[PATCH v2 04/13] perf tools: Add API to config maps in bpf object

From: Wang Nan
Date: Fri Nov 27 2015 - 03:50:55 EST

bpf__config_obj() is introduced as a core API to config BPF object
after loading. One configuration option of maps is introduced. After
this patch BPF object can accept configuration like:

maps:my_map:value=1234

(maps.my_map.value looks pretty. However, there's a small but hard
to fixed problem related to flex's greedy matching. Please see [1].
Choose ':' to avoid it in a simpler way.)

This patch is more complex than the work it really does because the
consideration of extension. In designing of BPF map configuration,
following things should be considered:

1. Array indics selection: perf should allow user setting different
value to different slots in an array, with syntax like:
maps:my_map:value[0,3...6]=1234;

2. A map can be config by different config terms, each for a part
of it. For example, set each slot to pid of a thread;

3. Type of value: integer is not the only valid value type. Perf
event can also be put into a map after commit 35578d7984003097af2b1e3
(bpf: Implement function bpf_perf_event_read() that get the selected
hardware PMU conuter);

4. For hash table, it is possible to use string or other as key;

5. It is possible that map configuration is unable to be setup
during parsing. Perf event is an example.

Therefore, this patch does following:

1. Instead of updating map element during parsing, this patch stores
map config options in 'struct bpf_map_priv'. Following patches
would apply those configs at proper time;

2. Link map operations to a list so a map can have multiple config
terms attached, so different parts can be configured separately;

3. Make 'struct bpf_map_priv' extensible so following patches can
add new types of keys and operations;

4. Use bpf_config_map_funcs array to support more maps config options.

Since the patch changing event parser to parse BPF object config is
relative large, I put in another commit. Code in this patch
could be tested after applying next patch.

[1] http://lkml.kernel.org/g/564ED621.4050500@xxxxxxxxxx

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
tools/perf/util/bpf-loader.c | 266 +++++++++++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.h | 38 +++++++
2 files changed, 304 insertions(+)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 540a7ef..989c80f 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -739,6 +739,251 @@ int bpf__foreach_tev(struct bpf_object *obj,
return 0;
}

