xref: /openbmc/linux/arch/x86/kernel/cpu/mtrr/if.c (revision ba61bb17)
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 
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
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
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
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 	size_t linelen;
103 
104 	if (!capable(CAP_SYS_ADMIN))
105 		return -EPERM;
106 
107 	memset(line, 0, LINE_SIZE);
108 
109 	length = strncpy_from_user(line, buf, LINE_SIZE - 1);
110 	if (length < 0)
111 		return length;
112 
113 	linelen = strlen(line);
114 	ptr = line + linelen - 1;
115 	if (linelen && *ptr == '\n')
116 		*ptr = '\0';
117 
118 	if (!strncmp(line, "disable=", 8)) {
119 		reg = simple_strtoul(line + 8, &ptr, 0);
120 		err = mtrr_del_page(reg, 0, 0);
121 		if (err < 0)
122 			return err;
123 		return len;
124 	}
125 
126 	if (strncmp(line, "base=", 5))
127 		return -EINVAL;
128 
129 	base = simple_strtoull(line + 5, &ptr, 0);
130 	ptr = skip_spaces(ptr);
131 
132 	if (strncmp(ptr, "size=", 5))
133 		return -EINVAL;
134 
135 	size = simple_strtoull(ptr + 5, &ptr, 0);
136 	if ((base & 0xfff) || (size & 0xfff))
137 		return -EINVAL;
138 	ptr = skip_spaces(ptr);
139 
140 	if (strncmp(ptr, "type=", 5))
141 		return -EINVAL;
142 	ptr = skip_spaces(ptr + 5);
143 
144 	i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
145 	if (i < 0)
146 		return i;
147 
148 	base >>= PAGE_SHIFT;
149 	size >>= PAGE_SHIFT;
150 	err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
151 	if (err < 0)
152 		return err;
153 	return len;
154 }
155 
156 static long
157 mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
158 {
159 	int err = 0;
160 	mtrr_type type;
161 	unsigned long base;
162 	unsigned long size;
163 	struct mtrr_sentry sentry;
164 	struct mtrr_gentry gentry;
165 	void __user *arg = (void __user *) __arg;
166 
167 	switch (cmd) {
168 	case MTRRIOC_ADD_ENTRY:
169 	case MTRRIOC_SET_ENTRY:
170 	case MTRRIOC_DEL_ENTRY:
171 	case MTRRIOC_KILL_ENTRY:
172 	case MTRRIOC_ADD_PAGE_ENTRY:
173 	case MTRRIOC_SET_PAGE_ENTRY:
174 	case MTRRIOC_DEL_PAGE_ENTRY:
175 	case MTRRIOC_KILL_PAGE_ENTRY:
176 		if (copy_from_user(&sentry, arg, sizeof sentry))
177 			return -EFAULT;
178 		break;
179 	case MTRRIOC_GET_ENTRY:
180 	case MTRRIOC_GET_PAGE_ENTRY:
181 		if (copy_from_user(&gentry, arg, sizeof gentry))
182 			return -EFAULT;
183 		break;
184 #ifdef CONFIG_COMPAT
185 	case MTRRIOC32_ADD_ENTRY:
186 	case MTRRIOC32_SET_ENTRY:
187 	case MTRRIOC32_DEL_ENTRY:
188 	case MTRRIOC32_KILL_ENTRY:
189 	case MTRRIOC32_ADD_PAGE_ENTRY:
190 	case MTRRIOC32_SET_PAGE_ENTRY:
191 	case MTRRIOC32_DEL_PAGE_ENTRY:
192 	case MTRRIOC32_KILL_PAGE_ENTRY: {
193 		struct mtrr_sentry32 __user *s32;
194 
195 		s32 = (struct mtrr_sentry32 __user *)__arg;
196 		err = get_user(sentry.base, &s32->base);
197 		err |= get_user(sentry.size, &s32->size);
198 		err |= get_user(sentry.type, &s32->type);
199 		if (err)
200 			return err;
201 		break;
202 	}
203 	case MTRRIOC32_GET_ENTRY:
204 	case MTRRIOC32_GET_PAGE_ENTRY: {
205 		struct mtrr_gentry32 __user *g32;
206 
207 		g32 = (struct mtrr_gentry32 __user *)__arg;
