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#if __GNUC__ && !__clang__
 26
 27/*
 28 * Pragma macros are broken on GCC
 29 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=55578
 30 * https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90400
 31 */
 32#define SEC(name) __attribute__((section(name), used))
 33
 34#else
 35
 36#define SEC(name) \
 37	_Pragma("GCC diagnostic push")					    \
 38	_Pragma("GCC diagnostic ignored \"-Wignored-attributes\"")	    \
 39	__attribute__((section(name), used))				    \
 40	_Pragma("GCC diagnostic pop")					    \
 41
 42#endif
 43
 44/* Avoid 'linux/stddef.h' definition of '__always_inline'. */
 45#undef __always_inline
 46#define __always_inline inline __attribute__((always_inline))
 47
 48#ifndef __noinline
 49#define __noinline __attribute__((noinline))
 50#endif
 51#ifndef __weak
 52#define __weak __attribute__((weak))
 53#endif
 54
 55/*
 56 * Use __hidden attribute to mark a non-static BPF subprogram effectively
 57 * static for BPF verifier's verification algorithm purposes, allowing more
 58 * extensive and permissive BPF verification process, taking into account
 59 * subprogram's caller context.
 60 */
 61#define __hidden __attribute__((visibility("hidden")))
 62
 63/* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include
 64 * any system-level headers (such as stddef.h, linux/version.h, etc), and
 65 * commonly-used macros like NULL and KERNEL_VERSION aren't available through
 66 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define
 67 * them on their own. So as a convenience, provide such definitions here.
 68 */
 69#ifndef NULL
 70#define NULL ((void *)0)
 71#endif
 72
 73#ifndef KERNEL_VERSION
 74#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
 75#endif
 76
 77/*
 78 * Helper macros to manipulate data structures
 79 */
 80#ifndef offsetof
 81#define offsetof(TYPE, MEMBER)	((unsigned long)&((TYPE *)0)->MEMBER)
 82#endif
 83#ifndef container_of
 84#define container_of(ptr, type, member)				\
 85	({							\
 86		void *__mptr = (void *)(ptr);			\
 87		((type *)(__mptr - offsetof(type, member)));	\
 88	})
 89#endif
 90
 91/*
 92 * Compiler (optimization) barrier.
 93 */
 94#ifndef barrier
 95#define barrier() asm volatile("" ::: "memory")
 96#endif
 97
 98/* Variable-specific compiler (optimization) barrier. It's a no-op which makes
 99 * compiler believe that there is some black box modification of a given
100 * variable and thus prevents compiler from making extra assumption about its
101 * value and potential simplifications and optimizations on this variable.
102 *
103 * E.g., compiler might often delay or even omit 32-bit to 64-bit casting of
104 * a variable, making some code patterns unverifiable. Putting barrier_var()
105 * in place will ensure that cast is performed before the barrier_var()
106 * invocation, because compiler has to pessimistically assume that embedded
107 * asm section might perform some extra operations on that variable.
108 *
109 * This is a variable-specific variant of more global barrier().
110 */
111#ifndef barrier_var
112#define barrier_var(var) asm volatile("" : "=r"(var) : "0"(var))
113#endif
114
115/*
116 * Helper macro to throw a compilation error if __bpf_unreachable() gets
117 * built into the resulting code. This works given BPF back end does not
118 * implement __builtin_trap(). This is useful to assert that certain paths
119 * of the program code are never used and hence eliminated by the compiler.
120 *
121 * For example, consider a switch statement that covers known cases used by
122 * the program. __bpf_unreachable() can then reside in the default case. If
123 * the program gets extended such that a case is not covered in the switch
124 * statement, then it will throw a build error due to the default case not
125 * being compiled out.
126 */
127#ifndef __bpf_unreachable
128# define __bpf_unreachable()	__builtin_trap()
129#endif
130
131/*
132 * Helper function to perform a tail call with a constant/immediate map slot.
133 */
134#if __clang_major__ >= 8 && defined(__bpf__)
135static __always_inline void
136bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
137{
138	if (!__builtin_constant_p(slot))
139		__bpf_unreachable();
140
141	/*
142	 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
143	 * pointer) and r3 (constant map index) from _different paths_ ending
144	 * up at the _same_ call insn as otherwise we won't be able to use the
145	 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
146	 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
147	 * tracking for prog array pokes") for details on verifier tracking.
148	 *
149	 * Note on clobber list: we need to stay in-line with BPF calling
150	 * convention, so even if we don't end up using r0, r4, r5, we need
151	 * to mark them as clobber so that LLVM doesn't end up using them
152	 * before / after the call.
