lib/bpf/btf.h

/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* Copyright (c) 2018 Facebook */
/*! \file */

#ifndef __LIBBPF_BTF_H
#define __LIBBPF_BTF_H

#include <stdarg.h>
#include <stdbool.h>
#include <linux/btf.h>
#include <linux/types.h>

#include "libbpf_common.h"

#ifdef __cplusplus
extern "C" {
#endif

#define BTF_ELF_SEC ".BTF"
#define BTF_EXT_ELF_SEC ".BTF.ext"
#define MAPS_ELF_SEC ".maps"

struct btf;
struct btf_ext;
struct btf_type;

struct bpf_object;

enum btf_endianness {
	BTF_LITTLE_ENDIAN = 0,
	BTF_BIG_ENDIAN = 1,
};

/**
 * @brief **btf__free()** frees all data of a BTF object
 * @param btf BTF object to free
 */
LIBBPF_API void btf__free(struct btf *btf);

/**
 * @brief **btf__new()** creates a new instance of a BTF object from the raw
 * bytes of an ELF's BTF section
 * @param data raw bytes
 * @param size number of bytes passed in `data`
 * @return new BTF object instance which has to be eventually freed with
 * **btf__free()**
 *
 * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
 * error code from such a pointer `libbpf_get_error()` should be used. If
 * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
 * returned on error instead. In both cases thread-local `errno` variable is
 * always set to error code as well.
 */
LIBBPF_API struct btf *btf__new(const void *data, __u32 size);

/**
 * @brief **btf__new_split()** create a new instance of a BTF object from the
 * provided raw data bytes. It takes another BTF instance, **base_btf**, which
 * serves as a base BTF, which is extended by types in a newly created BTF
 * instance
 * @param data raw bytes
 * @param size length of raw bytes
 * @param base_btf the base BTF object
 * @return new BTF object instance which has to be eventually freed with
 * **btf__free()**
 *
 * If *base_btf* is NULL, `btf__new_split()` is equivalent to `btf__new()` and
 * creates non-split BTF.
 *
 * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
 * error code from such a pointer `libbpf_get_error()` should be used. If
 * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
 * returned on error instead. In both cases thread-local `errno` variable is
 * always set to error code as well.
 */
LIBBPF_API struct btf *btf__new_split(const void *data, __u32 size, struct btf *base_btf);

/**
 * @brief **btf__new_empty()** creates an empty BTF object.  Use
 * `btf__add_*()` to populate such BTF object.
 * @return new BTF object instance which has to be eventually freed with
 * **btf__free()**
 *
 * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
 * error code from such a pointer `libbpf_get_error()` should be used. If
 * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
 * returned on error instead. In both cases thread-local `errno` variable is
 * always set to error code as well.
 */
LIBBPF_API struct btf *btf__new_empty(void);

/**
 * @brief **btf__new_empty_split()** creates an unpopulated BTF object from an
 * ELF BTF section except with a base BTF on top of which split BTF should be
 * based
 * @return new BTF object instance which has to be eventually freed with
 * **btf__free()**
 *
 * If *base_btf* is NULL, `btf__new_empty_split()` is equivalent to
 * `btf__new_empty()` and creates non-split BTF.
 *
 * On error, error-code-encoded-as-pointer is returned, not a NULL. To extract
 * error code from such a pointer `libbpf_get_error()` should be used. If
 * `libbpf_set_strict_mode(LIBBPF_STRICT_CLEAN_PTRS)` is enabled, NULL is
 * returned on error instead. In both cases thread-local `errno` variable is
 * always set to error code as well.
 */
LIBBPF_API struct btf *btf__new_empty_split(struct btf *base_btf);

LIBBPF_API struct btf *btf__parse(const char *path, struct btf_ext **btf_ext);
LIBBPF_API struct btf *btf__parse_split(const char *path, struct btf *base_btf);
LIBBPF_API struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext);
LIBBPF_API struct btf *btf__parse_elf_split(const char *path, struct btf *base_btf);
LIBBPF_API struct btf *btf__parse_raw(const char *path);
LIBBPF_API struct btf *btf__parse_raw_split(const char *path, struct btf *base_btf);

