..ffdd535 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -7,10 +7,28 @@
 #ifndef __BPF_LOADER_H
 #define __BPF_LOADER_H
 
+#include <linux/compiler.h> // for __maybe_unused
+
 int bpf_prepare_load(const char *filename);
 int bpf_probe(void);
 int bpf_load(void);
 
 int bpf_unprobe(void);
 void bpf_clear(void);
+
+typedef int (*bpf_prog_iter_callback_t)(const char *group,
+					const char *event,
+					int fd, void *arg);
+
+#ifdef HAVE_LIBELF_SUPPORT
+int bpf_for_each_program(bpf_prog_iter_callback_t func, void *arg);
+#else
+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 080be93..cc26317 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 +195,39 @@ error:
 	return -ENOMEM;
 }
 
+static int add_bpf_event(const char *group, const char *event, int fd,
+			 void *arg)
+{
+	struct perf_evlist *evlist = arg;
+	struct perf_evsel *pos;
+	struct list_head list;
+	int err, idx, entries;
+
+	pr_info("add bpf event %s:%s and attach bpf program %d\n",
+		group, event, fd);
+
+	INIT_LIST_HEAD(&list);
+	idx = evlist->nr_entries;
+	err = parse_events_add_tracepoint(&list, &idx, (char *)group,
+			(char *)event);
+	if (err) {
+		pr_err("Failed to add BPF event %s:%s\n",
+		       group, event);
+		return err;
+	}
+	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 b5cce95..032f04d 100644
--- a/tools/perf/util/evlist.h
+++ b/tools/perf/util/evlist.h
@@ -68,6 +68,7 @@ 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 33e3fd8..04d60a7 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 e486151..ff1f634 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -100,6 +100,7 @@ struct perf_evsel {
 	int			sample_read;
 	struct perf_evsel	*leader;
 	char			*group_name;
+	int			bpf_fd;
 };
 
 union u64_swap {
-- 
1.8.3.4

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