2 * Handle caching attributes in page tables (PAT)
4 * Authors: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
5 * Suresh B Siddha <suresh.b.siddha@intel.com>
7 * Loosely based on earlier PAT patchset from Eric Biederman and Andi Kleen.
10 #include <linux/seq_file.h>
11 #include <linux/bootmem.h>
12 #include <linux/debugfs.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/gfp.h>
18 #include <linux/rbtree.h>
20 #include <asm/cacheflush.h>
21 #include <asm/processor.h>
22 #include <asm/tlbflush.h>
23 #include <asm/pgtable.h>
24 #include <asm/fcntl.h>
33 int __read_mostly pat_enabled = 1;
35 static inline void pat_disable(const char *reason)
38 printk(KERN_INFO "%s\n", reason);
41 static int __init nopat(char *str)
43 pat_disable("PAT support disabled.");
46 early_param("nopat", nopat);
48 static inline void pat_disable(const char *reason)
55 static int debug_enable;
57 static int __init pat_debug_setup(char *str)
62 __setup("debugpat", pat_debug_setup);
64 #define dprintk(fmt, arg...) \
65 do { if (debug_enable) printk(KERN_INFO fmt, ##arg); } while (0)
68 static u64 __read_mostly boot_pat_state;
71 PAT_UC = 0, /* uncached */
72 PAT_WC = 1, /* Write combining */
73 PAT_WT = 4, /* Write Through */
74 PAT_WP = 5, /* Write Protected */
75 PAT_WB = 6, /* Write Back (default) */
76 PAT_UC_MINUS = 7, /* UC, but can be overriden by MTRR */
79 #define PAT(x, y) ((u64)PAT_ ## y << ((x)*8))
89 if (!boot_pat_state) {
90 pat_disable("PAT not supported by CPU.");
94 * If this happens we are on a secondary CPU, but
95 * switched to PAT on the boot CPU. We have no way to
98 printk(KERN_ERR "PAT enabled, "
99 "but not supported by secondary CPU\n");
104 /* Set PWT to Write-Combining. All other bits stay the same */
106 * PTE encoding used in Linux:
111 * 000 WB _PAGE_CACHE_WB
112 * 001 WC _PAGE_CACHE_WC
113 * 010 UC- _PAGE_CACHE_UC_MINUS
114 * 011 UC _PAGE_CACHE_UC
117 pat = PAT(0, WB) | PAT(1, WC) | PAT(2, UC_MINUS) | PAT(3, UC) |
118 PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
122 rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
124 wrmsrl(MSR_IA32_CR_PAT, pat);
125 printk(KERN_INFO "x86 PAT enabled: cpu %d, old 0x%Lx, new 0x%Lx\n",
126 smp_processor_id(), boot_pat_state, pat);
131 static char *cattr_name(unsigned long flags)
133 switch (flags & _PAGE_CACHE_MASK) {
134 case _PAGE_CACHE_UC: return "uncached";
135 case _PAGE_CACHE_UC_MINUS: return "uncached-minus";
136 case _PAGE_CACHE_WB: return "write-back";
137 case _PAGE_CACHE_WC: return "write-combining";
138 default: return "broken";
143 * The global memtype list keeps track of memory type for specific
144 * physical memory areas. Conflicting memory types in different
145 * mappings can cause CPU cache corruption. To avoid this we keep track.
147 * The list is sorted based on starting address and can contain multiple
148 * entries for each address (this allows reference counting for overlapping
149 * areas). All the aliases have the same cache attributes of course.
150 * Zero attributes are represented as holes.
152 * The data structure is a list that is also organized as an rbtree
153 * sorted on the start address of memtype range.
155 * memtype_lock protects both the linear list and rbtree.
