1 /*
2 * bpf-script-test-prologue.c
3 * Test BPF prologue
4 */
5 #ifndef LINUX_VERSION_CODE
6 # error Need LINUX_VERSION_CODE
7 # error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
8 #endif
9 #define SEC(NAME) __attribute__((section(NAME), used))
10
11 #include <uapi/linux/fs.h>
12
13 /*
14 * If CONFIG_PROFILE_ALL_BRANCHES is selected,
15 * 'if' is redefined after include kernel header.
16 * Recover 'if' for BPF object code.
17 */
18 #ifdef if
19 # undef if
20 #endif
21
22 #define FMODE_READ 0x1
23 #define FMODE_WRITE 0x2
24
25 static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
26 (void *) 6;
27
28 SEC("func=null_lseek file->f_mode offset orig")
29 int bpf_func__null_lseek(void *ctx, int err, unsigned long _f_mode,
30 unsigned long offset, unsigned long orig)
31 {
32 fmode_t f_mode = (fmode_t)_f_mode;
33
34 if (err)
35 return 0;
36 if (f_mode & FMODE_WRITE)
37 return 0;
38 if (offset & 1)
39 return 0;
40 if (orig == SEEK_CUR)
41 return 0;
42 return 1;
43 }
44
45 char _license[] SEC("license") = "GPL";
46 int _version SEC("version") = LINUX_VERSION_CODE;
47
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