1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * bpf-script-example.c
4*4882a593Smuzhiyun * Test basic LLVM building
5*4882a593Smuzhiyun */
6*4882a593Smuzhiyun #ifndef LINUX_VERSION_CODE
7*4882a593Smuzhiyun # error Need LINUX_VERSION_CODE
8*4882a593Smuzhiyun # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
9*4882a593Smuzhiyun #endif
10*4882a593Smuzhiyun #define BPF_ANY 0
11*4882a593Smuzhiyun #define BPF_MAP_TYPE_ARRAY 2
12*4882a593Smuzhiyun #define BPF_FUNC_map_lookup_elem 1
13*4882a593Smuzhiyun #define BPF_FUNC_map_update_elem 2
14*4882a593Smuzhiyun
15*4882a593Smuzhiyun static void *(*bpf_map_lookup_elem)(void *map, void *key) =
16*4882a593Smuzhiyun (void *) BPF_FUNC_map_lookup_elem;
17*4882a593Smuzhiyun static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
18*4882a593Smuzhiyun (void *) BPF_FUNC_map_update_elem;
19*4882a593Smuzhiyun
20*4882a593Smuzhiyun struct bpf_map_def {
21*4882a593Smuzhiyun unsigned int type;
22*4882a593Smuzhiyun unsigned int key_size;
23*4882a593Smuzhiyun unsigned int value_size;
24*4882a593Smuzhiyun unsigned int max_entries;
25*4882a593Smuzhiyun };
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun #define SEC(NAME) __attribute__((section(NAME), used))
28*4882a593Smuzhiyun struct bpf_map_def SEC("maps") flip_table = {
29*4882a593Smuzhiyun .type = BPF_MAP_TYPE_ARRAY,
30*4882a593Smuzhiyun .key_size = sizeof(int),
31*4882a593Smuzhiyun .value_size = sizeof(int),
32*4882a593Smuzhiyun .max_entries = 1,
33*4882a593Smuzhiyun };
34*4882a593Smuzhiyun
35*4882a593Smuzhiyun SEC("func=do_epoll_wait")
bpf_func__SyS_epoll_pwait(void * ctx)36*4882a593Smuzhiyun int bpf_func__SyS_epoll_pwait(void *ctx)
37*4882a593Smuzhiyun {
38*4882a593Smuzhiyun int ind =0;
39*4882a593Smuzhiyun int *flag = bpf_map_lookup_elem(&flip_table, &ind);
40*4882a593Smuzhiyun int new_flag;
41*4882a593Smuzhiyun if (!flag)
42*4882a593Smuzhiyun return 0;
43*4882a593Smuzhiyun /* flip flag and store back */
44*4882a593Smuzhiyun new_flag = !*flag;
45*4882a593Smuzhiyun bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
46*4882a593Smuzhiyun return new_flag;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun char _license[] SEC("license") = "GPL";
49*4882a593Smuzhiyun int _version SEC("version") = LINUX_VERSION_CODE;
50