166 static struct rb_root memtype_rbroot = RB_ROOT;
167 static LIST_HEAD(memtype_list);
168 static DEFINE_SPINLOCK(memtype_lock); /* protects memtype list */
170 static struct memtype *memtype_rb_search(struct rb_root *root, u64 start)
172 struct rb_node *node = root->rb_node;
173 struct memtype *last_lower = NULL;
176 struct memtype *data = container_of(node, struct memtype, rb);
178 if (data->start < start) {
180 node = node->rb_right;
181 } else if (data->start > start) {
182 node = node->rb_left;
187 /* Will return NULL if there is no entry with its start <= start */
191 static void memtype_rb_insert(struct rb_root *root, struct memtype *data)
193 struct rb_node **new = &(root->rb_node);
194 struct rb_node *parent = NULL;
197 struct memtype *this = container_of(*new, struct memtype, rb);
200 if (data->start <= this->start)
201 new = &((*new)->rb_left);
202 else if (data->start > this->start)
203 new = &((*new)->rb_right);
206 rb_link_node(&data->rb, parent, new);
207 rb_insert_color(&data->rb, root);
211 * Does intersection of PAT memory type and MTRR memory type and returns
212 * the resulting memory type as PAT understands it.
213 * (Type in pat and mtrr will not have same value)
214 * The intersection is based on "Effective Memory Type" tables in IA-32
217 static unsigned long pat_x_mtrr_type(u64 start, u64 end, unsigned long req_type)
220 * Look for MTRR hint to get the effective type in case where PAT
223 if (req_type == _PAGE_CACHE_WB) {
226 mtrr_type = mtrr_type_lookup(start, end);
227 if (mtrr_type != MTRR_TYPE_WRBACK)
228 return _PAGE_CACHE_UC_MINUS;
230 return _PAGE_CACHE_WB;
237 chk_conflict(struct memtype *new, struct memtype *entry, unsigned long *type)
239 if (new->type != entry->type) {
241 new->type = entry->type;
247 /* check overlaps with more than one entry in the list */
248 list_for_each_entry_continue(entry, &memtype_list, nd) {
249 if (new->end <= entry->start)
251 else if (new->type != entry->type)
257 printk(KERN_INFO "%s:%d conflicting memory types "
258 "%Lx-%Lx %s<->%s\n", current->comm, current->pid, new->start,
259 new->end, cattr_name(new->type), cattr_name(entry->type));
263 static int pat_pagerange_is_ram(unsigned long start, unsigned long end)
265 int ram_page = 0, not_rampage = 0;
266 unsigned long page_nr;
268 for (page_nr = (start >> PAGE_SHIFT); page_nr < (end >> PAGE_SHIFT);
271 * For legacy reasons, physical address range in the legacy ISA
272 * region is tracked as non-RAM. This will allow users of
273 * /dev/mem to map portions of legacy ISA region, even when
274 * some of those portions are listed(or not even listed) with
275 * different e820 types(RAM/reserved/..)
277 if (page_nr >= (ISA_END_ADDRESS >> PAGE_SHIFT) &&
278 page_is_ram(page_nr))
283 if (ram_page == not_rampage)
291 * For RAM pages, we use page flags to mark the pages with appropriate type.
292 * Here we do two pass:
293 * - Find the memtype of all the pages in the range, look for any conflicts
294 * - In case of no conflicts, set the new memtype for pages in the range
296 * Caller must hold memtype_lock for atomicity.
298 static int reserve_ram_pages_type(u64 start, u64 end, unsigned long req_type,
299 unsigned long *new_type)
304 if (req_type == _PAGE_CACHE_UC) {
305 /* We do not support strong UC */
307 req_type = _PAGE_CACHE_UC_MINUS;
310 for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
313 page = pfn_to_page(pfn);
314 type = get_page_memtype(page);
316 printk(KERN_INFO "reserve_ram_pages_type failed "
317 "0x%Lx-0x%Lx, track 0x%lx, req 0x%lx\n",
318 start, end, type, req_type);
327 *new_type = req_type;
329 for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
330 page = pfn_to_page(pfn);
331 set_page_memtype(page, req_type);
336 static int free_ram_pages_type(u64 start, u64 end)
341 for (pfn = (start >> PAGE_SHIFT); pfn < (end >> PAGE_SHIFT); ++pfn) {
342 page = pfn_to_page(pfn);
343 set_page_memtype(page, -1);
349 * req_type typically has one of the:
352 * - _PAGE_CACHE_UC_MINUS
355 * req_type will have a special case value '-1', when requester want to inherit
356 * the memory type from mtrr (if WB), existing PAT, defaulting to UC_MINUS.