208 		err = get_user(gentry.regnum, &g32->regnum);
209 		err |= get_user(gentry.base, &g32->base);
210 		err |= get_user(gentry.size, &g32->size);
211 		err |= get_user(gentry.type, &g32->type);
212 		if (err)
213 			return err;
214 		break;
215 	}
216 #endif
217 	}
218 
219 	switch (cmd) {
220 	default:
221 		return -ENOTTY;
222 	case MTRRIOC_ADD_ENTRY:
223 #ifdef CONFIG_COMPAT
224 	case MTRRIOC32_ADD_ENTRY:
225 #endif
226 		if (!capable(CAP_SYS_ADMIN))
227 			return -EPERM;
228 		err =
229 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
230 				  file, 0);
231 		break;
232 	case MTRRIOC_SET_ENTRY:
233 #ifdef CONFIG_COMPAT
234 	case MTRRIOC32_SET_ENTRY:
235 #endif
236 		if (!capable(CAP_SYS_ADMIN))
237 			return -EPERM;
238 		err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
239 		break;
240 	case MTRRIOC_DEL_ENTRY:
241 #ifdef CONFIG_COMPAT
242 	case MTRRIOC32_DEL_ENTRY:
243 #endif
244 		if (!capable(CAP_SYS_ADMIN))
245 			return -EPERM;
246 		err = mtrr_file_del(sentry.base, sentry.size, file, 0);
247 		break;
248 	case MTRRIOC_KILL_ENTRY:
249 #ifdef CONFIG_COMPAT
250 	case MTRRIOC32_KILL_ENTRY:
251 #endif
252 		if (!capable(CAP_SYS_ADMIN))
253 			return -EPERM;
254 		err = mtrr_del(-1, sentry.base, sentry.size);
255 		break;
256 	case MTRRIOC_GET_ENTRY:
257 #ifdef CONFIG_COMPAT
258 	case MTRRIOC32_GET_ENTRY:
259 #endif
260 		if (gentry.regnum >= num_var_ranges)
261 			return -EINVAL;
262 		mtrr_if->get(gentry.regnum, &base, &size, &type);
263 
264 		/* Hide entries that go above 4GB */
265 		if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
266 		    || size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
267 			gentry.base = gentry.size = gentry.type = 0;
268 		else {
269 			gentry.base = base << PAGE_SHIFT;
270 			gentry.size = size << PAGE_SHIFT;
271 			gentry.type = type;
272 		}
273 
274 		break;
275 	case MTRRIOC_ADD_PAGE_ENTRY:
276 #ifdef CONFIG_COMPAT
277 	case MTRRIOC32_ADD_PAGE_ENTRY:
278 #endif
279 		if (!capable(CAP_SYS_ADMIN))
280 			return -EPERM;
281 		err =
282 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
283 				  file, 1);
284 		break;
285 	case MTRRIOC_SET_PAGE_ENTRY:
286 #ifdef CONFIG_COMPAT
287 	case MTRRIOC32_SET_PAGE_ENTRY:
288 #endif
289 		if (!capable(CAP_SYS_ADMIN))
290 			return -EPERM;
291 		err =
292 		    mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
293 		break;
294 	case MTRRIOC_DEL_PAGE_ENTRY:
295 #ifdef CONFIG_COMPAT
296 	case MTRRIOC32_DEL_PAGE_ENTRY:
297 #endif
298 		if (!capable(CAP_SYS_ADMIN))
299 			return -EPERM;
300 		err = mtrr_file_del(sentry.base, sentry.size, file, 1);
301 		break;
302 	case MTRRIOC_KILL_PAGE_ENTRY:
303 #ifdef CONFIG_COMPAT
304 	case MTRRIOC32_KILL_PAGE_ENTRY:
305 #endif
306 		if (!capable(CAP_SYS_ADMIN))
307 			return -EPERM;
308 		err = mtrr_del_page(-1, sentry.base, sentry.size);
309 		break;
310 	case MTRRIOC_GET_PAGE_ENTRY:
311 #ifdef CONFIG_COMPAT
312 	case MTRRIOC32_GET_PAGE_ENTRY:
313 #endif
314 		if (gentry.regnum >= num_var_ranges)
315 			return -EINVAL;
316 		mtrr_if->get(gentry.regnum, &base, &size, &type);
317 		/* Hide entries that would overflow */
318 		if (size != (__typeof__(gentry.size))size)
