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ec6209c8d4
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
99 lines
3.3 KiB
C
99 lines
3.3 KiB
C
/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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/* Copyright (c) 2019 Facebook */
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#ifndef __RELO_CORE_H
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#define __RELO_CORE_H
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#include <linux/bpf.h>
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struct bpf_core_cand {
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const struct btf *btf;
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__u32 id;
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};
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/* dynamically sized list of type IDs and its associated struct btf */
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struct bpf_core_cand_list {
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struct bpf_core_cand *cands;
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int len;
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};
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#define BPF_CORE_SPEC_MAX_LEN 64
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/* represents BPF CO-RE field or array element accessor */
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struct bpf_core_accessor {
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__u32 type_id; /* struct/union type or array element type */
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__u32 idx; /* field index or array index */
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const char *name; /* field name or NULL for array accessor */
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};
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struct bpf_core_spec {
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const struct btf *btf;
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/* high-level spec: named fields and array indices only */
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struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
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/* original unresolved (no skip_mods_or_typedefs) root type ID */
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__u32 root_type_id;
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/* CO-RE relocation kind */
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enum bpf_core_relo_kind relo_kind;
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/* high-level spec length */
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int len;
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/* raw, low-level spec: 1-to-1 with accessor spec string */
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int raw_spec[BPF_CORE_SPEC_MAX_LEN];
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/* raw spec length */
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int raw_len;
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/* field bit offset represented by spec */
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__u32 bit_offset;
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};
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struct bpf_core_relo_res {
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/* expected value in the instruction, unless validate == false */
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__u64 orig_val;
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/* new value that needs to be patched up to */
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__u64 new_val;
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/* relocation unsuccessful, poison instruction, but don't fail load */
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bool poison;
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/* some relocations can't be validated against orig_val */
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bool validate;
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/* for field byte offset relocations or the forms:
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* *(T *)(rX + <off>) = rY
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* rX = *(T *)(rY + <off>),
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* we remember original and resolved field size to adjust direct
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* memory loads of pointers and integers; this is necessary for 32-bit
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* host kernel architectures, but also allows to automatically
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* relocate fields that were resized from, e.g., u32 to u64, etc.
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*/
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bool fail_memsz_adjust;
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__u32 orig_sz;
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__u32 orig_type_id;
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__u32 new_sz;
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__u32 new_type_id;
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};
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int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
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const struct btf *targ_btf, __u32 targ_id, int level);
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int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id,
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const struct btf *targ_btf, __u32 targ_id);
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int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
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__u32 targ_id, bool behind_ptr, int level);
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int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf,
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__u32 targ_id);
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size_t bpf_core_essential_name_len(const char *name);
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int bpf_core_calc_relo_insn(const char *prog_name,
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const struct bpf_core_relo *relo, int relo_idx,
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const struct btf *local_btf,
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struct bpf_core_cand_list *cands,
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struct bpf_core_spec *specs_scratch,
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struct bpf_core_relo_res *targ_res);
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int bpf_core_patch_insn(const char *prog_name, struct bpf_insn *insn,
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int insn_idx, const struct bpf_core_relo *relo,
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int relo_idx, const struct bpf_core_relo_res *res);
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int bpf_core_parse_spec(const char *prog_name, const struct btf *btf,
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const struct bpf_core_relo *relo,
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struct bpf_core_spec *spec);
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int bpf_core_format_spec(char *buf, size_t buf_sz, const struct bpf_core_spec *spec);
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#endif
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