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  * Compiler (optimization) barrier.
80  */
81 #ifndef barrier
82 #define barrier() asm volatile("" ::: "memory")
83 #endif
84 
85 /* Variable-specific compiler (optimization) barrier. It's a no-op which makes
86  * compiler believe that there is some black box modification of a given
87  * variable and thus prevents compiler from making extra assumption about its
88  * value and potential simplifications and optimizations on this variable.
89  *
90  * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of
91  * a variable, making some code patterns unverifiable. Putting barrier_var()
92  * in place will ensure that cast is performed before the barrier_var()
93  * invocation, because compiler has to pessimistically assume that embedded
94  * asm section might perform some extra operations on that variable.
95  *
96  * This is a variable-specific variant of more global barrier().
97  */
98 #ifndef barrier_var
99 #define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var))
100 #endif
101 
102 /*
103  * Helper macro to throw a compilation error if __bpf_unreachable() gets
104  * built into the resulting code. This works given BPF back end does not
105  * implement __builtin_trap(). This is useful to assert that certain paths
106  * of the program code are never used and hence eliminated by the compiler.
107  *
108  * For example, consider a switch statement that covers known cases used by
109  * the program. __bpf_unreachable() can then reside in the default case. If
110  * the program gets extended such that a case is not covered in the switch
111  * statement, then it will throw a build error due to the default case not
112  * being compiled out.
113  */
114 #ifndef __bpf_unreachable
115 # define __bpf_unreachable()	__builtin_trap()
116 #endif
117 
118 /*
119  * Helper function to perform a tail call with a constant/immediate map slot.
120  */
121 #if __clang_major__ >= 8 && defined(__bpf__)
122 static __always_inline void
bpf_tail_call_static(void * ctx,const void * map,const __u32 slot)123 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
124 {
125 	if (!__builtin_constant_p(slot))
126 		__bpf_unreachable();
127 
128 	/*
129 	 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
130 	 * pointer) and r3 (constant map index) from _different paths_ ending
131 	 * up at the _same_ call insn as otherwise we won't be able to use the
132 	 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
133 	 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
134 	 * tracking for prog array pokes") for details on verifier tracking.
135 	 *
136 	 * Note on clobber list: we need to stay in-line with BPF calling
137 	 * convention, so even if we don't end up using r0, r4, r5, we need
138 	 * to mark them as clobber so that LLVM doesn't end up using them
139 	 * before / after the call.
140 	 */
141 	asm volatile("r1 = %[ctx]\n\t"
142 		     "r2 = %[map]\n\t"
143 		     "r3 = %[slot]\n\t"
144 		     "call 12"
145 		     :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
146 		     : "r0", "r1", "r2", "r3", "r4", "r5");
147 }
148 #endif
149 
150 /*
151  * Helper structure used by eBPF C program
152  * to describe BPF map attributes to libbpf loader
153  */
154 struct bpf_map_def {
155 	unsigned int type;
156 	unsigned int key_size;
157 	unsigned int value_size;
158 	unsigned int max_entries;
159 	unsigned int map_flags;
160 } __attribute__((deprecated("use BTF-defined maps in .maps section")));
161 
162 enum libbpf_pin_type {
163 	LIBBPF_PIN_NONE,
164 	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
165 	LIBBPF_PIN_BY_NAME,
166 };
167 
168 enum libbpf_tristate {
169 	TRI_NO = 0,
170 	TRI_YES = 1,
171 	TRI_MODULE = 2,
172 };
173 
174 #define __kconfig __attribute__((section(".kconfig")))
175 #define __ksym __attribute__((section(".ksyms")))
176 #define __kptr __attribute__((btf_type_tag("kptr")))
177 #define __kptr_ref __attribute__((btf_type_tag("kptr_ref")))
178 
179 #ifndef ___bpf_concat
180 #define ___bpf_concat(a, b) a ## b
181 #endif
182 #ifndef ___bpf_apply
183 #define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
184 #endif
185 #ifndef ___bpf_nth
186 #define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
187 #endif
188 #ifndef ___bpf_narg
189 #define ___bpf_narg(...) \
190 	___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
191 #endif
192 
193 #define ___bpf_fill0(arr, p, x) do {} while (0)
194 #define ___bpf_fill1(arr, p, x) arr[p] = x
195 #define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
196 #define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
197 #define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
198 #define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
199 #define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
200 #define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
201 #define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
202 #define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
203 #define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
204 #define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
205 #define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
206 #define ___bpf_fill(arr, args...) \
207 	___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
208 
209 /*
210  * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
211  * in a structure.
212  */
213 #define BPF_SEQ_PRINTF(seq, 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_seq_printf(seq, ___fmt, sizeof(___fmt),		\
224 		       ___param, sizeof(___param));		\
225 })
226 
227 /*
228  * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
229  * an array of u64.
230  */
231 #define BPF_SNPRINTF(out, out_size, fmt, args...)		\
232 ({								\
233 	static const char ___fmt[] = fmt;			\
234 	unsigned long long ___param[___bpf_narg(args)];		\
235 								\
236 	_Pragma("GCC diagnostic push")				\
237 	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
238 	___bpf_fill(___param, args);				\
239 	_Pragma("GCC diagnostic pop")				\
240 								\
241 	bpf_snprintf(out, out_size, ___fmt,			\
242 		     ___param, sizeof(___param));		\
243 })
244 
245 #ifdef BPF_NO_GLOBAL_DATA
246 #define BPF_PRINTK_FMT_MOD
247 #else
248 #define BPF_PRINTK_FMT_MOD static const
249 #endif
250 
251 #define __bpf_printk(fmt, ...)				\
252 ({							\
253 	BPF_PRINTK_FMT_MOD char ____fmt[] = fmt;	\
254 	bpf_trace_printk(____fmt, sizeof(____fmt),	\
255 			 ##__VA_ARGS__);		\
256 })
257 
258 /*
259  * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
260  * instead of an array of u64.
261  */
262 #define __bpf_vprintk(fmt, args...)				\
263 ({								\
264 	static const char ___fmt[] = fmt;			\
265 	unsigned long long ___param[___bpf_narg(args)];		\
266 								\
267 	_Pragma("GCC diagnostic push")				\
268 	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
269 	___bpf_fill(___param, args);				\
270 	_Pragma("GCC diagnostic pop")				\
271 								\
272 	bpf_trace_vprintk(___fmt, sizeof(___fmt),		\
273 			  ___param, sizeof(___param));		\
274 })
275 
276 /* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
277  * Otherwise use __bpf_vprintk
278  */
279 #define ___bpf_pick_printk(...) \
280 	___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,	\
281 		   __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,		\
282 		   __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
283 		   __bpf_printk /*1*/, __bpf_printk /*0*/)
284 
285 /* Helper macro to print out debug messages */
286 #define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
287 
288 #endif
289