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 <linux/debugfs.h> 33 #include <linux/init.h> 34 #include <linux/mm.h> 35 #include <linux/types.h> 36 37 struct imr_device { 38 bool init; 39 struct mutex lock; 40 int max_imr; 41 int reg_base; 42 }; 43 44 static struct imr_device imr_dev; 45 46 /* 47 * IMR read/write mask control registers. 48 * See quark-x1000-datasheet.pdf sections 12.7.4.5 and 12.7.4.6 for 49 * bit definitions. 50 * 51 * addr_hi 52 * 31 Lock bit 53 * 30:24 Reserved 54 * 23:2 1 KiB aligned lo address 55 * 1:0 Reserved 56 * 57 * addr_hi 58 * 31:24 Reserved 59 * 23:2 1 KiB aligned hi address 60 * 1:0 Reserved 61 */ 62 #define IMR_LOCK BIT(31) 63 64 struct imr_regs { 65 u32 addr_lo; 66 u32 addr_hi; 67 u32 rmask; 68 u32 wmask; 69 }; 70 71 #define IMR_NUM_REGS (sizeof(struct imr_regs)/sizeof(u32)) 72 #define IMR_SHIFT 8 73 #define imr_to_phys(x) ((x) << IMR_SHIFT) 74 #define phys_to_imr(x) ((x) >> IMR_SHIFT) 75 76 /** 77 * imr_is_enabled - true if an IMR is enabled false otherwise. 78 * 79 * Determines if an IMR is enabled based on address range and read/write 80 * mask. An IMR set with an address range set to zero and a read/write 81 * access mask set to all is considered to be disabled. An IMR in any 82 * other state - for example set to zero but without read/write access 83 * all is considered to be enabled. This definition of disabled is how 84 * firmware switches off an IMR and is maintained in kernel for 85 * consistency. 86 * 87 * @imr: pointer to IMR descriptor. 88 * @return: true if IMR enabled false if disabled. 89 */ 90 static inline int imr_is_enabled(struct imr_regs *imr) 91 { 92 return !(imr->rmask == IMR_READ_ACCESS_ALL && 93 imr->wmask == IMR_WRITE_ACCESS_ALL && 94 imr_to_phys(imr->addr_lo) == 0 && 95 imr_to_phys(imr->addr_hi) == 0); 96 } 97 98 /** 99 * imr_read - read an IMR at a given index. 100 * 101 * Requires caller to hold imr mutex. 102 * 103 * @idev: pointer to imr_device structure. 104 * @imr_id: IMR entry to read. 105 * @imr: IMR structure representing address and access masks. 106 * @return: 0 on success or error code passed from mbi_iosf on failure. 107 */ 108 static int imr_read(struct imr_device *idev, u32 imr_id, struct imr_regs *imr) 109 { 110 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base; 111 int ret; 112 113 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_lo); 114 if (ret) 115 return ret; 116 117 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_hi); 118 if (ret) 119 return ret; 120 121 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->rmask); 122 if (ret) 123 return ret; 124 125 return iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->wmask); 126 } 127 128 /** 129 * imr_write - write an IMR at a given index. 130 * 131 * Requires caller to hold imr mutex. 132 * Note lock bits need to be written independently of address bits. 133 * 134 * @idev: pointer to imr_device structure. 135 * @imr_id: IMR entry to write. 136 * @imr: IMR structure representing address and access masks. 137 * @return: 0 on success or error code passed from mbi_iosf on failure. 138 */ 139 static int imr_write(struct imr_device *idev, u32 imr_id, struct imr_regs *imr) 140 { 141 unsigned long flags; 142 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base; 143 int ret; 144 145 local_irq_save(flags); 146 147 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_lo); 148 if (ret) 149 goto failed; 150 151 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_hi); 152 if (ret) 153 goto failed; 154 155 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->rmask); 156 if (ret) 157 goto failed; 158 159 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->wmask); 160 if (ret) 161 goto failed; 162 163 local_irq_restore(flags); 164 return 0; 165 failed: 166 /* 167 * If writing to the IOSF failed then we're in an unknown state, 168 * likely a very bad state. An IMR in an invalid state will almost 169 * certainly lead to a memory access violation. 