358 * If new_type is NULL, function will return an error if it cannot reserve the
359 * region with req_type. If new_type is non-NULL, function will return
360 * available type in new_type in case of no error. In case of any error
361 * it will return a negative return value.
363 int reserve_memtype(u64 start, u64 end, unsigned long req_type,
364 unsigned long *new_type)
366 struct memtype *new, *entry;
367 unsigned long actual_type;
368 struct list_head *where;
372 BUG_ON(start >= end); /* end is exclusive */
375 /* This is identical to page table setting without PAT */
378 *new_type = _PAGE_CACHE_WB;
379 else if (req_type == _PAGE_CACHE_WC)
380 *new_type = _PAGE_CACHE_UC_MINUS;
382 *new_type = req_type & _PAGE_CACHE_MASK;
387 /* Low ISA region is always mapped WB in page table. No need to track */
388 if (is_ISA_range(start, end - 1)) {
390 *new_type = _PAGE_CACHE_WB;
395 * Call mtrr_lookup to get the type hint. This is an
396 * optimization for /dev/mem mmap'ers into WB memory (BIOS
397 * tools and ACPI tools). Use WB request for WB memory and use
398 * UC_MINUS otherwise.
400 actual_type = pat_x_mtrr_type(start, end, req_type & _PAGE_CACHE_MASK);
403 *new_type = actual_type;
405 is_range_ram = pat_pagerange_is_ram(start, end);
406 if (is_range_ram == 1) {
408 spin_lock(&memtype_lock);
409 err = reserve_ram_pages_type(start, end, req_type, new_type);
410 spin_unlock(&memtype_lock);
413 } else if (is_range_ram < 0) {
417 new = kmalloc(sizeof(struct memtype), GFP_KERNEL);
423 new->type = actual_type;
425 spin_lock(&memtype_lock);
427 /* Search for existing mapping that overlaps the current range */
429 list_for_each_entry(entry, &memtype_list, nd) {
430 if (end <= entry->start) {
431 where = entry->nd.prev;
433 } else if (start <= entry->start) { /* end > entry->start */
434 err = chk_conflict(new, entry, new_type);
436 dprintk("Overlap at 0x%Lx-0x%Lx\n",
437 entry->start, entry->end);
438 where = entry->nd.prev;
441 } else if (start < entry->end) { /* start > entry->start */
442 err = chk_conflict(new, entry, new_type);
444 dprintk("Overlap at 0x%Lx-0x%Lx\n",
445 entry->start, entry->end);
448 * Move to right position in the linked
449 * list to add this new entry
451 list_for_each_entry_continue(entry,
453 if (start <= entry->start) {
454 where = entry->nd.prev;
464 printk(KERN_INFO "reserve_memtype failed 0x%Lx-0x%Lx, "
465 "track %s, req %s\n",
466 start, end, cattr_name(new->type), cattr_name(req_type));
468 spin_unlock(&memtype_lock);
474 list_add(&new->nd, where);
476 list_add_tail(&new->nd, &memtype_list);
478 memtype_rb_insert(&memtype_rbroot, new);
480 spin_unlock(&memtype_lock);
482 dprintk("reserve_memtype added 0x%Lx-0x%Lx, track %s, req %s, ret %s\n",
483 start, end, cattr_name(new->type), cattr_name(req_type),
484 new_type ? cattr_name(*new_type) : "-");
489 int free_memtype(u64 start, u64 end)
491 struct memtype *entry, *saved_entry;
498 /* Low ISA region is always mapped WB. No need to track */
499 if (is_ISA_range(start, end - 1))
502 is_range_ram = pat_pagerange_is_ram(start, end);
503 if (is_range_ram == 1) {
505 spin_lock(&memtype_lock);
506 err = free_ram_pages_type(start, end);
507 spin_unlock(&memtype_lock);
510 } else if (is_range_ram < 0) {
514 spin_lock(&memtype_lock);
516 entry = memtype_rb_search(&memtype_rbroot, start);
517 if (unlikely(entry == NULL))
521 * Saved entry points to an entry with start same or less than what
522 * we searched for. Now go through the list in both directions to look
523 * for the entry that matches with both start and end, with list stored
524 * in sorted start address
527 list_for_each_entry_from(entry, &memtype_list, nd) {
528 if (entry->start == start && entry->end == end) {
529 rb_erase(&entry->rb, &memtype_rbroot);
530 list_del(&entry->nd);
534 } else if (entry->start > start) {
543 list_for_each_entry_reverse(entry, &memtype_list, nd) {
544 if (entry->start == start && entry->end == end) {
545 rb_erase(&entry->rb, &memtype_rbroot);
546 list_del(&entry->nd);
550 } else if (entry->start < start) {
555 spin_unlock(&memtype_lock);
558 printk(KERN_INFO "%s:%d freeing invalid memtype %Lx-%Lx\n",
559 current->comm, current->pid, start, end);
562 dprintk("free_memtype request 0x%Lx-0x%Lx\n", start, end);
569 * lookup_memtype - Looksup the memory type for a physical address
570 * @paddr: physical address of which memory type needs to be looked up
572 * Only to be called when PAT is enabled
574 * Returns _PAGE_CACHE_WB, _PAGE_CACHE_WC, _PAGE_CACHE_UC_MINUS or
577 static unsigned long lookup_memtype(u64 paddr)
579 int rettype = _PAGE_CACHE_WB;
580 struct memtype *entry;
582 if (is_ISA_range(paddr, paddr + PAGE_SIZE - 1))
585 if (pat_pagerange_is_ram(paddr, paddr + PAGE_SIZE)) {
587 spin_lock(&memtype_lock);
588 page = pfn_to_page(paddr >> PAGE_SHIFT);
589 rettype = get_page_memtype(page);
590 spin_unlock(&memtype_lock);
592 * -1 from get_page_memtype() implies RAM page is in its
593 * default state and not reserved, and hence of type WB
596 rettype = _PAGE_CACHE_WB;
601 spin_lock(&memtype_lock);
603 entry = memtype_rb_search(&memtype_rbroot, paddr);
605 rettype = entry->type;
607 rettype = _PAGE_CACHE_UC_MINUS;
609 spin_unlock(&memtype_lock);
614 * io_reserve_memtype - Request a memory type mapping for a region of memory
615 * @start: start (physical address) of the region
616 * @end: end (physical address) of the region
617 * @type: A pointer to memtype, with requested type. On success, requested
618 * or any other compatible type that was available for the region is returned
620 * On success, returns 0
621 * On failure, returns non-zero
623 int io_reserve_memtype(resource_size_t start, resource_size_t end,
626 resource_size_t size = end - start;
627 unsigned long req_type = *type;
628 unsigned long new_type;
631 WARN_ON_ONCE(iomem_map_sanity_check(start, size));
633 ret = reserve_memtype(start, end, req_type, &new_type);
637 if (!is_new_memtype_allowed(start, size, req_type, new_type))
640 if (kernel_map_sync_memtype(start, size, new_type) < 0)
647 free_memtype(start, end);
654 * io_free_memtype - Release a memory type mapping for a region of memory
655 * @start: start (physical address) of the region
656 * @end: end (physical address) of the region
658 void io_free_memtype(resource_size_t start, resource_size_t end)
660 free_memtype(start, end);
663 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
664 unsigned long size, pgprot_t vma_prot)
669 #ifdef CONFIG_STRICT_DEVMEM
670 /* This check is done in drivers/char/mem.c in case of STRICT_DEVMEM*/
671 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
676 /* This check is needed to avoid cache aliasing when PAT is enabled */
677 static inline int range_is_allowed(unsigned long pfn, unsigned long size)
679 u64 from = ((u64)pfn) << PAGE_SHIFT;
680 u64 to = from + size;
686 while (cursor < to) {
687 if (!devmem_is_allowed(pfn)) {
689 "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
690 current->comm, from, to);
698 #endif /* CONFIG_STRICT_DEVMEM */
700 int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
701 unsigned long size, pgprot_t *vma_prot)
703 unsigned long flags = _PAGE_CACHE_WB;
705 if (!range_is_allowed(pfn, size))
708 if (file->f_flags & O_SYNC) {
709 flags = _PAGE_CACHE_UC_MINUS;
714 * On the PPro and successors, the MTRRs are used to set
715 * memory types for physical addresses outside main memory,
716 * so blindly setting UC or PWT on those pages is wrong.
