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 #define SEC(name) \
26 _Pragma("GCC diagnostic push") \
27 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \
28 __attribute__((section(name), used)) \
29 _Pragma("GCC diagnostic pop") \
30
31 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */
32 #undef __always_inline
33 #define __always_inline inline __attribute__((always_inline))
34
35 #ifndef __noinline
36 #define __noinline __attribute__((noinline))
37 #endif
38 #ifndef __weak
39 #define __weak __attribute__((weak))
40 #endif
41
42 /*
43 * Use __hidden attribute to mark a non-static BPF subprogram effectively
44 * static for BPF verifier's verification algorithm purposes, allowing more
45 * extensive and permissive BPF verification process, taking into account
46 * subprogram's caller context.
47 */
48 #define __hidden __attribute__((visibility("hidden")))
49
50 /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
51 * any system-level headers (such as stddef.h, linux/version.h, etc), and
52 * commonly-used macros like NULL and KERNEL_VERSION aren't available through
53 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define
54 * them on their own. So as a convenience, provide such definitions here.
55 */
56 #ifndef NULL
57 #define NULL ((void *)0)
58 #endif
59
60 #ifndef KERNEL_VERSION
61 #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
62 #endif
63
64 /*
65 * Helper macros to manipulate data structures
66 */
67 #ifndef offsetof
68 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER)
69 #endif
70 #ifndef container_of
71 #define container_of(ptr, type, member) \
72 ({ \
73 void *__mptr = (void *)(ptr); \
74 ((type *)(__mptr - offsetof(type, member))); \
75 })
76 #endif
77
78 /*
79 * Helper macro to throw a compilation error if __bpf_unreachable() gets
80 * built into the resulting code. This works given BPF back end does not
81 * implement __builtin_trap(). This is useful to assert that certain paths
82 * of the program code are never used and hence eliminated by the compiler.
83 *
84 * For example, consider a switch statement that covers known cases used by
85 * the program. __bpf_unreachable() can then reside in the default case. If
86 * the program gets extended such that a case is not covered in the switch
87 * statement, then it will throw a build error due to the default case not
88 * being compiled out.
89 */
90 #ifndef __bpf_unreachable
91 # define __bpf_unreachable() __builtin_trap()
92 #endif
93
94 /*
95 * Helper function to perform a tail call with a constant/immediate map slot.
96 */
97 #if __clang_major__ >= 8 && defined(__bpf__)
98 static __always_inline void
bpf_tail_call_static(void * ctx,const void * map,const __u32 slot)99 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
100 {
101 if (!__builtin_constant_p(slot))
102 __bpf_unreachable();
103
104 /*
105 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
106 * pointer) and r3 (constant map index) from _different paths_ ending
107 * up at the _same_ call insn as otherwise we won't be able to use the
108 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
109 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
110 * tracking for prog array pokes") for details on verifier tracking.
111 *
112 * Note on clobber list: we need to stay in-line with BPF calling
113 * convention, so even if we don't end up using r0, r4, r5, we need
114 * to mark them as clobber so that LLVM doesn't end up using them
115 * before / after the call.
116 */
117 asm volatile("r1 = %[ctx]\n\t"
118 "r2 = %[map]\n\t"
119 "r3 = %[slot]\n\t"
120 "call 12"
121 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
122 : "r0", "r1", "r2", "r3", "r4", "r5");
123 }
124 #endif
125
126 /*
127 * Helper structure used by eBPF C program
128 * to describe BPF map attributes to libbpf loader
129 */
130 struct bpf_map_def {
131 unsigned int type;
132 unsigned int key_size;
133 unsigned int value_size;
134 unsigned int max_entries;
135 unsigned int map_flags;
136 } __attribute__((deprecated("use BTF-defined maps in .maps section")));
137
138 enum libbpf_pin_type {
139 LIBBPF_PIN_NONE,
140 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
141 LIBBPF_PIN_BY_NAME,
142 };
143
144 enum libbpf_tristate {
145 TRI_NO = 0,
146 TRI_YES = 1,
147 TRI_MODULE = 2,
148 };
149
150 #define __kconfig __attribute__((section(".kconfig")))
151 #define __ksym __attribute__((section(".ksyms")))
152
153 #ifndef ___bpf_concat
154 #define ___bpf_concat(a, b) a ## b
155 #endif
156 #ifndef ___bpf_apply
157 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
158 #endif
159 #ifndef ___bpf_nth
160 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
161 #endif
162 #ifndef ___bpf_narg
163 #define ___bpf_narg(...) \
164 ___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
165 #endif
166
167 #define ___bpf_fill0(arr, p, x) do {} while (0)
168 #define ___bpf_fill1(arr, p, x) arr[p] = x
169 #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
170 #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
171 #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
172 #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
173 #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
174 #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
175 #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
176 #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
177 #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
178 #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
179 #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
180 #define ___bpf_fill(arr, args...) \
181 ___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
182
183 /*
184 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
185 * in a structure.
186 */
187 #define BPF_SEQ_PRINTF(seq, fmt, args...) \
188 ({ \
189 static const char ___fmt[] = fmt; \
190 unsigned long long ___param[___bpf_narg(args)]; \
191 \
192 _Pragma("GCC diagnostic push") \
193 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
194 ___bpf_fill(___param, args); \
195 _Pragma("GCC diagnostic pop") \
196 \
197 bpf_seq_printf(seq, ___fmt, sizeof(___fmt), \
198 ___param, sizeof(___param)); \
199 })
200
201 /*
202 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
203 * an array of u64.
204 */
205 #define BPF_SNPRINTF(out, out_size, fmt, args...) \
206 ({ \
207 static const char ___fmt[] = fmt; \
208 unsigned long long ___param[___bpf_narg(args)]; \
209 \
210 _Pragma("GCC diagnostic push") \
211 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
212 ___bpf_fill(___param, args); \
213 _Pragma("GCC diagnostic pop") \
214 \
215 bpf_snprintf(out, out_size, ___fmt, \
216 ___param, sizeof(___param)); \
217 })
218
219 #ifdef BPF_NO_GLOBAL_DATA
220 #define BPF_PRINTK_FMT_MOD
221 #else
222 #define BPF_PRINTK_FMT_MOD static const
223 #endif
224
225 #define __bpf_printk(fmt, ...) \
226 ({ \
227 BPF_PRINTK_FMT_MOD char ____fmt[] = fmt; \
228 bpf_trace_printk(____fmt, sizeof(____fmt), \
229 ##__VA_ARGS__); \
230 })
231
232 /*
233 * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
234 * instead of an array of u64.
235 */
236 #define __bpf_vprintk(fmt, args...) \
237 ({ \
238 static const char ___fmt[] = fmt; \
239 unsigned long long ___param[___bpf_narg(args)]; \
240 \
241 _Pragma("GCC diagnostic push") \
242 _Pragma("GCC diagnostic ignored \"-Wint-conversion\"") \
243 ___bpf_fill(___param, args); \
244 _Pragma("GCC diagnostic pop") \
245 \
246 bpf_trace_vprintk(___fmt, sizeof(___fmt), \
247 ___param, sizeof(___param)); \
248 })
249
250 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
251 * Otherwise use __bpf_vprintk
252 */
253 #define ___bpf_pick_printk(...) \
254 ___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
255 __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, \
256 __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
257 __bpf_printk /*1*/, __bpf_printk /*0*/)
258
259 /* Helper macro to print out debug messages */
260 #define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
261
262 #endif
263