LIBBPF_API struct btf *btf__load_vmlinux_btf(void);
LIBBPF_API struct btf *btf__load_module_btf(const char *module_name, struct btf *vmlinux_btf);
LIBBPF_API struct btf *libbpf_find_kernel_btf(void);

LIBBPF_API struct btf *btf__load_from_kernel_by_id(__u32 id);
LIBBPF_API struct btf *btf__load_from_kernel_by_id_split(__u32 id, struct btf *base_btf);
LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_from_kernel_by_id instead")
LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);

LIBBPF_DEPRECATED_SINCE(0, 6, "intended for internal libbpf use only")
LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__load_into_kernel instead")
LIBBPF_API int btf__load(struct btf *btf);
LIBBPF_API int btf__load_into_kernel(struct btf *btf);
LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
				   const char *type_name);
LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf,
					const char *type_name, __u32 kind);
LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__type_cnt() instead; note that btf__get_nr_types() == btf__type_cnt() - 1")
LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf);
LIBBPF_API __u32 btf__type_cnt(const struct btf *btf);
LIBBPF_API const struct btf *btf__base_btf(const struct btf *btf);
LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
						  __u32 id);
LIBBPF_API size_t btf__pointer_size(const struct btf *btf);
LIBBPF_API int btf__set_pointer_size(struct btf *btf, size_t ptr_sz);
LIBBPF_API enum btf_endianness btf__endianness(const struct btf *btf);
LIBBPF_API int btf__set_endianness(struct btf *btf, enum btf_endianness endian);
LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
LIBBPF_API int btf__fd(const struct btf *btf);
LIBBPF_API void btf__set_fd(struct btf *btf, int fd);
LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__raw_data() instead")
LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
LIBBPF_API const void *btf__raw_data(const struct btf *btf, __u32 *size);
LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset);
LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
				    __u32 expected_key_size,
				    __u32 expected_value_size,
				    __u32 *key_type_id, __u32 *value_type_id);

LIBBPF_API struct btf_ext *btf_ext__new(const __u8 *data, __u32 size);
LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
					     __u32 *size);
LIBBPF_API LIBBPF_DEPRECATED("btf_ext__reloc_func_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
int btf_ext__reloc_func_info(const struct btf *btf,
			     const struct btf_ext *btf_ext,
			     const char *sec_name, __u32 insns_cnt,
			     void **func_info, __u32 *cnt);
LIBBPF_API LIBBPF_DEPRECATED("btf_ext__reloc_line_info was never meant as a public API and has wrong assumptions embedded in it; it will be removed in the future libbpf versions")
int btf_ext__reloc_line_info(const struct btf *btf,
			     const struct btf_ext *btf_ext,
			     const char *sec_name, __u32 insns_cnt,
			     void **line_info, __u32 *cnt);
LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);

LIBBPF_API int btf__find_str(struct btf *btf, const char *s);
LIBBPF_API int btf__add_str(struct btf *btf, const char *s);
LIBBPF_API int btf__add_type(struct btf *btf, const struct btf *src_btf,
			     const struct btf_type *src_type);
/**
 * @brief **btf__add_btf()** appends all the BTF types from *src_btf* into *btf*
 * @param btf BTF object which all the BTF types and strings are added to
 * @param src_btf BTF object which all BTF types and referenced strings are copied from
 * @return BTF type ID of the first appended BTF type, or negative error code
 *
 * **btf__add_btf()** can be used to simply and efficiently append the entire
 * contents of one BTF object to another one. All the BTF type data is copied
 * over, all referenced type IDs are adjusted by adding a necessary ID offset.
 * Only strings referenced from BTF types are copied over and deduplicated, so
 * if there were some unused strings in *src_btf*, those won't be copied over,
 * which is consistent with the general string deduplication semantics of BTF
 * writing APIs.
 *
 * If any error is encountered during this process, the contents of *btf* is
 * left intact, which means that **btf__add_btf()** follows the transactional
 * semantics and the operation as a whole is all-or-nothing.
 *
 * *src_btf* has to be non-split BTF, as of now copying types from split BTF
 * is not supported and will result in -ENOTSUP error code returned.
 */
LIBBPF_API int btf__add_btf(struct btf *btf, const struct btf *src_btf);

