1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * imr.c -- Intel Isolated Memory Region driver
4 *
5 * Copyright(c) 2013 Intel Corporation.
6 * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
7 *
8 * IMR registers define an isolated region of memory that can
9 * be masked to prohibit certain system agents from accessing memory.
10 * When a device behind a masked port performs an access - snooped or
11 * not, an IMR may optionally prevent that transaction from changing
12 * the state of memory or from getting correct data in response to the
13 * operation.
14 *
15 * Write data will be dropped and reads will return 0xFFFFFFFF, the
16 * system will reset and system BIOS will print out an error message to
17 * inform the user that an IMR has been violated.
18 *
19 * This code is based on the Linux MTRR code and reference code from
20 * Intel's Quark BSP EFI, Linux and grub code.
21 *
22 * See quark-x1000-datasheet.pdf for register definitions.
23 * http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/quark-x1000-datasheet.pdf
24 */
25
26 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27
28 #include <asm-generic/sections.h>
29 #include <asm/cpu_device_id.h>
30 #include <asm/imr.h>
31 #include <asm/iosf_mbi.h>
32 #include <asm/io.h>
33
34 #include <linux/debugfs.h>
35 #include <linux/init.h>
36 #include <linux/mm.h>
37 #include <linux/types.h>
38
39 struct imr_device {
40 bool init;
41 struct mutex lock;
42 int max_imr;
43 int reg_base;
44 };
45
46 static struct imr_device imr_dev;
47
48 /*
49 * IMR read/write mask control registers.
50 * See quark-x1000-datasheet.pdf sections 12.7.4.5 and 12.7.4.6 for
51 * bit definitions.
52 *
53 * addr_hi
54 * 31 Lock bit
55 * 30:24 Reserved
56 * 23:2 1 KiB aligned lo address
57 * 1:0 Reserved
58 *
59 * addr_hi
60 * 31:24 Reserved
61 * 23:2 1 KiB aligned hi address
62 * 1:0 Reserved
63 */
64 #define IMR_LOCK BIT(31)
65
66 struct imr_regs {
67 u32 addr_lo;
68 u32 addr_hi;
69 u32 rmask;
70 u32 wmask;
71 };
72
73 #define IMR_NUM_REGS (sizeof(struct imr_regs)/sizeof(u32))
74 #define IMR_SHIFT 8
75 #define imr_to_phys(x) ((x) << IMR_SHIFT)
76 #define phys_to_imr(x) ((x) >> IMR_SHIFT)
77
78 /**
79 * imr_is_enabled - true if an IMR is enabled false otherwise.
80 *
81 * Determines if an IMR is enabled based on address range and read/write
82 * mask. An IMR set with an address range set to zero and a read/write
83 * access mask set to all is considered to be disabled. An IMR in any
84 * other state - for example set to zero but without read/write access
85 * all is considered to be enabled. This definition of disabled is how
86 * firmware switches off an IMR and is maintained in kernel for
87 * consistency.
88 *
89 * @imr: pointer to IMR descriptor.
90 * @return: true if IMR enabled false if disabled.
91 */
imr_is_enabled(struct imr_regs * imr)92 static inline int imr_is_enabled(struct imr_regs *imr)
93 {
94 return !(imr->rmask == IMR_READ_ACCESS_ALL &&
95 imr->wmask == IMR_WRITE_ACCESS_ALL &&
96 imr_to_phys(imr->addr_lo) == 0 &&
97 imr_to_phys(imr->addr_hi) == 0);
98 }
99
100 /**
101 * imr_read - read an IMR at a given index.
102 *
103 * Requires caller to hold imr mutex.
104 *
105 * @idev: pointer to imr_device structure.
106 * @imr_id: IMR entry to read.
107 * @imr: IMR structure representing address and access masks.
108 * @return: 0 on success or error code passed from mbi_iosf on failure.
