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5875cf4c | 1 | // SPDX-License-Identifier: GPL-2.0 |
b31de018 WN |
2 | /* |
3 | * bpf-script-example.c | |
4 | * Test basic LLVM building | |
5 | */ | |
d509db04 WN |
6 | #ifndef LINUX_VERSION_CODE |
7 | # error Need LINUX_VERSION_CODE | |
8 | # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig' | |
9 | #endif | |
10 | #define BPF_ANY 0 | |
11 | #define BPF_MAP_TYPE_ARRAY 2 | |
12 | #define BPF_FUNC_map_lookup_elem 1 | |
13 | #define BPF_FUNC_map_update_elem 2 | |
14 | ||
15 | static void *(*bpf_map_lookup_elem)(void *map, void *key) = | |
16 | (void *) BPF_FUNC_map_lookup_elem; | |
17 | static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) = | |
18 | (void *) BPF_FUNC_map_update_elem; | |
19 | ||
8b1e1a03 JO |
20 | /* |
21 | * Following macros are taken from tools/lib/bpf/bpf_helpers.h, | |
22 | * and are used to create BTF defined maps. It is easier to take | |
23 | * 2 simple macros, than being able to include above header in | |
24 | * runtime. | |
25 | * | |
26 | * __uint - defines integer attribute of BTF map definition, | |
27 | * Such attributes are represented using a pointer to an array, | |
28 | * in which dimensionality of array encodes specified integer | |
29 | * value. | |
30 | * | |
31 | * __type - defines pointer variable with typeof(val) type for | |
32 | * attributes like key or value, which will be defined by the | |
33 | * size of the type. | |
34 | */ | |
35 | #define __uint(name, val) int (*name)[val] | |
36 | #define __type(name, val) typeof(val) *name | |
d509db04 WN |
37 | |
38 | #define SEC(NAME) __attribute__((section(NAME), used)) | |
8b1e1a03 JO |
39 | struct { |
40 | __uint(type, BPF_MAP_TYPE_ARRAY); | |
41 | __uint(max_entries, 1); | |
42 | __type(key, int); | |
43 | __type(value, int); | |
44 | } flip_table SEC(".maps"); | |
d509db04 | 45 | |
7158005b | 46 | SEC("syscalls:sys_enter_epoll_pwait") |
e0337f4f | 47 | int bpf_func__SyS_epoll_pwait(void *ctx) |
d509db04 WN |
48 | { |
49 | int ind =0; | |
50 | int *flag = bpf_map_lookup_elem(&flip_table, &ind); | |
51 | int new_flag; | |
52 | if (!flag) | |
53 | return 0; | |
54 | /* flip flag and store back */ | |
55 | new_flag = !*flag; | |
56 | bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY); | |
57 | return new_flag; | |
58 | } | |
59 | char _license[] SEC("license") = "GPL"; | |
60 | int _version SEC("version") = LINUX_VERSION_CODE; |