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
bpf_tail_call_static(void * ctx,const void * map,const __u32 slot)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
