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 /* Avoid 'linux/stddef.h' definition of '__always_inline'. */ 33 #undef __always_inline 34 #define __always_inline inline __attribute__((always_inline)) 35 36 #ifndef __noinline 37 #define __noinline __attribute__((noinline)) 38 #endif 39 #ifndef __weak 40 #define __weak __attribute__((weak)) 41 #endif 42 43 /* When utilizing vmlinux.h with BPF CO-RE, user BPF programs can't include 44 * any system-level headers (such as stddef.h, linux/version.h, etc), and 45 * commonly-used macros like NULL and KERNEL_VERSION aren't available through 46 * vmlinux.h. This just adds unnecessary hurdles and forces users to re-define 47 * them on their own. So as a convenience, provide such definitions here. 48 */ 49 #ifndef NULL 50 #define NULL ((void *)0) 51 #endif 52 53 #ifndef KERNEL_VERSION 54 #define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + ((c) > 255 ? 255 : (c)) 55 #endif 56 57 /* 58 * Helper macros to manipulate data structures 59 */ 60 #ifndef offsetof 61 #define offsetof(TYPE, MEMBER) ((unsigned long)&((TYPE *)0)->MEMBER) 62 #endif 63 #ifndef container_of 64 #define container_of(ptr, type, member) \ 65 ({ \ 66 void *__mptr = (void *)(ptr); \ 67 ((type *)(__mptr - offsetof(type, member))); \ 68 }) 69 #endif 70 71 /* 72 * Helper macro to throw a compilation error if __bpf_unreachable() gets 73 * built into the resulting code. This works given BPF back end does not 74 * implement __builtin_trap(). This is useful to assert that certain paths 75 * of the program code are never used and hence eliminated by the compiler. 76 * 77 * For example, consider a switch statement that covers known cases used by 78 * the program. __bpf_unreachable() can then reside in the default case. If 79 * the program gets extended such that a case is not covered in the switch 80 * statement, then it will throw a build error due to the default case not 81 * being compiled out. 82 */ 83 #ifndef __bpf_unreachable 84 # define __bpf_unreachable() __builtin_trap() 85 #endif 86 87 /* 88 * Helper function to perform a tail call with a constant/immediate map slot. 89 */ 90 #if __clang_major__ >= 8 && defined(__bpf__) 91 static __always_inline void 92 bpf_tail_call_static(void *ctx, const void *map, const __u32 slot) 93 { 94 if (!__builtin_constant_p(slot)) 95 __bpf_unreachable(); 96 97 /* 98 * Provide a hard guarantee that LLVM won't optimize setting r2 (map 99 * pointer) and r3 (constant map index) from _different paths_ ending 100 * up at the _same_ call insn as otherwise we won't be able to use the 101 * jmpq/nopl retpoline-free patching by the x86-64 JIT in the kernel 102 * given they mismatch. See also d2e4c1e6c294 ("bpf: Constant map key 103 * tracking for prog array pokes") for details on verifier tracking. 104 * 105 * Note on clobber list: we need to stay in-line with BPF calling 106 * convention, so even if we don't end up using r0, r4, r5, we need 107 * to mark them as clobber so that LLVM doesn't end up using them 108 * before / after the call. 109 */ 110 asm volatile("r1 = %[ctx]\n\t" 111 "r2 = %[map]\n\t" 112 "r3 = %[slot]\n\t" 113 "call 12" 114 :: [ctx]"r"(ctx), [map]"r"(map), [slot]"i"(slot) 115 : "r0", "r1", "r2", "r3", "r4", "r5"); 116 } 117 #endif 118 119 /* 120 * Helper structure used by eBPF C program 121 * to describe BPF map attributes to libbpf loader 122 */ 123 struct bpf_map_def { 124 unsigned int type; 125 unsigned int key_size; 126 unsigned int value_size; 127 unsigned int max_entries; 128 unsigned int map_flags; 129 }; 130 131 enum libbpf_pin_type { 132 LIBBPF_PIN_NONE, 133 /* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */ 134 LIBBPF_PIN_BY_NAME, 135 }; 136 137 enum libbpf_tristate { 138 TRI_NO = 0, 139 TRI_YES = 1, 140 TRI_MODULE = 2, 141 }; 142 143 #define __kconfig __attribute__((section(".kconfig"))) 144 #define __ksym __attribute__((section(".ksyms"))) 145 146 #endif 147