1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/capability.h>
3 #include <linux/seq_file.h>
4 #include <linux/uaccess.h>
5 #include <linux/proc_fs.h>
6 #include <linux/ctype.h>
7 #include <linux/string.h>
8 #include <linux/slab.h>
9 #include <linux/init.h>
10 
11 #define LINE_SIZE 80
12 
13 #include <asm/mtrr.h>
14 
15 #include "mtrr.h"
16 
17 #define FILE_FCOUNT(f) (((struct seq_file *)((f)->private_data))->private)
18 
19 static const char *const mtrr_strings[MTRR_NUM_TYPES] =
20 {
21 	"uncachable",		/* 0 */
22 	"write-combining",	/* 1 */
23 	"?",			/* 2 */
24 	"?",			/* 3 */
25 	"write-through",	/* 4 */
26 	"write-protect",	/* 5 */
27 	"write-back",		/* 6 */
28 };
29 
mtrr_attrib_to_str(int x)30 const char *mtrr_attrib_to_str(int x)
31 {
32 	return (x <= 6) ? mtrr_strings[x] : "?";
33 }
34 
35 #ifdef CONFIG_PROC_FS
36 
37 static int
mtrr_file_add(unsigned long base,unsigned long size,unsigned int type,bool increment,struct file * file,int page)38 mtrr_file_add(unsigned long base, unsigned long size,
39 	      unsigned int type, bool increment, struct file *file, int page)
40 {
41 	unsigned int *fcount = FILE_FCOUNT(file);
42 	int reg, max;
43 
44 	max = num_var_ranges;
45 	if (fcount == NULL) {
46 		fcount = kcalloc(max, sizeof(*fcount), GFP_KERNEL);
47 		if (!fcount)
48 			return -ENOMEM;
49 		FILE_FCOUNT(file) = fcount;
50 	}
51 	if (!page) {
52 		if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
53 			return -EINVAL;
54 		base >>= PAGE_SHIFT;
55 		size >>= PAGE_SHIFT;
56 	}
57 	reg = mtrr_add_page(base, size, type, true);
58 	if (reg >= 0)
59 		++fcount[reg];
60 	return reg;
61 }
62 
63 static int
mtrr_file_del(unsigned long base,unsigned long size,struct file * file,int page)64 mtrr_file_del(unsigned long base, unsigned long size,
65 	      struct file *file, int page)
66 {
67 	unsigned int *fcount = FILE_FCOUNT(file);
68 	int reg;
69 
70 	if (!page) {
71 		if ((base & (PAGE_SIZE - 1)) || (size & (PAGE_SIZE - 1)))
72 			return -EINVAL;
73 		base >>= PAGE_SHIFT;
74 		size >>= PAGE_SHIFT;
75 	}
76 	reg = mtrr_del_page(-1, base, size);
77 	if (reg < 0)
78 		return reg;
79 	if (fcount == NULL)
80 		return reg;
81 	if (fcount[reg] < 1)
82 		return -EINVAL;
83 	--fcount[reg];
84 	return reg;
85 }
86 
87 /*
88  * seq_file can seek but we ignore it.