+enum bpf_map_op_type {
+ BPF_MAP_OP_SET_VALUE,
+};
+
+enum bpf_map_key_type {
+ BPF_MAP_KEY_ALL,
+};
+
+struct bpf_map_op {
+ struct list_head list;
+ enum bpf_map_op_type op_type;
+ enum bpf_map_key_type key_type;
+ union {
+ u64 value;
+ } v;
+};
+
+struct bpf_map_priv {
+ struct list_head ops_list;
+};
+
+static void
+bpf_map_op__free(struct bpf_map_op *op)
+{
+ struct list_head *list = &op->list;
+ /*
+ * bpf_map_op__free() needs to consider following cases:
+ * 1. When the op is created but not linked to any list:
+ * impossible. This only happen in bpf_map_op__alloc()
+ * and it would be freed directly;
+ * 2. Normal case, when the op is linked to a list;
+ * 3. After the op has already be removed.
+ * Thanks to list.h, if it has removed by list_del() then
+ * list->{next,prev} should have been set to LIST_POISON{1,2}.
+ */
+ if ((list->next != LIST_POISON1) && (list->prev != LIST_POISON2))
+ list_del(list);
+ free(op);
+}
+
+static void
+bpf_map_priv__clear(struct bpf_map *map __maybe_unused,
+ void *_priv)
+{
+ struct bpf_map_priv *priv = _priv;
+ struct bpf_map_op *pos, *n;
+
+ list_for_each_entry_safe(pos, n, &priv->ops_list, list)
+ bpf_map_op__free(pos);
+ free(priv);
+}
+
+static struct bpf_map_op *
+bpf_map_op__alloc(struct bpf_map *map)
+{
+ struct bpf_map_op *op;
+ struct bpf_map_priv *priv;
+ const char *map_name;
+ int err;
+
+ map_name = bpf_map__get_name(map);
+ err = bpf_map__get_private(map, (void **)&priv);
+ if (err) {
+ pr_debug("Failed to get private from map %s\n", map_name);
+ return ERR_PTR(err);
+ }
+
+ if (!priv) {
+ priv = zalloc(sizeof(*priv));
+ if (!priv) {
+ pr_debug("No enough memory to alloc map private\n");
+ return ERR_PTR(-ENOMEM);
+ }
+ INIT_LIST_HEAD(&priv->ops_list);
+
+ if (bpf_map__set_private(map, priv, bpf_map_priv__clear)) {
+ free(priv);
+ return ERR_PTR(-BPF_LOADER_ERRNO__INTERNAL);
+ }
+ }
+
+ op = zalloc(sizeof(*op));
+ if (!op) {
+ pr_debug("Failed to alloc bpf_map_op\n");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ op->key_type = BPF_MAP_KEY_ALL;
+ list_add_tail(&op->list, &priv->ops_list);
+ return op;
+}
+
+static int
+bpf__obj_config_map_array_value(struct bpf_map *map,
+ struct parse_events_term *term)
+{
+ struct bpf_map_def def;
+ struct bpf_map_op *op;
+ const char *map_name;
+ int err;
+
+ map_name = bpf_map__get_name(map);
+
+ err = bpf_map__get_def(map, &def);
+ if (err) {
+ pr_debug("Unable to get map definition from '%s'\n",
+ map_name);
+ return -BPF_LOADER_ERRNO__INTERNAL;
+ }
+
+ if (def.type != BPF_MAP_TYPE_ARRAY) {
+ pr_debug("Map %s type is not BPF_MAP_TYPE_ARRAY\n",
+ map_name);
+ return -BPF_LOADER_ERRNO__OBJCONF_MAP_TYPE;
+ }
+ if (def.key_size < sizeof(unsigned int)) {
+ pr_debug("Map %s has incorrect key size\n", map_name);
+ return -BPF_LOADER_ERRNO__OBJCONF_MAP_KEYSIZE;
+ }
+ switch (def.value_size) {
+ case 1:
+ case 2:
+ case 4:
+ case 8:
+ break;
+ default:
+ pr_debug("Map %s has incorrect value size\n", map_name);
+ return -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUESIZE;
+ }
+
+ op = bpf_map_op__alloc(map);
+ if (IS_ERR(op))
+ return PTR_ERR(op);
+ op->op_type = BPF_MAP_OP_SET_VALUE;
+ op->v.value = term->val.num;
+ return 0;
+}
+
+static int
+bpf__obj_config_map_value(struct bpf_map *map,
+ struct parse_events_term *term,
+ struct perf_evlist *evlist __maybe_unused)
+{
+ if (!term->err_val) {
+ pr_debug("Config value not set\n");