717 * For Pentiums and earlier, the surround logic should disable
718 * caching for the high addresses through the KEN pin, but
719 * we maintain the tradition of paranoia in this code.
722 !(boot_cpu_has(X86_FEATURE_MTRR) ||
723 boot_cpu_has(X86_FEATURE_K6_MTRR) ||
724 boot_cpu_has(X86_FEATURE_CYRIX_ARR) ||
725 boot_cpu_has(X86_FEATURE_CENTAUR_MCR)) &&
726 (pfn << PAGE_SHIFT) >= __pa(high_memory)) {
727 flags = _PAGE_CACHE_UC;
731 *vma_prot = __pgprot((pgprot_val(*vma_prot) & ~_PAGE_CACHE_MASK) |
737 * Change the memory type for the physial address range in kernel identity
738 * mapping space if that range is a part of identity map.
740 int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
744 if (base >= __pa(high_memory))
747 id_sz = (__pa(high_memory) < base + size) ?
748 __pa(high_memory) - base :
751 if (ioremap_change_attr((unsigned long)__va(base), id_sz, flags) < 0) {
753 "%s:%d ioremap_change_attr failed %s "
755 current->comm, current->pid,
757 base, (unsigned long long)(base + size));
764 * Internal interface to reserve a range of physical memory with prot.
765 * Reserved non RAM regions only and after successful reserve_memtype,
766 * this func also keeps identity mapping (if any) in sync with this new prot.
768 static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
773 unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
774 unsigned long flags = want_flags;
776 is_ram = pat_pagerange_is_ram(paddr, paddr + size);
779 * reserve_pfn_range() for RAM pages. We do not refcount to keep
780 * track of number of mappings of RAM pages. We can assert that
781 * the type requested matches the type of first page in the range.
787 flags = lookup_memtype(paddr);
788 if (want_flags != flags) {
790 "%s:%d map pfn RAM range req %s for %Lx-%Lx, got %s\n",
791 current->comm, current->pid,
792 cattr_name(want_flags),
793 (unsigned long long)paddr,
794 (unsigned long long)(paddr + size),
796 *vma_prot = __pgprot((pgprot_val(*vma_prot) &
797 (~_PAGE_CACHE_MASK)) |
803 ret = reserve_memtype(paddr, paddr + size, want_flags, &flags);
807 if (flags != want_flags) {
809 !is_new_memtype_allowed(paddr, size, want_flags, flags)) {
810 free_memtype(paddr, paddr + size);
811 printk(KERN_ERR "%s:%d map pfn expected mapping type %s"
812 " for %Lx-%Lx, got %s\n",
813 current->comm, current->pid,
814 cattr_name(want_flags),
815 (unsigned long long)paddr,
816 (unsigned long long)(paddr + size),
821 * We allow returning different type than the one requested in
824 *vma_prot = __pgprot((pgprot_val(*vma_prot) &
825 (~_PAGE_CACHE_MASK)) |
829 if (kernel_map_sync_memtype(paddr, size, flags) < 0) {
830 free_memtype(paddr, paddr + size);
837 * Internal interface to free a range of physical memory.
838 * Frees non RAM regions only.
840 static void free_pfn_range(u64 paddr, unsigned long size)
844 is_ram = pat_pagerange_is_ram(paddr, paddr + size);
846 free_memtype(paddr, paddr + size);
850 * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
851 * copied through copy_page_range().
853 * If the vma has a linear pfn mapping for the entire range, we get the prot
854 * from pte and reserve the entire vma range with single reserve_pfn_range call.
856 int track_pfn_vma_copy(struct vm_area_struct *vma)
858 resource_size_t paddr;
860 unsigned long vma_size = vma->vm_end - vma->vm_start;
863 if (is_linear_pfn_mapping(vma)) {
865 * reserve the whole chunk covered by vma. We need the
866 * starting address and protection from pte.
