tools/lib/bpf/libbpf_internal.h

   1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
   2
   3 /*
   4  * Internal libbpf helpers.
   5  *
   6  * Copyright (c) 2019 Facebook
   7  */
   8
   9 #ifndef __LIBBPF_LIBBPF_INTERNAL_H
  10 #define __LIBBPF_LIBBPF_INTERNAL_H
  11
  12 #include <stdlib.h>
  13 #include <limits.h>
  14
  15 /* make sure libbpf doesn't use kernel-only integer typedefs */
  16 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
  17
  18 /* prevent accidental re-addition of reallocarray() */
  19 #pragma GCC poison reallocarray
  20
  21 #include "libbpf.h"
  22
  23 #define BTF_INFO_ENC(kind, kind_flag, vlen) \
  24         ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
  25 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
  26 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
  27         ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
  28 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
  29         BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
  30         BTF_INT_ENC(encoding, bits_offset, bits)
  31 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
  32 #define BTF_PARAM_ENC(name, type) (name), (type)
  33 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
  34
  35 #ifndef likely
  36 #define likely(x) __builtin_expect(!!(x), 1)
  37 #endif
  38 #ifndef unlikely
  39 #define unlikely(x) __builtin_expect(!!(x), 0)
  40 #endif
  41 #ifndef min
  42 # define min(x, y) ((x) < (y) ? (x) : (y))
  43 #endif
  44 #ifndef max
  45 # define max(x, y) ((x) < (y) ? (y) : (x))
  46 #endif
  47 #ifndef offsetofend
  48 # define offsetofend(TYPE, FIELD) \
  49         (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
  50 #endif
  51
  52 /* Symbol versioning is different between static and shared library.
  53  * Properly versioned symbols are needed for shared library, but
  54  * only the symbol of the new version is needed for static library.
  55  */
  56 #ifdef SHARED
  57 # define COMPAT_VERSION(internal_name, api_name, version) \
  58         asm(".symver " #internal_name "," #api_name "@" #version);
  59 # define DEFAULT_VERSION(internal_name, api_name, version) \
  60         asm(".symver " #internal_name "," #api_name "@@" #version);
  61 #else
  62 # define COMPAT_VERSION(internal_name, api_name, version)
  63 # define DEFAULT_VERSION(internal_name, api_name, version) \
  64         extern typeof(internal_name) api_name \
  65         __attribute__((alias(#internal_name)));
  66 #endif
  67
  68 extern void libbpf_print(enum libbpf_print_level level,
  69                          const char *format, ...)
  70         __attribute__((format(printf, 2, 3)));
  71
  72 #define __pr(level, fmt, ...)   \
  73 do {                            \
  74         libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);     \
  75 } while (0)
  76
  77 #define pr_warn(fmt, ...)       __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
  78 #define pr_info(fmt, ...)       __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
  79 #define pr_debug(fmt, ...)      __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
  80
  81 #ifndef __has_builtin
  82 #define __has_builtin(x) 0
  83 #endif
  84 /*
  85  * Re-implement glibc's reallocarray() for libbpf internal-only use.
  86  * reallocarray(), unfortunately, is not available in all versions of glibc,
  87  * so requires extra feature detection and using reallocarray() stub from
  88  * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
  89  * build of libbpf unnecessarily and is just a maintenance burden. Instead,
  90  * it's trivial to implement libbpf-specific internal version and use it
  91  * throughout libbpf.
  92  */
  93 static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
  94 {
  95         size_t total;
  96
  97 #if __has_builtin(__builtin_mul_overflow)
  98         if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
  99                 return NULL;
 100 #else
 101         if (size == 0 || nmemb > ULONG_MAX / size)
 102                 return NULL;
 103         total = nmemb * size;
 104 #endif
 105         return realloc(ptr, total);
 106 }
 107
 108 void *btf_add_mem(void **data, size_t *cap_cnt, size_t elem_sz,
 109                   size_t cur_cnt, size_t max_cnt, size_t add_cnt);
 110 int btf_ensure_mem(void **data, size_t *cap_cnt, size_t elem_sz, size_t need_cnt);
 111
 112 static inline bool libbpf_validate_opts(const char *opts,
 113                                         size_t opts_sz, size_t user_sz,
 114                                         const char *type_name)
 115 {
 116         if (user_sz < sizeof(size_t)) {
 117                 pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
 118                 return false;
 119         }
 120         if (user_sz > opts_sz) {
 121                 size_t i;
 122
 123                 for (i = opts_sz; i < user_sz; i++) {
 124                         if (opts[i]) {
 125                                 pr_warn("%s has non-zero extra bytes\n",
 126                                         type_name);
 127                                 return false;
 128                         }
 129                 }
 130         }
 131         return true;
 132 }
 133
 134 #define OPTS_VALID(opts, type)                                                \
 135         (!(opts) || libbpf_validate_opts((const char *)opts,                  \
 136                                          offsetofend(struct type,             \
 137                                                      type##__last_field),     \
 138                                          (opts)->sz, #type))
 139 #define OPTS_HAS(opts, field) \
 140         ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
 141 #define OPTS_GET(opts, field, fallback_value) \
 142         (OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
 143 #define OPTS_SET(opts, field, value)            \
 144         do {                                    \
 145                 if (OPTS_HAS(opts, field))      \
 146                         (opts)->field = value;  \
 147         } while (0)
 148
 149 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
 150 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
 151 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
 152                          const char *str_sec, size_t str_len);
 153
 154 struct bpf_prog_load_params {
 155         enum bpf_prog_type prog_type;
 156         enum bpf_attach_type expected_attach_type;
 157         const char *name;
 158         const struct bpf_insn *insns;
 159         size_t insn_cnt;
 160         const char *license;
 161         __u32 kern_version;
 162         __u32 attach_prog_fd;
 163         __u32 attach_btf_obj_fd;
 164         __u32 attach_btf_id;
 165         __u32 prog_ifindex;
 166         __u32 prog_btf_fd;
 167         __u32 prog_flags;
 168
 169         __u32 func_info_rec_size;
 170         const void *func_info;
 171         __u32 func_info_cnt;
 172
 173         __u32 line_info_rec_size;
 174         const void *line_info;
 175         __u32 line_info_cnt;
 176
 177         __u32 log_level;
 178         char *log_buf;
 179         size_t log_buf_sz;
 180 };
 181
 182 int libbpf__bpf_prog_load(const struct bpf_prog_load_params *load_attr);
 183
 184 int bpf_object__section_size(const struct bpf_object *obj, const char *name,
 185                              __u32 *size);
 186 int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
 187                                 __u32 *off);
 188 struct btf *btf_get_from_fd(int btf_fd, struct btf *base_btf);
 189
 190 struct btf_ext_info {
 191         /*
 192          * info points to the individual info section (e.g. func_info and
 193          * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
 194          */
 195         void *info;
 196         __u32 rec_size;
 197         __u32 len;
 198 };
 199
 200 #define for_each_btf_ext_sec(seg, sec)                                  \
 201         for (sec = (seg)->info;                                         \
 202              (void *)sec < (seg)->info + (seg)->len;                    \
 203              sec = (void *)sec + sizeof(struct btf_ext_info_sec) +      \
 204                    (seg)->rec_size * sec->num_info)
 205
 206 #define for_each_btf_ext_rec(seg, sec, i, rec)                          \
 207         for (i = 0, rec = (void *)&(sec)->data;                         \
 208              i < (sec)->num_info;                                       \
 209              i++, rec = (void *)rec + (seg)->rec_size)
 210
 211 /*
 212  * The .BTF.ext ELF section layout defined as
 213  *   struct btf_ext_header
 214  *   func_info subsection
 215  *
 216  * The func_info subsection layout:
 217  *   record size for struct bpf_func_info in the func_info subsection
 218  *   struct btf_sec_func_info for section #1
 219  *   a list of bpf_func_info records for section #1
 220  *     where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
 221  *     but may not be identical
 222  *   struct btf_sec_func_info for section #2
 223  *   a list of bpf_func_info records for section #2
 224  *   ......
 225  *
 226  * Note that the bpf_func_info record size in .BTF.ext may not
 227  * be the same as the one defined in include/uapi/linux/bpf.h.
 228  * The loader should ensure that record_size meets minimum
 229  * requirement and pass the record as is to the kernel. The
 230  * kernel will handle the func_info properly based on its contents.