LIBBPF_API int btf__add_int(struct btf *btf, const char *name, size_t byte_sz, int encoding);
LIBBPF_API int btf__add_float(struct btf *btf, const char *name, size_t byte_sz);
LIBBPF_API int btf__add_ptr(struct btf *btf, int ref_type_id);
LIBBPF_API int btf__add_array(struct btf *btf,
			      int index_type_id, int elem_type_id, __u32 nr_elems);
/* struct/union construction APIs */
LIBBPF_API int btf__add_struct(struct btf *btf, const char *name, __u32 sz);
LIBBPF_API int btf__add_union(struct btf *btf, const char *name, __u32 sz);
LIBBPF_API int btf__add_field(struct btf *btf, const char *name, int field_type_id,
			      __u32 bit_offset, __u32 bit_size);

/* enum construction APIs */
LIBBPF_API int btf__add_enum(struct btf *btf, const char *name, __u32 bytes_sz);
LIBBPF_API int btf__add_enum_value(struct btf *btf, const char *name, __s64 value);

enum btf_fwd_kind {
	BTF_FWD_STRUCT = 0,
	BTF_FWD_UNION = 1,
	BTF_FWD_ENUM = 2,
};

LIBBPF_API int btf__add_fwd(struct btf *btf, const char *name, enum btf_fwd_kind fwd_kind);
LIBBPF_API int btf__add_typedef(struct btf *btf, const char *name, int ref_type_id);
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,
			     enum btf_func_linkage linkage, int proto_type_id);
LIBBPF_API int btf__add_func_proto(struct btf *btf, int ret_type_id);
LIBBPF_API int btf__add_func_param(struct btf *btf, const char *name, int type_id);

/* var & datasec construction APIs */
LIBBPF_API int btf__add_var(struct btf *btf, const char *name, int linkage, int type_id);
LIBBPF_API int btf__add_datasec(struct btf *btf, const char *name, __u32 byte_sz);
LIBBPF_API int btf__add_datasec_var_info(struct btf *btf, int var_type_id,
					 __u32 offset, __u32 byte_sz);

/* tag construction API */
LIBBPF_API int btf__add_decl_tag(struct btf *btf, const char *value, int ref_type_id,
			    int component_idx);

struct btf_dedup_opts {
	size_t sz;
	/* optional .BTF.ext info to dedup along the main BTF info */
	struct btf_ext *btf_ext;
	/* force hash collisions (used for testing) */
	bool force_collisions;
	size_t :0;
};
#define btf_dedup_opts__last_field force_collisions

LIBBPF_API int btf__dedup(struct btf *btf, const struct btf_dedup_opts *opts);

LIBBPF_API int btf__dedup_v0_6_0(struct btf *btf, const struct btf_dedup_opts *opts);

LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__dedup() instead")
LIBBPF_API int btf__dedup_deprecated(struct btf *btf, struct btf_ext *btf_ext, const void *opts);
#define btf__dedup(...) ___libbpf_overload(___btf_dedup, __VA_ARGS__)
#define ___btf_dedup3(btf, btf_ext, opts) btf__dedup_deprecated(btf, btf_ext, opts)
#define ___btf_dedup2(btf, opts) btf__dedup(btf, opts)

struct btf_dump;

struct btf_dump_opts {
	union {
		size_t sz;
		void *ctx; /* DEPRECATED: will be gone in v1.0 */
	};
};

typedef void (*btf_dump_printf_fn_t)(void *ctx, const char *fmt, va_list args);

LIBBPF_API struct btf_dump *btf_dump__new(const struct btf *btf,
					  btf_dump_printf_fn_t printf_fn,
					  void *ctx,
					  const struct btf_dump_opts *opts);

LIBBPF_API struct btf_dump *btf_dump__new_v0_6_0(const struct btf *btf,
						 btf_dump_printf_fn_t printf_fn,
						 void *ctx,
						 const struct btf_dump_opts *opts);

