/* * bpf-script-example.c * Test basic LLVM building */#ifndef LINUX_VERSION_CODE# error Need LINUX_VERSION_CODE# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'#endif#define BPF_ANY 0#define BPF_MAP_TYPE_ARRAY 2#define BPF_FUNC_map_lookup_elem 1#define BPF_FUNC_map_update_elem 2 static void *(*bpf_map_lookup_elem)(void *map, void *key) =	(void *) BPF_FUNC_map_lookup_elem;static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =	(void *) BPF_FUNC_map_update_elem; struct bpf_map_def {	unsigned int type;	unsigned int key_size;	unsigned int value_size;	unsigned int max_entries;}; #define SEC(NAME) __attribute__((section(NAME), used))struct bpf_map_def SEC("maps") flip_table = {	.type = BPF_MAP_TYPE_ARRAY,	.key_size = sizeof(int),	.value_size = sizeof(int),	.max_entries = 1,}; SEC("func=SyS_epoll_wait")int bpf_func__SyS_epoll_wait(void *ctx){	int ind =0;	int *flag = bpf_map_lookup_elem(&flip_table, &ind);	int new_flag;	if (!flag)		return 0;	/* flip flag and store back */	new_flag = !*flag;	bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);	return new_flag;}char _license[] SEC("license") = "GPL";int _version SEC("version") = LINUX_VERSION_CODE;