arch/x86/mm/pageattr_64.c

   1 /*
   2  * Copyright 2002 Andi Kleen, SuSE Labs.
   3  * Thanks to Ben LaHaise for precious feedback.
   4  */
   5
   6 #include <linux/highmem.h>
   7 #include <linux/module.h>
   8 #include <linux/sched.h>
   9 #include <linux/slab.h>
  10 #include <linux/mm.h>
  11
  12 #include <asm/processor.h>
  13 #include <asm/tlbflush.h>
  14 #include <asm/uaccess.h>
  15 #include <asm/io.h>
  16
  17 pte_t *lookup_address(unsigned long address, int *level)
  18 {
  19         pgd_t *pgd = pgd_offset_k(address);
  20         pud_t *pud;
  21         pmd_t *pmd;
  22         pte_t *pte;
  23
  24         if (pgd_none(*pgd))
  25                 return NULL;
  26         pud = pud_offset(pgd, address);
  27         if (!pud_present(*pud))
  28                 return NULL;
  29         pmd = pmd_offset(pud, address);
  30         if (!pmd_present(*pmd))
  31                 return NULL;
  32         *level = 3;
  33         if (pmd_large(*pmd))
  34                 return (pte_t *)pmd;
  35         *level = 4;
  36
  37         pte = pte_offset_kernel(pmd, address);
  38         if (pte && !pte_present(*pte))
  39                 pte = NULL;
  40
  41         return pte;
  42 }
  43
  44 static struct page *
  45 split_large_page(unsigned long address, pgprot_t prot, pgprot_t ref_prot)
  46 {
  47         unsigned long addr;
  48         struct page *base;
  49         pte_t *pbase;
  50         int i;
  51
  52         base = alloc_pages(GFP_KERNEL, 0);
  53         if (!base)
  54                 return NULL;
  55         /*
  56          * page_private is used to track the number of entries in
  57          * the page table page have non standard attributes.
  58          */
  59         SetPagePrivate(base);
  60         page_private(base) = 0;
  61
  62         address = __pa(address);
  63         addr = address & LARGE_PAGE_MASK;
  64         pbase = (pte_t *)page_address(base);
  65         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
  66                 pbase[i] = pfn_pte(addr >> PAGE_SHIFT,
  67                                    addr == address ? prot : ref_prot);
  68         }
  69         return base;
  70 }
  71
  72 void clflush_cache_range(void *addr, int size)
  73 {
  74         int i;
  75
  76         for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
  77                 clflush(addr+i);
  78 }
  79
  80 static void flush_kernel_map(void *arg)
  81 {
  82         struct list_head *l = (struct list_head *)arg;
  83         struct page *pg;
  84
  85         /* When clflush is available always use it because it is
  86            much cheaper than WBINVD. */
  87         /* clflush is still broken. Disable for now. */
  88         if (1 || !cpu_has_clflush) {
  89                 asm volatile("wbinvd" ::: "memory");
  90         } else {
  91                 list_for_each_entry(pg, l, lru) {
  92                         void *addr = page_address(pg);
  93
  94                         clflush_cache_range(addr, PAGE_SIZE);
  95                 }
  96         }
  97         __flush_tlb_all();
  98 }
  99
 100 static inline void flush_map(struct list_head *l)
 101 {
 102         on_each_cpu(flush_kernel_map, l, 1, 1);
 103 }
 104
 105 static LIST_HEAD(deferred_pages); /* protected by init_mm.mmap_sem */
 106
 107 static inline void save_page(struct page *fpage)
 108 {
 109         if (!test_and_set_bit(PG_arch_1, &fpage->flags))
 110                 list_add(&fpage->lru, &deferred_pages);
 111 }
 112
 113 /*
 114  * No more special protections in this 2/4MB area - revert to a
 115  * large page again.
 116  */
 117 static void revert_page(unsigned long address, pgprot_t ref_prot)
 118 {
 119         unsigned long pfn;
 120         pgd_t *pgd;
 121         pud_t *pud;
 122         pmd_t *pmd;
 123         pte_t large_pte;
 124
 125         pgd = pgd_offset_k(address);
 126         BUG_ON(pgd_none(*pgd));
 127         pud = pud_offset(pgd, address);
 128         BUG_ON(pud_none(*pud));
 129         pmd = pmd_offset(pud, address);
 130         BUG_ON(pmd_val(*pmd) & _PAGE_PSE);
 131         pfn = (__pa(address) & LARGE_PAGE_MASK) >> PAGE_SHIFT;
 132         large_pte = pfn_pte(pfn, ref_prot);
 133         large_pte = pte_mkhuge(large_pte);
 134
 135         set_pte((pte_t *)pmd, large_pte);
 136 }
 137
 138 static int
 139 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
 140                    pgprot_t ref_prot)
 141 {
 142         struct page *kpte_page;
 143         pgprot_t ref_prot2;
 144         pte_t *kpte;
 145         int level;
 146
 147         kpte = lookup_address(address, &level);
 148         if (!kpte)
 149                 return 0;
 150
 151         kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
 152         BUG_ON(PageLRU(kpte_page));
 153         BUG_ON(PageCompound(kpte_page));
 154         if (pgprot_val(prot) != pgprot_val(ref_prot)) {
 155                 if (!pte_huge(*kpte)) {
 156                         set_pte(kpte, pfn_pte(pfn, prot));
 157                 } else {
 158                         /*
 159                          * split_large_page will take the reference for this
 160                          * change_page_attr on the split page.
 161                          */
 162                         struct page *split;
 163
 164                         ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
 165                         split = split_large_page(address, prot, ref_prot2);
 166                         if (!split)
 167                                 return -ENOMEM;
 168                         pgprot_val(ref_prot2) &= ~_PAGE_NX;
 169                         set_pte(kpte, mk_pte(split, ref_prot2));
 170                         kpte_page = split;
 171                 }
 172                 page_private(kpte_page)++;
 173         } else {
 174                 if (!pte_huge(*kpte)) {
 175                         set_pte(kpte, pfn_pte(pfn, ref_prot));
 176                         BUG_ON(page_private(kpte_page) == 0);
 177                         page_private(kpte_page)--;
 178                 } else
 179                         BUG();
 180         }
 181
 182         /* on x86-64 the direct mapping set at boot is not using 4k pages */
 183         BUG_ON(PageReserved(kpte_page));
 184
 185         save_page(kpte_page);
 186         if (page_private(kpte_page) == 0)
 187                 revert_page(address, ref_prot);
 188         return 0;
 189 }
 190
 191 /*
 192  * Change the page attributes of an page in the linear mapping.
 193  *
 194  * This should be used when a page is mapped with a different caching policy
 195  * than write-back somewhere - some CPUs do not like it when mappings with
 196  * different caching policies exist. This changes the page attributes of the
 197  * in kernel linear mapping too.
 198  *
 199  * The caller needs to ensure that there are no conflicting mappings elsewhere.
 200  * This function only deals with the kernel linear map.
 201  *
 202  * