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