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__) |
141 | static __always_inline void |
142 | bpf_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 | |
169 | enum 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 | |
175 | enum 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 | |
307 | struct bpf_iter_num; |
308 | |
309 | extern int bpf_iter_num_new(struct bpf_iter_num *it, int start, int end) __weak __ksym; |
310 | extern int *bpf_iter_num_next(struct bpf_iter_num *it) __weak __ksym; |
311 | extern 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 | |