Merge branch 'fix-BTF-enum' (f7861a55) · Commits · 戴 / test

Yoshiki Komachi says: ==================== btf_enum_check_member() checked if the size of "enum" as a struct member exceeded struct_size or not. Then, the function compared it with the size of "int". Although the size of "enum" is 4-byte by default (i.e., equivalent to "int"), the packing feature enables us to reduce it, as illustrated by the following example: struct A { char m; enum { E0, E1 } __attribute__((packed)) n; }; With such a setup above, the bpf loader gave an error attempting to load it: ------------------------------------------------------------------ ... [3] ENUM (anon) size=1 vlen=2 E0 val=0 E1 val=1 [4] STRUCT A size=2 vlen=2 m type_id=2 bits_offset=0 n type_id=3 bits_offset=8 [4] STRUCT A size=2 vlen=2 n type_id=3 bits_offset=8 Member exceeds struct_size libbpf: Error loading .BTF into kernel: -22. ------------------------------------------------------------------ The related issue was previously fixed by the commit ("bpf: fix BTF verification of enums"). On the other hand, this series fixes this issue as well, and adds a selftest program for it. Changes in v2: - change an example in commit message based on Andrii's review - add a selftest program for packed "enum" type members in struct/union ==================== Acked-by:

Andrii Nakryiko <andriin@fb.com> Acked-by:

Martin KaFai Lau <kafai@fb.com> Signed-off-by:

Alexei Starovoitov <ast@kernel.org>

kernel/bpf/btf.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2418,7 +2418,7 @@ static int btf_enum_check_member(struct btf_verifier_env *env,

		struct_size = struct_type->size;
		bytes_offset = BITS_ROUNDDOWN_BYTES(struct_bits_off);
		if (struct_size - bytes_offset < sizeof(int)) {
		if (struct_size - bytes_offset < member_type->size) {
		btf_verifier_log_member(env, struct_type, member,
		"Member exceeds struct_size");
		return -EINVAL;

tools/testing/selftests/bpf/test_btf.c

+42 −0

Original line number	Diff line number	Diff line
		@@ -1062,6 +1062,48 @@ static struct btf_raw_test raw_tests[] = {
		.err_str = "Member exceeds struct_size",
		},

		/* Test member unexceeds the size of struct
		*
		* enum E {
		* E0,
		* E1,
		* };
		*
		* struct A {
		* char m;
		* enum E __attribute__((packed)) n;
		* };
		*/
		{
		.descr = "size check test #5",
		.raw_types = {
		/* int / / [1] */
		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, sizeof(int)),
		/* char / / [2] */
		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 8, 1),
		/* enum E { / / [3] */
		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_ENUM, 0, 2), 1),
		BTF_ENUM_ENC(NAME_TBD, 0),
		BTF_ENUM_ENC(NAME_TBD, 1),
		/* } */
		/* struct A { / / [4] */
		BTF_TYPE_ENC(NAME_TBD, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 2),
		BTF_MEMBER_ENC(NAME_TBD, 2, 0), /* char m; */
		BTF_MEMBER_ENC(NAME_TBD, 3, 8),/* enum E __attribute__((packed)) n; */
		/* } */
		BTF_END_RAW,
		},
		.str_sec = "\0E\0E0\0E1\0A\0m\0n",
		.str_sec_size = sizeof("\0E\0E0\0E1\0A\0m\0n"),
		.map_type = BPF_MAP_TYPE_ARRAY,
		.map_name = "size_check5_map",
		.key_size = sizeof(int),
		.value_size = 2,
		.key_type_id = 1,
		.value_type_id = 4,
		.max_entries = 4,
		},

		/* typedef const void * const_void_ptr;
		* struct A {
		* const_void_ptr m;

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