include/linux/btf.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 /* Copyright (c) 2018 Facebook */
   3
   4 #ifndef _LINUX_BTF_H
   5 #define _LINUX_BTF_H 1
   6
   7 #include <linux/types.h>
   8 #include <uapi/linux/btf.h>
   9 #include <uapi/linux/bpf.h>
  10
  11 #define BTF_TYPE_EMIT(type) ((void)(type *)0)
  12 #define BTF_TYPE_EMIT_ENUM(enum_val) ((void)enum_val)
  13
  14 struct btf;
  15 struct btf_member;
  16 struct btf_type;
  17 union bpf_attr;
  18 struct btf_show;
  19
  20 extern const struct file_operations btf_fops;
  21
  22 void btf_get(struct btf *btf);
  23 void btf_put(struct btf *btf);
  24 int btf_new_fd(const union bpf_attr *attr);
  25 struct btf *btf_get_by_fd(int fd);
  26 int btf_get_info_by_fd(const struct btf *btf,
  27                        const union bpf_attr *attr,
  28                        union bpf_attr __user *uattr);
  29 /* Figure out the size of a type_id.  If type_id is a modifier
  30  * (e.g. const), it will be resolved to find out the type with size.
  31  *
  32  * For example:
  33  * In describing "const void *",  type_id is "const" and "const"
  34  * refers to "void *".  The return type will be "void *".
  35  *
  36  * If type_id is a simple "int", then return type will be "int".
  37  *
  38  * @btf: struct btf object
  39  * @type_id: Find out the size of type_id. The type_id of the return
  40  *           type is set to *type_id.
  41  * @ret_size: It can be NULL.  If not NULL, the size of the return
  42  *            type is set to *ret_size.
  43  * Return: The btf_type (resolved to another type with size info if needed).
  44  *         NULL is returned if type_id itself does not have size info
  45  *         (e.g. void) or it cannot be resolved to another type that
  46  *         has size info.
  47  *         *type_id and *ret_size will not be changed in the
  48  *         NULL return case.
  49  */
  50 const struct btf_type *btf_type_id_size(const struct btf *btf,
  51                                         u32 *type_id,
  52                                         u32 *ret_size);
  53
  54 /*
  55  * Options to control show behaviour.
  56  *      - BTF_SHOW_COMPACT: no formatting around type information
  57  *      - BTF_SHOW_NONAME: no struct/union member names/types
  58  *      - BTF_SHOW_PTR_RAW: show raw (unobfuscated) pointer values;
  59  *        equivalent to %px.
  60  *      - BTF_SHOW_ZERO: show zero-valued struct/union members; they
  61  *        are not displayed by default
  62  *      - BTF_SHOW_UNSAFE: skip use of bpf_probe_read() to safely read
  63  *        data before displaying it.
  64  */
  65 #define BTF_SHOW_COMPACT        BTF_F_COMPACT
  66 #define BTF_SHOW_NONAME         BTF_F_NONAME
  67 #define BTF_SHOW_PTR_RAW        BTF_F_PTR_RAW
  68 #define BTF_SHOW_ZERO           BTF_F_ZERO
  69 #define BTF_SHOW_UNSAFE         (1ULL << 4)
  70
  71 void btf_type_seq_show(const struct btf *btf, u32 type_id, void *obj,
  72                        struct seq_file *m);
  73 int btf_type_seq_show_flags(const struct btf *btf, u32 type_id, void *obj,
  74                             struct seq_file *m, u64 flags);
  75
  76 /*
  77  * Copy len bytes of string representation of obj of BTF type_id into buf.
  78  *
  79  * @btf: struct btf object
  80  * @type_id: type id of type obj points to
  81  * @obj: pointer to typed data
  82  * @buf: buffer to write to
  83  * @len: maximum length to write to buf
  84  * @flags: show options (see above)
  85  *
  86  * Return: length that would have been/was copied as per snprintf, or
  87  *         negative error.