89  *
90  * Format of control line:
91  *    "base=%Lx size=%Lx type=%s" or "disable=%d"
92  */
93 static ssize_t
mtrr_write(struct file * file,const char __user * buf,size_t len,loff_t * ppos)94 mtrr_write(struct file *file, const char __user *buf, size_t len, loff_t * ppos)
95 {
96 	int i, err;
97 	unsigned long reg;
98 	unsigned long long base, size;
99 	char *ptr;
100 	char line[LINE_SIZE];
101 	int length;
102 
103 	memset(line, 0, LINE_SIZE);
104 
105 	len = min_t(size_t, len, LINE_SIZE - 1);
106 	length = strncpy_from_user(line, buf, len);
107 	if (length < 0)
108 		return length;
109 
110 	ptr = line + length - 1;
111 	if (length && *ptr == '\n')
112 		*ptr = '\0';
113 
114 	if (!strncmp(line, "disable=", 8)) {
115 		reg = simple_strtoul(line + 8, &ptr, 0);
116 		err = mtrr_del_page(reg, 0, 0);
117 		if (err < 0)
118 			return err;
119 		return len;
120 	}
121 
122 	if (strncmp(line, "base=", 5))
123 		return -EINVAL;
124 
125 	base = simple_strtoull(line + 5, &ptr, 0);
126 	ptr = skip_spaces(ptr);
127 
128 	if (strncmp(ptr, "size=", 5))
129 		return -EINVAL;
130 
131 	size = simple_strtoull(ptr + 5, &ptr, 0);
132 	if ((base & 0xfff) || (size & 0xfff))
133 		return -EINVAL;
134 	ptr = skip_spaces(ptr);
135 
136 	if (strncmp(ptr, "type=", 5))
137 		return -EINVAL;
138 	ptr = skip_spaces(ptr + 5);
139 
140 	i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
141 	if (i < 0)
142 		return i;
143 
144 	base >>= PAGE_SHIFT;
145 	size >>= PAGE_SHIFT;
146 	err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
147 	if (err < 0)
148 		return err;
149 	return len;
150 }
151 
152 static long
mtrr_ioctl(struct file * file,unsigned int cmd,unsigned long __arg)153 mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
154 {
155 	int err = 0;
156 	mtrr_type type;
157 	unsigned long base;
158 	unsigned long size;
159 	struct mtrr_sentry sentry;
160 	struct mtrr_gentry gentry;
161 	void __user *arg = (void __user *) __arg;
162 
163 	memset(&gentry, 0, sizeof(gentry));
164 
165 	switch (cmd) {
166 	case MTRRIOC_ADD_ENTRY:
167 	case MTRRIOC_SET_ENTRY:
168 	case MTRRIOC_DEL_ENTRY:
169 	case MTRRIOC_KILL_ENTRY:
170 	case MTRRIOC_ADD_PAGE_ENTRY:
171 	case MTRRIOC_SET_PAGE_ENTRY:
172 	case MTRRIOC_DEL_PAGE_ENTRY:
173 	case MTRRIOC_KILL_PAGE_ENTRY:
174 		if (copy_from_user(&sentry, arg, sizeof(sentry)))
175 			return -EFAULT;
176 		break;
177 	case MTRRIOC_GET_ENTRY:
178 	case MTRRIOC_GET_PAGE_ENTRY:
179 		if (copy_from_user(&gentry, arg, sizeof(gentry)))
180 			return -EFAULT;
181 		break;
182 #ifdef CONFIG_COMPAT
183 	case MTRRIOC32_ADD_ENTRY:
184 	case MTRRIOC32_SET_ENTRY:
185 	case MTRRIOC32_DEL_ENTRY:
186 	case MTRRIOC32_KILL_ENTRY:
187 	case MTRRIOC32_ADD_PAGE_ENTRY:
188 	case MTRRIOC32_SET_PAGE_ENTRY:
189 	case MTRRIOC32_DEL_PAGE_ENTRY:
190 	case MTRRIOC32_KILL_PAGE_ENTRY: {
191 		struct mtrr_sentry32 __user *s32;
192 
193 		s32 = (struct mtrr_sentry32 __user *)__arg;
194 		err = get_user(sentry.base, &s32->base);
195 		err |= get_user(sentry.size, &s32->size);
196 		err |= get_user(sentry.type, &s32->type);
197 		if (err)
198 			return err;
199 		break;
200 	}
