Commit 2dc1e488 authored by Yonghong Song's avatar Yonghong Song Committed by Alexei Starovoitov
Browse files

libbpf: Support BTF_KIND_TYPE_TAG 



Add libbpf support for BTF_KIND_TYPE_TAG.

Signed-off-by: default avatarYonghong Song <yhs@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20211112012614.1505315-1-yhs@fb.com
parent 8c42d2fa

tools/lib/bpf/btf.c

+23 −0
Original line number Diff line number Diff line
@@ -299,6 +299,7 @@ static int btf_type_size(const struct btf_type *t) 
	case BTF_KIND_TYPEDEF:

	case BTF_KIND_FUNC:

	case BTF_KIND_FLOAT:

	case BTF_KIND_TYPE_TAG:

		return base_size;

	case BTF_KIND_INT:

		return base_size + sizeof(__u32);
@@ -349,6 +350,7 @@ static int btf_bswap_type_rest(struct btf_type *t) 
	case BTF_KIND_TYPEDEF:

	case BTF_KIND_FUNC:

	case BTF_KIND_FLOAT:

	case BTF_KIND_TYPE_TAG:

		return 0;

	case BTF_KIND_INT:

		*(__u32 *)(t + 1) = bswap_32(*(__u32 *)(t + 1));
@@ -649,6 +651,7 @@ int btf__align_of(const struct btf *btf, __u32 id) 
	case BTF_KIND_VOLATILE:

	case BTF_KIND_CONST:

	case BTF_KIND_RESTRICT:

	case BTF_KIND_TYPE_TAG:

		return btf__align_of(btf, t->type);

	case BTF_KIND_ARRAY:

		return btf__align_of(btf, btf_array(t)->type);
@@ -2235,6 +2238,22 @@ int btf__add_restrict(struct btf *btf, int ref_type_id) 
	return btf_add_ref_kind(btf, BTF_KIND_RESTRICT, NULL, ref_type_id);

}



/*

 * Append new BTF_KIND_TYPE_TAG type with:

 *   - *value*, non-empty/non-NULL tag value;

 *   - *ref_type_id* - referenced type ID, it might not exist yet;

 * Returns:

 *   - >0, type ID of newly added BTF type;

 *   - <0, on error.

 */

int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id)

{

	if (!value|| !value[0])

		return libbpf_err(-EINVAL);



	return btf_add_ref_kind(btf, BTF_KIND_TYPE_TAG, value, ref_type_id);

}



/*

 * Append new BTF_KIND_FUNC type with:

 *   - *name*, non-empty/non-NULL name;
@@ -3639,6 +3658,7 @@ static int btf_dedup_prep(struct btf_dedup *d) 
		case BTF_KIND_TYPEDEF:

		case BTF_KIND_FUNC:

		case BTF_KIND_FLOAT:

		case BTF_KIND_TYPE_TAG:

			h = btf_hash_common(t);

			break;

		case BTF_KIND_INT:
@@ -3699,6 +3719,7 @@ static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id) 
	case BTF_KIND_VAR:

	case BTF_KIND_DATASEC:

	case BTF_KIND_DECL_TAG:

	case BTF_KIND_TYPE_TAG:

		return 0;



	case BTF_KIND_INT:
@@ -4297,6 +4318,7 @@ static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id) 
	case BTF_KIND_PTR:

	case BTF_KIND_TYPEDEF:

	case BTF_KIND_FUNC:

	case BTF_KIND_TYPE_TAG:

		ref_type_id = btf_dedup_ref_type(d, t->type);

		if (ref_type_id < 0)

			return ref_type_id;
@@ -4603,6 +4625,7 @@ int btf_type_visit_type_ids(struct btf_type *t, type_id_visit_fn visit, void *ct 
	case BTF_KIND_FUNC:

	case BTF_KIND_VAR:

	case BTF_KIND_DECL_TAG:

	case BTF_KIND_TYPE_TAG:

		return visit(&t->type, ctx);



	case BTF_KIND_ARRAY: {

tools/lib/bpf/btf.h

+8 −1
Original line number Diff line number Diff line
@@ -227,6 +227,7 @@ LIBBPF_API int btf__add_typedef(struct btf *btf, const char *name, int ref_type_ 
LIBBPF_API int btf__add_volatile(struct btf *btf, int ref_type_id);

LIBBPF_API int btf__add_const(struct btf *btf, int ref_type_id);

LIBBPF_API int btf__add_restrict(struct btf *btf, int ref_type_id);

LIBBPF_API int btf__add_type_tag(struct btf *btf, const char *value, int ref_type_id);



/* func and func_proto construction APIs */

LIBBPF_API int btf__add_func(struct btf *btf, const char *name,
@@ -458,7 +459,8 @@ static inline bool btf_is_mod(const struct btf_type *t) 


	return kind == BTF_KIND_VOLATILE ||

	       kind == BTF_KIND_CONST ||

	       kind == BTF_KIND_RESTRICT;

	       kind == BTF_KIND_RESTRICT ||

	       kind == BTF_KIND_TYPE_TAG;

}



static inline bool btf_is_func(const struct btf_type *t)
@@ -491,6 +493,11 @@ static inline bool btf_is_decl_tag(const struct btf_type *t) 
	return btf_kind(t) == BTF_KIND_DECL_TAG;

}



static inline bool btf_is_type_tag(const struct btf_type *t)

{

	return btf_kind(t) == BTF_KIND_TYPE_TAG;

}



static inline __u8 btf_int_encoding(const struct btf_type *t)