868 if (follow_phys(vma, vma->vm_start, 0, &prot, &paddr)) {
872 pgprot = __pgprot(prot);
873 return reserve_pfn_range(paddr, vma_size, &pgprot, 1);
880 * track_pfn_vma_new is called when a _new_ pfn mapping is being established
881 * for physical range indicated by pfn and size.
883 * prot is passed in as a parameter for the new mapping. If the vma has a
884 * linear pfn mapping for the entire range reserve the entire vma range with
885 * single reserve_pfn_range call.
887 int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
888 unsigned long pfn, unsigned long size)
891 resource_size_t paddr;
892 unsigned long vma_size = vma->vm_end - vma->vm_start;
894 if (is_linear_pfn_mapping(vma)) {
895 /* reserve the whole chunk starting from vm_pgoff */
896 paddr = (resource_size_t)vma->vm_pgoff << PAGE_SHIFT;
897 return reserve_pfn_range(paddr, vma_size, prot, 0);
903 /* for vm_insert_pfn and friends, we set prot based on lookup */
904 flags = lookup_memtype(pfn << PAGE_SHIFT);
905 *prot = __pgprot((pgprot_val(vma->vm_page_prot) & (~_PAGE_CACHE_MASK)) |
912 * untrack_pfn_vma is called while unmapping a pfnmap for a region.
913 * untrack can be called for a specific region indicated by pfn and size or
914 * can be for the entire vma (in which case size can be zero).
916 void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
919 resource_size_t paddr;
920 unsigned long vma_size = vma->vm_end - vma->vm_start;
922 if (is_linear_pfn_mapping(vma)) {
923 /* free the whole chunk starting from vm_pgoff */
924 paddr = (resource_size_t)vma->vm_pgoff << PAGE_SHIFT;
925 free_pfn_range(paddr, vma_size);
930 pgprot_t pgprot_writecombine(pgprot_t prot)
933 return __pgprot(pgprot_val(prot) | _PAGE_CACHE_WC);
935 return pgprot_noncached(prot);
937 EXPORT_SYMBOL_GPL(pgprot_writecombine);
939 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_X86_PAT)
941 /* get Nth element of the linked list */
942 static struct memtype *memtype_get_idx(loff_t pos)
944 struct memtype *list_node, *print_entry;
947 print_entry = kmalloc(sizeof(struct memtype), GFP_KERNEL);
951 spin_lock(&memtype_lock);
952 list_for_each_entry(list_node, &memtype_list, nd) {
954 *print_entry = *list_node;
955 spin_unlock(&memtype_lock);
960 spin_unlock(&memtype_lock);
966 static void *memtype_seq_start(struct seq_file *seq, loff_t *pos)
970 seq_printf(seq, "PAT memtype list:\n");
973 return memtype_get_idx(*pos);
976 static void *memtype_seq_next(struct seq_file *seq, void *v, loff_t *pos)
979 return memtype_get_idx(*pos);
982 static void memtype_seq_stop(struct seq_file *seq, void *v)
986 static int memtype_seq_show(struct seq_file *seq, void *v)
988 struct memtype *print_entry = (struct memtype *)v;
990 seq_printf(seq, "%s @ 0x%Lx-0x%Lx\n", cattr_name(print_entry->type),
991 print_entry->start, print_entry->end);
997 static const struct seq_operations memtype_seq_ops = {
998 .start = memtype_seq_start,
999 .next = memtype_seq_next,
1000 .stop = memtype_seq_stop,
1001 .show = memtype_seq_show,
1004 static int memtype_seq_open(struct inode *inode, struct file *file)
1006 return seq_open(file, &memtype_seq_ops);
1009 static const struct file_operations memtype_fops = {
1010 .open = memtype_seq_open,
1012 .llseek = seq_lseek,
1013 .release = seq_release,
1016 static int __init pat_memtype_list_init(void)
1018 debugfs_create_file("pat_memtype_list", S_IRUSR, arch_debugfs_dir,
1019 NULL, &memtype_fops);
1023 late_initcall(pat_memtype_list_init);
1025 #endif /* CONFIG_DEBUG_FS && CONFIG_X86_PAT */