// 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;
|
|
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=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;
|