{

	return BTF_INT_ENCODING(*(__u32 *)(t + 1));

tools/lib/bpf/btf_dump.c

+9 −0
Original line number Diff line number Diff line
@@ -330,6 +330,7 @@ static int btf_dump_mark_referenced(struct btf_dump *d) 
		case BTF_KIND_FUNC:

		case BTF_KIND_VAR:

		case BTF_KIND_DECL_TAG:

		case BTF_KIND_TYPE_TAG:

			d->type_states[t->type].referenced = 1;

			break;
@@ -573,6 +574,7 @@ static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr) 
	case BTF_KIND_VOLATILE:

	case BTF_KIND_CONST:

	case BTF_KIND_RESTRICT:

	case BTF_KIND_TYPE_TAG:

		return btf_dump_order_type(d, t->type, through_ptr);



	case BTF_KIND_FUNC_PROTO: {
@@ -747,6 +749,7 @@ static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id) 
	case BTF_KIND_VOLATILE:

	case BTF_KIND_CONST:

	case BTF_KIND_RESTRICT:

	case BTF_KIND_TYPE_TAG:

		btf_dump_emit_type(d, t->type, cont_id);

		break;

	case BTF_KIND_ARRAY:
@@ -1167,6 +1170,7 @@ static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id, 
		case BTF_KIND_CONST:

		case BTF_KIND_RESTRICT:

		case BTF_KIND_FUNC_PROTO:

		case BTF_KIND_TYPE_TAG:

			id = t->type;

			break;

		case BTF_KIND_ARRAY:
@@ -1335,6 +1339,11 @@ static void btf_dump_emit_type_chain(struct btf_dump *d, 
		case BTF_KIND_RESTRICT:

			btf_dump_printf(d, " restrict");

			break;

		case BTF_KIND_TYPE_TAG:

			btf_dump_emit_mods(d, decls);

			name = btf_name_of(d, t->name_off);

			btf_dump_printf(d, " __attribute__((btf_type_tag(\"%s\")))", name);

			break;

		case BTF_KIND_ARRAY: {

			const struct btf_array *a = btf_array(t);

			const struct btf_type *next_t;

tools/lib/bpf/libbpf.c

+30 −1
Original line number Diff line number Diff line
@@ -197,6 +197,8 @@ enum kern_feature_id { 
	FEAT_PERF_LINK,

	/* BTF_KIND_DECL_TAG support */

	FEAT_BTF_DECL_TAG,

	/* BTF_KIND_TYPE_TAG support */

	FEAT_BTF_TYPE_TAG,

	__FEAT_CNT,

};
@@ -2076,6 +2078,7 @@ static const char *__btf_kind_str(__u16 kind) 
	case BTF_KIND_DATASEC: return "datasec";

	case BTF_KIND_FLOAT: return "float";

	case BTF_KIND_DECL_TAG: return "decl_tag";

	case BTF_KIND_TYPE_TAG: return "type_tag";

	default: return "unknown";

	}

}
@@ -2588,8 +2591,10 @@ static bool btf_needs_sanitization(struct bpf_object *obj) 
	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);

	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);

	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);

	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);



	return !has_func || !has_datasec || !has_func_global || !has_float || !has_decl_tag;

	return !has_func || !has_datasec || !has_func_global || !has_float ||

	       !has_decl_tag || !has_type_tag;

}



static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf)
@@ -2599,6 +2604,7 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) 
	bool has_float = kernel_supports(obj, FEAT_BTF_FLOAT);

	bool has_func = kernel_supports(obj, FEAT_BTF_FUNC);

	bool has_decl_tag = kernel_supports(obj, FEAT_BTF_DECL_TAG);

	bool has_type_tag = kernel_supports(obj, FEAT_BTF_TYPE_TAG);

	struct btf_type *t;

	int i, j, vlen;
@@ -2657,6 +2663,10 @@ static void bpf_object__sanitize_btf(struct bpf_object *obj, struct btf *btf) 
			 */

			t->name_off = 0;

			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 0);

		} else if (!has_type_tag && btf_is_type_tag(t)) {

			/* replace TYPE_TAG with a CONST */

			t->name_off = 0;

			t->info = BTF_INFO_ENC(BTF_KIND_CONST, 0, 0);

		}

	}

}
@@ -4460,6 +4470,22 @@ static int probe_kern_btf_decl_tag(void) 
					     strs, sizeof(strs)));

}



static int probe_kern_btf_type_tag(void)

{

	static const char strs[] = "\0tag";

	__u32 types[] = {

		/* int */

		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),		/* [1] */

		/* attr */

		BTF_TYPE_TYPE_TAG_ENC(1, 1),				/* [2] */

		/* ptr */

		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_PTR, 0, 0), 2),	/* [3] */

	};



	return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types),

					     strs, sizeof(strs)));

}



static int probe_kern_array_mmap(void)

{

	struct bpf_create_map_attr attr = {
@@ -4657,6 +4683,9 @@ static struct kern_feature_desc { 
	[FEAT_BTF_DECL_TAG] = {

		"BTF_KIND_DECL_TAG support", probe_kern_btf_decl_tag,

	},

	[FEAT_BTF_TYPE_TAG] = {

		"BTF_KIND_TYPE_TAG support", probe_kern_btf_type_tag,

	},

};



static bool kernel_supports(const struct bpf_object *obj, enum kern_feature_id feat_id)

tools/lib/bpf/libbpf.map

+1 −0
Original line number Diff line number Diff line
@@ -403,6 +403,7 @@ LIBBPF_0.6.0 { 
		bpf_program__set_extra_flags;

		btf__add_btf;

		btf__add_decl_tag;

		btf__add_type_tag;

		btf__dedup;

		btf__dedup_deprecated;

		btf__raw_data;