201 	case MTRRIOC32_GET_ENTRY:
202 	case MTRRIOC32_GET_PAGE_ENTRY: {
203 		struct mtrr_gentry32 __user *g32;
204 
205 		g32 = (struct mtrr_gentry32 __user *)__arg;
206 		err = get_user(gentry.regnum, &g32->regnum);
207 		err |= get_user(gentry.base, &g32->base);
208 		err |= get_user(gentry.size, &g32->size);
209 		err |= get_user(gentry.type, &g32->type);
210 		if (err)
211 			return err;
212 		break;
213 	}
214 #endif
215 	}
216 
217 	switch (cmd) {
218 	default:
219 		return -ENOTTY;
220 	case MTRRIOC_ADD_ENTRY:
221 #ifdef CONFIG_COMPAT
222 	case MTRRIOC32_ADD_ENTRY:
223 #endif
224 		err =
225 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
226 				  file, 0);
227 		break;
228 	case MTRRIOC_SET_ENTRY:
229 #ifdef CONFIG_COMPAT
230 	case MTRRIOC32_SET_ENTRY:
231 #endif
232 		err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
233 		break;
234 	case MTRRIOC_DEL_ENTRY:
235 #ifdef CONFIG_COMPAT
236 	case MTRRIOC32_DEL_ENTRY:
237 #endif
238 		err = mtrr_file_del(sentry.base, sentry.size, file, 0);
239 		break;
240 	case MTRRIOC_KILL_ENTRY:
241 #ifdef CONFIG_COMPAT
242 	case MTRRIOC32_KILL_ENTRY:
243 #endif
244 		err = mtrr_del(-1, sentry.base, sentry.size);
245 		break;
246 	case MTRRIOC_GET_ENTRY:
247 #ifdef CONFIG_COMPAT
248 	case MTRRIOC32_GET_ENTRY:
249 #endif
250 		if (gentry.regnum >= num_var_ranges)
251 			return -EINVAL;
252 		mtrr_if->get(gentry.regnum, &base, &size, &type);
253 
254 		/* Hide entries that go above 4GB */
255 		if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
256 		    || size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
257 			gentry.base = gentry.size = gentry.type = 0;
258 		else {
259 			gentry.base = base << PAGE_SHIFT;
260 			gentry.size = size << PAGE_SHIFT;
261 			gentry.type = type;
262 		}
263 
264 		break;
265 	case MTRRIOC_ADD_PAGE_ENTRY:
266 #ifdef CONFIG_COMPAT
267 	case MTRRIOC32_ADD_PAGE_ENTRY:
268 #endif
269 		err =
270 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
271 				  file, 1);
272 		break;
273 	case MTRRIOC_SET_PAGE_ENTRY:
274 #ifdef CONFIG_COMPAT
275 	case MTRRIOC32_SET_PAGE_ENTRY:
276 #endif
277 		err =
278 		    mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
279 		break;
280 	case MTRRIOC_DEL_PAGE_ENTRY:
281 #ifdef CONFIG_COMPAT
282 	case MTRRIOC32_DEL_PAGE_ENTRY:
283 #endif
284 		err = mtrr_file_del(sentry.base, sentry.size, file, 1);
285 		break;
286 	case MTRRIOC_KILL_PAGE_ENTRY:
287 #ifdef CONFIG_COMPAT
288 	case MTRRIOC32_KILL_PAGE_ENTRY:
289 #endif
290 		err = mtrr_del_page(-1, sentry.base, sentry.size);
291 		break;
292 	case MTRRIOC_GET_PAGE_ENTRY:
293 #ifdef CONFIG_COMPAT
294 	case MTRRIOC32_GET_PAGE_ENTRY:
295 #endif
296 		if (gentry.regnum >= num_var_ranges)
297 			return -EINVAL;
298 		mtrr_if->get(gentry.regnum, &base, &size, &type);
299 		/* Hide entries that would overflow */
300 		if (size != (__typeof__(gentry.size))size)
301 			gentry.base = gentry.size = gentry.type = 0;
302 		else {
303 			gentry.base = base;
304 			gentry.size = size;
305 			gentry.type = type;
306 		}
307 		break;
308 	}
309 
310 	if (err)
311 		return err;
312 
313 	switch (cmd) {
314 	case MTRRIOC_GET_ENTRY:
