1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
4 */
5
6#include <linux/ctype.h>
7#include <linux/init.h>
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/proc_fs.h>
11#include <linux/seq_file.h>
12#include <linux/types.h>
13#include <linux/uaccess.h>
14
15/*
16 * If read and write race, the read will still atomically read a valid
17 * value.
18 */
19int uml_exitcode = 0;
20
21static int exitcode_proc_show(struct seq_file *m, void *v)
22{
23 int val;
24
25 /*
26 * Save uml_exitcode in a local so that we don't need to guarantee
27 * that sprintf accesses it atomically.
28 */
29 val = uml_exitcode;
30 seq_printf(m, fmt: "%d\n", val);
31 return 0;
32}
33
34static int exitcode_proc_open(struct inode *inode, struct file *file)
35{
36 return single_open(file, exitcode_proc_show, NULL);
37}
38
39static ssize_t exitcode_proc_write(struct file *file,
40 const char __user *buffer, size_t count, loff_t *pos)
41{
42 char *end, buf[sizeof("nnnnn\0")];
43 size_t size;
44 int tmp;
45
46 size = min(count, sizeof(buf));
47 if (copy_from_user(to: buf, from: buffer, n: size))
48 return -EFAULT;
49
50 tmp = simple_strtol(buf, &end, 0);
51 if ((*end != '\0') && !isspace(*end))
52 return -EINVAL;
53
54 uml_exitcode = tmp;
55 return count;
56}
57
58static const struct proc_ops exitcode_proc_ops = {
59 .proc_open = exitcode_proc_open,
60 .proc_read = seq_read,
61 .proc_lseek = seq_lseek,
62 .proc_release = single_release,
63 .proc_write = exitcode_proc_write,
64};
65
66static int make_proc_exitcode(void)
67{
68 struct proc_dir_entry *ent;
69
70 ent = proc_create(name: "exitcode", mode: 0600, NULL, proc_ops: &exitcode_proc_ops);
71 if (ent == NULL) {
72 printk(KERN_WARNING "make_proc_exitcode : Failed to register "
73 "/proc/exitcode\n");
74 return 0;
75 }
76 return 0;
77}
78
79__initcall(make_proc_exitcode);
80

source code of linux/arch/um/kernel/exitcode.c