4 * Copyright(c) 2013 Intel Corporation.
5 * Copyright(c) 2015 Bryan O'Donoghue <pure.logic@nexus-software.ie>
7 * IMR registers define an isolated region of memory that can
8 * be masked to prohibit certain system agents from accessing memory.
9 * When a device behind a masked port performs an access - snooped or
10 * not, an IMR may optionally prevent that transaction from changing
11 * the state of memory or from getting correct data in response to the
14 * Write data will be dropped and reads will return 0xFFFFFFFF, the
15 * system will reset and system BIOS will print out an error message to
16 * inform the user that an IMR has been violated.
18 * This code is based on the Linux MTRR code and reference code from
19 * Intel's Quark BSP EFI, Linux and grub code.
21 * See quark-x1000-datasheet.pdf for register definitions.
22 * http://www.intel.com/content/dam/www/public/us/en/documents/datasheets/quark-x1000-datasheet.pdf
25 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
27 #include <asm-generic/sections.h>
28 #include <asm/cpu_device_id.h>
30 #include <asm/iosf_mbi.h>
31 #include <linux/debugfs.h>
32 #include <linux/init.h>
34 #include <linux/module.h>
35 #include <linux/types.h>
45 static struct imr_device imr_dev;
48 * IMR read/write mask control registers.
49 * See quark-x1000-datasheet.pdf sections 12.7.4.5 and 12.7.4.6 for
55 * 23:2 1 KiB aligned lo address
60 * 23:2 1 KiB aligned hi address
63 #define IMR_LOCK BIT(31)
72 #define IMR_NUM_REGS (sizeof(struct imr_regs)/sizeof(u32))
74 #define imr_to_phys(x) ((x) << IMR_SHIFT)
75 #define phys_to_imr(x) ((x) >> IMR_SHIFT)
78 * imr_is_enabled - true if an IMR is enabled false otherwise.
80 * Determines if an IMR is enabled based on address range and read/write
81 * mask. An IMR set with an address range set to zero and a read/write
82 * access mask set to all is considered to be disabled. An IMR in any
83 * other state - for example set to zero but without read/write access
84 * all is considered to be enabled. This definition of disabled is how
85 * firmware switches off an IMR and is maintained in kernel for
88 * @imr: pointer to IMR descriptor.
89 * @return: true if IMR enabled false if disabled.
91 static inline int imr_is_enabled(struct imr_regs *imr)
93 return !(imr->rmask == IMR_READ_ACCESS_ALL &&
94 imr->wmask == IMR_WRITE_ACCESS_ALL &&
95 imr_to_phys(imr->addr_lo) == 0 &&
96 imr_to_phys(imr->addr_hi) == 0);
100 * imr_read - read an IMR at a given index.
102 * Requires caller to hold imr mutex.
104 * @idev: pointer to imr_device structure.
105 * @imr_id: IMR entry to read.
106 * @imr: IMR structure representing address and access masks.
107 * @return: 0 on success or error code passed from mbi_iosf on failure.
109 static int imr_read(struct imr_device *idev, u32 imr_id, struct imr_regs *imr)
111 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
114 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_lo);
118 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->addr_hi);
122 ret = iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->rmask);
126 return iosf_mbi_read(QRK_MBI_UNIT_MM, MBI_REG_READ, reg++, &imr->wmask);
130 * imr_write - write an IMR at a given index.
132 * Requires caller to hold imr mutex.
133 * Note lock bits need to be written independently of address bits.
135 * @idev: pointer to imr_device structure.
136 * @imr_id: IMR entry to write.
137 * @imr: IMR structure representing address and access masks.
138 * @lock: indicates if the IMR lock bit should be applied.
139 * @return: 0 on success or error code passed from mbi_iosf on failure.
141 static int imr_write(struct imr_device *idev, u32 imr_id,
142 struct imr_regs *imr, bool lock)
145 u32 reg = imr_id * IMR_NUM_REGS + idev->reg_base;
148 local_irq_save(flags);
150 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_lo);
154 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->addr_hi);
158 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->rmask);
162 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE, reg++, imr->wmask);
166 /* Lock bit must be set separately to addr_lo address bits. */
168 imr->addr_lo |= IMR_LOCK;
169 ret = iosf_mbi_write(QRK_MBI_UNIT_MM, MBI_REG_WRITE,
170 reg - IMR_NUM_REGS, imr->addr_lo);
175 local_irq_restore(flags);
179 * If writing to the IOSF failed then we're in an unknown state,
180 * likely a very bad state. An IMR in an invalid state will almost
181 * certainly lead to a memory access violation.
183 local_irq_restore(flags);
184 WARN(ret, "IOSF-MBI write fail range 0x%08x-0x%08x unreliable\n",
185 imr_to_phys(imr->addr_lo), imr_to_phys(imr->addr_hi) + IMR_MASK);
191 * imr_dbgfs_state_show - print state of IMR registers.
193 * @s: pointer to seq_file for output.
194 * @unused: unused parameter.
195 * @return: 0 on success or error code passed from mbi_iosf on failure.
197 static int imr_dbgfs_state_show(struct seq_file *s, void *unused)
202 struct imr_device *idev = s->private;
207 mutex_lock(&idev->lock);
209 for (i = 0; i < idev->max_imr; i++) {
211 ret = imr_read(idev, i, &imr);
216 * Remember to add IMR_ALIGN bytes to size to indicate the
217 * inherent IMR_ALIGN size bytes contained in the masked away
220 if (imr_is_enabled(&imr)) {
221 base = imr_to_phys(imr.addr_lo);
222 end = imr_to_phys(imr.addr_hi) + IMR_MASK;
223 size = end - base + 1;
229 seq_printf(s, "imr%02i: base=%pa, end=%pa, size=0x%08zx "
230 "rmask=0x%08x, wmask=0x%08x, %s, %s\n", i,
231 &base, &end, size, imr.rmask, imr.wmask,
232 imr_is_enabled(&imr) ? "enabled " : "disabled",
233 imr.addr_lo & IMR_LOCK ? "locked" : "unlocked");
236 mutex_unlock(&idev->lock);
241 * imr_state_open - debugfs open callback.
243 * @inode: pointer to struct inode.
244 * @file: pointer to struct file.
245 * @return: result of single open.
247 static int imr_state_open(struct inode *inode, struct file *file)
249 return single_open(file, imr_dbgfs_state_show, inode->i_private);
252 static const struct file_operations imr_state_ops = {
253 .open = imr_state_open,
256 .release = single_release,
260 * imr_debugfs_register - register debugfs hooks.
262 * @idev: pointer to imr_device structure.
263 * @return: 0 on success - errno on failure.
265 static int imr_debugfs_register(struct imr_device *idev)
267 idev->file = debugfs_create_file("imr_state", S_IFREG | S_IRUGO, NULL,
268 idev, &imr_state_ops);
269 return PTR_ERR_OR_ZERO(idev->file);
273 * imr_debugfs_unregister - unregister debugfs hooks.
275 * @idev: pointer to imr_device structure.
278 static void imr_debugfs_unregister(struct imr_device *idev)
280 debugfs_remove(idev->file);
284 * imr_check_params - check passed address range IMR alignment and non-zero size
286 * @base: base address of intended IMR.
287 * @size: size of intended IMR.
288 * @return: zero on valid range -EINVAL on unaligned base/size.
290 static int imr_check_params(phys_addr_t base, size_t size)
292 if ((base & IMR_MASK) || (size & IMR_MASK)) {
293 pr_err("base %pa size 0x%08zx must align to 1KiB\n",
304 * imr_raw_size - account for the IMR_ALIGN bytes that addr_hi appends.
306 * IMR addr_hi has a built in offset of plus IMR_ALIGN (0x400) bytes from the
307 * value in the register. We need to subtract IMR_ALIGN bytes from input sizes
310 * @size: input size bytes.
311 * @return: reduced size.
313 static inline size_t imr_raw_size(size_t size)
315 return size - IMR_ALIGN;
319 * imr_address_overlap - detects an address overlap.
321 * @addr: address to check against an existing IMR.
322 * @imr: imr being checked.
323 * @return: true for overlap false for no overlap.
325 static inline int imr_address_overlap(phys_addr_t addr, struct imr_regs *imr)
327 return addr >= imr_to_phys(imr->addr_lo) && addr <= imr_to_phys(imr->addr_hi);
331 * imr_add_range - add an Isolated Memory Region.
333 * @base: physical base address of region aligned to 1KiB.
334 * @size: physical size of region in bytes must be aligned to 1KiB.