  88  */
  89 int btf_type_snprintf_show(const struct btf *btf, u32 type_id, void *obj,
  90                            char *buf, int len, u64 flags);
  91
  92 int btf_get_fd_by_id(u32 id);
  93 u32 btf_obj_id(const struct btf *btf);
  94 bool btf_is_kernel(const struct btf *btf);
  95 bool btf_is_module(const struct btf *btf);
  96 struct module *btf_try_get_module(const struct btf *btf);
  97 u32 btf_nr_types(const struct btf *btf);
  98 bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s,
  99                            const struct btf_member *m,
 100                            u32 expected_offset, u32 expected_size);
 101 int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t);
 102 bool btf_type_is_void(const struct btf_type *t);
 103 s32 btf_find_by_name_kind(const struct btf *btf, const char *name, u8 kind);
 104 const struct btf_type *btf_type_skip_modifiers(const struct btf *btf,
 105                                                u32 id, u32 *res_id);
 106 const struct btf_type *btf_type_resolve_ptr(const struct btf *btf,
 107                                             u32 id, u32 *res_id);
 108 const struct btf_type *btf_type_resolve_func_ptr(const struct btf *btf,
 109                                                  u32 id, u32 *res_id);
 110 const struct btf_type *
 111 btf_resolve_size(const struct btf *btf, const struct btf_type *type,
 112                  u32 *type_size);
 113 const char *btf_type_str(const struct btf_type *t);
 114
 115 #define for_each_member(i, struct_type, member)                 \
 116         for (i = 0, member = btf_type_member(struct_type);      \
 117              i < btf_type_vlen(struct_type);                    \
 118              i++, member++)
 119
 120 #define for_each_vsi(i, datasec_type, member)                   \
 121         for (i = 0, member = btf_type_var_secinfo(datasec_type);        \
 122              i < btf_type_vlen(datasec_type);                   \
 123              i++, member++)
 124
 125 static inline bool btf_type_is_ptr(const struct btf_type *t)
 126 {
 127         return BTF_INFO_KIND(t->info) == BTF_KIND_PTR;
 128 }
 129
 130 static inline bool btf_type_is_int(const struct btf_type *t)
 131 {
 132         return BTF_INFO_KIND(t->info) == BTF_KIND_INT;
 133 }
 134
 135 static inline bool btf_type_is_small_int(const struct btf_type *t)
 136 {
 137         return btf_type_is_int(t) && t->size <= sizeof(u64);
 138 }
 139
 140 static inline bool btf_type_is_enum(const struct btf_type *t)
 141 {
 142         return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM;
 143 }
 144
 145 static inline bool btf_type_is_scalar(const struct btf_type *t)
 146 {
 147         return btf_type_is_int(t) || btf_type_is_enum(t);
 148 }
 149
 150 static inline bool btf_type_is_typedef(const struct btf_type *t)
 151 {
 152         return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF;
 153 }
 154
 155 static inline bool btf_type_is_func(const struct btf_type *t)
 156 {
 157         return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC;
 158 }
 159
 160 static inline bool btf_type_is_func_proto(const struct btf_type *t)
 161 {
 162         return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO;
 163 }
 164
 165 static inline bool btf_type_is_var(const struct btf_type *t)
 166 {
 167         return BTF_INFO_KIND(t->info) == BTF_KIND_VAR;
 168 }
 169
 170 /* union is only a special case of struct:
 171  * all its offsetof(member) == 0
 172  */
 173 static inline bool btf_type_is_struct(const struct btf_type *t)
 174 {
 175         u8 kind = BTF_INFO_KIND(t->info);
 176
 177         return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
 178 }
 179
 180 static inline u16 btf_type_vlen(const struct btf_type *t)
 181 {
 182         return BTF_INFO_VLEN(t->info);
 183 }
 184
 185 static inline u16 btf_func_linkage(const struct btf_type *t)
 186 {
 187         return BTF_INFO_VLEN(t->info);
 188 }
 189
 190 static inline bool btf_type_kflag(const struct btf_type *t)
 191 {
 192         return BTF_INFO_KFLAG(t->info);
 193 }
 194
 195 static inline u32 btf_member_bit_offset(const struct btf_type *struct_type,
 196                                         const struct btf_member *member)
 197 {
 198         return btf_type_kflag(struct_type) ? BTF_MEMBER_BIT_OFFSET(member->offset)
 199                                            : member->offset;
 200 }
 201
 202 static inline u32 btf_member_bitfield_size(const struct btf_type *struct_type,
 203                                            const struct btf_member *member)
 204 {
 205         return btf_type_kflag(struct_type) ? BTF_MEMBER_BITFIELD_SIZE(member->offset)
 206                                            : 0;
 207 }
 208
 209 static inline const struct btf_member *btf_type_member(const struct btf_type *t)
 210 {
 211         return (const struct btf_member *)(t + 1);
 212 }
 213
 214 static inline const struct btf_var_secinfo *btf_type_var_secinfo(
 215                 const struct btf_type *t)
 216 {
 217         return (const struct btf_var_secinfo *)(t + 1);
 218 }
 219
 220 #ifdef CONFIG_BPF_SYSCALL
 221 struct bpf_prog;
 222
 223 const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id);
 224 const char *btf_name_by_offset(const struct btf *btf, u32 offset);
 225 struct btf *btf_parse_vmlinux(void);
 226 struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog);
 227 #else
 228 static inline const struct btf_type *btf_type_by_id(const struct btf *btf,
 229                                                     u32 type_id)
 230 {
 231         return NULL;
 232 }
 233 static inline const char *btf_name_by_offset(const struct btf *btf,
 234                                              u32 offset)
 235 {
 236         return NULL;
 237 }
 238 #endif
 239
 240 #endif