+ return -BPF_LOADER_ERRNO__OBJCONF_CONF;
+ }
+
+ if (term->type_val == PARSE_EVENTS__TERM_TYPE_NUM)
+ return bpf__obj_config_map_array_value(map, term);
+
+ pr_debug("ERROR: wrong value type\n");
+ return -BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE;
+}
+
+struct bpf_obj_config_map_func {
+ const char *config_opt;
+ int (*config_func)(struct bpf_map *, struct parse_events_term *,
+ struct perf_evlist *);
+};
+
+struct bpf_obj_config_map_func bpf_obj_config_map_funcs[] = {
+ {"value", bpf__obj_config_map_value},
+};
+
+static int
+bpf__obj_config_map(struct bpf_object *obj,
+ struct parse_events_term *term,
+ struct perf_evlist *evlist,
+ int *key_scan_pos)
+{
+ /* key is "maps:<mapname>:<config opt>" */
+ char *map_name = strdup(term->config + sizeof("maps:") - 1);
+ struct bpf_map *map;
+ int err = -BPF_LOADER_ERRNO__OBJCONF_OPT;
+ char *map_opt;
+ size_t i;
+
+ if (!map_name)
+ return -ENOMEM;
+
+ map_opt = strchr(map_name, ':');
+ if (!map_opt) {
+ pr_debug("ERROR: Invalid map config: %s\n", map_name);
+ goto out;
+ }
+
+ *map_opt++ = '\0';
+ if (*map_opt == '\0') {
+ pr_debug("ERROR: Invalid map option: %s\n", term->config);
+ goto out;
+ }
+
+ map = bpf_object__get_map_by_name(obj, map_name);
+ if (!map) {
+ pr_debug("ERROR: Map %s is not exist\n", map_name);
+ err = -BPF_LOADER_ERRNO__OBJCONF_MAP_NOTEXIST;
+ goto out;
+ }
+
+ *key_scan_pos += map_opt - map_name;
+ for (i = 0; i < ARRAY_SIZE(bpf_obj_config_map_funcs); i++) {
+ struct bpf_obj_config_map_func *func =
+ &bpf_obj_config_map_funcs[i];
+
+ if (strcmp(map_opt, func->config_opt) == 0) {
+ err = func->config_func(map, term, evlist);
+ goto out;
+ }
+ }
+
+ pr_debug("ERROR: invalid config option '%s' for maps\n",
+ map_opt);
+ err = -BPF_LOADER_ERRNO__OBJCONF_MAP_OPT;
+out:
+ free(map_name);
+ if (!err)
+ key_scan_pos += strlen(map_opt);
+ return err;
+}
+
+int bpf__config_obj(struct bpf_object *obj,
+ struct parse_events_term *term,
+ struct perf_evlist *evlist,
+ int *error_pos)
+{
+ int key_scan_pos = 0;
+ int err;
+
+ if (!obj || !term || !term->config)
+ return -EINVAL;
+
+ if (!prefixcmp(term->config, "maps:")) {
+ key_scan_pos = sizeof("maps:") - 1;
+ err = bpf__obj_config_map(obj, term, evlist, &key_scan_pos);
+ goto out;
+ }
+ err = -BPF_LOADER_ERRNO__OBJCONF_OPT;
+out:
+ if (error_pos)
+ *error_pos = key_scan_pos;
+ return err;
+
+}
+
#define ERRNO_OFFSET(e) ((e) - __BPF_LOADER_ERRNO__START)
#define ERRCODE_OFFSET(c) ERRNO_OFFSET(BPF_LOADER_ERRNO__##c)
#define NR_ERRNO (__BPF_LOADER_ERRNO__END - __BPF_LOADER_ERRNO__START)
@@ -753,6 +998,14 @@ static const char *bpf_loader_strerror_table[NR_ERRNO] = {
[ERRCODE_OFFSET(PROLOGUE)] = "Failed to generate prologue",
[ERRCODE_OFFSET(PROLOGUE2BIG)] = "Prologue too big for program",
[ERRCODE_OFFSET(PROLOGUEOOB)] = "Offset out of bound for prologue",
+ [ERRCODE_OFFSET(OBJCONF_OPT)] = "Invalid object config option",
+ [ERRCODE_OFFSET(OBJCONF_CONF)] = "Config value not set (lost '=')",
+ [ERRCODE_OFFSET(OBJCONF_MAP_OPT)] = "Invalid object maps config option",
+ [ERRCODE_OFFSET(OBJCONF_MAP_NOTEXIST)] = "Target map not exist",
+ [ERRCODE_OFFSET(OBJCONF_MAP_VALUE)] = "Incorrect value type for map",
+ [ERRCODE_OFFSET(OBJCONF_MAP_TYPE)] = "Incorrect map type",
+ [ERRCODE_OFFSET(OBJCONF_MAP_KEYSIZE)] = "Incorrect map key size",
+ [ERRCODE_OFFSET(OBJCONF_MAP_VALUESIZE)] = "Incorrect map value size",
};

static int
@@ -872,3 +1125,16 @@ int bpf__strerror_load(struct bpf_object *obj,
bpf__strerror_end(buf, size);
return 0;
}
+
+int bpf__strerror_config_obj(struct bpf_object *obj __maybe_unused,
+ struct parse_events_term *term __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused,
+ int *error_pos __maybe_unused, int err,
+ char *buf, size_t size)
+{
+ bpf__strerror_head(err, buf, size);
+ bpf__strerror_entry(BPF_LOADER_ERRNO__OBJCONF_MAP_TYPE,
+ "Can't use this config term to this type of map");
+ bpf__strerror_end(buf, size);
+ return 0;
+}
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 6fdc045..2464db9 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -10,6 +10,7 @@
#include <string.h>
#include <bpf/libbpf.h>
#include "probe-event.h"
+#include "evlist.h"
#include "debug.h"

enum bpf_loader_errno {
@@ -24,10 +25,19 @@ enum bpf_loader_errno {
BPF_LOADER_ERRNO__PROLOGUE, /* Failed to generate prologue */
BPF_LOADER_ERRNO__PROLOGUE2BIG, /* Prologue too big for program */
BPF_LOADER_ERRNO__PROLOGUEOOB, /* Offset out of bound for prologue */
+ BPF_LOADER_ERRNO__OBJCONF_OPT, /* Invalid object config option */
+ BPF_LOADER_ERRNO__OBJCONF_CONF, /* Config value not set (lost '=')) */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_OPT, /* Invalid object maps config option */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_NOTEXIST, /* Target map not exist */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_VALUE, /* Incorrect value type for map */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_TYPE, /* Incorrect map type */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_KEYSIZE, /* Incorrect map key size */
+ BPF_LOADER_ERRNO__OBJCONF_MAP_VALUESIZE,/* Incorrect map value size */
__BPF_LOADER_ERRNO__END,
};

struct bpf_object;
+struct parse_events_term;
#define PERF_BPF_PROBE_GROUP "perf_bpf_probe"

typedef int (*bpf_prog_iter_callback_t)(struct probe_trace_event *tev,
@@ -53,6 +63,14 @@ int bpf__strerror_load(struct bpf_object *obj, int err,
char *buf, size_t size);
int bpf__foreach_tev(struct bpf_object *obj,
bpf_prog_iter_callback_t func, void *arg);
+
+int bpf__config_obj(struct bpf_object *obj, struct parse_events_term *term,
+ struct perf_evlist *evlist, int *error_pos);
+int bpf__strerror_config_obj(struct bpf_object *obj,
+ struct parse_events_term *term,
+ struct perf_evlist *evlist,
+ int *error_pos, int err, char *buf,
+ size_t size);
#else
static inline struct bpf_object *
bpf__prepare_load(const char *filename __maybe_unused,
@@ -84,6 +102,15 @@ bpf__foreach_tev(struct bpf_object *obj __maybe_unused,
}

static inline int
+bpf__config_obj(struct bpf_object *obj __maybe_unused,
+ struct parse_events_term *term __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused,
+ int *error_pos __maybe_unused)
+{
+ return 0;
+}
+
+static inline int
__bpf_strerror(char *buf, size_t size)
{
if (!size)
@@ -118,5 +145,16 @@ static inline int bpf__strerror_load(struct bpf_object *obj __maybe_unused,
{
return __bpf_strerror(buf, size);
}
+
+static inline int
+bpf__strerror_config_obj(struct bpf_object *obj __maybe_unused,
+ struct parse_events_term *term __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused,
+ int *error_pos __maybe_unused,
+ int err __maybe_unused,
+ char *buf, size_t size)
+{
+ return __bpf_strerror(buf, size);
+}
#endif
#endif
--
1.8.3.4

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