335 * @read_mask: read access mask.
336 * @write_mask: write access mask.
337 * @lock: indicates whether or not to permanently lock this region.
338 * @return: zero on success or negative value indicating error.
340 int imr_add_range(phys_addr_t base, size_t size,
341 unsigned int rmask, unsigned int wmask, bool lock)
345 struct imr_device *idev = &imr_dev;
351 if (WARN_ONCE(idev->init == false, "driver not initialized"))
354 ret = imr_check_params(base, size);
358 /* Tweak the size value. */
359 raw_size = imr_raw_size(size);
360 end = base + raw_size;
363 * Check for reserved IMR value common to firmware, kernel and grub
364 * indicating a disabled IMR.
366 imr.addr_lo = phys_to_imr(base);
367 imr.addr_hi = phys_to_imr(end);
370 if (!imr_is_enabled(&imr))
373 mutex_lock(&idev->lock);
376 * Find a free IMR while checking for an existing overlapping range.
377 * Note there's no restriction in silicon to prevent IMR overlaps.
378 * For the sake of simplicity and ease in defining/debugging an IMR
379 * memory map we exclude IMR overlaps.
382 for (i = 0; i < idev->max_imr; i++) {
383 ret = imr_read(idev, i, &imr);
387 /* Find overlap @ base or end of requested range. */
389 if (imr_is_enabled(&imr)) {
390 if (imr_address_overlap(base, &imr))
392 if (imr_address_overlap(end, &imr))
399 /* Error out if we have no free IMR entries. */
405 pr_debug("add %d phys %pa-%pa size %zx mask 0x%08x wmask 0x%08x\n",
406 reg, &base, &end, raw_size, rmask, wmask);
408 /* Enable IMR at specified range and access mask. */
409 imr.addr_lo = phys_to_imr(base);
410 imr.addr_hi = phys_to_imr(end);
414 ret = imr_write(idev, reg, &imr, lock);
417 * In the highly unlikely event iosf_mbi_write failed
418 * attempt to rollback the IMR setup skipping the trapping
419 * of further IOSF write failures.
423 imr.rmask = IMR_READ_ACCESS_ALL;
424 imr.wmask = IMR_WRITE_ACCESS_ALL;
425 imr_write(idev, reg, &imr, false);
428 mutex_unlock(&idev->lock);
431 EXPORT_SYMBOL_GPL(imr_add_range);
434 * __imr_remove_range - delete an Isolated Memory Region.
436 * This function allows you to delete an IMR by its index specified by reg or
437 * by address range specified by base and size respectively. If you specify an
438 * index on its own the base and size parameters are ignored.
439 * imr_remove_range(0, base, size); delete IMR at index 0 base/size ignored.
440 * imr_remove_range(-1, base, size); delete IMR from base to base+size.
442 * @reg: imr index to remove.
443 * @base: physical base address of region aligned to 1 KiB.
444 * @size: physical size of region in bytes aligned to 1 KiB.
445 * @return: -EINVAL on invalid range or out or range id
446 * -ENODEV if reg is valid but no IMR exists or is locked
449 static int __imr_remove_range(int reg, phys_addr_t base, size_t size)
454 struct imr_device *idev = &imr_dev;
459 if (WARN_ONCE(idev->init == false, "driver not initialized"))
463 * Validate address range if deleting by address, else we are
464 * deleting by index where base and size will be ignored.
467 ret = imr_check_params(base, size);
472 /* Tweak the size value. */
473 raw_size = imr_raw_size(size);
474 end = base + raw_size;
476 mutex_lock(&idev->lock);
479 /* If a specific IMR is given try to use it. */
480 ret = imr_read(idev, reg, &imr);
484 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK) {
490 /* Search for match based on address range. */
491 for (i = 0; i < idev->max_imr; i++) {
492 ret = imr_read(idev, i, &imr);
496 if (!imr_is_enabled(&imr) || imr.addr_lo & IMR_LOCK)
499 if ((imr_to_phys(imr.addr_lo) == base) &&
500 (imr_to_phys(imr.addr_hi) == end)) {
513 pr_debug("remove %d phys %pa-%pa size %zx\n", reg, &base, &end, raw_size);
515 /* Tear down the IMR. */
518 imr.rmask = IMR_READ_ACCESS_ALL;
519 imr.wmask = IMR_WRITE_ACCESS_ALL;
521 ret = imr_write(idev, reg, &imr, false);
524 mutex_unlock(&idev->lock);
529 * imr_remove_range - delete an Isolated Memory Region by address
531 * This function allows you to delete an IMR by an address range specified
532 * by base and size respectively.
