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 elf_bpf loader
29 */
30#define SEC(NAME) __attribute__((section(NAME), used))
31
32#ifndef __always_inline
33#define __always_inline __attribute__((always_inline))
34#endif
35#ifndef __noinline
36#define __noinline __attribute__((noinline))
37#endif
38#ifndef __weak
39#define __weak __attribute__((weak))
40#endif
41
42/*
43 * Helper macro to manipulate data structures
44 */
45
46/* offsetof() definition that uses __builtin_offset() might not preserve field
47 * offset CO-RE relocation properly, so force-redefine offsetof() using
48 * old-school approach which works with CO-RE correctly
49 */
50#undef offsetof
51#define offsetof(type, member)	((unsigned long)&((type *)0)->member)
52
53/* redefined container_of() to ensure we use the above offsetof() macro */
54#undef container_of
55#define container_of(ptr, type, member)				\
56	({							\
57		void *__mptr = (void *)(ptr);			\
58		((type *)(__mptr - offsetof(type, member)));	\
59	})
60
61/*
62 * Helper macro to throw a compilation error if __bpf_unreachable() gets
63 * built into the resulting code. This works given BPF back end does not
64 * implement __builtin_trap(). This is useful to assert that certain paths
65 * of the program code are never used and hence eliminated by the compiler.
66 *
67 * For example, consider a switch statement that covers known cases used by
68 * the program. __bpf_unreachable() can then reside in the default case. If
69 * the program gets extended such that a case is not covered in the switch
70 * statement, then it will throw a build error due to the default case not
71 * being compiled out.
72 */
73#ifndef __bpf_unreachable
74# define __bpf_unreachable()	__builtin_trap()
75#endif
76
77/*
78 * Helper function to perform a tail call with a constant/immediate map slot.
79 */
80#if __clang_major__ >= 8 && defined(__bpf__)
81static __always_inline void
82bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
83{
84	if (!__builtin_constant_p(slot))
85		__bpf_unreachable();
86
87	/*
88	 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
89	 * pointer) and r3 (constant map index) from _different paths_ ending
90	 * up at the _same_ call insn as otherwise we won't be able to use the
91	 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
92	 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
93	 * tracking for prog array pokes") for details on verifier tracking.
94	 *
95	 * Note on clobber list: we need to stay in-line with BPF calling
96	 * convention, so even if we don't end up using r0, r4, r5, we need
97	 * to mark them as clobber so that LLVM doesn't end up using them
98	 * before / after the call.
99	 */
100	asm volatile("r1 = %[ctx]\n\t"
101		     "r2 = %[map]\n\t"
102		     "r3 = %[slot]\n\t"
103		     "call 12"
104		     :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
105		     : "r0", "r1", "r2", "r3", "r4", "r5");
106}
107#endif
108
109/*
110 * Helper structure used by eBPF C program
111 * to describe BPF map attributes to libbpf loader
112 */
113struct bpf_map_def {
114	unsigned int type;
115	unsigned int key_size;
116	unsigned int value_size;
117	unsigned int max_entries;
118	unsigned int map_flags;
119};
120
121enum libbpf_pin_type {
122	LIBBPF_PIN_NONE,
123	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
124	LIBBPF_PIN_BY_NAME,
125};
126
127enum libbpf_tristate {
128	TRI_NO = 0,
129	TRI_YES = 1,
130	TRI_MODULE = 2,
131};
132
133#define __kconfig __attribute__((section(".kconfig")))
134#define __ksym __attribute__((section(".ksyms")))
135
136#endif
137