1// SPDX-License-Identifier: GPL-2.0
2/*
3 * bpf-script-test-prologue.c
4 * Test BPF prologue
5 */
6#ifndef LINUX_VERSION_CODE
7# error Need LINUX_VERSION_CODE
8# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
9#endif
10#define SEC(NAME) __attribute__((section(NAME), used))
11
12#include <uapi/linux/fs.h>
13
14/*
15 * If CONFIG_PROFILE_ALL_BRANCHES is selected,
16 * 'if' is redefined after include kernel header.
17 * Recover 'if' for BPF object code.
18 */
19#ifdef if
20# undef if
21#endif
22
23#define FMODE_READ		0x1
24#define FMODE_WRITE		0x2
25
26static void (*bpf_trace_printk)(const char *fmt, int fmt_size, ...) =
27	(void *) 6;
28
29SEC("func=null_lseek file->f_mode offset orig")
30int bpf_func__null_lseek(void *ctx, int err, unsigned long _f_mode,
31			 unsigned long offset, unsigned long orig)
32{
33	fmode_t f_mode = (fmode_t)_f_mode;
34
35	if (err)
36		return 0;
37	if (f_mode & FMODE_WRITE)
38		return 0;
39	if (offset & 1)
40		return 0;
41	if (orig == SEEK_CUR)
42		return 0;
43	return 1;
44}
45
46char _license[] SEC("license") = "GPL";
47int _version SEC("version") = LINUX_VERSION_CODE;
48