perf bpf: Add defines for map insertion/lookup

Starting with a helper for a basic pid_map(), a hash using a pid as a
key.

Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: https://lkml.kernel.org/n/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/include/bpf/bpf.h

···
         unsigned int numa_node;
 };
 
+#define pid_map(name, value_type)		\
+struct bpf_map SEC("maps") name = {		\
+	.type	     = BPF_MAP_TYPE_HASH,	\
+	.key_size    = sizeof(pid_t),		\
+	.value_size  = sizeof(value_type),	\
+	.max_entries = 512,			\
+}
+
+static int (*bpf_map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags) = (void *)BPF_FUNC_map_update_elem;
+static void *(*bpf_map_lookup_elem)(struct bpf_map *map, void *key) = (void *)BPF_FUNC_map_lookup_elem;
+
 #define SEC(NAME) __attribute__((section(NAME),  used))
 
 #define probe(function, vars) \