56 lines
1.8 KiB
C
56 lines
1.8 KiB
C
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/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
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#ifndef __BPF_HELPERS__
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#define __BPF_HELPERS__
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#include "bpf_helper_defs.h"
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#define __uint(name, val) int (*name)[val]
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#define __type(name, val) typeof(val) *name
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/* helper macro to print out debug messages */
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#define bpf_printk(fmt, ...) \
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({ \
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char ____fmt[] = fmt; \
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bpf_trace_printk(____fmt, sizeof(____fmt), \
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##__VA_ARGS__); \
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})
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/* helper macro to place programs, maps, license in
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* different sections in elf_bpf file. Section names
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* are interpreted by elf_bpf loader
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*/
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#define SEC(NAME) __attribute__((section(NAME), used))
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/* a helper structure used by eBPF C program
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* to describe BPF map attributes to libbpf loader
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*/
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struct bpf_map_def {
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unsigned int type;
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unsigned int key_size;
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unsigned int value_size;
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unsigned int max_entries;
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unsigned int map_flags;
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};
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/*
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* bpf_core_read() abstracts away bpf_probe_read() call and captures offset
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* relocation for source address using __builtin_preserve_access_index()
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* built-in, provided by Clang.
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*
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* __builtin_preserve_access_index() takes as an argument an expression of
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* taking an address of a field within struct/union. It makes compiler emit
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* a relocation, which records BTF type ID describing root struct/union and an
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* accessor string which describes exact embedded field that was used to take
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* an address. See detailed description of this relocation format and
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* semantics in comments to struct bpf_offset_reloc in libbpf_internal.h.
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*
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* This relocation allows libbpf to adjust BPF instruction to use correct
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* actual field offset, based on target kernel BTF type that matches original
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* (local) BTF, used to record relocation.
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*/
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#define bpf_core_read(dst, sz, src) \
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bpf_probe_read(dst, sz, \
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(const void *)__builtin_preserve_access_index(src))
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#endif
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