4ffde49246
The prototype for epoll_wait() is available in older distros, so use it instead of epoll_pwait() (removing the last NULL arg, the sigmask, makes it the same thing anyway) to avoid breaking the build. Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/n/tip-pwiwizloxt0jujy8em80qut3@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
49 lines
1.3 KiB
C
49 lines
1.3 KiB
C
/*
|
|
* 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;
|