170 */ 171 local_irq_restore(flags); 172 WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n", 173 imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK); 174 175 return ret; 176 } 177 178 /** 179 * imr_dbgfs_state_show - print state of IMR registers. 180 * 181 * @s: pointer to seq_file for output. 182 * @unused: unused parameter. 183 * @return: 0 on success or error code passed from mbi_iosf on failure. 184 */ 185 static int imr_dbgfs_state_show(struct seq_file *s, void *unused) 186 { 187 phys_addr_t base; 188 phys_addr_t end; 189 int i; 190 struct imr_device *idev = s->private; 191 struct imr_regs imr; 192 size_t size; 193 int ret = -ENODEV; 194 195 mutex_lock(&idev->lock); 196 197 for (i = 0; i < idev->max_imr; i++) { 198 199 ret = imr_read(idev, i, &imr); 200 if (ret) 201 break; 202 203 /* 204 * Remember to add IMR_ALIGN bytes to size to indicate the 205 * inherent IMR_ALIGN size bytes contained in the masked away 206 * lower ten bits. 207 */ 208 if (imr_is_enabled(&imr)) { 209 base = imr_to_phys(imr.addr_lo); 210 end = imr_to_phys(imr.addr_hi) + IMR_MASK; 211 size = end - base + 1; 212 } else { 213 base = 0; 214 end = 0; 215 size = 0; 216 } 217 seq_printf(s, "imr%02i: base=%pa, end=%pa, size=0x%08zx " 218 "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i, 219 &base, &end, size, imr.rmask, imr.wmask, 220 imr_is_enabled(&imr) ? "enabled " : "disabled", 221 imr.addr_lo & IMR_LOCK ? "locked" : "unlocked"); 222 } 223 224 mutex_unlock(&idev->lock); 225 return ret; 226 } 227 DEFINE_SHOW_ATTRIBUTE(imr_dbgfs_state); 228 229 /** 230 * imr_debugfs_register - register debugfs hooks. 231 * 232 * @idev: pointer to imr_device structure. 233 */ 234 static void imr_debugfs_register(struct imr_device *idev) 235 { 236 debugfs_create_file("imr_state", 0444, NULL, idev, 237 &imr_dbgfs_state_fops); 238 } 239 240 /** 241 * imr_check_params - check passed address range IMR alignment and non-zero size 242 * 243 * @base: base address of intended IMR. 244 * @size: size of intended IMR. 245 * @return: zero on valid range -EINVAL on unaligned base/size. 246 */ 247 static int imr_check_params(phys_addr_t base, size_t size) 248 { 249 if ((base & IMR_MASK) || (size & IMR_MASK)) { 250 pr_err("base %pa size 0x%08zx must align to 1KiB\n", 251 &base, size); 252 return -EINVAL; 253 } 254 if (size == 0) 255 return -EINVAL; 256 257 return 0; 258 } 259 260 /** 261 * imr_raw_size - account for the IMR_ALIGN bytes that addr_hi appends. 262 * 263 * IMR addr_hi has a built in offset of plus IMR_ALIGN (0x400) bytes from the 264 * value in the register. We need to subtract IMR_ALIGN bytes from input sizes 265 * as a result. 266 * 267 * @size: input size bytes. 268 * @return: reduced size. 269 */ 270 static inline size_t imr_raw_size(size_t size) 271 { 272 return size - IMR_ALIGN; 273 } 274 275 /** 276 * imr_address_overlap - detects an address overlap. 277 * 278 * @addr: address to check against an existing IMR. 279 * @imr: imr being checked. 280 * @return: true for overlap false for no overlap. 281 */ 282 static inline int imr_address_overlap(phys_addr_t addr, struct imr_regs *imr) 283 { 284 return addr >= imr_to_phys(imr->addr_lo) && addr <= imr_to_phys(imr->addr_hi); 285 } 286 287 /** 288 * imr_add_range - add an Isolated Memory Region. 289 * 290 * @base: physical base address of region aligned to 1KiB. 291 * @size: physical size of region in bytes must be aligned to 1KiB. 292 * @read_mask: read access mask. 293 * @write_mask: write access mask. 294 * @return: zero on success or negative value indicating error. 295 */ 296 int imr_add_range(phys_addr_t base, size_t size, 297 unsigned int rmask, unsigned int wmask) 298 { 299 phys_addr_t end; 300 unsigned int i; 301 struct imr_device *idev = &imr_dev; 302 struct imr_regs imr; 303 size_t raw_size; 304 int reg; 305 int ret; 306 307 if (WARN_ONCE(idev->init == false, "driver not initialized")) 308 return -ENODEV; 309 310 ret = imr_check_params(base, size); 311 if (ret) 312 return ret; 313 314 /* Tweak the size value. */ 315 raw_size = imr_raw_size(size); 316 end = base + raw_size; 317 318 /* 319 * Check for reserved IMR value common to firmware, kernel and grub 320 * indicating a disabled IMR. 321 */ 322 imr.addr_lo = phys_to_imr(base); 323 imr.addr_hi = phys_to_imr(end); 324 imr.rmask = rmask; 325 imr.wmask = wmask; 326 if (!imr_is_enabled(&imr)) 327 return -ENOTSUPP; 328 329 mutex_lock(&idev->lock); 330 331 /* 332 * Find a free IMR while checking for an existing overlapping range. 