forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
60 lines
1.8 KiB
60 lines
1.8 KiB
// 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;
|
|
|