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#define __ulong(name, val) enum { ___bpf_concat(__unique_value, __COUNTER__) = val } name 17 18/* 19 * Helper macro to place programs, maps, license in 20 * different sections in elf_bpf file. Section names 21 * are interpreted by libbpf depending on the context (BPF programs, BPF maps, 22 * extern variables, etc). 23 * To allow use of SEC() with externs (e.g., for extern .maps declarations), 24 * make sure __attribute__((unused)) doesn't trigger compilation warning. 25 */ 26#if __GNUC__ && !__clang__ 27 28/* 29 * Pragma macros are broken on GCC 30 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578 31 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400 32 */ 33#define SEC(name) __attribute__((section(name), used)) 34 35#else 36 37#define SEC(name) \ 38 _Pragma("GCC diagnostic push") \ 39 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \ 40 __attribute__((section(name), used)) \ 41 _Pragma("GCC diagnostic pop") \ 42 43#endif 44 45/* Avoid 'linux/stddef.h' definition of '__always_inline'. */ 46#undef __always_inline 47#define __always_inline inline __attribute__((always_inline)) 48 49#ifndef __noinline 50#define __noinline __attribute__((noinline)) 51#endif 52#ifndef __weak 53#define __weak __attribute__((weak)) 54#endif 55 56/* 57 * Use __hidden attribute to mark a non-static BPF subprogram effectively 58 * static for BPF verifier's verification algorithm purposes, allowing more 59 * extensive and permissive BPF verification process, taking into account 60 * subprogram's caller context. 61 */ 62#define __hidden __attribute__((visibility("hidden"))) 63 64/* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include 65 * any system-level headers (such as stddef.h, linux/version.h, etc), and 66 * commonly-used macros like NULL and KERNEL_VERSION aren't available through 67 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define 68 * them on their own. So as a convenience, provide such definitions here. 69 */ 70#ifndef NULL 71#define NULL ((void *)0) 72#endif 73 74#ifndef KERNEL_VERSION 75#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c))) 76#endif 77 78/* 79 * Helper macros to manipulate data structures 80 */ 81 82/* offsetof() definition that uses __builtin_offset() might not preserve field 83 * offset CO-RE relocation properly, so force-redefine offsetof() using 84 * old-school approach which works with CO-RE correctly 85 */ 86#undef offsetof 87#define offsetof(type, member) ((unsigned long)&((type *)0)->member) 88 89/* redefined container_of() to ensure we use the above offsetof() macro */ 90#undef container_of 91#define container_of(ptr, type, member) \ 92 ({ \ 93 void *__mptr = (void *)(ptr); \ 94 ((type *)(__mptr - offsetof(type, member))); \ 95 }) 96 97/* 98 * Compiler (optimization) barrier. 99 */ 100#ifndef barrier 101#define barrier() asm volatile("" ::: "memory") 102#endif 103 104/* Variable-specific compiler (optimization) barrier. It's a no-op which makes 105 * compiler believe that there is some black box modification of a given 106 * variable and thus prevents compiler from making extra assumption about its 107 * value and potential simplifications and optimizations on this variable. 108 * 109 * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of 110 * a variable, making some code patterns unverifiable. Putting barrier_var() 111 * in place will ensure that cast is performed before the barrier_var() 112 * invocation, because compiler has to pessimistically assume that embedded 113 * asm section might perform some extra operations on that variable. 114 * 115 * This is a variable-specific variant of more global barrier(). 116 */ 117#ifndef barrier_var 118#define barrier_var(var) asm volatile("" : "+r"(var)) 119#endif 120 121/* 122 * Helper macro to throw a compilation error if __bpf_unreachable() gets 123 * built into the resulting code. This works given BPF back end does not 124 * implement __builtin_trap(). This is useful to assert that certain paths 125 * of the program code are never used and hence eliminated by the compiler. 126 * 127 * For example, consider a switch statement that covers known cases used by 128 * the program. __bpf_unreachable() can then reside in the default case. If 129 * the program gets extended such that a case is not covered in the switch 130 * statement, then it will throw a build error due to the default case not 131 * being compiled out. 132 */ 133#ifndef __bpf_unreachable 134# define __bpf_unreachable() __builtin_trap() 135#endif 136 137/* 138 * Helper function to perform a tail call with a constant/immediate map slot. 139 */ 140#if __clang_major__ >= 8 && defined(__bpf__) 141static __always_inline void 142bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) 143{ 144 if (!__builtin_constant_p(slot)) 145 __bpf_unreachable(); 146 147 /* 148 * Provide a hard guarantee that LLVM won't optimize setting r2 (map 149 * pointer) and r3 (constant map index) from _different paths_ ending 150 * up at the _same_ call insn as otherwise we won't be able to use the 151 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel 152 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key 153 * tracking for prog array pokes") for details on verifier tracking. 