533 * imr_remove_range(base, size); delete IMR from base to base+size.
535 * @base: physical base address of region aligned to 1 KiB.
536 * @size: physical size of region in bytes aligned to 1 KiB.
537 * @return: -EINVAL on invalid range or out or range id
538 * -ENODEV if reg is valid but no IMR exists or is locked
541 int imr_remove_range(phys_addr_t base, size_t size)
543 return __imr_remove_range(-1, base, size);
545 EXPORT_SYMBOL_GPL(imr_remove_range);
548 * imr_clear - delete an Isolated Memory Region by index
550 * This function allows you to delete an IMR by an address range specified
551 * by the index of the IMR. Useful for initial sanitization of the IMR
553 * imr_ge(base, size); delete IMR from base to base+size.
555 * @reg: imr index to remove.
556 * @return: -EINVAL on invalid range or out or range id
557 * -ENODEV if reg is valid but no IMR exists or is locked
560 static inline int imr_clear(int reg)
562 return __imr_remove_range(reg, 0, 0);
566 * imr_fixup_memmap - Tear down IMRs used during bootup.
568 * BIOS and Grub both setup IMRs around compressed kernel, initrd memory
569 * that need to be removed before the kernel hands out one of the IMR
570 * encased addresses to a downstream DMA agent such as the SD or Ethernet.
571 * IMRs on Galileo are setup to immediately reset the system on violation.
572 * As a result if you're running a root filesystem from SD - you'll need
573 * the boot-time IMRs torn down or you'll find seemingly random resets when
574 * using your filesystem.
576 * @idev: pointer to imr_device structure.
579 static void __init imr_fixup_memmap(struct imr_device *idev)
581 phys_addr_t base = virt_to_phys(&_text);
582 size_t size = virt_to_phys(&__end_rodata) - base;
583 unsigned long start, end;
587 /* Tear down all existing unlocked IMRs. */
588 for (i = 0; i < idev->max_imr; i++)
591 start = (unsigned long)_text;
592 end = (unsigned long)__end_rodata - 1;
595 * Setup a locked IMR around the physical extent of the kernel
596 * from the beginning of the .text secton to the end of the
597 * .rodata section as one physically contiguous block.
599 * We don't round up @size since it is already PAGE_SIZE aligned.
600 * See vmlinux.lds.S for details.
602 ret = imr_add_range(base, size, IMR_CPU, IMR_CPU, true);
604 pr_err("unable to setup IMR for kernel: %zu KiB (%lx - %lx)\n",
605 size / 1024, start, end);
607 pr_info("protecting kernel .text - .rodata: %zu KiB (%lx - %lx)\n",
608 size / 1024, start, end);
613 static const struct x86_cpu_id imr_ids[] __initconst = {
614 { X86_VENDOR_INTEL, 5, 9 }, /* Intel Quark SoC X1000. */
617 MODULE_DEVICE_TABLE(x86cpu, imr_ids);
620 * imr_init - entry point for IMR driver.
622 * return: -ENODEV for no IMR support 0 if good to go.
624 static int __init imr_init(void)
626 struct imr_device *idev = &imr_dev;
629 if (!x86_match_cpu(imr_ids) || !iosf_mbi_available())
632 idev->max_imr = QUARK_X1000_IMR_MAX;
633 idev->reg_base = QUARK_X1000_IMR_REGBASE;
636 mutex_init(&idev->lock);
637 ret = imr_debugfs_register(idev);
639 pr_warn("debugfs register failed!\n");
640 imr_fixup_memmap(idev);
645 * imr_exit - exit point for IMR code.
647 * Deregisters debugfs, leave IMR state as-is.
651 static void __exit imr_exit(void)
653 imr_debugfs_unregister(&imr_dev);
656 module_init(imr_init);
657 module_exit(imr_exit);
659 MODULE_AUTHOR("Bryan O'Donoghue <pure.logic@nexus-software.ie>");
660 MODULE_DESCRIPTION("Intel Isolated Memory Region driver");
661 MODULE_LICENSE("Dual BSD/GPL");