 231  */
 232 struct btf_ext_header {
 233         __u16   magic;
 234         __u8    version;
 235         __u8    flags;
 236         __u32   hdr_len;
 237
 238         /* All offsets are in bytes relative to the end of this header */
 239         __u32   func_info_off;
 240         __u32   func_info_len;
 241         __u32   line_info_off;
 242         __u32   line_info_len;
 243
 244         /* optional part of .BTF.ext header */
 245         __u32   core_relo_off;
 246         __u32   core_relo_len;
 247 };
 248
 249 struct btf_ext {
 250         union {
 251                 struct btf_ext_header *hdr;
 252                 void *data;
 253         };
 254         struct btf_ext_info func_info;
 255         struct btf_ext_info line_info;
 256         struct btf_ext_info core_relo_info;
 257         __u32 data_size;
 258 };
 259
 260 struct btf_ext_info_sec {
 261         __u32   sec_name_off;
 262         __u32   num_info;
 263         /* Followed by num_info * record_size number of bytes */
 264         __u8    data[];
 265 };
 266
 267 /* The minimum bpf_func_info checked by the loader */
 268 struct bpf_func_info_min {
 269         __u32   insn_off;
 270         __u32   type_id;
 271 };
 272
 273 /* The minimum bpf_line_info checked by the loader */
 274 struct bpf_line_info_min {
 275         __u32   insn_off;
 276         __u32   file_name_off;
 277         __u32   line_off;
 278         __u32   line_col;
 279 };
 280
 281 /* bpf_core_relo_kind encodes which aspect of captured field/type/enum value
 282  * has to be adjusted by relocations.
 283  */
 284 enum bpf_core_relo_kind {
 285         BPF_FIELD_BYTE_OFFSET = 0,      /* field byte offset */
 286         BPF_FIELD_BYTE_SIZE = 1,        /* field size in bytes */
 287         BPF_FIELD_EXISTS = 2,           /* field existence in target kernel */
 288         BPF_FIELD_SIGNED = 3,           /* field signedness (0 - unsigned, 1 - signed) */
 289         BPF_FIELD_LSHIFT_U64 = 4,       /* bitfield-specific left bitshift */
 290         BPF_FIELD_RSHIFT_U64 = 5,       /* bitfield-specific right bitshift */
 291         BPF_TYPE_ID_LOCAL = 6,          /* type ID in local BPF object */
 292         BPF_TYPE_ID_TARGET = 7,         /* type ID in target kernel */
 293         BPF_TYPE_EXISTS = 8,            /* type existence in target kernel */
 294         BPF_TYPE_SIZE = 9,              /* type size in bytes */
 295         BPF_ENUMVAL_EXISTS = 10,        /* enum value existence in target kernel */
 296         BPF_ENUMVAL_VALUE = 11,         /* enum value integer value */
 297 };
 298
 299 /* The minimum bpf_core_relo checked by the loader
 300  *
 301  * CO-RE relocation captures the following data:
 302  * - insn_off - instruction offset (in bytes) within a BPF program that needs
 303  *   its insn->imm field to be relocated with actual field info;
 304  * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
 305  *   type or field;
 306  * - access_str_off - offset into corresponding .BTF string section. String
 307  *   interpretation depends on specific relocation kind:
 308  *     - for field-based relocations, string encodes an accessed field using
 309  *     a sequence of field and array indices, separated by colon (:). It's
 310  *     conceptually very close to LLVM's getelementptr ([0]) instruction's
 311  *     arguments for identifying offset to a field.
 312  *     - for type-based relocations, strings is expected to be just "0";
 313  *     - for enum value-based relocations, string contains an index of enum
 314  *     value within its enum type;
 315  *
 316  * Example to provide a better feel.
 317  *
 318  *   struct sample {
 319  *       int a;
 320  *       struct {
 321  *           int b[10];
 322  *       };
 323  *   };
 324  *
 325  *   struct sample *s = ...;
 326  *   int x = &s->a;     // encoded as "0:0" (a is field #0)
 327  *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1,
 328  *                      // b is field #0 inside anon struct, accessing elem #5)
 329  *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
 330  *
 331  * type_id for all relocs in this example  will capture BTF type id of
 332  * `struct sample`.
 333  *
 334  * Such relocation is emitted when using __builtin_preserve_access_index()
 335  * Clang built-in, passing expression that captures field address, e.g.:
 336  *
 337  * bpf_probe_read(&dst, sizeof(dst),
 338  *                __builtin_preserve_access_index(&src->a.b.c));
 339  *
 340  * In this case Clang will emit field relocation recording necessary data to
 341  * be able to find offset of embedded `a.b.c` field within `src` struct.
 342  *
 343  *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
 344  */
 345 struct bpf_core_relo {
 346         __u32   insn_off;
 347         __u32   type_id;
 348         __u32   access_str_off;
 349         enum bpf_core_relo_kind kind;
 350 };
 351
 352 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */