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 /* 18 * Helper macro to place programs, maps, license in 19 * different sections in elf_bpf file. Section names 20 * are interpreted by libbpf depending on the context (BPF programs, BPF maps, 21 * extern variables, etc). 22 * To allow use of SEC() with externs (e.g., for extern .maps declarations), 23 * make sure __attribute__((unused)) doesn't trigger compilation warning. 24 */ 25 #if __GNUC__ && !__clang__ 26 27 /* 28 * Pragma macros are broken on GCC 29 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578 30 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400 31 */ 32 #define SEC(name) __attribute__((section(name), used)) 33 34 #else 35 36 #define SEC(name) \ 37 _Pragma("GCC diagnostic push") \ 38 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \ 39 __attribute__((section(name), used)) \ 40 _Pragma("GCC diagnostic pop") \ 41 42 #endif 43 44 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */ 45 #undef __always_inline 46 #define __always_inline inline __attribute__((always_inline)) 47 48 #ifndef __noinline 49 #define __noinline __attribute__((noinline)) 50 #endif 51 #ifndef __weak 52 #define __weak __attribute__((weak)) 53 #endif 54 55 /* 56 * Use __hidden attribute to mark a non-static BPF subprogram effectively 57 * static for BPF verifier's verification algorithm purposes, allowing more 58 * extensive and permissive BPF verification process, taking into account 59 * subprogram's caller context. 60 */ 61 #define __hidden __attribute__((visibility("hidden"))) 62 63 /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include 64 * any system-level headers (such as stddef.h, linux/version.h, etc), and 65 * commonly-used macros like NULL and KERNEL_VERSION aren't available through 66 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define 67 * them on their own. So as a convenience, provide such definitions here. 68 */ 69 #ifndef NULL 70 #define NULL ((void *)0) 71 #endif 72 73 #ifndef KERNEL_VERSION 74 #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))) 75 #endif 76 77 /* 78 * Helper macros to manipulate data structures 79 */ 80 #ifndef offsetof 81 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) 82 #endif 83 #ifndef container_of 84 #define container_of(ptr, type, member) \ 85 ({ \ 86 void *__mptr = (void *)(ptr); \ 87 ((type *)(__mptr - offsetof(type, member))); \ 88 }) 89 #endif 90 91 /* 92 * Compiler (optimization) barrier. 93 */ 94 #ifndef barrier 95 #define barrier() asm volatile("" ::: "memory") 96 #endif 97 98 /* Variable-specific compiler (optimization) barrier. It's a no-op which makes 99 * compiler believe that there is some black box modification of a given 100 * variable and thus prevents compiler from making extra assumption about its 101 * value and potential simplifications and optimizations on this variable. 102 * 103 * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of 104 * a variable, making some code patterns unverifiable. Putting barrier_var() 105 * in place will ensure that cast is performed before the barrier_var() 106 * invocation, because compiler has to pessimistically assume that embedded 107 * asm section might perform some extra operations on that variable. 108 * 109 * This is a variable-specific variant of more global barrier(). 110 */ 111 #ifndef barrier_var 112 #define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var)) 113 #endif 114 115 /* 116 * Helper macro to throw a compilation error if __bpf_unreachable() gets 117 * built into the resulting code. This works given BPF back end does not 118 * implement __builtin_trap(). This is useful to assert that certain paths 119 * of the program code are never used and hence eliminated by the compiler. 120 * 121 * For example, consider a switch statement that covers known cases used by 122 * the program. __bpf_unreachable() can then reside in the default case. If 123 * the program gets extended such that a case is not covered in the switch 124 * statement, then it will throw a build error due to the default case not 125 * being compiled out. 126 */ 127 #ifndef __bpf_unreachable 128 # define __bpf_unreachable() __builtin_trap() 129 #endif 130 131 /* 132 * Helper function to perform a tail call with a constant/immediate map slot. 133 */ 134 #if __clang_major__ >= 8 && defined(__bpf__) 135 static __always_inline void 136 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) 137 { 138 if (!__builtin_constant_p(slot)) 139 __bpf_unreachable(); 140 141 /* 142 * Provide a hard guarantee that LLVM won't optimize setting r2 (map 143 * pointer) and r3 (constant map index) from _different paths_ ending 144 * up at the _same_ call insn as otherwise we won't be able to use the 145 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel 146 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key 147 * tracking for prog array pokes") for details on verifier tracking. 