1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * srm_env.c - Access to SRM environment
4  *             variables through linux' procfs
5  *
6  * (C) 2001,2002,2006 by Jan-Benedict Glaw <jbglaw@lug-owl.de>
7  *
8  * This driver is a modified version of Erik Mouw's example proc
9  * interface, so: thank you, Erik! He can be reached via email at
10  * <J.A.K.Mouw@its.tudelft.nl>. It is based on an idea
11  * provided by DEC^WCompaq^WIntel's "Jumpstart" CD. They
12  * included a patch like this as well. Thanks for idea!
13  */
14 
15 #include <linux/kernel.h>
16 #include <linux/gfp.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/proc_fs.h>
20 #include <linux/seq_file.h>
21 #include <asm/console.h>
22 #include <linux/uaccess.h>
23 #include <asm/machvec.h>
24 
25 #define BASE_DIR	"srm_environment"	/* Subdir in /proc/		*/
26 #define NAMED_DIR	"named_variables"	/* Subdir for known variables	*/
27 #define NUMBERED_DIR	"numbered_variables"	/* Subdir for all variables	*/
28 #define VERSION		"0.0.6"			/* Module version		*/
29 #define NAME		"srm_env"		/* Module name			*/
30 
31 MODULE_AUTHOR("Jan-Benedict Glaw <jbglaw@lug-owl.de>");
32 MODULE_DESCRIPTION("Accessing Alpha SRM environment through procfs interface");
33 MODULE_LICENSE("GPL");
34 
35 typedef struct _srm_env {
36 	char			*name;
37 	unsigned long		id;
38 } srm_env_t;
39 
40 static struct proc_dir_entry	*base_dir;
41 static struct proc_dir_entry	*named_dir;
42 static struct proc_dir_entry	*numbered_dir;
43 
44 static srm_env_t	srm_named_entries[] = {
45 	{ "auto_action",	ENV_AUTO_ACTION		},
46 	{ "boot_dev",		ENV_BOOT_DEV		},
47 	{ "bootdef_dev",	ENV_BOOTDEF_DEV		},
48 	{ "booted_dev",		ENV_BOOTED_DEV		},
49 	{ "boot_file",		ENV_BOOT_FILE		},
50 	{ "booted_file",	ENV_BOOTED_FILE		},
51 	{ "boot_osflags",	ENV_BOOT_OSFLAGS	},
52 	{ "booted_osflags",	ENV_BOOTED_OSFLAGS	},
53 	{ "boot_reset",		ENV_BOOT_RESET		},
54 	{ "dump_dev",		ENV_DUMP_DEV		},
55 	{ "enable_audit",	ENV_ENABLE_AUDIT	},
56 	{ "license",		ENV_LICENSE		},
57 	{ "char_set",		ENV_CHAR_SET		},
58 	{ "language",		ENV_LANGUAGE		},
59 	{ "tty_dev",		ENV_TTY_DEV		},
60 	{ NULL,			0			},
61 };
62 
srm_env_proc_show(struct seq_file * m,void * v)63 static int srm_env_proc_show(struct seq_file *m, void *v)
64 {
65 	unsigned long	ret;
66 	unsigned long	id = (unsigned long)m->private;
67 	char		*page;
68 
69 	page = (char *)__get_free_page(GFP_USER);
70 	if (!page)
71 		return -ENOMEM;
72 
73 	ret = callback_getenv(id, page, PAGE_SIZE);
74 
75 	if ((ret >> 61) == 0) {
76 		seq_write(m, page, ret);
77 		ret = 0;
78 	} else
79 		ret = -EFAULT;
80 	free_page((unsigned long)page);
81 	return ret;
82 }
83 
srm_env_proc_open(struct inode * inode,struct file * file)84 static int srm_env_proc_open(struct inode *inode, struct file *file)
85 {
86 	return single_open(file, srm_env_proc_show, PDE_DATA(inode));
87 }
88 
srm_env_proc_write(struct file * file,const char __user * buffer,size_t count,loff_t * pos)89 static ssize_t srm_env_proc_write(struct file *file, const char __user *buffer,
90 				  size_t count, loff_t *pos)