109 */
imr_read(struct imr_device * idev,u32 imr_id,struct imr_regs * imr)110 static int imr_read(struct imr_device *idev, u32 imr_id, struct imr_regs *imr)
111 {
112 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
113 int ret;
114
115 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_lo);
116 if (ret)
117 return ret;
118
119 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_hi);
120 if (ret)
121 return ret;
122
123 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->rmask);
124 if (ret)
125 return ret;
126
127 return iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->wmask);
128 }
129
130 /**
131 * imr_write - write an IMR at a given index.
132 *
133 * Requires caller to hold imr mutex.
134 * Note lock bits need to be written independently of address bits.
135 *
136 * @idev: pointer to imr_device structure.
137 * @imr_id: IMR entry to write.
138 * @imr: IMR structure representing address and access masks.
139 * @return: 0 on success or error code passed from mbi_iosf on failure.
140 */
imr_write(struct imr_device * idev,u32 imr_id,struct imr_regs * imr)141 static int imr_write(struct imr_device *idev, u32 imr_id, struct imr_regs *imr)
142 {
143 unsigned long flags;
144 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
145 int ret;
146
147 local_irq_save(flags);
148
149 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_lo);
150 if (ret)
151 goto failed;
152
153 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_hi);
154 if (ret)
155 goto failed;
156
157 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->rmask);
158 if (ret)
159 goto failed;
160
161 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->wmask);
162 if (ret)
163 goto failed;
164
165 local_irq_restore(flags);
166 return 0;
167 failed:
168 /*
169 * If writing to the IOSF failed then we're in an unknown state,
170 * likely a very bad state. An IMR in an invalid state will almost
171 * certainly lead to a memory access violation.
172 */
173 local_irq_restore(flags);
174 WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
175 imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK);
176
177 return ret;
178 }
179
180 /**
181 * imr_dbgfs_state_show - print state of IMR registers.
182 *
183 * @s: pointer to seq_file for output.
184 * @unused: unused parameter.
185 * @return: 0 on success or error code passed from mbi_iosf on failure.
186 */
imr_dbgfs_state_show(struct seq_file * s,void * unused)187 static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
188 {
189 phys_addr_t base;
190 phys_addr_t end;
191 int i;
192 struct imr_device *idev = s->private;
193 struct imr_regs imr;
194 size_t size;
195 int ret = -ENODEV;
196
197 mutex_lock(&idev->lock);
198
199 for (i = 0; i < idev->max_imr; i++) {
200
201 ret = imr_read(idev, i, &imr);
202 if (ret)
203 break;
204
205 /*
206 * Remember to add IMR_ALIGN bytes to size to indicate the
207 * inherent IMR_ALIGN size bytes contained in the masked away
208 * lower ten bits.
209 */
210 if (imr_is_enabled(&imr)) {
211 base = imr_to_phys(imr.addr_lo);
212 end = imr_to_phys(imr.addr_hi) + IMR_MASK;
213 size = end - base + 1;
214 } else {
215 base = 0;
216 end = 0;
217 size = 0;
218 }
219 seq_printf(s, "imr%02i: base=%pa, end=%pa, size=0x%08zx "
220 "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
221 &base, &end, size, imr.rmask, imr.wmask,
222 imr_is_enabled(&imr) ? "enabled " : "disabled",
223 imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
224 }
225
226 mutex_unlock(&idev->lock);
227 return ret;
228 }
229 DEFINE_SHOW_ATTRIBUTE(imr_dbgfs_state);
230
231 /**
232 * imr_debugfs_register - register debugfs hooks.
233 *
234 * @idev: pointer to imr_device structure.
235 */
imr_debugfs_register(struct imr_device * idev)236 static void imr_debugfs_register(struct imr_device *idev)
237 {
238 debugfs_create_file("imr_state", 0444, NULL, idev,
239 &imr_dbgfs_state_fops);
240 }
241
242 /**
243 * imr_check_params - check passed address range IMR alignment and non-zero size
244 *
245 * @base: base address of intended IMR.
246 * @size: size of intended IMR.
247 * @return: zero on valid range -EINVAL on unaligned base/size.