319 			gentry.base = gentry.size = gentry.type = 0;
320 		else {
321 			gentry.base = base;
322 			gentry.size = size;
323 			gentry.type = type;
324 		}
325 		break;
326 	}
327 
328 	if (err)
329 		return err;
330 
331 	switch (cmd) {
332 	case MTRRIOC_GET_ENTRY:
333 	case MTRRIOC_GET_PAGE_ENTRY:
334 		if (copy_to_user(arg, &gentry, sizeof gentry))
335 			err = -EFAULT;
336 		break;
337 #ifdef CONFIG_COMPAT
338 	case MTRRIOC32_GET_ENTRY:
339 	case MTRRIOC32_GET_PAGE_ENTRY: {
340 		struct mtrr_gentry32 __user *g32;
341 
342 		g32 = (struct mtrr_gentry32 __user *)__arg;
343 		err = put_user(gentry.base, &g32->base);
344 		err |= put_user(gentry.size, &g32->size);
345 		err |= put_user(gentry.regnum, &g32->regnum);
346 		err |= put_user(gentry.type, &g32->type);
347 		break;
348 	}
349 #endif
350 	}
351 	return err;
352 }
353 
354 static int mtrr_close(struct inode *ino, struct file *file)
355 {
356 	unsigned int *fcount = FILE_FCOUNT(file);
357 	int i, max;
358 
359 	if (fcount != NULL) {
360 		max = num_var_ranges;
361 		for (i = 0; i < max; ++i) {
362 			while (fcount[i] > 0) {
363 				mtrr_del(i, 0, 0);
364 				--fcount[i];
365 			}
366 		}
367 		kfree(fcount);
368 		FILE_FCOUNT(file) = NULL;
369 	}
370 	return single_release(ino, file);
371 }
372 
373 static int mtrr_seq_show(struct seq_file *seq, void *offset);
374 
375 static int mtrr_open(struct inode *inode, struct file *file)
376 {
377 	if (!mtrr_if)
378 		return -EIO;
379 	if (!mtrr_if->get)
380 		return -ENXIO;
381 	return single_open(file, mtrr_seq_show, NULL);
382 }
383 
384 static const struct file_operations mtrr_fops = {
385 	.owner			= THIS_MODULE,
386 	.open			= mtrr_open,
387 	.read			= seq_read,
388 	.llseek			= seq_lseek,
389 	.write			= mtrr_write,
390 	.unlocked_ioctl		= mtrr_ioctl,
391 	.compat_ioctl		= mtrr_ioctl,
392 	.release		= mtrr_close,
393 };
394 
395 static int mtrr_seq_show(struct seq_file *seq, void *offset)
396 {
397 	char factor;
398 	int i, max;
399 	mtrr_type type;
400 	unsigned long base, size;
401 
402 	max = num_var_ranges;
403 	for (i = 0; i < max; i++) {
404 		mtrr_if->get(i, &base, &size, &type);
405 		if (size == 0) {
406 			mtrr_usage_table[i] = 0;
407 			continue;
408 		}
409 		if (size < (0x100000 >> PAGE_SHIFT)) {
410 			/* less than 1MB */
411 			factor = 'K';
412 			size <<= PAGE_SHIFT - 10;
413 		} else {
414 			factor = 'M';
415 			size >>= 20 - PAGE_SHIFT;
416 		}
417 		/* Base can be > 32bit */
418 		seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
419 			   i, base, base >> (20 - PAGE_SHIFT),
420 			   size, factor,
421 			   mtrr_usage_table[i], mtrr_attrib_to_str(type));
422 	}
423 	return 0;
424 }
425 
426 static int __init mtrr_if_init(void)
427 {
428 	struct cpuinfo_x86 *c = &boot_cpu_data;
429 
430 	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
431 	    (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
432 	    (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
433 	    (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
434 		return -ENODEV;
435 
436 	proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_fops);
437 	return 0;
438 }
439 arch_initcall(mtrr_if_init);
440 #endif			/*  CONFIG_PROC_FS  */
441