154 * 155 * Note on clobber list: we need to stay in-line with BPF calling 156 * convention, so even if we don't end up using r0, r4, r5, we need 157 * to mark them as clobber so that LLVM doesn't end up using them 158 * before / after the call. 159 */ 160 asm volatile("r1 = %[ctx]\n\t" 161 "r2 = %[map]\n\t" 162 "r3 = %[slot]\n\t" 163 "call 12" 164 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) 165 : "r0", "r1", "r2", "r3", "r4", "r5"); 166} 167#endif 168 169enum libbpf_pin_type { 170 LIBBPF_PIN_NONE, 171 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ 172 LIBBPF_PIN_BY_NAME, 173}; 174 175enum libbpf_tristate { 176 TRI_NO = 0, 177 TRI_YES = 1, 178 TRI_MODULE = 2, 179}; 180 181#define __kconfig __attribute__((section(".kconfig"))) 182#define __ksym __attribute__((section(".ksyms"))) 183#define __kptr_untrusted __attribute__((btf_type_tag("kptr_untrusted"))) 184#define __kptr __attribute__((btf_type_tag("kptr"))) 185#define __percpu_kptr __attribute__((btf_type_tag("percpu_kptr"))) 186 187#define bpf_ksym_exists(sym) ({ \ 188 _Static_assert(!__builtin_constant_p(!!sym), #sym " should be marked as __weak"); \ 189 !!sym; \ 190}) 191 192#define __arg_ctx __attribute__((btf_decl_tag("arg:ctx"))) 193#define __arg_nonnull __attribute((btf_decl_tag("arg:nonnull"))) 194#define __arg_nullable __attribute((btf_decl_tag("arg:nullable"))) 195#define __arg_trusted __attribute((btf_decl_tag("arg:trusted"))) 196#define __arg_arena __attribute((btf_decl_tag("arg:arena"))) 197 198#ifndef ___bpf_concat 199#define ___bpf_concat(a, b) a ## b 200#endif 201#ifndef ___bpf_apply 202#define ___bpf_apply(fn, n) ___bpf_concat(fn, n) 203#endif 204#ifndef ___bpf_nth 205#define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N 206#endif 207#ifndef ___bpf_narg 208#define ___bpf_narg(...) \ 209 ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0) 210#endif 211 212#define ___bpf_fill0(arr, p, x) do {} while (0) 213#define ___bpf_fill1(arr, p, x) arr[p] = x 214#define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args) 215#define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args) 216#define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args) 217#define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args) 218#define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args) 219#define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args) 220#define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args) 221#define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args) 222#define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args) 223#define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args) 224#define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args) 225#define ___bpf_fill(arr, args...) \ 226 ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args) 227 228/* 229 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values 230 * in a structure. 231 */ 232#define BPF_SEQ_PRINTF(seq, fmt, args...) \ 233({ \ 234 static const char ___fmt[] = fmt; \ 235 unsigned long long ___param[___bpf_narg(args)]; \ 236 \ 237 _Pragma("GCC diagnostic push") \ 238 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 239 ___bpf_fill(___param, args); \ 240 _Pragma("GCC diagnostic pop") \ 241 \ 242 bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \ 243 ___param, sizeof(___param)); \ 244}) 245 246/* 247 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of 248 * an array of u64. 249 */ 250#define BPF_SNPRINTF(out, out_size, fmt, args...) \ 251({ \ 252 static const char ___fmt[] = fmt; \ 253 unsigned long long ___param[___bpf_narg(args)]; \ 254 \ 255 _Pragma("GCC diagnostic push") \ 256 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 257 ___bpf_fill(___param, args); \ 258 _Pragma("GCC diagnostic pop") \ 259 \ 260 bpf_snprintf(out, out_size, ___fmt, \ 261 ___param, sizeof(___param)); \ 262}) 263 264#ifdef BPF_NO_GLOBAL_DATA 265#define BPF_PRINTK_FMT_MOD 266#else 267#define BPF_PRINTK_FMT_MOD static const 268#endif 269 270#define __bpf_printk(fmt, ...) \ 271({ \ 272 BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \ 273 bpf_trace_printk(____fmt, sizeof(____fmt), \ 274 ##__VA_ARGS__); \ 275}) 276 277/* 278 * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments 279 * instead of an array of u64. 