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#define FMODE_READ		0x1
14#define FMODE_WRITE		0x2
15
16static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
17	(void *) 6;
18
19SEC("func=null_lseek file->f_mode offset orig")
20int bpf_func__null_lseek(void *ctx, int err, unsigned long f_mode,
21			 unsigned long offset, unsigned long orig)
22{
23	if (err)
24		return 0;
25	if (f_mode & FMODE_WRITE)
26		return 0;
27	if (offset & 1)
28		return 0;
29	if (orig == SEEK_CUR)
30		return 0;
31	return 1;
32}
33
34char _license[] SEC("license") = "GPL";
35int _version SEC("version") = LINUX_VERSION_CODE;