linux-stable/tools/lib/bpf/relo_core.h
Daniel Müller ec6209c8d4 bpf, libbpf: Add type match support
This patch adds support for the proposed type match relation to
relo_core where it is shared between userspace and kernel. It plumbs
through both kernel-side and libbpf-side support.

The matching relation is defined as follows (copy from source):
- modifiers and typedefs are stripped (and, hence, effectively ignored)
- generally speaking types need to be of same kind (struct vs. struct, union
  vs. union, etc.)
  - exceptions are struct/union behind a pointer which could also match a
    forward declaration of a struct or union, respectively, and enum vs.
    enum64 (see below)
Then, depending on type:
- integers:
  - match if size and signedness match
- arrays & pointers:
  - target types are recursively matched
- structs & unions:
  - local members need to exist in target with the same name
  - for each member we recursively check match unless it is already behind a
    pointer, in which case we only check matching names and compatible kind
- enums:
  - local variants have to have a match in target by symbolic name (but not
    numeric value)
  - size has to match (but enum may match enum64 and vice versa)
- function pointers:
  - number and position of arguments in local type has to match target
  - for each argument and the return value we recursively check match

Signed-off-by: Daniel Müller <deso@posteo.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220628160127.607834-5-deso@posteo.net
2022-07-05 21:14:25 -07:00

99 lines
3.3 KiB
C

/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
/* Copyright (c) 2019 Facebook */
#ifndef __RELO_CORE_H
#define __RELO_CORE_H
#include <linux/bpf.h>
struct bpf_core_cand {
const struct btf *btf;
__u32 id;
};
/* dynamically sized list of type IDs and its associated struct btf */
struct bpf_core_cand_list {
struct bpf_core_cand *cands;
int len;
};
#define BPF_CORE_SPEC_MAX_LEN 64
/* represents BPF CO-RE field or array element accessor */
struct bpf_core_accessor {
__u32 type_id; /* struct/union type or array element type */
__u32 idx; /* field index or array index */
const char *name; /* field name or NULL for array accessor */
};
struct bpf_core_spec {
const struct btf *btf;
/* high-level spec: named fields and array indices only */
struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
/* original unresolved (no skip_mods_or_typedefs) root type ID */
__u32 root_type_id;
/* CO-RE relocation kind */
enum bpf_core_relo_kind relo_kind;
/* high-level spec length */
int len;
/* raw, low-level spec: 1-to-1 with accessor spec string */
int raw_spec[BPF_CORE_SPEC_MAX_LEN];
/* raw spec length */
int raw_len;
/* field bit offset represented by spec */
__u32 bit_offset;
};
struct bpf_core_relo_res {
/* expected value in the instruction, unless validate == false */
__u64 orig_val;
/* new value that needs to be patched up to */
__u64 new_val;
/* relocation unsuccessful, poison instruction, but don't fail load */
bool poison;
/* some relocations can't be validated against orig_val */
bool validate;
/* for field byte offset relocations or the forms:
* *(T *)(rX + <off>) = rY
* rX = *(T *)(rY + <off>),
* we remember original and resolved field size to adjust direct
* memory loads of pointers and integers; this is necessary for 32-bit
* host kernel architectures, but also allows to automatically
* relocate fields that were resized from, e.g., u32 to u64, etc.
*/
bool fail_memsz_adjust;
__u32 orig_sz;
__u32 orig_type_id;
__u32 new_sz;
__u32 new_type_id;
};
int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id, int level);
int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
const struct btf *targ_btf, __u32 targ_id);
int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
__u32 targ_id, bool behind_ptr, int level);
int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
__u32 targ_id);
size_t bpf_core_essential_name_len(const char *name);
int bpf_core_calc_relo_insn(const char *prog_name,
const struct bpf_core_relo *relo, int relo_idx,
const struct btf *local_btf,
struct bpf_core_cand_list *cands,
struct bpf_core_spec *specs_scratch,
struct bpf_core_relo_res *targ_res);
int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
int insn_idx, const struct bpf_core_relo *relo,
int relo_idx, const struct bpf_core_relo_res *res);
int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
const struct bpf_core_relo *relo,
struct bpf_core_spec *spec);
int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec);
#endif