122 lines
3.1 KiB
C
122 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2021 Facebook */
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#include <linux/stddef.h>
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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#include <bpf/bpf_tracing.h>
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#include <../../../tools/include/linux/filter.h>
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#include <linux/btf.h>
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char _license[] SEC("license") = "GPL";
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struct args {
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__u64 log_buf;
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__u32 log_size;
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int max_entries;
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int map_fd;
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int prog_fd;
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int btf_fd;
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};
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#define BTF_INFO_ENC(kind, kind_flag, vlen) \
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((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
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#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
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#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
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((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
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#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
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BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
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BTF_INT_ENC(encoding, bits_offset, bits)
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static int btf_load(void)
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{
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struct btf_blob {
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struct btf_header btf_hdr;
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__u32 types[8];
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__u32 str;
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} raw_btf = {
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.btf_hdr = {
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.magic = BTF_MAGIC,
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.version = BTF_VERSION,
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.hdr_len = sizeof(struct btf_header),
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.type_len = sizeof(__u32) * 8,
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.str_off = sizeof(__u32) * 8,
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.str_len = sizeof(__u32),
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},
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.types = {
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/* long */
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BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8), /* [1] */
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/* unsigned long */
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BTF_TYPE_INT_ENC(0, 0, 0, 64, 8), /* [2] */
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},
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};
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static union bpf_attr btf_load_attr = {
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.btf_size = sizeof(raw_btf),
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};
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btf_load_attr.btf = (long)&raw_btf;
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return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr));
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}
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SEC("syscall")
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int bpf_prog(struct args *ctx)
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{
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static char license[] = "GPL";
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static struct bpf_insn insns[] = {
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BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0),
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BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
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BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8),
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BPF_LD_MAP_FD(BPF_REG_1, 0),
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BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
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BPF_MOV64_IMM(BPF_REG_0, 0),
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BPF_EXIT_INSN(),
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};
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static union bpf_attr map_create_attr = {
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.map_type = BPF_MAP_TYPE_HASH,
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.key_size = 8,
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.value_size = 8,
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.btf_key_type_id = 1,
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.btf_value_type_id = 2,
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};
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static union bpf_attr map_update_attr = { .map_fd = 1, };
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static __u64 key = 12;
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static __u64 value = 34;
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static union bpf_attr prog_load_attr = {
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.prog_type = BPF_PROG_TYPE_XDP,
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.insn_cnt = sizeof(insns) / sizeof(insns[0]),
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};
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int ret;
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ret = btf_load();
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if (ret <= 0)
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return ret;
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ctx->btf_fd = ret;
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map_create_attr.max_entries = ctx->max_entries;
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map_create_attr.btf_fd = ret;
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prog_load_attr.license = (long) license;
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prog_load_attr.insns = (long) insns;
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prog_load_attr.log_buf = ctx->log_buf;
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prog_load_attr.log_size = ctx->log_size;
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prog_load_attr.log_level = 1;
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ret = bpf_sys_bpf(BPF_MAP_CREATE, &map_create_attr, sizeof(map_create_attr));
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if (ret <= 0)
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return ret;
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ctx->map_fd = ret;
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insns[3].imm = ret;
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map_update_attr.map_fd = ret;
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map_update_attr.key = (long) &key;
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map_update_attr.value = (long) &value;
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ret = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, &map_update_attr, sizeof(map_update_attr));
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if (ret < 0)
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return ret;
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ret = bpf_sys_bpf(BPF_PROG_LOAD, &prog_load_attr, sizeof(prog_load_attr));
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if (ret <= 0)
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return ret;
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ctx->prog_fd = ret;
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return 1;
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}
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