tools/lib/bpf/relo_core.h

   1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
   2 /* Copyright (c) 2019 Facebook */
   3
   4 #ifndef __RELO_CORE_H
   5 #define __RELO_CORE_H
   6
   7 #include <linux/bpf.h>
   8
   9 struct bpf_core_cand {
  10         const struct btf *btf;
  11         __u32 id;
  12 };
  13
  14 /* dynamically sized list of type IDs and its associated struct btf */
  15 struct bpf_core_cand_list {
  16         struct bpf_core_cand *cands;
  17         int len;
  18 };
  19
  20 #define BPF_CORE_SPEC_MAX_LEN 64
  21
  22 /* represents BPF CO-RE field or array element accessor */
  23 struct bpf_core_accessor {
  24         __u32 type_id;          /* struct/union type or array element type */
  25         __u32 idx;              /* field index or array index */
  26         const char *name;       /* field name or NULL for array accessor */
  27 };
  28
  29 struct bpf_core_spec {
  30         const struct btf *btf;
  31         /* high-level spec: named fields and array indices only */
  32         struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
  33         /* original unresolved (no skip_mods_or_typedefs) root type ID */
  34         __u32 root_type_id;
  35         /* CO-RE relocation kind */
  36         enum bpf_core_relo_kind relo_kind;
  37         /* high-level spec length */
  38         int len;
  39         /* raw, low-level spec: 1-to-1 with accessor spec string */
  40         int raw_spec[BPF_CORE_SPEC_MAX_LEN];
  41         /* raw spec length */
  42         int raw_len;
  43         /* field bit offset represented by spec */
  44         __u32 bit_offset;
  45 };
  46
  47 struct bpf_core_relo_res {
  48         /* expected value in the instruction, unless validate == false */
  49         __u64 orig_val;
  50         /* new value that needs to be patched up to */
  51         __u64 new_val;
  52         /* relocation unsuccessful, poison instruction, but don't fail load */
  53         bool poison;
  54         /* some relocations can't be validated against orig_val */
  55         bool validate;
  56         /* for field byte offset relocations or the forms:
  57          *     *(T *)(rX + <off>) = rY
  58          *     rX = *(T *)(rY + <off>),
  59          * we remember original and resolved field size to adjust direct
  60          * memory loads of pointers and integers; this is necessary for 32-bit
  61          * host kernel architectures, but also allows to automatically
  62          * relocate fields that were resized from, e.g., u32 to u64, etc.
  63          */
  64         bool fail_memsz_adjust;
  65         __u32 orig_sz;
  66         __u32 orig_type_id;
  67         __u32 new_sz;
  68         __u32 new_type_id;
  69 };
  70
  71 int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
  72                                 const struct btf *targ_btf, __u32 targ_id, int level);
  73 int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
  74                               const struct btf *targ_btf, __u32 targ_id);
  75 int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
  76                            __u32 targ_id, bool behind_ptr, int level);
  77 int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
  78                          __u32 targ_id);
  79
  80 size_t bpf_core_essential_name_len(const char *name);
  81
  82 int bpf_core_calc_relo_insn(const char *prog_name,
  83                             const struct bpf_core_relo *relo, int relo_idx,
  84                             const struct btf *local_btf,
  85                             struct bpf_core_cand_list *cands,
  86                             struct bpf_core_spec *specs_scratch,
  87                             struct bpf_core_relo_res *targ_res);
  88
  89 int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
  90                         int insn_idx, const struct bpf_core_relo *relo,
  91                         int relo_idx, const struct bpf_core_relo_res *res);
  92
  93 int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
  94                         const struct bpf_core_relo *relo,
  95                         struct bpf_core_spec *spec);
  96
  97 int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec);
  98
  99 #endif