153	 */
154	asm volatile("r1 = %[ctx]\n\t"
155		     "r2 = %[map]\n\t"
156		     "r3 = %[slot]\n\t"
157		     "call 12"
158		     :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
159		     : "r0", "r1", "r2", "r3", "r4", "r5");
160}
161#endif
162
163enum libbpf_pin_type {
164	LIBBPF_PIN_NONE,
165	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
166	LIBBPF_PIN_BY_NAME,
167};
168
169enum libbpf_tristate {
170	TRI_NO = 0,
171	TRI_YES = 1,
172	TRI_MODULE = 2,
173};
174
175#define __kconfig __attribute__((section(".kconfig")))
176#define __ksym __attribute__((section(".ksyms")))
177#define __kptr __attribute__((btf_type_tag("kptr")))
178#define __kptr_ref __attribute__((btf_type_tag("kptr_ref")))
179
180#ifndef ___bpf_concat
181#define ___bpf_concat(a, b) a ## b
182#endif
183#ifndef ___bpf_apply
184#define ___bpf_apply(fn, n) ___bpf_concat(fn, n)
185#endif
186#ifndef ___bpf_nth
187#define ___bpf_nth(_, _1, _2, _3, _4, _5, _6, _7, _8, _9, _a, _b, _c, N, ...) N
188#endif
189#ifndef ___bpf_narg
190#define ___bpf_narg(...) \
191	___bpf_nth(_, ##__VA_ARGS__, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
192#endif
193
194#define ___bpf_fill0(arr, p, x) do {} while (0)
195#define ___bpf_fill1(arr, p, x) arr[p] = x
196#define ___bpf_fill2(arr, p, x, args...) arr[p] = x; ___bpf_fill1(arr, p + 1, args)
197#define ___bpf_fill3(arr, p, x, args...) arr[p] = x; ___bpf_fill2(arr, p + 1, args)
198#define ___bpf_fill4(arr, p, x, args...) arr[p] = x; ___bpf_fill3(arr, p + 1, args)
199#define ___bpf_fill5(arr, p, x, args...) arr[p] = x; ___bpf_fill4(arr, p + 1, args)
200#define ___bpf_fill6(arr, p, x, args...) arr[p] = x; ___bpf_fill5(arr, p + 1, args)
201#define ___bpf_fill7(arr, p, x, args...) arr[p] = x; ___bpf_fill6(arr, p + 1, args)
202#define ___bpf_fill8(arr, p, x, args...) arr[p] = x; ___bpf_fill7(arr, p + 1, args)
203#define ___bpf_fill9(arr, p, x, args...) arr[p] = x; ___bpf_fill8(arr, p + 1, args)
204#define ___bpf_fill10(arr, p, x, args...) arr[p] = x; ___bpf_fill9(arr, p + 1, args)
205#define ___bpf_fill11(arr, p, x, args...) arr[p] = x; ___bpf_fill10(arr, p + 1, args)
206#define ___bpf_fill12(arr, p, x, args...) arr[p] = x; ___bpf_fill11(arr, p + 1, args)
207#define ___bpf_fill(arr, args...) \
208	___bpf_apply(___bpf_fill, ___bpf_narg(args))(arr, 0, args)
209
210/*
211 * BPF_SEQ_PRINTF to wrap bpf_seq_printf to-be-printed values
212 * in a structure.
213 */
214#define BPF_SEQ_PRINTF(seq, fmt, args...)			\
215({								\
216	static const char ___fmt[] = fmt;			\
217	unsigned long long ___param[___bpf_narg(args)];		\
218								\
219	_Pragma("GCC diagnostic push")				\
220	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
221	___bpf_fill(___param, args);				\
222	_Pragma("GCC diagnostic pop")				\
223								\
224	bpf_seq_printf(seq, ___fmt, sizeof(___fmt),		\
225		       ___param, sizeof(___param));		\
226})
227
228/*
229 * BPF_SNPRINTF wraps the bpf_snprintf helper with variadic arguments instead of
230 * an array of u64.
231 */
232#define BPF_SNPRINTF(out, out_size, 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_snprintf(out, out_size, ___fmt,			\
243		     ___param, sizeof(___param));		\
244})
245
246#ifdef BPF_NO_GLOBAL_DATA
247#define BPF_PRINTK_FMT_MOD
248#else
249#define BPF_PRINTK_FMT_MOD static const
250#endif
251
252#define __bpf_printk(fmt, ...)				\
253({							\
254	BPF_PRINTK_FMT_MOD char ____fmt[] = fmt;	\
255	bpf_trace_printk(____fmt, sizeof(____fmt),	\
256			 ##__VA_ARGS__);		\
257})
258
259/*
260 * __bpf_vprintk wraps the bpf_trace_vprintk helper with variadic arguments
261 * instead of an array of u64.
262 */
263#define __bpf_vprintk(fmt, args...)				\
264({								\
265	static const char ___fmt[] = fmt;			\
266	unsigned long long ___param[___bpf_narg(args)];		\
267								\
268	_Pragma("GCC diagnostic push")				\
269	_Pragma("GCC diagnostic ignored \"-Wint-conversion\"")	\
270	___bpf_fill(___param, args);				\
271	_Pragma("GCC diagnostic pop")				\
272								\
273	bpf_trace_vprintk(___fmt, sizeof(___fmt),		\
274			  ___param, sizeof(___param));		\
275})
276
277/* Use __bpf_printk when bpf_printk call has 3 or fewer fmt args
278 * Otherwise use __bpf_vprintk
279 */
280#define ___bpf_pick_printk(...) \
281	___bpf_nth(_, ##__VA_ARGS__, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,	\
282		   __bpf_vprintk, __bpf_vprintk, __bpf_vprintk, __bpf_vprintk,		\
283		   __bpf_vprintk, __bpf_vprintk, __bpf_printk /*3*/, __bpf_printk /*2*/,\
284		   __bpf_printk /*1*/, __bpf_printk /*0*/)
285
286/* Helper macro to print out debug messages */
287#define bpf_printk(fmt, args...) ___bpf_pick_printk(args)(fmt, ##args)
288
289#endif