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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/tools/lib/bpf/btf_iter.c
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// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)

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/* Copyright (c) 2021 Facebook */

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/* Copyright (c) 2024, Oracle and/or its affiliates. */

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#ifdef __KERNEL__

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#include <linux/bpf.h>

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#include <linux/btf.h>

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#define btf_var_secinfos(t)	(struct btf_var_secinfo *)btf_type_var_secinfo(t)

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#else

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#include "btf.h"

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#include "libbpf_internal.h"

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#endif

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int btf_field_iter_init(struct btf_field_iter *it, struct btf_type *t,

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			enum btf_field_iter_kind iter_kind)

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{

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	it->p = NULL;

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	it->m_idx = -1;

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	it->off_idx = 0;

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	it->vlen = 0;

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	switch (iter_kind) {

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	case BTF_FIELD_ITER_IDS:

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		switch (btf_kind(t)) {

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		case BTF_KIND_UNKN:

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		case BTF_KIND_INT:

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		case BTF_KIND_FLOAT:

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		case BTF_KIND_ENUM:

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		case BTF_KIND_ENUM64:

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			it->desc = (struct btf_field_desc) {};

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			break;

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		case BTF_KIND_FWD:

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		case BTF_KIND_CONST:

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		case BTF_KIND_VOLATILE:

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		case BTF_KIND_RESTRICT:

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		case BTF_KIND_PTR:

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		case BTF_KIND_TYPEDEF:

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		case BTF_KIND_FUNC:

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		case BTF_KIND_VAR:

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		case BTF_KIND_DECL_TAG:

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		case BTF_KIND_TYPE_TAG:

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			it->desc = (struct btf_field_desc) { 1, {offsetof(struct btf_type, type)} };

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			break;

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		case BTF_KIND_ARRAY:

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			it->desc = (struct btf_field_desc) {

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				2, {sizeof(struct btf_type) + offsetof(struct btf_array, type),

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				sizeof(struct btf_type) + offsetof(struct btf_array, index_type)}

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			};

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			break;

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		case BTF_KIND_STRUCT:

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		case BTF_KIND_UNION:

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			it->desc = (struct btf_field_desc) {

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				0, {},

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				sizeof(struct btf_member),

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				1, {offsetof(struct btf_member, type)}

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			};

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			break;

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		case BTF_KIND_FUNC_PROTO:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, type)},

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				sizeof(struct btf_param),

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				1, {offsetof(struct btf_param, type)}

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			};

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			break;

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		case BTF_KIND_DATASEC:

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			it->desc = (struct btf_field_desc) {

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				0, {},

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				sizeof(struct btf_var_secinfo),

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				1, {offsetof(struct btf_var_secinfo, type)}

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			};

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			break;

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		default:

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			return -EINVAL;

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		}

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		break;

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	case BTF_FIELD_ITER_STRS:

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		switch (btf_kind(t)) {

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		case BTF_KIND_UNKN:

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			it->desc = (struct btf_field_desc) {};

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			break;

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		case BTF_KIND_INT:

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		case BTF_KIND_FLOAT:

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		case BTF_KIND_FWD:

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		case BTF_KIND_ARRAY:

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		case BTF_KIND_CONST:

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		case BTF_KIND_VOLATILE:

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		case BTF_KIND_RESTRICT:

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		case BTF_KIND_PTR:

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		case BTF_KIND_TYPEDEF:

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		case BTF_KIND_FUNC:

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		case BTF_KIND_VAR:

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		case BTF_KIND_DECL_TAG:

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		case BTF_KIND_TYPE_TAG:

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		case BTF_KIND_DATASEC:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, name_off)}

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			};

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			break;

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		case BTF_KIND_ENUM:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, name_off)},

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				sizeof(struct btf_enum),

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				1, {offsetof(struct btf_enum, name_off)}

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			};

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			break;

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		case BTF_KIND_ENUM64:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, name_off)},

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				sizeof(struct btf_enum64),

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				1, {offsetof(struct btf_enum64, name_off)}

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			};

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			break;

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		case BTF_KIND_STRUCT:

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		case BTF_KIND_UNION:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, name_off)},

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				sizeof(struct btf_member),

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				1, {offsetof(struct btf_member, name_off)}

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			};

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			break;

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		case BTF_KIND_FUNC_PROTO:

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			it->desc = (struct btf_field_desc) {

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				1, {offsetof(struct btf_type, name_off)},

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				sizeof(struct btf_param),

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				1, {offsetof(struct btf_param, name_off)}

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			};

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			break;

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		default:

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			return -EINVAL;

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		}

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		break;

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	default:

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		return -EINVAL;

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	}

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	if (it->desc.m_sz)

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		it->vlen = btf_vlen(t);

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	it->p = t;

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	return 0;

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}

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__u32 *btf_field_iter_next(struct btf_field_iter *it)

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{

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	if (!it->p)

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		return NULL;

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	if (it->m_idx < 0) {

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		if (it->off_idx < it->desc.t_off_cnt)

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			return it->p + it->desc.t_offs[it->off_idx++];

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		/* move to per-member iteration */

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		it->m_idx = 0;

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		it->p += sizeof(struct btf_type);

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		it->off_idx = 0;

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	}

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	/* if type doesn't have members, stop */

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	if (it->desc.m_sz == 0) {

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		it->p = NULL;

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		return NULL;

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	}

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	if (it->off_idx >= it->desc.m_off_cnt) {

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		/* exhausted this member's fields, go to the next member */

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		it->m_idx++;

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		it->p += it->desc.m_sz;

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		it->off_idx = 0;

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	}

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	if (it->m_idx < it->vlen)

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		return it->p + it->desc.m_offs[it->off_idx++];

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	it->p = NULL;

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	return NULL;

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}

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