315 	case MTRRIOC_GET_PAGE_ENTRY:
316 		if (copy_to_user(arg, &gentry, sizeof(gentry)))
317 			err = -EFAULT;
318 		break;
319 #ifdef CONFIG_COMPAT
320 	case MTRRIOC32_GET_ENTRY:
321 	case MTRRIOC32_GET_PAGE_ENTRY: {
322 		struct mtrr_gentry32 __user *g32;
323 
324 		g32 = (struct mtrr_gentry32 __user *)__arg;
325 		err = put_user(gentry.base, &g32->base);
326 		err |= put_user(gentry.size, &g32->size);
327 		err |= put_user(gentry.regnum, &g32->regnum);
328 		err |= put_user(gentry.type, &g32->type);
329 		break;
330 	}
331 #endif
332 	}
333 	return err;
334 }
335 
mtrr_close(struct inode * ino,struct file * file)336 static int mtrr_close(struct inode *ino, struct file *file)
337 {
338 	unsigned int *fcount = FILE_FCOUNT(file);
339 	int i, max;
340 
341 	if (fcount != NULL) {
342 		max = num_var_ranges;
343 		for (i = 0; i < max; ++i) {
344 			while (fcount[i] > 0) {
345 				mtrr_del(i, 0, 0);
346 				--fcount[i];
347 			}
348 		}
349 		kfree(fcount);
350 		FILE_FCOUNT(file) = NULL;
351 	}
352 	return single_release(ino, file);
353 }
354 
mtrr_seq_show(struct seq_file * seq,void * offset)355 static int mtrr_seq_show(struct seq_file *seq, void *offset)
356 {
357 	char factor;
358 	int i, max;
359 	mtrr_type type;
360 	unsigned long base, size;
361 
362 	max = num_var_ranges;
363 	for (i = 0; i < max; i++) {
364 		mtrr_if->get(i, &base, &size, &type);
365 		if (size == 0) {
366 			mtrr_usage_table[i] = 0;
367 			continue;
368 		}
369 		if (size < (0x100000 >> PAGE_SHIFT)) {
370 			/* less than 1MB */
371 			factor = 'K';
372 			size <<= PAGE_SHIFT - 10;
373 		} else {
374 			factor = 'M';
375 			size >>= 20 - PAGE_SHIFT;
376 		}
377 		/* Base can be > 32bit */
378 		seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
379 			   i, base, base >> (20 - PAGE_SHIFT),
380 			   size, factor,
381 			   mtrr_usage_table[i], mtrr_attrib_to_str(type));
382 	}
383 	return 0;
384 }
385 
mtrr_open(struct inode * inode,struct file * file)386 static int mtrr_open(struct inode *inode, struct file *file)
387 {
388 	if (!mtrr_if)
389 		return -EIO;
390 	if (!mtrr_if->get)
391 		return -ENXIO;
392 	if (!capable(CAP_SYS_ADMIN))
393 		return -EPERM;
394 	return single_open(file, mtrr_seq_show, NULL);
395 }
396 
397 static const struct proc_ops mtrr_proc_ops = {
398 	.proc_open		= mtrr_open,
399 	.proc_read		= seq_read,
400 	.proc_lseek		= seq_lseek,
401 	.proc_write		= mtrr_write,
402 	.proc_ioctl		= mtrr_ioctl,
403 #ifdef CONFIG_COMPAT
404 	.proc_compat_ioctl	= mtrr_ioctl,
405 #endif
406 	.proc_release		= mtrr_close,
407 };
408 
mtrr_if_init(void)409 static int __init mtrr_if_init(void)
410 {
411 	struct cpuinfo_x86 *c = &boot_cpu_data;
412 
413 	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
414 	    (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
415 	    (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
416 	    (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
417 		return -ENODEV;
418 
419 	proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_proc_ops);
420 	return 0;
421 }
422 arch_initcall(mtrr_if_init);
423 #endif			/*  CONFIG_PROC_FS  */
424