Commit b1828f0b authored by Ilya Leoshkevich's avatar Ilya Leoshkevich Committed by Alexei Starovoitov
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bpf: Add BTF_KIND_FLOAT support 



On the kernel side, introduce a new btf_kind_operations. It is
similar to that of BTF_KIND_INT, however, it does not need to
handle encodings and bit offsets. Do not implement printing, since
the kernel does not know how to format floating-point values.

Signed-off-by: default avatarIlya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210226202256.116518-7-iii@linux.ibm.com
parent eea154a8

kernel/bpf/btf.c

+81 −2
Original line number Diff line number Diff line
@@ -173,7 +173,7 @@ 
#define BITS_ROUNDUP_BYTES(bits) \

	(BITS_ROUNDDOWN_BYTES(bits) + !!BITS_PER_BYTE_MASKED(bits))



#define BTF_INFO_MASK 0x8f00ffff

#define BTF_INFO_MASK 0x9f00ffff

#define BTF_INT_MASK 0x0fffffff

#define BTF_TYPE_ID_VALID(type_id) ((type_id) <= BTF_MAX_TYPE)

#define BTF_STR_OFFSET_VALID(name_off) ((name_off) <= BTF_MAX_NAME_OFFSET)
@@ -280,6 +280,7 @@ static const char * const btf_kind_str[NR_BTF_KINDS] = { 
	[BTF_KIND_FUNC_PROTO]	= "FUNC_PROTO",

	[BTF_KIND_VAR]		= "VAR",

	[BTF_KIND_DATASEC]	= "DATASEC",

	[BTF_KIND_FLOAT]	= "FLOAT",

};



static const char *btf_type_str(const struct btf_type *t)
@@ -574,6 +575,7 @@ static bool btf_type_has_size(const struct btf_type *t) 
	case BTF_KIND_UNION:

	case BTF_KIND_ENUM:

	case BTF_KIND_DATASEC:

	case BTF_KIND_FLOAT:

		return true;

	}
@@ -1704,6 +1706,7 @@ __btf_resolve_size(const struct btf *btf, const struct btf_type *type, 
		case BTF_KIND_STRUCT:

		case BTF_KIND_UNION:

		case BTF_KIND_ENUM:

		case BTF_KIND_FLOAT:

			size = type->size;

			goto resolved;
@@ -1849,7 +1852,7 @@ static int btf_df_check_kflag_member(struct btf_verifier_env *env, 
	return -EINVAL;

}



/* Used for ptr, array and struct/union type members.

/* Used for ptr, array struct/union and float type members.

 * int, enum and modifier types have their specific callback functions.

 */

static int btf_generic_check_kflag_member(struct btf_verifier_env *env,
@@ -3675,6 +3678,81 @@ static const struct btf_kind_operations datasec_ops = { 
	.show			= btf_datasec_show,

};



static s32 btf_float_check_meta(struct btf_verifier_env *env,

				const struct btf_type *t,

				u32 meta_left)

{

	if (btf_type_vlen(t)) {

		btf_verifier_log_type(env, t, "vlen != 0");

		return -EINVAL;

	}



	if (btf_type_kflag(t)) {

		btf_verifier_log_type(env, t, "Invalid btf_info kind_flag");

		return -EINVAL;

	}



	if (t->size != 2 && t->size != 4 && t->size != 8 && t->size != 12 &&

	    t->size != 16) {

		btf_verifier_log_type(env, t, "Invalid type_size");

		return -EINVAL;

	}



	btf_verifier_log_type(env, t, NULL);



	return 0;

}



static int btf_float_check_member(struct btf_verifier_env *env,

				  const struct btf_type *struct_type,

				  const struct btf_member *member,

				  const struct btf_type *member_type)

{

	u64 start_offset_bytes;

	u64 end_offset_bytes;

	u64 misalign_bits;

	u64 align_bytes;

	u64 align_bits;



	/* Different architectures have different alignment requirements, so

	 * here we check only for the reasonable minimum. This way we ensure

	 * that types after CO-RE can pass the kernel BTF verifier.

	 */

	align_bytes = min_t(u64, sizeof(void *), member_type->size);

	align_bits = align_bytes * BITS_PER_BYTE;

	div64_u64_rem(member->offset, align_bits, &misalign_bits);

	if (misalign_bits) {

		btf_verifier_log_member(env, struct_type, member,

					"Member is not properly aligned");

		return -EINVAL;

	}



	start_offset_bytes = member->offset / BITS_PER_BYTE;

	end_offset_bytes = start_offset_bytes + member_type->size;

	if (end_offset_bytes > struct_type->size) {

		btf_verifier_log_member(env, struct_type, member,

					"Member exceeds struct_size");

		return -EINVAL;

	}



	return 0;

}



static void btf_float_log(struct btf_verifier_env *env,

			  const struct btf_type *t)

{

	btf_verifier_log(env, "size=%u", t->size);

}



static const struct btf_kind_operations float_ops = {

	.check_meta = btf_float_check_meta,

	.resolve = btf_df_resolve,

	.check_member = btf_float_check_member,

	.check_kflag_member = btf_generic_check_kflag_member,

	.log_details = btf_float_log,

	.show = btf_df_show,

};



static int btf_func_proto_check(struct btf_verifier_env *env,

				const struct btf_type *t)

{
@@ -3808,6 +3886,7 @@ static const struct btf_kind_operations * const kind_ops[NR_BTF_KINDS] = { 
	[BTF_KIND_FUNC_PROTO] = &func_proto_ops,

	[BTF_KIND_VAR] = &var_ops,

	[BTF_KIND_DATASEC] = &datasec_ops,

	[BTF_KIND_FLOAT] = &float_ops,

};



static s32 btf_check_meta(struct btf_verifier_env *env,