1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) 2021. Huawei Technologies Co., Ltd */
3 #include <linux/types.h>
4 #include <linux/bpf.h>
5 #include <bpf/bpf_helpers.h>
6 #include <bpf/bpf_tracing.h>
7
8 #define STRNCMP_STR_SZ 4096
9
10 /* Will be updated by benchmark before program loading */
11 const volatile unsigned int cmp_str_len = 1;
12 const char target[STRNCMP_STR_SZ];
13
14 long hits = 0;
15 char str[STRNCMP_STR_SZ];
16
17 char _license[] SEC("license") = "GPL";
18
local_strncmp(const char * s1,unsigned int sz,const char * s2)19 static __always_inline int local_strncmp(const char *s1, unsigned int sz,
20 const char *s2)
21 {
22 int ret = 0;
23 unsigned int i;
24
25 for (i = 0; i < sz; i++) {
26 /* E.g. 0xff > 0x31 */
27 ret = (unsigned char)s1[i] - (unsigned char)s2[i];
28 if (ret || !s1[i])
29 break;
30 }
31
32 return ret;
33 }
34
35 SEC("tp/syscalls/sys_enter_getpgid")
strncmp_no_helper(void * ctx)36 int strncmp_no_helper(void *ctx)
37 {
38 if (local_strncmp(str, cmp_str_len + 1, target) < 0)
39 __sync_add_and_fetch(&hits, 1);
40 return 0;
41 }
42
43 SEC("tp/syscalls/sys_enter_getpgid")
strncmp_helper(void * ctx)44 int strncmp_helper(void *ctx)
45 {
46 if (bpf_strncmp(str, cmp_str_len + 1, target) < 0)
47 __sync_add_and_fetch(&hits, 1);
48 return 0;
49 }
50
51