1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */ 2 #ifndef __BPF_HELPERS__ 3 #define __BPF_HELPERS__ 4 5 /* 6 * Note that bpf programs need to include either 7 * vmlinux.h (auto-generated from BTF) or linux/types.h 8 * in advance since bpf_helper_defs.h uses such types 9 * as __u64. 10 */ 11 #include "bpf_helper_defs.h" 12 13 #define __uint(name, val) int (*name)[val] 14 #define __type(name, val) typeof(val) *name 15 #define __array(name, val) typeof(val) *name[] 16 17 /* Helper macro to print out debug messages */ 18 #define bpf_printk(fmt, ...) \ 19 ({ \ 20 char ____fmt[] = fmt; \ 21 bpf_trace_printk(____fmt, sizeof(____fmt), \ 22 ##__VA_ARGS__); \ 23 }) 24 25 /* 26 * Helper macro to place programs, maps, license in 27 * different sections in elf_bpf file. Section names 28 * are interpreted by libbpf depending on the context (BPF programs, BPF maps, 29 * extern variables, etc). 30 * To allow use of SEC() with externs (e.g., for extern .maps declarations), 31 * make sure __attribute__((unused)) doesn't trigger compilation warning. 32 */ 33 #define SEC(name) \ 34 _Pragma("GCC diagnostic push") \ 35 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \ 36 __attribute__((section(name), used)) \ 37 _Pragma("GCC diagnostic pop") \ 38 39 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */ 40 #undef __always_inline 41 #define __always_inline inline __attribute__((always_inline)) 42 43 #ifndef __noinline 44 #define __noinline __attribute__((noinline)) 45 #endif 46 #ifndef __weak 47 #define __weak __attribute__((weak)) 48 #endif 49 50 /* 51 * Use __hidden attribute to mark a non-static BPF subprogram effectively 52 * static for BPF verifier's verification algorithm purposes, allowing more 53 * extensive and permissive BPF verification process, taking into account 54 * subprogram's caller context. 55 */ 56 #define __hidden __attribute__((visibility("hidden"))) 57 58 /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include 59 * any system-level headers (such as stddef.h, linux/version.h, etc), and 60 * commonly-used macros like NULL and KERNEL_VERSION aren't available through 61 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define 62 * them on their own. So as a convenience, provide such definitions here. 63 */ 64 #ifndef NULL 65 #define NULL ((void *)0) 66 #endif 67 68 #ifndef KERNEL_VERSION 69 #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))) 70 #endif 71 72 /* 73 * Helper macros to manipulate data structures 74 */ 75 #ifndef offsetof 76 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) 77 #endif 78 #ifndef container_of 79 #define container_of(ptr, type, member) \ 80 ({ \ 81 void *__mptr = (void *)(ptr); \ 82 ((type *)(__mptr - offsetof(type, member))); \ 83 }) 84 #endif 85 86 /* 87 * Helper macro to throw a compilation error if __bpf_unreachable() gets 88 * built into the resulting code. This works given BPF back end does not 89 * implement __builtin_trap(). This is useful to assert that certain paths 90 * of the program code are never used and hence eliminated by the compiler. 91 * 92 * For example, consider a switch statement that covers known cases used by 93 * the program. __bpf_unreachable() can then reside in the default case. If 94 * the program gets extended such that a case is not covered in the switch 95 * statement, then it will throw a build error due to the default case not 96 * being compiled out. 97 */ 98 #ifndef __bpf_unreachable 99 # define __bpf_unreachable() __builtin_trap() 100 #endif 101 102 /* 103 * Helper function to perform a tail call with a constant/immediate map slot. 104 */ 105 #if __clang_major__ >= 8 && defined(__bpf__) 106 static __always_inline void 107 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) 108 { 109 if (!__builtin_constant_p(slot)) 110 __bpf_unreachable(); 111 112 /* 113 * Provide a hard guarantee that LLVM won't optimize setting r2 (map 114 * pointer) and r3 (constant map index) from _different paths_ ending 115 * up at the _same_ call insn as otherwise we won't be able to use the 116 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel 117 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key 118 * tracking for prog array pokes") for details on verifier tracking. 119 * 120 * Note on clobber list: we need to stay in-line with BPF calling 121 * convention, so even if we don't end up using r0, r4, r5, we need 122 * to mark them as clobber so that LLVM doesn't end up using them 123 * before / after the call. 124 */ 125 asm volatile("r1 = %[ctx]\n\t" 126 "r2 = %[map]\n\t" 127 "r3 = %[slot]\n\t" 128 "call 12" 129 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) 130 : "r0", "r1", "r2", "r3", "r4", "r5"); 131 } 132 #endif 133 134 /* 135 * Helper structure used by eBPF C program 136 * to describe BPF map attributes to libbpf loader 137 */ 138 struct bpf_map_def { 139 unsigned int type; 140 unsigned int key_size; 141 unsigned int value_size; 142 unsigned int max_entries; 143 unsigned int map_flags; 144 }; 145 146 enum libbpf_pin_type { 147 LIBBPF_PIN_NONE, 148 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ 149 LIBBPF_PIN_BY_NAME, 150 }; 151 152 enum libbpf_tristate { 153 TRI_NO = 0, 154 TRI_YES = 1, 155 TRI_MODULE = 2, 156 }; 157 158 #define __kconfig __attribute__((section(".kconfig"))) 159 #define __ksym __attribute__((section(".ksyms"))) 160 161 #ifndef ___bpf_concat 162 #define ___bpf_concat(a, b) a ## b 163 #endif 164 #ifndef ___bpf_apply 165 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n) 166 #endif 167 #ifndef ___bpf_nth 168 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N 169 #endif 170 #ifndef ___bpf_narg 171 #define ___bpf_narg(...) \ 172 ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 173 #endif 174 175 #define ___bpf_fill0(arr, p, x) do {} while (0) 176 #define ___bpf_fill1(arr, p, x) arr[p] = x 177 #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args) 178 #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args) 179 #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args) 180 #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args) 181 #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args) 182 #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args) 183 #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args) 184 #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args) 185 #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args) 186 #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args) 187 #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args) 188 #define ___bpf_fill(arr, args...) \ 189 ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args) 190 191 /* 192 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values 193 * in a structure. 194 */ 195 #define BPF_SEQ_PRINTF(seq, fmt, args...) \ 196 ({ \ 197 static const char ___fmt[] = fmt; \ 198 unsigned long long ___param[___bpf_narg(args)]; \ 199 \ 200 _Pragma("GCC diagnostic push") \ 201 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 202 ___bpf_fill(___param, args); \ 203 _Pragma("GCC diagnostic pop") \ 204 \ 205 bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ 206 ___param, sizeof(___param)); \ 207 }) 208 209 /* 210 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of 211 * an array of u64. 212 */ 213 #define BPF_SNPRINTF(out, out_size, fmt, args...) \ 214 ({ \ 215 static const char ___fmt[] = fmt; \ 216 unsigned long long ___param[___bpf_narg(args)]; \ 217 \ 218 _Pragma("GCC diagnostic push") \ 219 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 220 ___bpf_fill(___param, args); \ 221 _Pragma("GCC diagnostic pop") \ 222 \ 223 bpf_snprintf(out, out_size, ___fmt, \ 224 ___param, sizeof(___param)); \ 225 }) 226 227 #endif 228