root/tools/lib/bpf/libbpf_internal.h

INCLUDED FROM

   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_warning(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 int parse_cpu_mask_str(const char *s, bool **mask, int *mask_sz);
  67 int parse_cpu_mask_file(const char *fcpu, bool **mask, int *mask_sz);
  68 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
  69                          const char *str_sec, size_t str_len);
  70 
  71 struct btf_ext_info {
  72         /*
  73          * info points to the individual info section (e.g. func_info and
  74          * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
  75          */
  76         void *info;
  77         __u32 rec_size;
  78         __u32 len;
  79 };
  80 
  81 #define for_each_btf_ext_sec(seg, sec)                                  \
  82         for (sec = (seg)->info;                                         \
  83              (void *)sec < (seg)->info + (seg)->len;                    \
  84              sec = (void *)sec + sizeof(struct btf_ext_info_sec) +      \
  85                    (seg)->rec_size * sec->num_info)
  86 
  87 #define for_each_btf_ext_rec(seg, sec, i, rec)                          \
  88         for (i = 0, rec = (void *)&(sec)->data;                         \
  89              i < (sec)->num_info;                                       \
  90              i++, rec = (void *)rec + (seg)->rec_size)
  91 
  92 struct btf_ext {
  93         union {
  94                 struct btf_ext_header *hdr;
  95                 void *data;
  96         };
  97         struct btf_ext_info func_info;
  98         struct btf_ext_info line_info;
  99         struct btf_ext_info offset_reloc_info;
 100         __u32 data_size;
 101 };
 102 
 103 struct btf_ext_info_sec {
 104         __u32   sec_name_off;
 105         __u32   num_info;
 106         /* Followed by num_info * record_size number of bytes */
 107         __u8    data[0];
 108 };
 109 
 110 /* The minimum bpf_func_info checked by the loader */
 111 struct bpf_func_info_min {
 112         __u32   insn_off;
 113         __u32   type_id;
 114 };
 115 
 116 /* The minimum bpf_line_info checked by the loader */
 117 struct bpf_line_info_min {
 118         __u32   insn_off;
 119         __u32   file_name_off;
 120         __u32   line_off;
 121         __u32   line_col;
 122 };
 123 
 124 /* The minimum bpf_offset_reloc checked by the loader
 125  *
 126  * Offset relocation captures the following data:
 127  * - insn_off - instruction offset (in bytes) within a BPF program that needs
 128  *   its insn->imm field to be relocated with actual offset;
 129  * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
 130  *   offset;
 131  * - access_str_off - offset into corresponding .BTF string section. String
 132  *   itself encodes an accessed field using a sequence of field and array
 133  *   indicies, separated by colon (:). It's conceptually very close to LLVM's
 134  *   getelementptr ([0]) instruction's arguments for identifying offset to 
 135  *   a field.
 136  *
 137  * Example to provide a better feel.
 138  *
 139  *   struct sample {
 140  *       int a;
 141  *       struct {
 142  *           int b[10];
 143  *       };
 144  *   };
 145  *
 146  *   struct sample *s = ...;
 147  *   int x = &s->a;     // encoded as "0:0" (a is field #0)
 148  *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1, 
 149  *                      // b is field #0 inside anon struct, accessing elem #5)
 150  *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
 151  *
 152  * type_id for all relocs in this example  will capture BTF type id of
 153  * `struct sample`.
 154  *
 155  * Such relocation is emitted when using __builtin_preserve_access_index()
 156  * Clang built-in, passing expression that captures field address, e.g.:
 157  *
 158  * bpf_probe_read(&dst, sizeof(dst),
 159  *                __builtin_preserve_access_index(&src->a.b.c));
 160  *
 161  * In this case Clang will emit offset relocation recording necessary data to
 162  * be able to find offset of embedded `a.b.c` field within `src` struct.
 163  *
 164  *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
 165  */
 166 struct bpf_offset_reloc {
 167         __u32   insn_off;
 168         __u32   type_id;
 169         __u32   access_str_off;
 170 };
 171 
 172 #endif /* __LIBBPF_LIBBPF_INTERNAL_H */