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 "libbpf.h"
  13
  14 #define BTF_INFO_ENC(kind, kind_flag, vlen) \
  15         ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
  16 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
  17 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
  18         ((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
  19 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
  20         BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
  21         BTF_INT_ENC(encoding, bits_offset, bits)
  22 #define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
  23 #define BTF_PARAM_ENC(name, type) (name), (type)
  24 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
  25
  26 #ifndef min
  27 # define min(x, y) ((x) < (y) ? (x) : (y))
  28 #endif
  29 #ifndef max
  30 # define max(x, y) ((x) < (y) ? (y) : (x))
  31 #endif
  32 #ifndef offsetofend
  33 # define offsetofend(TYPE, FIELD) \
  34         (offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
  35 #endif
  36
  37 /* Symbol versioning is different between static and shared library.
  38  * Properly versioned symbols are needed for shared library, but
  39  * only the symbol of the new version is needed for static library.
  40  */
  41 #ifdef SHARED
  42 # define COMPAT_VERSION(internal_name, api_name, version) \
  43         asm(".symver " #internal_name "," #api_name "@" #version);
  44 # define DEFAULT_VERSION(internal_name, api_name, version) \
  45         asm(".symver " #internal_name "," #api_name "@@" #version);
  46 #else
  47 # define COMPAT_VERSION(internal_name, api_name, version)
  48 # define DEFAULT_VERSION(internal_name, api_name, version) \
  49         extern typeof(internal_name) api_name \
  50         __attribute__((alias(#internal_name)));
  51 #endif
  52
  53 extern void libbpf_print(enum libbpf_print_level level,
  54                          const char *format, ...)
  55         __attribute__((format(printf, 2, 3)));
  56
  57 #define __pr(level, fmt, ...)   \
  58 do {                            \
  59         libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);     \
  60 } while (0)
  61
  62 #define pr_warn(fmt, ...)       __pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
  63 #define pr_info(fmt, ...)       __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
  64 #define pr_debug(fmt, ...)      __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
  65
  66 static inline bool libbpf_validate_opts(const char *opts,
  67                                         size_t opts_sz, size_t user_sz,
  68                                         const char *type_name)
  69 {
  70         if (user_sz < sizeof(size_t)) {
  71                 pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
  72                 return false;
  73         }
  74         if (user_sz > opts_sz) {
  75                 size_t i;
  76
  77                 for (i = opts_sz; i < user_sz; i++) {
  78                         if (opts[i]) {
  79                                 pr_warn("%s has non-zero extra bytes\n",
  80                                         type_name);
  81                                 return false;
  82                         }
  83                 }
  84         }
  85         return true;
  86 }
  87
  88 #define OPTS_VALID(opts, type)                                                \
  89         (!(opts) || libbpf_validate_opts((const char *)opts,                  \
  90                                          offsetofend(struct type,             \
  91                                                      type##__last_field),     \
  92                                          (opts)->sz, #type))
  93 #define OPTS_HAS(opts, field) \
  94         ((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
  95 #define OPTS_GET(opts, field, fallback_value) \
  96         (OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
  97
  98 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
  99 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
 100 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
 101                          const char *str_sec, size_t str_len);
 102
 103 int bpf_object__section_size(const struct bpf_object *obj, const char *name,
 104                              __u32 *size);
 105 int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
 106                                 __u32 *off);
 107
 108 struct nlattr;
 109 typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
 110 int libbpf_netlink_open(unsigned int *nl_pid);
 111 int libbpf_nl_get_link(int sock, unsigned int nl_pid,
 112                        libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie);
 113 int libbpf_nl_get_class(int sock, unsigned int nl_pid, int ifindex,
 114                         libbpf_dump_nlmsg_t dump_class_nlmsg, void *cookie);
