// SPDX-License-Identifier: GPL-2.0/* * 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; /* * Following macros are taken from tools/lib/bpf/bpf_helpers.h, * and are used to create BTF defined maps. It is easier to take * 2 simple macros, than being able to include above header in * runtime. * * __uint - defines integer attribute of BTF map definition, * Such attributes are represented using a pointer to an array, * in which dimensionality of array encodes specified integer * value. * * __type - defines pointer variable with typeof(val) type for * attributes like key or value, which will be defined by the * size of the type. */#define __uint(name, val) int (*name)[val]#define __type(name, val) typeof(val) *name #define SEC(NAME) __attribute__((section(NAME), used))struct {	__uint(type, BPF_MAP_TYPE_ARRAY);	__uint(max_entries, 1);	__type(key, int);	__type(value, int);} flip_table SEC(".maps"); SEC("func=do_epoll_wait")int bpf_func__SyS_epoll_pwait(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;