333 * Note there's no restriction in silicon to prevent IMR overlaps. 334 * For the sake of simplicity and ease in defining/debugging an IMR 335 * memory map we exclude IMR overlaps. 336 */ 337 reg = -1; 338 for (i = 0; i < idev->max_imr; i++) { 339 ret = imr_read(idev, i, &imr); 340 if (ret) 341 goto failed; 342 343 /* Find overlap @ base or end of requested range. */ 344 ret = -EINVAL; 345 if (imr_is_enabled(&imr)) { 346 if (imr_address_overlap(base, &imr)) 347 goto failed; 348 if (imr_address_overlap(end, &imr)) 349 goto failed; 350 } else { 351 reg = i; 352 } 353 } 354 355 /* Error out if we have no free IMR entries. */ 356 if (reg == -1) { 357 ret = -ENOMEM; 358 goto failed; 359 } 360 361 pr_debug("add %d phys %pa-%pa size %zx mask 0x%08x wmask 0x%08x\n", 362 reg, &base, &end, raw_size, rmask, wmask); 363 364 /* Enable IMR at specified range and access mask. */ 365 imr.addr_lo = phys_to_imr(base); 366 imr.addr_hi = phys_to_imr(end); 367 imr.rmask = rmask; 368 imr.wmask = wmask; 369 370 ret = imr_write(idev, reg, &imr); 371 if (ret < 0) { 372 /* 373 * In the highly unlikely event iosf_mbi_write failed 374 * attempt to rollback the IMR setup skipping the trapping 375 * of further IOSF write failures. 376 */ 377 imr.addr_lo = 0; 378 imr.addr_hi = 0; 379 imr.rmask = IMR_READ_ACCESS_ALL; 380 imr.wmask = IMR_WRITE_ACCESS_ALL; 381 imr_write(idev, reg, &imr); 382 } 383 failed: 384 mutex_unlock(&idev->lock); 385 return ret; 386 } 387 EXPORT_SYMBOL_GPL(imr_add_range); 388 389 /** 390 * __imr_remove_range - delete an Isolated Memory Region. 391 * 392 * This function allows you to delete an IMR by its index specified by reg or 393 * by address range specified by base and size respectively. If you specify an 394 * index on its own the base and size parameters are ignored. 395 * imr_remove_range(0, base, size); delete IMR at index 0 base/size ignored. 396 * imr_remove_range(-1, base, size); delete IMR from base to base+size. 397 * 398 * @reg: imr index to remove. 399 * @base: physical base address of region aligned to 1 KiB. 400 * @size: physical size of region in bytes aligned to 1 KiB. 401 * @return: -EINVAL on invalid range or out or range id 402 * -ENODEV if reg is valid but no IMR exists or is locked 403 * 0 on success. 404 */ 405 static int __imr_remove_range(int reg, phys_addr_t base, size_t size) 406 { 407 phys_addr_t end; 408 bool found = false; 409 unsigned int i; 410 struct imr_device *idev = &imr_dev; 411 struct imr_regs imr; 412 size_t raw_size; 413 int ret = 0; 414 415 if (WARN_ONCE(idev->init == false, "driver not initialized")) 416 return -ENODEV; 417 418 /* 419 * Validate address range if deleting by address, else we are 420 * deleting by index where base and size will be ignored. 421 */ 422 if (reg == -1) { 423 ret = imr_check_params(base, size); 424 if (ret) 425 return ret; 426 } 427 428 /* Tweak the size value. */ 429 raw_size = imr_raw_size(size); 430 end = base + raw_size; 431 432 mutex_lock(&idev->lock); 433 434 if (reg >= 0) { 435 /* If a specific IMR is given try to use it. */ 436 ret = imr_read(idev, reg, &imr); 437 if (ret) 438 goto failed; 439 440 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) { 441 ret = -ENODEV; 442 goto failed; 443 } 444 found = true; 445 } else { 446 /* Search for match based on address range. */ 447 for (i = 0; i < idev->max_imr; i++) { 448 ret = imr_read(idev, i, &imr); 449 if (ret) 450 goto failed; 451 452 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) 453 continue; 454 455 if ((imr_to_phys(imr.addr_lo) == base) && 456 (imr_to_phys(imr.addr_hi) == end)) { 457 found = true; 458 reg = i; 459 break; 460 } 461 } 462 } 463 464 if (!found) { 465 ret = -ENODEV; 466 goto failed; 467 } 468 469 pr_debug("remove %d phys %pa-%pa size %zx\n", reg, &base, &end, raw_size); 470 471 /* Tear down the IMR. */ 472 imr.addr_lo = 0; 473 imr.addr_hi = 0; 474 imr.rmask = IMR_READ_ACCESS_ALL; 475 imr.wmask = IMR_WRITE_ACCESS_ALL; 476 477 ret = imr_write(idev, reg, &imr); 478 479 failed: 480 mutex_unlock(&idev->lock); 481 return ret; 482 } 483 484 /** 485 * imr_remove_range - delete an Isolated Memory Region by address 486 * 487 * This function allows you to delete an IMR by an address range specified 488 * by base and size respectively. 