LIBBPF_API struct btf_dump *btf_dump__new_deprecated(const struct btf *btf,
						     const struct btf_ext *btf_ext,
						     const struct btf_dump_opts *opts,
						     btf_dump_printf_fn_t printf_fn);

/* Choose either btf_dump__new() or btf_dump__new_deprecated() based on the
 * type of 4th argument. If it's btf_dump's print callback, use deprecated
 * API; otherwise, choose the new btf_dump__new(). ___libbpf_override()
 * doesn't work here because both variants have 4 input arguments.
 *
 * (void *) casts are necessary to avoid compilation warnings about type
 * mismatches, because even though __builtin_choose_expr() only ever evaluates
 * one side the other side still has to satisfy type constraints (this is
 * compiler implementation limitation which might be lifted eventually,
 * according to the documentation). So passing struct btf_ext in place of
 * btf_dump_printf_fn_t would be generating compilation warning.  Casting to
 * void * avoids this issue.
 *
 * Also, two type compatibility checks for a function and function pointer are
 * required because passing function reference into btf_dump__new() as
 * btf_dump__new(..., my_callback, ...) and as btf_dump__new(...,
 * &my_callback, ...) (not explicit ampersand in the latter case) actually
 * differs as far as __builtin_types_compatible_p() is concerned. Thus two
 * checks are combined to detect callback argument.
 *
 * The rest works just like in case of ___libbpf_override() usage with symbol
 * versioning.
 *
 * C++ compilers don't support __builtin_types_compatible_p(), so at least
 * don't screw up compilation for them and let C++ users pick btf_dump__new
 * vs btf_dump__new_deprecated explicitly.
 */
#ifndef __cplusplus
#define btf_dump__new(a1, a2, a3, a4) __builtin_choose_expr(				\
	__builtin_types_compatible_p(typeof(a4), btf_dump_printf_fn_t) ||		\
	__builtin_types_compatible_p(typeof(a4), void(void *, const char *, va_list)),	\
	btf_dump__new_deprecated((void *)a1, (void *)a2, (void *)a3, (void *)a4),	\
	btf_dump__new((void *)a1, (void *)a2, (void *)a3, (void *)a4))
#endif

LIBBPF_API void btf_dump__free(struct btf_dump *d);

LIBBPF_API int btf_dump__dump_type(struct btf_dump *d, __u32 id);

struct btf_dump_emit_type_decl_opts {
	/* size of this struct, for forward/backward compatiblity */
	size_t sz;
	/* optional field name for type declaration, e.g.:
	 * - struct my_struct <FNAME>
	 * - void (*<FNAME>)(int)
	 * - char (*<FNAME>)[123]
	 */
	const char *field_name;
	/* extra indentation level (in number of tabs) to emit for multi-line
	 * type declarations (e.g., anonymous struct); applies for lines
	 * starting from the second one (first line is assumed to have
	 * necessary indentation already
	 */
	int indent_level;
	/* strip all the const/volatile/restrict mods */
	bool strip_mods;
	size_t :0;
};
#define btf_dump_emit_type_decl_opts__last_field strip_mods

LIBBPF_API int
btf_dump__emit_type_decl(struct btf_dump *d, __u32 id,
			 const struct btf_dump_emit_type_decl_opts *opts);


struct btf_dump_type_data_opts {
	/* size of this struct, for forward/backward compatibility */
	size_t sz;
	const char *indent_str;
	int indent_level;
	/* below match "show" flags for bpf_show_snprintf() */
	bool compact;		/* no newlines/indentation */
	bool skip_names;	/* skip member/type names */
	bool emit_zeroes;	/* show 0-valued fields */
	size_t :0;
};
#define btf_dump_type_data_opts__last_field emit_zeroes

LIBBPF_API int
btf_dump__dump_type_data(struct btf_dump *d, __u32 id,
			 const void *data, size_t data_sz,
			 const struct btf_dump_type_data_opts *opts);

/*
 * A set of helpers for easier BTF types handling
 */
static inline __u16 btf_kind(const struct btf_type *t)
{
	return BTF_INFO_KIND(t->info);
}

static inline __u16 btf_vlen(const struct btf_type *t)
{
	return BTF_INFO_VLEN(t->info);
}

static inline bool btf_kflag(const struct btf_type *t)
{
	return BTF_INFO_KFLAG(t->info);
}

static inline bool btf_is_void(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_UNKN;
}

static inline bool btf_is_int(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_INT;
}

static inline bool btf_is_ptr(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_PTR;
}

static inline bool btf_is_array(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_ARRAY;
}

static inline bool btf_is_struct(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_STRUCT;
}

static inline bool btf_is_union(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_UNION;
}

static inline bool btf_is_composite(const struct btf_type *t)
{
	__u16 kind = btf_kind(t);

	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
}

static inline bool btf_is_enum(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_ENUM;
}

static inline bool btf_is_fwd(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_FWD;
}

static inline bool btf_is_typedef(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_TYPEDEF;
}

static inline bool btf_is_volatile(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_VOLATILE;
}

static inline bool btf_is_const(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_CONST;
}

static inline bool btf_is_restrict(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_RESTRICT;
}

static inline bool btf_is_mod(const struct btf_type *t)
{
	__u16 kind = btf_kind(t);

	return kind == BTF_KIND_VOLATILE ||
	       kind == BTF_KIND_CONST ||
	       kind == BTF_KIND_RESTRICT ||
	       kind == BTF_KIND_TYPE_TAG;
}

static inline bool btf_is_func(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_FUNC;
}

static inline bool btf_is_func_proto(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_FUNC_PROTO;
}

static inline bool btf_is_var(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_VAR;
}

static inline bool btf_is_datasec(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_DATASEC;
}

static inline bool btf_is_float(const struct btf_type *t)
{
	return btf_kind(t) == BTF_KIND_FLOAT;
}

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));
}

static inline __u8 btf_int_offset(const struct btf_type *t)
{
	return BTF_INT_OFFSET(*(__u32 *)(t + 1));
}

static inline __u8 btf_int_bits(const struct btf_type *t)
{
	return BTF_INT_BITS(*(__u32 *)(t + 1));
}

static inline struct btf_array *btf_array(const struct btf_type *t)
{
	return (struct btf_array *)(t + 1);
}

static inline struct btf_enum *btf_enum(const struct btf_type *t)
{
	return (struct btf_enum *)(t + 1);
}

static inline struct btf_member *btf_members(const struct btf_type *t)
{
	return (struct btf_member *)(t + 1);
}

/* Get bit offset of a member with specified index. */
static inline __u32 btf_member_bit_offset(const struct btf_type *t,
					  __u32 member_idx)
{
	const struct btf_member *m = btf_members(t) + member_idx;
	bool kflag = btf_kflag(t);

	return kflag ? BTF_MEMBER_BIT_OFFSET(m->offset) : m->offset;
}
/*
 * Get bitfield size of a member, assuming t is BTF_KIND_STRUCT or
 * BTF_KIND_UNION. If member is not a bitfield, zero is returned.
 */
static inline __u32 btf_member_bitfield_size(const struct btf_type *t,
					     __u32 member_idx)
{
	const struct btf_member *m = btf_members(t) + member_idx;
	bool kflag = btf_kflag(t);

	return kflag ? BTF_MEMBER_BITFIELD_SIZE(m->offset) : 0;
}

static inline struct btf_param *btf_params(const struct btf_type *t)
{
	return (struct btf_param *)(t + 1);
}

static inline struct btf_var *btf_var(const struct btf_type *t)
{
	return (struct btf_var *)(t + 1);
}

static inline struct btf_var_secinfo *
btf_var_secinfos(const struct btf_type *t)
{
	return (struct btf_var_secinfo *)(t + 1);
}

struct btf_decl_tag;
static inline struct btf_decl_tag *btf_decl_tag(const struct btf_type *t)
{
	return (struct btf_decl_tag *)(t + 1);
}

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* __LIBBPF_BTF_H */