xref: /linux/arch/x86/kernel/cpu/mtrr/if.c (revision 8dd06ef34b6e2f41b29fbf5fc1663780f2524285)
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 	size_t linelen;
103 
104 	memset(line, 0, LINE_SIZE);
105 
106 	len = min_t(size_t, len, LINE_SIZE - 1);
107 	length = strncpy_from_user(line, buf, len);
108 	if (length < 0)
109 		return length;
110 
111 	linelen = strlen(line);
112 	ptr = line + linelen - 1;
113 	if (linelen && *ptr == '\n')
114 		*ptr = '\0';
115 
116 	if (!strncmp(line, "disable=", 8)) {
117 		reg = simple_strtoul(line + 8, &ptr, 0);
118 		err = mtrr_del_page(reg, 0, 0);
119 		if (err < 0)
120 			return err;
121 		return len;
122 	}
123 
124 	if (strncmp(line, "base=", 5))
125 		return -EINVAL;
126 
127 	base = simple_strtoull(line + 5, &ptr, 0);
128 	ptr = skip_spaces(ptr);
129 
130 	if (strncmp(ptr, "size=", 5))
131 		return -EINVAL;
132 
133 	size = simple_strtoull(ptr + 5, &ptr, 0);
134 	if ((base & 0xfff) || (size & 0xfff))
135 		return -EINVAL;
136 	ptr = skip_spaces(ptr);
137 
138 	if (strncmp(ptr, "type=", 5))
139 		return -EINVAL;
140 	ptr = skip_spaces(ptr + 5);
141 
142 	i = match_string(mtrr_strings, MTRR_NUM_TYPES, ptr);
143 	if (i < 0)
144 		return i;
145 
146 	base >>= PAGE_SHIFT;
147 	size >>= PAGE_SHIFT;
148 	err = mtrr_add_page((unsigned long)base, (unsigned long)size, i, true);
149 	if (err < 0)
150 		return err;
151 	return len;
152 }
153 
154 static long
mtrr_ioctl(struct file * file,unsigned int cmd,unsigned long __arg)155 mtrr_ioctl(struct file *file, unsigned int cmd, unsigned long __arg)
156 {
157 	int err = 0;
158 	mtrr_type type;
159 	unsigned long base;
160 	unsigned long size;
161 	struct mtrr_sentry sentry;
162 	struct mtrr_gentry gentry;
163 	void __user *arg = (void __user *) __arg;
164 
165 	memset(&gentry, 0, sizeof(gentry));
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 		err =
227 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
228 				  file, 0);
229 		break;
230 	case MTRRIOC_SET_ENTRY:
231 #ifdef CONFIG_COMPAT
232 	case MTRRIOC32_SET_ENTRY:
233 #endif
234 		err = mtrr_add(sentry.base, sentry.size, sentry.type, false);
235 		break;
236 	case MTRRIOC_DEL_ENTRY:
237 #ifdef CONFIG_COMPAT
238 	case MTRRIOC32_DEL_ENTRY:
239 #endif
240 		err = mtrr_file_del(sentry.base, sentry.size, file, 0);
241 		break;
242 	case MTRRIOC_KILL_ENTRY:
243 #ifdef CONFIG_COMPAT
244 	case MTRRIOC32_KILL_ENTRY:
245 #endif
246 		err = mtrr_del(-1, sentry.base, sentry.size);
247 		break;
248 	case MTRRIOC_GET_ENTRY:
249 #ifdef CONFIG_COMPAT
250 	case MTRRIOC32_GET_ENTRY:
251 #endif
252 		if (gentry.regnum >= num_var_ranges)
253 			return -EINVAL;
254 		mtrr_if->get(gentry.regnum, &base, &size, &type);
255 
256 		/* Hide entries that go above 4GB */
257 		if (base + size - 1 >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT))
258 		    || size >= (1UL << (8 * sizeof(gentry.size) - PAGE_SHIFT)))
259 			gentry.base = gentry.size = gentry.type = 0;
260 		else {
261 			gentry.base = base << PAGE_SHIFT;
262 			gentry.size = size << PAGE_SHIFT;
263 			gentry.type = type;
264 		}
265 
266 		break;
267 	case MTRRIOC_ADD_PAGE_ENTRY:
268 #ifdef CONFIG_COMPAT
269 	case MTRRIOC32_ADD_PAGE_ENTRY:
270 #endif
271 		err =
272 		    mtrr_file_add(sentry.base, sentry.size, sentry.type, true,
273 				  file, 1);
274 		break;
275 	case MTRRIOC_SET_PAGE_ENTRY:
276 #ifdef CONFIG_COMPAT
277 	case MTRRIOC32_SET_PAGE_ENTRY:
278 #endif
279 		err =
280 		    mtrr_add_page(sentry.base, sentry.size, sentry.type, false);
281 		break;
282 	case MTRRIOC_DEL_PAGE_ENTRY:
283 #ifdef CONFIG_COMPAT
284 	case MTRRIOC32_DEL_PAGE_ENTRY:
285 #endif
286 		err = mtrr_file_del(sentry.base, sentry.size, file, 1);
287 		break;
288 	case MTRRIOC_KILL_PAGE_ENTRY:
289 #ifdef CONFIG_COMPAT
