Commit 1c508843 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

Merge branch 'bpf: add support for BTF_KIND_DECL_TAG typedef' 

Yonghong Song says:

====================

Latest upstream llvm-project added support for btf_decl_tag attributes
for typedef declarations ([1], [2]). Similar to other btf_decl_tag cases,
func/func_param/global_var/struct/union/field, btf_decl_tag with typedef
declaration can carry information from kernel source to clang compiler
and then to dwarf/BTF, for bpf verification or other use cases.

This patch set added kernel support for BTF_KIND_DECL_TAG to typedef
declaration (Patch 1). Additional selftests are added to cover
unit testing, dedup, or bpf program usage of btf_decl_tag with typedef.
(Patches 2, 3 and 4). The btf documentation is updated to include
BTF_KIND_DECL_TAG typedef (Patch 5).

  [1] https://reviews.llvm.org/D110127
  [2] https://reviews.llvm.org/D112259


====================

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parents a33f607f 5a867134

Documentation/bpf/btf.rst

+3 −3
Original line number Diff line number Diff line
@@ -474,7 +474,7 @@ No additional type data follow ``btf_type``. 
 * ``info.kind_flag``: 0

 * ``info.kind``: BTF_KIND_DECL_TAG

 * ``info.vlen``: 0

 * ``type``: ``struct``, ``union``, ``func`` or ``var``

 * ``type``: ``struct``, ``union``, ``func``, ``var`` or ``typedef``



``btf_type`` is followed by ``struct btf_decl_tag``.::
@@ -483,8 +483,8 @@ No additional type data follow ``btf_type``. 
    };



The ``name_off`` encodes btf_decl_tag attribute string.

The ``type`` should be ``struct``, ``union``, ``func`` or ``var``.

For ``var`` type, ``btf_decl_tag.component_idx`` must be ``-1``.

The ``type`` should be ``struct``, ``union``, ``func``, ``var`` or ``typedef``.

For ``var`` or ``typedef`` type, ``btf_decl_tag.component_idx`` must be ``-1``.

For the other three types, if the btf_decl_tag attribute is

applied to the ``struct``, ``union`` or ``func`` itself,

``btf_decl_tag.component_idx`` must be ``-1``. Otherwise,

kernel/bpf/btf.c

+2 −2
Original line number Diff line number Diff line
@@ -468,7 +468,7 @@ static bool btf_type_is_decl_tag(const struct btf_type *t) 
static bool btf_type_is_decl_tag_target(const struct btf_type *t)

{

	return btf_type_is_func(t) || btf_type_is_struct(t) ||

	       btf_type_is_var(t);

	       btf_type_is_var(t) || btf_type_is_typedef(t);

}



u32 btf_nr_types(const struct btf *btf)
@@ -3885,7 +3885,7 @@ static int btf_decl_tag_resolve(struct btf_verifier_env *env, 


	component_idx = btf_type_decl_tag(t)->component_idx;

	if (component_idx != -1) {

		if (btf_type_is_var(next_type)) {

		if (btf_type_is_var(next_type) || btf_type_is_typedef(next_type)) {

			btf_verifier_log_type(env, v->t, "Invalid component_idx");

			return -EINVAL;

		}

tools/testing/selftests/bpf/prog_tests/btf.c

+77 −6
Original line number Diff line number Diff line
@@ -3903,6 +3903,42 @@ static struct btf_raw_test raw_tests[] = { 
	.btf_load_err = true,

	.err_str = "Invalid component_idx",

},

{

	.descr = "decl_tag test #13, typedef, well-formed",

	.raw_types = {

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

		BTF_TYPEDEF_ENC(NAME_TBD, 1),			/* [2] */

		BTF_DECL_TAG_ENC(NAME_TBD, 2, -1),

		BTF_END_RAW,

	},

	BTF_STR_SEC("\0t\0tag"),

	.map_type = BPF_MAP_TYPE_ARRAY,

	.map_name = "tag_type_check_btf",

	.key_size = sizeof(int),

	.value_size = 4,

	.key_type_id = 1,

	.value_type_id = 1,

	.max_entries = 1,

},

{

	.descr = "decl_tag test #14, typedef, invalid component_idx",

	.raw_types = {

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

		BTF_TYPEDEF_ENC(NAME_TBD, 1),			/* [2] */

		BTF_DECL_TAG_ENC(NAME_TBD, 2, 0),

		BTF_END_RAW,

	},

	BTF_STR_SEC("\0local\0tag"),

	.map_type = BPF_MAP_TYPE_ARRAY,

	.map_name = "tag_type_check_btf",

	.key_size = sizeof(int),

	.value_size = 4,

	.key_type_id = 1,

	.value_type_id = 1,

	.max_entries = 1,

	.btf_load_err = true,

	.err_str = "Invalid component_idx",

},



}; /* struct btf_raw_test raw_tests[] */
@@ -6841,11 +6877,12 @@ const struct btf_dedup_test dedup_tests[] = { 
				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),