489 * imr_remove_range(base, size); delete IMR from base to base+size. 490 * 491 * @base: physical base address of region aligned to 1 KiB. 492 * @size: physical size of region in bytes aligned to 1 KiB. 493 * @return: -EINVAL on invalid range or out or range id 494 * -ENODEV if reg is valid but no IMR exists or is locked 495 * 0 on success. 496 */ 497 int imr_remove_range(phys_addr_t base, size_t size) 498 { 499 return __imr_remove_range(-1, base, size); 500 } 501 EXPORT_SYMBOL_GPL(imr_remove_range); 502 503 /** 504 * imr_clear - delete an Isolated Memory Region by index 505 * 506 * This function allows you to delete an IMR by an address range specified 507 * by the index of the IMR. Useful for initial sanitization of the IMR 508 * address map. 509 * imr_ge(base, size); delete IMR from base to base+size. 510 * 511 * @reg: imr index to remove. 512 * @return: -EINVAL on invalid range or out or range id 513 * -ENODEV if reg is valid but no IMR exists or is locked 514 * 0 on success. 515 */ 516 static inline int imr_clear(int reg) 517 { 518 return __imr_remove_range(reg, 0, 0); 519 } 520 521 /** 522 * imr_fixup_memmap - Tear down IMRs used during bootup. 523 * 524 * BIOS and Grub both setup IMRs around compressed kernel, initrd memory 525 * that need to be removed before the kernel hands out one of the IMR 526 * encased addresses to a downstream DMA agent such as the SD or Ethernet. 527 * IMRs on Galileo are setup to immediately reset the system on violation. 528 * As a result if you're running a root filesystem from SD - you'll need 529 * the boot-time IMRs torn down or you'll find seemingly random resets when 530 * using your filesystem. 531 * 532 * @idev: pointer to imr_device structure. 533 * @return: 534 */ 535 static void __init imr_fixup_memmap(struct imr_device *idev) 536 { 537 phys_addr_t base = virt_to_phys(&_text); 538 size_t size = virt_to_phys(&__end_rodata) - base; 539 unsigned long start, end; 540 int i; 541 int ret; 542 543 /* Tear down all existing unlocked IMRs. */ 544 for (i = 0; i < idev->max_imr; i++) 545 imr_clear(i); 546 547 start = (unsigned long)_text; 548 end = (unsigned long)__end_rodata - 1; 549 550 /* 551 * Setup an unlocked IMR around the physical extent of the kernel 552 * from the beginning of the .text secton to the end of the 553 * .rodata section as one physically contiguous block. 554 * 555 * We don't round up @size since it is already PAGE_SIZE aligned. 556 * See vmlinux.lds.S for details. 557 */ 558 ret = imr_add_range(base, size, IMR_CPU, IMR_CPU); 559 if (ret < 0) { 560 pr_err("unable to setup IMR for kernel: %zu KiB (%lx - %lx)\n", 561 size / 1024, start, end); 562 } else { 563 pr_info("protecting kernel .text - .rodata: %zu KiB (%lx - %lx)\n", 564 size / 1024, start, end); 565 } 566 567 } 568 569 static const struct x86_cpu_id imr_ids[] __initconst = { 570 { X86_VENDOR_INTEL, 5, 9 }, /* Intel Quark SoC X1000. */ 571 {} 572 }; 573 574 /** 575 * imr_init - entry point for IMR driver. 576 * 577 * return: -ENODEV for no IMR support 0 if good to go. 578 */ 579 static int __init imr_init(void) 580 { 581 struct imr_device *idev = &imr_dev; 582 583 if (!x86_match_cpu(imr_ids) || !iosf_mbi_available()) 584 return -ENODEV; 585 586 idev->max_imr = QUARK_X1000_IMR_MAX; 587 idev->reg_base = QUARK_X1000_IMR_REGBASE; 588 idev->init = true; 589 590 mutex_init(&idev->lock); 591 imr_debugfs_register(idev); 592 imr_fixup_memmap(idev); 593 return 0; 594 } 595 device_initcall(imr_init); 596