290 	case MTRRIOC32_KILL_PAGE_ENTRY:
291 #endif
292 		err = mtrr_del_page(-1, sentry.base, sentry.size);
293 		break;
294 	case MTRRIOC_GET_PAGE_ENTRY:
295 #ifdef CONFIG_COMPAT
296 	case MTRRIOC32_GET_PAGE_ENTRY:
297 #endif
298 		if (gentry.regnum >= num_var_ranges)
299 			return -EINVAL;
300 		mtrr_if->get(gentry.regnum, &base, &size, &type);
301 		/* Hide entries that would overflow */
302 		if (size != (__typeof__(gentry.size))size)
303 			gentry.base = gentry.size = gentry.type = 0;
304 		else {
305 			gentry.base = base;
306 			gentry.size = size;
307 			gentry.type = type;
308 		}
309 		break;
310 	}
311 
312 	if (err)
313 		return err;
314 
315 	switch (cmd) {
316 	case MTRRIOC_GET_ENTRY:
317 	case MTRRIOC_GET_PAGE_ENTRY:
318 		if (copy_to_user(arg, &gentry, sizeof(gentry)))
319 			err = -EFAULT;
320 		break;
321 #ifdef CONFIG_COMPAT
322 	case MTRRIOC32_GET_ENTRY:
323 	case MTRRIOC32_GET_PAGE_ENTRY: {
324 		struct mtrr_gentry32 __user *g32;
325 
326 		g32 = (struct mtrr_gentry32 __user *)__arg;
327 		err = put_user(gentry.base, &g32->base);
328 		err |= put_user(gentry.size, &g32->size);
329 		err |= put_user(gentry.regnum, &g32->regnum);
330 		err |= put_user(gentry.type, &g32->type);
331 		break;
332 	}
333 #endif
334 	}
335 	return err;
336 }
337 
mtrr_close(struct inode * ino,struct file * file)338 static int mtrr_close(struct inode *ino, struct file *file)
339 {
340 	unsigned int *fcount = FILE_FCOUNT(file);
341 	int i, max;
342 
343 	if (fcount != NULL) {
344 		max = num_var_ranges;
345 		for (i = 0; i < max; ++i) {
346 			while (fcount[i] > 0) {
347 				mtrr_del(i, 0, 0);
348 				--fcount[i];
349 			}
350 		}
351 		kfree(fcount);
352 		FILE_FCOUNT(file) = NULL;
353 	}
354 	return single_release(ino, file);
355 }
356 
mtrr_seq_show(struct seq_file * seq,void * offset)357 static int mtrr_seq_show(struct seq_file *seq, void *offset)
358 {
359 	char factor;
360 	int i, max;
361 	mtrr_type type;
362 	unsigned long base, size;
363 
364 	max = num_var_ranges;
365 	for (i = 0; i < max; i++) {
366 		mtrr_if->get(i, &base, &size, &type);
367 		if (size == 0) {
368 			mtrr_usage_table[i] = 0;
369 			continue;
370 		}
371 		if (size < (0x100000 >> PAGE_SHIFT)) {
372 			/* less than 1MB */
373 			factor = 'K';
374 			size <<= PAGE_SHIFT - 10;
375 		} else {
376 			factor = 'M';
377 			size >>= 20 - PAGE_SHIFT;
378 		}
379 		/* Base can be > 32bit */
380 		seq_printf(seq, "reg%02i: base=0x%06lx000 (%5luMB), size=%5lu%cB, count=%d: %s\n",
381 			   i, base, base >> (20 - PAGE_SHIFT),
382 			   size, factor,
383 			   mtrr_usage_table[i], mtrr_attrib_to_str(type));
384 	}
385 	return 0;
386 }
387 
mtrr_open(struct inode * inode,struct file * file)388 static int mtrr_open(struct inode *inode, struct file *file)
389 {
390 	if (!mtrr_if)
391 		return -EIO;
392 	if (!mtrr_if->get)
393 		return -ENXIO;
394 	if (!capable(CAP_SYS_ADMIN))
395 		return -EPERM;
396 	return single_open(file, mtrr_seq_show, NULL);
397 }
398 
399 static const struct proc_ops mtrr_proc_ops = {
400 	.proc_open		= mtrr_open,
401 	.proc_read		= seq_read,
402 	.proc_lseek		= seq_lseek,
403 	.proc_write		= mtrr_write,
404 	.proc_ioctl		= mtrr_ioctl,
405 #ifdef CONFIG_COMPAT
406 	.proc_compat_ioctl	= mtrr_ioctl,
407 #endif
408 	.proc_release		= mtrr_close,
409 };
410 
mtrr_if_init(void)411 static int __init mtrr_if_init(void)
412 {
413 	struct cpuinfo_x86 *c = &boot_cpu_data;
414 
415 	if ((!cpu_has(c, X86_FEATURE_MTRR)) &&
416 	    (!cpu_has(c, X86_FEATURE_K6_MTRR)) &&
417 	    (!cpu_has(c, X86_FEATURE_CYRIX_ARR)) &&
418 	    (!cpu_has(c, X86_FEATURE_CENTAUR_MCR)))
419 		return -ENODEV;
420 
421 	proc_create("mtrr", S_IWUSR | S_IRUGO, NULL, &mtrr_proc_ops);
422 	return 0;
423 }
424 arch_initcall(mtrr_if_init);
425 #endif			/*  CONFIG_PROC_FS  */
426