248 */
imr_check_params(phys_addr_t base,size_t size)249 static int imr_check_params(phys_addr_t base, size_t size)
250 {
251 if ((base & IMR_MASK) || (size & IMR_MASK)) {
252 pr_err("base %pa size 0x%08zx must align to 1KiB\n",
253 &base, size);
254 return -EINVAL;
255 }
256 if (size == 0)
257 return -EINVAL;
258
259 return 0;
260 }
261
262 /**
263 * imr_raw_size - account for the IMR_ALIGN bytes that addr_hi appends.
264 *
265 * IMR addr_hi has a built in offset of plus IMR_ALIGN (0x400) bytes from the
266 * value in the register. We need to subtract IMR_ALIGN bytes from input sizes
267 * as a result.
268 *
269 * @size: input size bytes.
270 * @return: reduced size.
271 */
imr_raw_size(size_t size)272 static inline size_t imr_raw_size(size_t size)
273 {
274 return size - IMR_ALIGN;
275 }
276
277 /**
278 * imr_address_overlap - detects an address overlap.
279 *
280 * @addr: address to check against an existing IMR.
281 * @imr: imr being checked.
282 * @return: true for overlap false for no overlap.
283 */
imr_address_overlap(phys_addr_t addr,struct imr_regs * imr)284 static inline int imr_address_overlap(phys_addr_t addr, struct imr_regs *imr)
285 {
286 return addr >= imr_to_phys(imr->addr_lo) && addr <= imr_to_phys(imr->addr_hi);
287 }
288
289 /**
290 * imr_add_range - add an Isolated Memory Region.
291 *
292 * @base: physical base address of region aligned to 1KiB.
293 * @size: physical size of region in bytes must be aligned to 1KiB.
294 * @read_mask: read access mask.
295 * @write_mask: write access mask.
296 * @return: zero on success or negative value indicating error.
297 */
imr_add_range(phys_addr_t base,size_t size,unsigned int rmask,unsigned int wmask)298 int imr_add_range(phys_addr_t base, size_t size,
299 unsigned int rmask, unsigned int wmask)
300 {
301 phys_addr_t end;
302 unsigned int i;
303 struct imr_device *idev = &imr_dev;
304 struct imr_regs imr;
305 size_t raw_size;
306 int reg;
307 int ret;
308
309 if (WARN_ONCE(idev->init == false, "driver not initialized"))
310 return -ENODEV;
311
312 ret = imr_check_params(base, size);
313 if (ret)
314 return ret;
315
316 /* Tweak the size value. */
317 raw_size = imr_raw_size(size);
318 end = base + raw_size;
319
320 /*
321 * Check for reserved IMR value common to firmware, kernel and grub
322 * indicating a disabled IMR.
323 */
324 imr.addr_lo = phys_to_imr(base);
325 imr.addr_hi = phys_to_imr(end);
326 imr.rmask = rmask;
327 imr.wmask = wmask;
328 if (!imr_is_enabled(&imr))
329 return -ENOTSUPP;
330
331 mutex_lock(&idev->lock);
332
333 /*
334 * Find a free IMR while checking for an existing overlapping range.
335 * Note there's no restriction in silicon to prevent IMR overlaps.
336 * For the sake of simplicity and ease in defining/debugging an IMR
337 * memory map we exclude IMR overlaps.
338 */
339 reg = -1;
340 for (i = 0; i < idev->max_imr; i++) {
341 ret = imr_read(idev, i, &imr);
342 if (ret)
343 goto failed;
344
345 /* Find overlap @ base or end of requested range. */
346 ret = -EINVAL;
347 if (imr_is_enabled(&imr)) {
348 if (imr_address_overlap(base, &imr))
349 goto failed;
350 if (imr_address_overlap(end, &imr))
351 goto failed;
352 } else {
353 reg = i;
354 }
355 }
356
357 /* Error out if we have no free IMR entries. */
358 if (reg == -1) {
359 ret = -ENOMEM;
360 goto failed;
361 }
362
363 pr_debug("add %d phys %pa-%pa size %zx mask 0x%08x wmask 0x%08x\n",
364 reg, &base, &end, raw_size, rmask, wmask);
365
366 /* Enable IMR at specified range and access mask. */
367 imr.addr_lo = phys_to_imr(base);
368 imr.addr_hi = phys_to_imr(end);
369 imr.rmask = rmask;
370 imr.wmask = wmask;
371
372 ret = imr_write(idev, reg, &imr);
373 if (ret < 0) {
374 /*
375 * In the highly unlikely event iosf_mbi_write failed
376 * attempt to rollback the IMR setup skipping the trapping
377 * of further IOSF write failures.
378 */
379 imr.addr_lo = 0;
380 imr.addr_hi = 0;
381 imr.rmask = IMR_READ_ACCESS_ALL;
382 imr.wmask = IMR_WRITE_ACCESS_ALL;
383 imr_write(idev, reg, &imr);
384 }
385 failed:
386 mutex_unlock(&idev->lock);
387 return ret;
388 }
389 EXPORT_SYMBOL_GPL(imr_add_range);
390
391 /**
392 * __imr_remove_range - delete an Isolated Memory Region.
393 *
394 * This function allows you to delete an IMR by its index specified by reg or
395 * by address range specified by base and size respectively. If you specify an
396 * index on its own the base and size parameters are ignored.
397 * imr_remove_range(0, base, size); delete IMR at index 0 base/size ignored.
398 * imr_remove_range(-1, base, size); delete IMR from base to base+size.
399 *
400 * @reg: imr index to remove.
401 * @base: physical base address of region aligned to 1 KiB.
402 * @size: physical size of region in bytes aligned to 1 KiB.
403 * @return: -EINVAL on invalid range or out or range id
404 * -ENODEV if reg is valid but no IMR exists or is locked
405 * 0 on success.
406 */
__imr_remove_range(int reg,phys_addr_t base,size_t size)407 static int __imr_remove_range(int reg, phys_addr_t base, size_t size)
408 {
409 phys_addr_t end;
410 bool found = false;
411 unsigned int i;
412 struct imr_device *idev = &imr_dev;
413 struct imr_regs imr;
414 size_t raw_size;
415 int ret = 0;
416
417 if (WARN_ONCE(idev->init == false, "driver not initialized"))
418 return -ENODEV;
419
420 /*
421 * Validate address range if deleting by address, else we are
422 * deleting by index where base and size will be ignored.
423 */
424 if (reg == -1) {
425 ret = imr_check_params(base, size);
426 if (ret)
427 return ret;
428 }
429
430 /* Tweak the size value. */
431 raw_size = imr_raw_size(size);
432 end = base + raw_size;
433
434 mutex_lock(&idev->lock);
435
436 if (reg >= 0) {
437 /* If a specific IMR is given try to use it. */
438 ret = imr_read(idev, reg, &imr);
439 if (ret)
440 goto failed;
441
442 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
443 ret = -ENODEV;
444 goto failed;
445 }
446 found = true;
447 } else {
448 /* Search for match based on address range. */
449 for (i = 0; i < idev->max_imr; i++) {
450 ret = imr_read(idev, i, &imr);
451 if (ret)
452 goto failed;
453
454 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK)
455 continue;
456
457 if ((imr_to_phys(imr.addr_lo) == base) &&
458 (imr_to_phys(imr.addr_hi) == end)) {
459 found = true;
460 reg = i;
461 break;
462 }
463 }
464 }
465
466 if (!found) {
467 ret = -ENODEV;
468 goto failed;
469 }
470
471 pr_debug("remove %d phys %pa-%pa size %zx\n", reg, &base, &end, raw_size);
472
473 /* Tear down the IMR. */
474 imr.addr_lo = 0;
475 imr.addr_hi = 0;
476 imr.rmask = IMR_READ_ACCESS_ALL;
477 imr.wmask = IMR_WRITE_ACCESS_ALL;
478
479 ret = imr_write(idev, reg, &imr);
480
481 failed:
482 mutex_unlock(&idev->lock);
483 return ret;
484 }
485
486 /**
487 * imr_remove_range - delete an Isolated Memory Region by address
488 *
489 * This function allows you to delete an IMR by an address range specified
490 * by base and size respectively.
491 * imr_remove_range(base, size); delete IMR from base to base+size.
492 *
493 * @base: physical base address of region aligned to 1 KiB.
