1 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
2 #ifndef __BPF_HELPERS__
3 #define __BPF_HELPERS__
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
11 #include "bpf_helper_defs.h"
13 #define __uint(name, val) int (*name)[val]
14 #define __type(name, val) typeof(val) *name
15 #define __array(name, val) typeof(val) *name[]
17 /* Helper macro to print out debug messages */
18 #define bpf_printk(fmt, ...) \
20 char ____fmt[] = fmt; \
21 bpf_trace_printk(____fmt, sizeof(____fmt), \
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.
34 _Pragma("GCC diagnostic push") \
35 _Pragma("GCC diagnostic ignored \"-Wignored-attributes\"") \
36 __attribute__((section(name), used)) \
37 _Pragma("GCC diagnostic pop") \
39 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */
40 #undef __always_inline
41 #define __always_inline inline __attribute__((always_inline))
44 #define __noinline __attribute__((noinline))
47 #define __weak __attribute__((weak))
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.
57 #define NULL ((void *)0)
60 #ifndef KERNEL_VERSION
61 #define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)))
65 * Helper macros to manipulate data structures
68 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER)
71 #define container_of(ptr, type, member) \
73 void *__mptr = (void *)(ptr); \
74 ((type *)(__mptr - offsetof(type, member))); \
79 * Helper macro to throw a compilation error if __bpf_unreachable() gets
80 * built into the resulting code. This works given BPF back end does not
81 * implement __builtin_trap(). This is useful to assert that certain paths
82 * of the program code are never used and hence eliminated by the compiler.
84 * For example, consider a switch statement that covers known cases used by
85 * the program. __bpf_unreachable() can then reside in the default case. If
86 * the program gets extended such that a case is not covered in the switch
87 * statement, then it will throw a build error due to the default case not
90 #ifndef __bpf_unreachable
91 # define __bpf_unreachable() __builtin_trap()
95 * Helper function to perform a tail call with a constant/immediate map slot.
97 #if __clang_major__ >= 8 && defined(__bpf__)
98 static __always_inline void
99 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot)
101 if (!__builtin_constant_p(slot))
105 * Provide a hard guarantee that LLVM won't optimize setting r2 (map
106 * pointer) and r3 (constant map index) from _different paths_ ending
107 * up at the _same_ call insn as otherwise we won't be able to use the
108 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel
109 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key
110 * tracking for prog array pokes") for details on verifier tracking.
112 * Note on clobber list: we need to stay in-line with BPF calling
113 * convention, so even if we don't end up using r0, r4, r5, we need
114 * to mark them as clobber so that LLVM doesn't end up using them
115 * before / after the call.
117 asm volatile("r1 = %[ctx]\n\t"
121 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot)
122 : "r0", "r1", "r2", "r3", "r4", "r5");
127 * Helper structure used by eBPF C program
128 * to describe BPF map attributes to libbpf loader
132 unsigned int key_size;
133 unsigned int value_size;
134 unsigned int max_entries;
135 unsigned int map_flags;
138 enum libbpf_pin_type {
140 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
144 enum libbpf_tristate {
150 #define __kconfig __attribute__((section(".kconfig")))
151 #define __ksym __attribute__((section(".ksyms")))