148 * 149 * Note on clobber list: we need to stay in-line with BPF calling 150 * convention, so even if we don't end up using r0, r4, r5, we need 151 * to mark them as clobber so that LLVM doesn't end up using them 152 * before / after the call. 153 */ 154 asm volatile("r1 = %[ctx]\n\t" 155 "r2 = %[map]\n\t" 156 "r3 = %[slot]\n\t" 157 "call 12" 158 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) 159 : "r0", "r1", "r2", "r3", "r4", "r5"); 160 } 161 #endif 162 163 /* 164 * Helper structure used by eBPF C program 165 * to describe BPF map attributes to libbpf loader 166 */ 167 struct bpf_map_def { 168 unsigned int type; 169 unsigned int key_size; 170 unsigned int value_size; 171 unsigned int max_entries; 172 unsigned int map_flags; 173 } __attribute__((deprecated("use BTF-defined maps in .maps section"))); 174 175 enum libbpf_pin_type { 176 LIBBPF_PIN_NONE, 177 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ 178 LIBBPF_PIN_BY_NAME, 179 }; 180 181 enum libbpf_tristate { 182 TRI_NO = 0, 183 TRI_YES = 1, 184 TRI_MODULE = 2, 185 }; 186 187 #define __kconfig __attribute__((section(".kconfig"))) 188 #define __ksym __attribute__((section(".ksyms"))) 189 #define __kptr __attribute__((btf_type_tag("kptr"))) 190 #define __kptr_ref __attribute__((btf_type_tag("kptr_ref"))) 191 192 #ifndef ___bpf_concat 193 #define ___bpf_concat(a, b) a ## b 194 #endif 195 #ifndef ___bpf_apply 196 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n) 197 #endif 198 #ifndef ___bpf_nth 199 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N 200 #endif 201 #ifndef ___bpf_narg 202 #define ___bpf_narg(...) \ 203 ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 204 #endif 205 206 #define ___bpf_fill0(arr, p, x) do {} while (0) 207 #define ___bpf_fill1(arr, p, x) arr[p] = x 208 #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args) 209 #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args) 210 #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args) 211 #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args) 212 #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args) 213 #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args) 214 #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args) 215 #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args) 216 #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args) 217 #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args) 218 #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args) 219 #define ___bpf_fill(arr, args...) \ 220 ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args) 221 222 /* 223 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values 224 * in a structure. 225 */ 226 #define BPF_SEQ_PRINTF(seq, fmt, args...) \ 227 ({ \ 228 static const char ___fmt[] = fmt; \ 229 unsigned long long ___param[___bpf_narg(args)]; \ 230 \ 231 _Pragma("GCC diagnostic push") \ 232 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 233 ___bpf_fill(___param, args); \ 234 _Pragma("GCC diagnostic pop") \ 235 \ 236 bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ 237 ___param, sizeof(___param)); \ 238 }) 239 240 /* 241 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of 242 * an array of u64. 243 */ 244 #define BPF_SNPRINTF(out, out_size, fmt, args...) \ 245 ({ \ 246 static const char ___fmt[] = fmt; \ 247 unsigned long long ___param[___bpf_narg(args)]; \ 248 \ 249 _Pragma("GCC diagnostic push") \ 250 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 251 ___bpf_fill(___param, args); \ 252 _Pragma("GCC diagnostic pop") \ 253 \ 254 bpf_snprintf(out, out_size, ___fmt, \ 255 ___param, sizeof(___param)); \ 256 }) 257 258 #ifdef BPF_NO_GLOBAL_DATA 259 #define BPF_PRINTK_FMT_MOD 260 #else 261 #define BPF_PRINTK_FMT_MOD static const 262 #endif 263 264 #define __bpf_printk(fmt, ...) \ 265 ({ \ 266 BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \ 267 bpf_trace_printk(____fmt, sizeof(____fmt), \ 268 ##__VA_ARGS__); \ 269 }) 270 271 /* 272 * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments 273 * instead of an array of u64. 274 */ 275 #define __bpf_vprintk(fmt, args...) \ 276 ({ \ 277 static const char ___fmt[] = fmt; \ 278 unsigned long long ___param[___bpf_narg(args)]; \ 279 \ 280 _Pragma("GCC diagnostic push") \ 281 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 282 ___bpf_fill(___param, args); \ 283 _Pragma("GCC diagnostic pop") \ 284 \ 285 bpf_trace_vprintk(___fmt, sizeof(___fmt), \ 286 ___param, sizeof(___param)); \ 287 }) 288 289 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args 290 * Otherwise use __bpf_vprintk 291 */ 292 #define ___bpf_pick_printk(...) \ 293 ___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ 294 __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ 295 __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\ 296 __bpf_printk /*1*/, __bpf_printk /*0*/) 297 298 /* Helper macro to print out debug messages */ 299 #define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args) 300 301 #endif 302