1 // SPDX-License-Identifier: GPL-2.0 2 /* Copyright (c) 2021 Facebook */ 3 #include <linux/stddef.h> 4 #include <linux/bpf.h> 5 #include <bpf/bpf_helpers.h> 6 #include <bpf/bpf_tracing.h> 7 #include <../../../tools/include/linux/filter.h> 8 #include <linux/btf.h> 9 10 char _license[] SEC("license") = "GPL"; 11 12 struct args { 13 __u64 log_buf; 14 __u32 log_size; 15 int max_entries; 16 int map_fd; 17 int prog_fd; 18 int btf_fd; 19 }; 20 21 #define BTF_INFO_ENC(kind, kind_flag, vlen) \ 22 ((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN)) 23 #define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type) 24 #define BTF_INT_ENC(encoding, bits_offset, nr_bits) \ 25 ((encoding) << 24 | (bits_offset) << 16 | (nr_bits)) 26 #define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \ 27 BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \ 28 BTF_INT_ENC(encoding, bits_offset, bits) 29 30 static int btf_load(void) 31 { 32 struct btf_blob { 33 struct btf_header btf_hdr; 34 __u32 types[8]; 35 __u32 str; 36 } raw_btf = { 37 .btf_hdr = { 38 .magic = BTF_MAGIC, 39 .version = BTF_VERSION, 40 .hdr_len = sizeof(struct btf_header), 41 .type_len = sizeof(__u32) * 8, 42 .str_off = sizeof(__u32) * 8, 43 .str_len = sizeof(__u32), 44 }, 45 .types = { 46 /* long */ 47 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 64, 8), /* [1] */ 48 /* unsigned long */ 49 BTF_TYPE_INT_ENC(0, 0, 0, 64, 8), /* [2] */ 50 }, 51 }; 52 static union bpf_attr btf_load_attr = { 53 .btf_size = sizeof(raw_btf), 54 }; 55 56 btf_load_attr.btf = (long)&raw_btf; 57 return bpf_sys_bpf(BPF_BTF_LOAD, &btf_load_attr, sizeof(btf_load_attr)); 58 } 59 60 SEC("syscall") 61 int bpf_prog(struct args *ctx) 62 { 63 static char license[] = "GPL"; 64 static struct bpf_insn insns[] = { 65 BPF_ST_MEM(BPF_DW, BPF_REG_10, -8, 0), 66 BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), 67 BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -8), 68 BPF_LD_MAP_FD(BPF_REG_1, 0), 69 BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem), 70 BPF_MOV64_IMM(BPF_REG_0, 0), 71 BPF_EXIT_INSN(), 72 }; 73 static union bpf_attr map_create_attr = { 74 .map_type = BPF_MAP_TYPE_HASH, 75 .key_size = 8, 76 .value_size = 8, 77 .btf_key_type_id = 1, 78 .btf_value_type_id = 2, 79 }; 80 static union bpf_attr map_update_attr = { .map_fd = 1, }; 81 static __u64 key = 12; 82 static __u64 value = 34; 83 static union bpf_attr prog_load_attr = { 84 .prog_type = BPF_PROG_TYPE_XDP, 85 .insn_cnt = sizeof(insns) / sizeof(insns[0]), 86 }; 87 int ret; 88 89 ret = btf_load(); 90 if (ret <= 0) 91 return ret; 92 93 ctx->btf_fd = ret; 94 map_create_attr.max_entries = ctx->max_entries; 95 map_create_attr.btf_fd = ret; 96 97 prog_load_attr.license = (long) license; 98 prog_load_attr.insns = (long) insns; 99 prog_load_attr.log_buf = ctx->log_buf; 100 prog_load_attr.log_size = ctx->log_size; 101 prog_load_attr.log_level = 1; 102 103 ret = bpf_sys_bpf(BPF_MAP_CREATE, &map_create_attr, sizeof(map_create_attr)); 104 if (ret <= 0) 105 return ret; 106 ctx->map_fd = ret; 107 insns[3].imm = ret; 108 109 map_update_attr.map_fd = ret; 110 map_update_attr.key = (long) &key; 111 map_update_attr.value = (long) &value; 112 ret = bpf_sys_bpf(BPF_MAP_UPDATE_ELEM, &map_update_attr, sizeof(map_update_attr)); 113 if (ret < 0) 114 return ret; 115 116 ret = bpf_sys_bpf(BPF_PROG_LOAD, &prog_load_attr, sizeof(prog_load_attr)); 117 if (ret <= 0) 118 return ret; 119 ctx->prog_fd = ret; 120 return 1; 121 } 122