 115 int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
 116                         libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie);
 117 int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
 118                          libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie);
 119
 120 struct btf_ext_info {
 121         /*
 122          * info points to the individual info section (e.g. func_info and
 123          * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
 124          */
 125         void *info;
 126         __u32 rec_size;
 127         __u32 len;
 128 };
 129
 130 #define for_each_btf_ext_sec(seg, sec)                                  \
 131         for (sec = (seg)->info;                                         \
 132              (void *)sec < (seg)->info + (seg)->len;                    \
 133              sec = (void *)sec + sizeof(struct btf_ext_info_sec) +      \
 134                    (seg)->rec_size * sec->num_info)
 135
 136 #define for_each_btf_ext_rec(seg, sec, i, rec)                          \
 137         for (i = 0, rec = (void *)&(sec)->data;                         \
 138              i < (sec)->num_info;                                       \
 139              i++, rec = (void *)rec + (seg)->rec_size)
 140
 141 struct btf_ext {
 142         union {
 143                 struct btf_ext_header *hdr;
 144                 void *data;
 145         };
 146         struct btf_ext_info func_info;
 147         struct btf_ext_info line_info;
 148         struct btf_ext_info field_reloc_info;
 149         __u32 data_size;
 150 };
 151
 152 struct btf_ext_info_sec {
 153         __u32   sec_name_off;
 154         __u32   num_info;
 155         /* Followed by num_info * record_size number of bytes */
 156         __u8    data[0];
 157 };
 158
 159 /* The minimum bpf_func_info checked by the loader */
 160 struct bpf_func_info_min {
 161         __u32   insn_off;
 162         __u32   type_id;
 163 };
 164
 165 /* The minimum bpf_line_info checked by the loader */
 166 struct bpf_line_info_min {
 167         __u32   insn_off;
 168         __u32   file_name_off;
 169         __u32   line_off;
 170         __u32   line_col;
 171 };
 172
 173 /* bpf_field_info_kind encodes which aspect of captured field has to be
 174  * adjusted by relocations. Currently supported values are:
 175  *   - BPF_FIELD_BYTE_OFFSET: field offset (in bytes);
 176  *   - BPF_FIELD_EXISTS: field existence (1, if field exists; 0, otherwise);
 177  */
 178 enum bpf_field_info_kind {
 179         BPF_FIELD_BYTE_OFFSET = 0,      /* field byte offset */
 180         BPF_FIELD_BYTE_SIZE = 1,
 181         BPF_FIELD_EXISTS = 2,           /* field existence in target kernel */
 182         BPF_FIELD_SIGNED = 3,
 183         BPF_FIELD_LSHIFT_U64 = 4,
 184         BPF_FIELD_RSHIFT_U64 = 5,
 185 };
 186
 187 /* The minimum bpf_field_reloc checked by the loader
 188  *
 189  * Field relocation captures the following data:
 190  * - insn_off - instruction offset (in bytes) within a BPF program that needs
 191  *   its insn->imm field to be relocated with actual field info;
 192  * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
 193  *   field;
 194  * - access_str_off - offset into corresponding .BTF string section. String
 195  *   itself encodes an accessed field using a sequence of field and array
 196  *   indicies, separated by colon (:). It's conceptually very close to LLVM's
 197  *   getelementptr ([0]) instruction's arguments for identifying offset to
 198  *   a field.
 199  *
 200  * Example to provide a better feel.
 201  *
 202  *   struct sample {
 203  *       int a;
 204  *       struct {
 205  *           int b[10];
 206  *       };
 207  *   };
 208  *
 209  *   struct sample *s = ...;
 210  *   int x = &s->a;     // encoded as "0:0" (a is field #0)
 211  *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1,
 212  *                      // b is field #0 inside anon struct, accessing elem #5)
 213  *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
 214  *
 215  * type_id for all relocs in this example  will capture BTF type id of
 216  * `struct sample`.
 217  *
 218  * Such relocation is emitted when using __builtin_preserve_access_index()
 219  * Clang built-in, passing expression that captures field address, e.g.:
 220  *
 221  * bpf_probe_read(&dst, sizeof(dst),
 222  *                __builtin_preserve_access_index(&src->a.b.c));
 223  *
 224  * In this case Clang will emit field relocation recording necessary data to
 225  * be able to find offset of embedded `a.b.c` field within `src` struct.
 226  *
 227  *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
 228  */
 229 struct bpf_field_reloc {
 230         __u32   insn_off;
 231         __u32   type_id;
 232         __u32   access_str_off;
 233         enum bpf_field_info_kind kind;
 234 };
 235
 236 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */