1 files changed, 242 insertions, 4 deletions

diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c
index ee3ce2b8000d..1f579eacd9d4 100644
--- a/tools/bpf/bpftool/gen.c
+++ b/tools/bpf/bpftool/gen.c
@@ -7,6 +7,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <libgen.h>
 #include <linux/err.h>
 #include <stdbool.h>
 #include <stdio.h>
@@ -54,11 +55,27 @@ static bool str_has_suffix(const char *str, const char *suffix)
 	return true;
 }
 
+static const struct btf_type *
+resolve_func_ptr(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t;
+
+	t = skip_mods_and_typedefs(btf, id, NULL);
+	if (!btf_is_ptr(t))
+		return NULL;
+
+	t = skip_mods_and_typedefs(btf, t->type, res_id);
+
+	return btf_is_func_proto(t) ? t : NULL;
+}
+
 static void get_obj_name(char *name, const char *file)
 {
-	/* Using basename() GNU version which doesn't modify arg. */
-	strncpy(name, basename(file), MAX_OBJ_NAME_LEN - 1);
-	name[MAX_OBJ_NAME_LEN - 1] = '\0';
+	char file_copy[PATH_MAX];
+
+	/* Using basename() POSIX version to be more portable. */
+	strncpy(file_copy, file, PATH_MAX - 1)[PATH_MAX - 1] = '\0';
+	strncpy(name, basename(file_copy), MAX_OBJ_NAME_LEN - 1)[MAX_OBJ_NAME_LEN - 1] = '\0';
 	if (str_has_suffix(name, ".o"))
 		name[strlen(name) - 2] = '\0';
 	sanitize_identifier(name);
@@ -906,6 +923,207 @@ codegen_progs_skeleton(struct bpf_object *obj, size_t prog_cnt, bool populate_li
 	}
 }
 
+static int walk_st_ops_shadow_vars(struct btf *btf, const char *ident,
+				   const struct btf_type *map_type, __u32 map_type_id)
+{
+	LIBBPF_OPTS(btf_dump_emit_type_decl_opts, opts, .indent_level = 3);
+	const struct btf_type *member_type;
+	__u32 offset, next_offset = 0;
+	const struct btf_member *m;
+	struct btf_dump *d = NULL;
+	const char *member_name;
+	__u32 member_type_id;
+	int i, err = 0, n;
+	int size;
+
+	d = btf_dump__new(btf, codegen_btf_dump_printf, NULL, NULL);
+	if (!d)
+		return -errno;
+
+	n = btf_vlen(map_type);
+	for (i = 0, m = btf_members(map_type); i < n; i++, m++) {
+		member_type = skip_mods_and_typedefs(btf, m->type, &member_type_id);
+		member_name = btf__name_by_offset(btf, m->name_off);
+
+		offset = m->offset / 8;
+		if (next_offset < offset)
+			printf("\t\t\tchar __padding_%d[%d];\n", i, offset - next_offset);
+
+		switch (btf_kind(member_type)) {
+		case BTF_KIND_INT:
+		case BTF_KIND_FLOAT:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_ENUM64:
+			/* scalar type */
+			printf("\t\t\t");
+			opts.field_name = member_name;
+			err = btf_dump__emit_type_decl(d, member_type_id, &opts);
+			if (err) {
+				p_err("Failed to emit type declaration for %s: %d", member_name, err);
+				goto out;
+			}
+			printf(";\n");
+
+			size = btf__resolve_size(btf, member_type_id);
+			if (size < 0) {
+				p_err("Failed to resolve size of %s: %d\n", member_name, size);
+				err = size;
+				goto out;
+			}
+
+			next_offset = offset + size;
+			break;
+
+		case BTF_KIND_PTR:
+			if (resolve_func_ptr(btf, m->type, NULL)) {
+				/* Function pointer */
+				printf("\t\t\tstruct bpf_program *%s;\n", member_name);
+
+				next_offset = offset + sizeof(void *);
+				break;
+			}
+			/* All pointer types are unsupported except for
+			 * function pointers.
+			 */
+			fallthrough;
+
+		default:
+			/* Unsupported types
+			 *
+			 * Types other than scalar types and function
+			 * pointers are currently not supported in order to
+			 * prevent conflicts in the generated code caused
+			 * by multiple definitions. For instance, if the
+			 * struct type FOO is used in a struct_ops map,
+			 * bpftool has to generate definitions for FOO,
+			 * which may result in conflicts if FOO is defined
+			 * in different skeleton files.
+			 */
+			size = btf__resolve_size(btf, member_type_id);
+			if (size < 0) {
+				p_err("Failed to resolve size of %s: %d\n", member_name, size);
+				err = size;
+				goto out;
+			}
+			printf("\t\t\tchar __unsupported_%d[%d];\n", i, size);
+
+			next_offset = offset + size;
+			break;
+		}
+	}
+
+	/* Cannot fail since it must be a struct type */
+	size = btf__resolve_size(btf, map_type_id);
+	if (next_offset < (__u32)size)
+		printf("\t\t\tchar __padding_end[%d];\n", size - next_offset);
+
+out:
+	btf_dump__free(d);
+
+	return err;
+}
+
+/* Generate the pointer of the shadow type for a struct_ops map.
+ *
+ * This function adds a pointer of the shadow type for a struct_ops map.
+ * The members of a struct_ops map can be exported through a pointer to a
+ * shadow type. The user can access these members through the pointer.
+ *
+ * A shadow type includes not all members, only members of some types.
+ * They are scalar types and function pointers. The function pointers are
+ * translated to the pointer of the struct bpf_program. The scalar types
+ * are translated to the original type without any modifiers.
+ *
+ * Unsupported types will be translated to a char array to occupy the same
+ * space as the original field, being renamed as __unsupported_*.  The user
+ * should treat these fields as opaque data.
+ */
+static int gen_st_ops_shadow_type(const char *obj_name, struct btf *btf, const char *ident,
+				  const struct bpf_map *map)
+{
+	const struct btf_type *map_type;
+	const char *type_name;
+	__u32 map_type_id;
+	int err;
+
+	map_type_id = bpf_map__btf_value_type_id(map);
+	if (map_type_id == 0)
+		return -EINVAL;
+	map_type = btf__type_by_id(btf, map_type_id);
+	if (!map_type)
+		return -EINVAL;
+
+	type_name = btf__name_by_offset(btf, map_type->name_off);
+
+	printf("\t\tstruct %s__%s__%s {\n", obj_name, ident, type_name);
+
+	err = walk_st_ops_shadow_vars(btf, ident, map_type, map_type_id);
+	if (err)
+		return err;
+
+	printf("\t\t} *%s;\n", ident);
+
+	return 0;
+}
+
+static int gen_st_ops_shadow(const char *obj_name, struct btf *btf, struct bpf_object *obj)
+{
+	int err, st_ops_cnt = 0;
+	struct bpf_map *map;
+	char ident[256];
+
+	if (!btf)
+		return 0;
+
+	/* Generate the pointers to shadow types of
+	 * struct_ops maps.
+	 */
+	bpf_object__for_each_map(map, obj) {
+		if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
+			continue;
+		if (!get_map_ident(map, ident, sizeof(ident)))
+			continue;
+
+		if (st_ops_cnt == 0) /* first struct_ops map */
+			printf("\tstruct {\n");
+		st_ops_cnt++;
+
+		err = gen_st_ops_shadow_type(obj_name, btf, ident, map);
+		if (err)
+			return err;
+	}
+
+	if (st_ops_cnt)
+		printf("\t} struct_ops;\n");
+
+	return 0;
+}
+
+/* Generate the code to initialize the pointers of shadow types. */
+static void gen_st_ops_shadow_init(struct btf *btf, struct bpf_object *obj)
+{
+	struct bpf_map *map;
+	char ident[256];
+
+	if (!btf)
+		return;
+
+	/* Initialize the pointers to_ops shadow types of
+	 * struct_ops maps.
+	 */
+	bpf_object__for_each_map(map, obj) {
+		if (bpf_map__type(map) != BPF_MAP_TYPE_STRUCT_OPS)
+			continue;
+		if (!get_map_ident(map, ident, sizeof(ident)))
+			continue;
+		codegen("\
+			\n\
+				obj->struct_ops.%1$s = bpf_map__initial_value(obj->maps.%1$s, NULL);\n\
+			\n\
+			", ident);
+	}
+}
+
 static int do_skeleton(int argc, char **argv)
 {
 	char header_guard[MAX_OBJ_NAME_LEN + sizeof("__SKEL_H__")];
@@ -1049,6 +1267,11 @@ static int do_skeleton(int argc, char **argv)
 		printf("\t} maps;\n");
 	}
 
+	btf = bpf_object__btf(obj);
+	err = gen_st_ops_shadow(obj_name, btf, obj);
+	if (err)
+		goto out;
+
 	if (prog_cnt) {
 		printf("\tstruct {\n");
 		bpf_object__for_each_program(prog, obj) {
@@ -1072,7 +1295,6 @@ static int do_skeleton(int argc, char **argv)
 		printf("\t} links;\n");
 	}
 
-	btf = bpf_object__btf(obj);
 	if (btf) {
 		err = codegen_datasecs(obj, obj_name);
 		if (err)
@@ -1130,6 +1352,12 @@ static int do_skeleton(int argc, char **argv)
 			if (err)					    \n\
 				goto err_out;				    \n\
 									    \n\
+		", obj_name);
+
+	gen_st_ops_shadow_init(btf, obj);
+
+	codegen("\
+		\n\
 			return obj;					    \n\
 		err_out:						    \n\
 			%1$s__destroy(obj);				    \n\
@@ -1439,6 +1667,10 @@ static int do_subskeleton(int argc, char **argv)
 		printf("\t} maps;\n");
 	}
 
+	err = gen_st_ops_shadow(obj_name, btf, obj);
+	if (err)
+		goto out;
+
 	if (prog_cnt) {
 		printf("\tstruct {\n");
 		bpf_object__for_each_program(prog, obj) {
@@ -1550,6 +1782,12 @@ static int do_subskeleton(int argc, char **argv)
 			if (err)					    \n\
 				goto err;				    \n\
 									    \n\
+		");
+
+	gen_st_ops_shadow_init(btf, obj);
+
+	codegen("\
+		\n\
 			return obj;					    \n\
 		err:							    \n\
 			%1$s__destroy(obj);				    \n\