			BTF_FUNC_ENC(NAME_TBD, 12),					/* [13] func */

			BTF_TYPE_FLOAT_ENC(NAME_TBD, 2),				/* [14] float */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, -1),				/* [15] tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, 1),				/* [16] tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, -1),				/* [15] decl_tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, 1),				/* [16] decl_tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 7, -1),				/* [17] decl_tag */

			BTF_END_RAW,

		},

		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P"),

		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P\0Q"),

	},

	.expect = {

		.raw_types = {
@@ -6869,11 +6906,12 @@ const struct btf_dedup_test dedup_tests[] = { 
				BTF_FUNC_PROTO_ARG_ENC(NAME_TBD, 8),

			BTF_FUNC_ENC(NAME_TBD, 12),					/* [13] func */

			BTF_TYPE_FLOAT_ENC(NAME_TBD, 2),				/* [14] float */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, -1),				/* [15] tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, 1),				/* [16] tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, -1),				/* [15] decl_tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 13, 1),				/* [16] decl_tag */

			BTF_DECL_TAG_ENC(NAME_TBD, 7, -1),				/* [17] decl_tag */

			BTF_END_RAW,

		},

		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P"),

		BTF_STR_SEC("\0A\0B\0C\0D\0E\0F\0G\0H\0I\0J\0K\0L\0M\0N\0O\0P\0Q"),

	},

	.opts = {

		.dont_resolve_fwds = false,
@@ -7168,6 +7206,39 @@ const struct btf_dedup_test dedup_tests[] = { 
		.dont_resolve_fwds = false,

	},

},

{

	.descr = "dedup: typedef tags",

	.input = {

		.raw_types = {

			/* int */

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

			BTF_TYPEDEF_ENC(NAME_NTH(1), 1),		/* [2] */

			BTF_TYPEDEF_ENC(NAME_NTH(1), 1),		/* [3] */

			/* tag -> t: tag1, tag2 */

			BTF_DECL_TAG_ENC(NAME_NTH(2), 2, -1),		/* [4] */

			BTF_DECL_TAG_ENC(NAME_NTH(3), 2, -1),		/* [5] */

			/* tag -> t: tag1, tag3 */

			BTF_DECL_TAG_ENC(NAME_NTH(2), 3, -1),		/* [6] */

			BTF_DECL_TAG_ENC(NAME_NTH(4), 3, -1),		/* [7] */

			BTF_END_RAW,

		},

		BTF_STR_SEC("\0t\0tag1\0tag2\0tag3"),

	},

	.expect = {

		.raw_types = {

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

			BTF_TYPEDEF_ENC(NAME_NTH(1), 1),		/* [2] */

			BTF_DECL_TAG_ENC(NAME_NTH(2), 2, -1),		/* [3] */

			BTF_DECL_TAG_ENC(NAME_NTH(3), 2, -1),		/* [4] */

			BTF_DECL_TAG_ENC(NAME_NTH(4), 2, -1),		/* [5] */

			BTF_END_RAW,

		},

		BTF_STR_SEC("\0t\0tag1\0tag2\0tag3"),

	},

	.opts = {

		.dont_resolve_fwds = false,

	},

},



};

tools/testing/selftests/bpf/progs/tag.c

+7 −2
Original line number Diff line number Diff line
@@ -24,18 +24,23 @@ struct key_t { 
	int c;

} __tag1 __tag2;



typedef struct {

	int a;

	int b;

} value_t __tag1 __tag2;



struct {

	__uint(type, BPF_MAP_TYPE_HASH);

	__uint(max_entries, 3);

	__type(key, struct key_t);

	__type(value, __u64);

	__type(value, value_t);

} hashmap1 SEC(".maps");





static __noinline int foo(int x __tag1 __tag2) __tag1 __tag2

{

	struct key_t key;

	__u64 val = 1;

	value_t val = {};



	key.a = key.b = key.c = x;

	bpf_map_update_elem(&hashmap1, &key, &val, 0);