280 */ 281#define __bpf_vprintk(fmt, args...) \ 282({ \ 283 static const char ___fmt[] = fmt; \ 284 unsigned long long ___param[___bpf_narg(args)]; \ 285 \ 286 _Pragma("GCC diagnostic push") \ 287 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \ 288 ___bpf_fill(___param, args); \ 289 _Pragma("GCC diagnostic pop") \ 290 \ 291 bpf_trace_vprintk(___fmt, sizeof(___fmt), \ 292 ___param, sizeof(___param)); \ 293}) 294 295/* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args 296 * Otherwise use __bpf_vprintk 297 */ 298#define ___bpf_pick_printk(...) \ 299 ___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ 300 __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \ 301 __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\ 302 __bpf_printk /*1*/, __bpf_printk /*0*/) 303 304/* Helper macro to print out debug messages */ 305#define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args) 306 307struct bpf_iter_num; 308 309extern int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) __weak __ksym; 310extern int *bpf_iter_num_next(struct bpf_iter_num *it) __weak __ksym; 311extern void bpf_iter_num_destroy(struct bpf_iter_num *it) __weak __ksym; 312 313#ifndef bpf_for_each 314/* bpf_for_each(iter_type, cur_elem, args...) provides generic construct for 315 * using BPF open-coded iterators without having to write mundane explicit 316 * low-level loop logic. Instead, it provides for()-like generic construct 317 * that can be used pretty naturally. E.g., for some hypothetical cgroup 318 * iterator, you'd write: 319 * 320 * struct cgroup *cg, *parent_cg = <...>; 321 * 322 * bpf_for_each(cgroup, cg, parent_cg, CG_ITER_CHILDREN) { 323 * bpf_printk("Child cgroup id = %d", cg->cgroup_id); 324 * if (cg->cgroup_id == 123) 325 * break; 326 * } 327 * 328 * I.e., it looks almost like high-level for each loop in other languages, 329 * supports continue/break, and is verifiable by BPF verifier. 330 * 331 * For iterating integers, the difference betwen bpf_for_each(num, i, N, M) 332 * and bpf_for(i, N, M) is in that bpf_for() provides additional proof to 333 * verifier that i is in [N, M) range, and in bpf_for_each() case i is `int 334 * *`, not just `int`. So for integers bpf_for() is more convenient. 335 * 336 * Note: this macro relies on C99 feature of allowing to declare variables 337 * inside for() loop, bound to for() loop lifetime. It also utilizes GCC 338 * extension: __attribute__((cleanup(<func>))), supported by both GCC and 339 * Clang. 340 */ 341#define bpf_for_each(type, cur, args...) for ( \ 342 /* initialize and define destructor */ \ 343 struct bpf_iter_##type ___it __attribute__((aligned(8), /* enforce, just in case */, \ 344 cleanup(bpf_iter_##type##_destroy))), \ 345 /* ___p pointer is just to call bpf_iter_##type##_new() *once* to init ___it */ \ 346 *___p __attribute__((unused)) = ( \ 347 bpf_iter_##type##_new(&___it, ##args), \ 348 /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ 349 /* for bpf_iter_##type##_destroy() when used from cleanup() attribute */ \ 350 (void)bpf_iter_##type##_destroy, (void *)0); \ 351 /* iteration and termination check */ \ 352 (((cur) = bpf_iter_##type##_next(&___it))); \ 353) 354#endif /* bpf_for_each */ 355 356#ifndef bpf_for 357/* bpf_for(i, start, end) implements a for()-like looping construct that sets 358 * provided integer variable *i* to values starting from *start* through, 359 * but not including, *end*. It also proves to BPF verifier that *i* belongs 360 * to range [start, end), so this can be used for accessing arrays without 361 * extra checks. 362 * 363 * Note: *start* and *end* are assumed to be expressions with no side effects 364 * and whose values do not change throughout bpf_for() loop execution. They do 365 * not have to be statically known or constant, though. 366 * 367 * Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for() 368 * loop bound variables and cleanup attribute, supported by GCC and Clang. 369 */ 370#define bpf_for(i, start, end) for ( \ 371 /* initialize and define destructor */ \ 372 struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \ 373 cleanup(bpf_iter_num_destroy))), \ 374 /* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \ 375 *___p __attribute__((unused)) = ( \ 376 bpf_iter_num_new(&___it, (start), (end)), \ 377 /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ 378 /* for bpf_iter_num_destroy() when used from cleanup() attribute */ \ 379 (void)bpf_iter_num_destroy, (void *)0); \ 380 ({ \ 381 /* iteration step */ \ 382 int *___t = bpf_iter_num_next(&___it); \ 383 /* termination and bounds check */ \ 384 (___t && ((i) = *___t, (i) >= (start) && (i) < (end))); \ 385 }); \ 386) 387#endif /* bpf_for */ 388 389#ifndef bpf_repeat 390/* bpf_repeat(N) performs N iterations without exposing iteration number 391 * 392 * Note: similarly to bpf_for_each(), it relies on C99 feature of declaring for() 393 * loop bound variables and cleanup attribute, supported by GCC and Clang. 394 */ 395#define bpf_repeat(N) for ( \ 396 /* initialize and define destructor */ \ 397 struct bpf_iter_num ___it __attribute__((aligned(8), /* enforce, just in case */ \ 398 cleanup(bpf_iter_num_destroy))), \ 399 /* ___p pointer is necessary to call bpf_iter_num_new() *once* to init ___it */ \ 400 *___p __attribute__((unused)) = ( \ 401 bpf_iter_num_new(&___it, 0, (N)), \ 402 /* this is a workaround for Clang bug: it currently doesn't emit BTF */ \ 403 /* for bpf_iter_num_destroy() when used from cleanup() attribute */ \ 404 (void)bpf_iter_num_destroy, (void *)0); \ 405 bpf_iter_num_next(&___it); \ 406 /* nothing here */ \ 407) 408#endif /* bpf_repeat */ 409 410#endif 411