[PATCH 29/31] perf tools: Add API to apply config to BPF map

[Wang Nan]

bpf__apply_config() is introduced as the core CPI to apply config
options to all BPF objects. This patch also does the real work for
setting maps events for BPF_MAP_TYPE_PERF_EVENT_ARRAY maps by inserting
file descriptions of a evsel into the BPF map.

This patch is required because we are unable to set all BPF config
during parsing. Events in BPF_MAP_TYPE_PERF_EVENT_ARRAY maps is an
example: during parsing, fds of events is not ready yet.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/n/ebpf-tmg65cm1zaf1zxs7zmvxmxp4@xxxxxxxxxxxxxx
---
 tools/perf/util/bpf-loader.c | 109 +++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/bpf-loader.h |  15 ++++++
 2 files changed, 124 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index b92c2f7..9d661c0 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -7,6 +7,7 @@
 
 #include <linux/bpf.h>
 #include <bpf/libbpf.h>
+#include <bpf/bpf.h>
 #include <linux/err.h>
 #include "perf.h"
 #include "debug.h"
@@ -767,6 +768,107 @@ int bpf__config_obj(struct bpf_object *obj,
 	return -ENODEV;
 }
 
+static int
+bpf__apply_config_map(struct bpf_map *map)
+{
+	struct bpf_map_priv *priv;
+	struct bpf_map_def def;
+	const char *name;
+	int err, map_fd;
+
+	name = bpf_map__get_name(map);
+	err = bpf_map__get_private(map, (void **)&priv);
+	if (err) {
+		pr_debug("ERROR: failed to get private field from map %s\n",
+			 name);
+		return err;
+	}
+	if (!priv) {
+		pr_debug("INFO: nothing to config for map %s\n", name);
+		return 0;
+	}
+
+	map_fd = bpf_map__get_fd(map);
+	if (map_fd < 0) {
+		pr_debug("ERROR: failed to get fd from map %s\n", name);
+		return map_fd;
+	}
+
+	err = bpf_map__get_def(map, &def);
+	if (err) {
+		pr_debug("ERROR: failed to retrive map def from map %s\n",
+			 name);
+		return err;
+	}
+
+	if (priv->evsel) {
+		struct xyarray *xy = priv->evsel->fd;
+		unsigned int cpus, i;
+
+		if (!xy) {
+			pr_debug("ERROR: event is not ready for map %s\n", name);
+			return -EINVAL;
+		}
+
+		if (xy->row_size / xy->entry_size != 1) {
+			pr_debug("ERROR: Dimension of target event is incorrect for map %s\n",
+				 name);
+			return -EINVAL;
+		}
+
+		cpus = xy->entries / (xy->row_size / xy->entry_size);
+		if (cpus > def.max_entries) {
+			pr_debug("ERROR: map %s needs to be enlarge to %d for its event\n",
+				 name, cpus);
+			return -EINVAL;
+		} else if (cpus < def.max_entries)
+			pr_debug("WARNING: map %s has more entries than required\n",
+				 name);
+
+		for (i = 0; i < cpus; i++) {
+			int *evt_fd = xyarray__entry(xy, i, 0);
+
+			err = bpf_map_update_elem(map_fd, &i, evt_fd,
+						  BPF_ANY);
+
+			if (err) {
+				pr_debug("ERROR: failed to insert fd %d to %s[%d]\n",
+					 *evt_fd, name, i);
+				return -errno;
+			}
+		}
+	}
+	return 0;
+}
+
+static int
+bpf__apply_config_object(struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	int err;
+
+	bpf_map__for_each(map, obj) {
+		err = bpf__apply_config_map(map);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+int bpf__apply_config(void)
+{
+	struct bpf_object *obj, *tmp;
+	int err;
+
+	bpf_object__for_each_safe(obj, tmp) {
+		err = bpf__apply_config_object(obj);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
 #define bpf__strerror_head(err, buf, size) \
 	char sbuf[STRERR_BUFSIZE], *emsg;\
 	if (!size)\
@@ -822,3 +924,10 @@ int bpf__strerror_config_obj(struct bpf_object *obj __maybe_unused,
 	bpf__strerror_end(buf, size);
 	return 0;
 }
+
+int bpf__strerror_apply_config(int err, char *buf, size_t size)
+{
+	bpf__strerror_head(err, buf, size);
+	bpf__strerror_end(buf, size);
+	return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 4c99b21..3a93ba3 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -53,6 +53,8 @@ int bpf__strerror_config_obj(struct bpf_object *obj,
 			     const char *key, struct bpf_config_val *val,
 			     struct perf_evlist *evlist,
 			     int err, char *buf, size_t size);
+int bpf__apply_config(void);
+int bpf__strerror_apply_config(int err, char *buf, size_t size);
 #else
 static inline struct bpf_object *
 bpf__prepare_load(const char *filename __maybe_unused,
@@ -93,6 +95,12 @@ bpf__config_obj(struct bpf_object *obj __maybe_unused,
 }
 
 static inline int
+bpf__apply_config(void)
+{
+	return 0;
+}
+
+static inline int
 __bpf_strerror(char *buf, size_t size)
 {
 	if (!size)
@@ -129,5 +137,12 @@ bpf__strerror_config_obj(struct bpf_object *obj __maybe_unused,
 {
 	return __bpf_strerror(buf, size);
 }
+
+static inline int
+bpf__strerror_apply_config(int err __maybe_unused,
+			   char *buf, size_t size)
+{
+	return __bpf_strerror(buf, size);
+}
 #endif
 #endif
-- 
1.8.3.4

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