494 * @size: physical size of region in bytes aligned to 1 KiB.
495 * @return: -EINVAL on invalid range or out or range id
496 * -ENODEV if reg is valid but no IMR exists or is locked
497 * 0 on success.
498 */
imr_remove_range(phys_addr_t base,size_t size)499 int imr_remove_range(phys_addr_t base, size_t size)
500 {
501 return __imr_remove_range(-1, base, size);
502 }
503 EXPORT_SYMBOL_GPL(imr_remove_range);
504
505 /**
506 * imr_clear - delete an Isolated Memory Region by index
507 *
508 * This function allows you to delete an IMR by an address range specified
509 * by the index of the IMR. Useful for initial sanitization of the IMR
510 * address map.
511 * imr_ge(base, size); delete IMR from base to base+size.
512 *
513 * @reg: imr index to remove.
514 * @return: -EINVAL on invalid range or out or range id
515 * -ENODEV if reg is valid but no IMR exists or is locked
516 * 0 on success.
517 */
imr_clear(int reg)518 static inline int imr_clear(int reg)
519 {
520 return __imr_remove_range(reg, 0, 0);
521 }
522
523 /**
524 * imr_fixup_memmap - Tear down IMRs used during bootup.
525 *
526 * BIOS and Grub both setup IMRs around compressed kernel, initrd memory
527 * that need to be removed before the kernel hands out one of the IMR
528 * encased addresses to a downstream DMA agent such as the SD or Ethernet.
529 * IMRs on Galileo are setup to immediately reset the system on violation.
530 * As a result if you're running a root filesystem from SD - you'll need
531 * the boot-time IMRs torn down or you'll find seemingly random resets when
532 * using your filesystem.
533 *
534 * @idev: pointer to imr_device structure.
535 * @return:
536 */
imr_fixup_memmap(struct imr_device * idev)537 static void __init imr_fixup_memmap(struct imr_device *idev)
538 {
539 phys_addr_t base = virt_to_phys(&_text);
540 size_t size = virt_to_phys(&__end_rodata) - base;
541 unsigned long start, end;
542 int i;
543 int ret;
544
545 /* Tear down all existing unlocked IMRs. */
546 for (i = 0; i < idev->max_imr; i++)
547 imr_clear(i);
548
549 start = (unsigned long)_text;
550 end = (unsigned long)__end_rodata - 1;
551
552 /*
553 * Setup an unlocked IMR around the physical extent of the kernel
554 * from the beginning of the .text section to the end of the
555 * .rodata section as one physically contiguous block.
556 *
557 * We don't round up @size since it is already PAGE_SIZE aligned.
558 * See vmlinux.lds.S for details.
559 */
560 ret = imr_add_range(base, size, IMR_CPU, IMR_CPU);
561 if (ret < 0) {
562 pr_err("unable to setup IMR for kernel: %zu KiB (%lx - %lx)\n",
563 size / 1024, start, end);
564 } else {
565 pr_info("protecting kernel .text - .rodata: %zu KiB (%lx - %lx)\n",
566 size / 1024, start, end);
567 }
568
569 }
570
571 static const struct x86_cpu_id imr_ids[] __initconst = {
572 X86_MATCH_VENDOR_FAM_MODEL(INTEL, 5, INTEL_FAM5_QUARK_X1000, NULL),
573 {}
574 };
575
576 /**
577 * imr_init - entry point for IMR driver.
578 *
579 * return: -ENODEV for no IMR support 0 if good to go.
580 */
imr_init(void)581 static int __init imr_init(void)
582 {
583 struct imr_device *idev = &imr_dev;
584
585 if (!x86_match_cpu(imr_ids) || !iosf_mbi_available())
586 return -ENODEV;
587
588 idev->max_imr = QUARK_X1000_IMR_MAX;
589 idev->reg_base = QUARK_X1000_IMR_REGBASE;
590 idev->init = true;
591
592 mutex_init(&idev->lock);
593 imr_debugfs_register(idev);
594 imr_fixup_memmap(idev);
595 return 0;
596 }
597 device_initcall(imr_init);
598