91 {
92 	int res;
93 	unsigned long	id = (unsigned long)PDE_DATA(file_inode(file));
94 	char		*buf = (char *) __get_free_page(GFP_USER);
95 	unsigned long	ret1, ret2;
96 
97 	if (!buf)
98 		return -ENOMEM;
99 
100 	res = -EINVAL;
101 	if (count >= PAGE_SIZE)
102 		goto out;
103 
104 	res = -EFAULT;
105 	if (copy_from_user(buf, buffer, count))
106 		goto out;
107 	buf[count] = '\0';
108 
109 	ret1 = callback_setenv(id, buf, count);
110 	if ((ret1 >> 61) == 0) {
111 		do
112 			ret2 = callback_save_env();
113 		while((ret2 >> 61) == 1);
114 		res = (int) ret1;
115 	}
116 
117  out:
118 	free_page((unsigned long)buf);
119 	return res;
120 }
121 
122 static const struct proc_ops srm_env_proc_ops = {
123 	.proc_open	= srm_env_proc_open,
124 	.proc_read	= seq_read,
125 	.proc_lseek	= seq_lseek,
126 	.proc_release	= single_release,
127 	.proc_write	= srm_env_proc_write,
128 };
129 
130 static int __init
srm_env_init(void)131 srm_env_init(void)
132 {
133 	srm_env_t	*entry;
134 	unsigned long	var_num;
135 
136 	/*
137 	 * Check system
138 	 */
139 	if (!alpha_using_srm) {
140 		printk(KERN_INFO "%s: This Alpha system doesn't "
141 				"know about SRM (or you've booted "
142 				"SRM->MILO->Linux, which gets "
143 				"misdetected)...\n", __func__);
144 		return -ENODEV;
145 	}
146 
147 	/*
148 	 * Create base directory
149 	 */
150 	base_dir = proc_mkdir(BASE_DIR, NULL);
151 	if (!base_dir) {
152 		printk(KERN_ERR "Couldn't create base dir /proc/%s\n",
153 				BASE_DIR);
154 		return -ENOMEM;
155 	}
156 
157 	/*
158 	 * Create per-name subdirectory
159 	 */
160 	named_dir = proc_mkdir(NAMED_DIR, base_dir);
161 	if (!named_dir) {
162 		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
163 				BASE_DIR, NAMED_DIR);
164 		goto cleanup;
165 	}
166 
167 	/*
168 	 * Create per-number subdirectory
169 	 */
170 	numbered_dir = proc_mkdir(NUMBERED_DIR, base_dir);
171 	if (!numbered_dir) {
172 		printk(KERN_ERR "Couldn't create dir /proc/%s/%s\n",
173 				BASE_DIR, NUMBERED_DIR);
174 		goto cleanup;
175 
176 	}
177 
178 	/*
179 	 * Create all named nodes
180 	 */
181 	entry = srm_named_entries;
182 	while (entry->name && entry->id) {
183 		if (!proc_create_data(entry->name, 0644, named_dir,
184 			     &srm_env_proc_ops, (void *)entry->id))
185 			goto cleanup;
186 		entry++;
187 	}
188 
189 	/*
190 	 * Create all numbered nodes
191 	 */
192 	for (var_num = 0; var_num <= 255; var_num++) {
193 		char name[4];
194 		sprintf(name, "%ld", var_num);
195 		if (!proc_create_data(name, 0644, numbered_dir,
196 			     &srm_env_proc_ops, (void *)var_num))
197 			goto cleanup;
198 	}
199 
200 	printk(KERN_INFO "%s: version %s loaded successfully\n", NAME,
201 			VERSION);
202 
203 	return 0;
204 
205 cleanup:
206 	remove_proc_subtree(BASE_DIR, NULL);
207 	return -ENOMEM;
208 }
209 
210 static void __exit
srm_env_exit(void)211 srm_env_exit(void)
212 {
213 	remove_proc_subtree(BASE_DIR, NULL);
214 	printk(KERN_INFO "%s: unloaded successfully\n", NAME);
215 }
216 
217 module_init(srm_env_init);
218 module_exit(srm_env_exit);
219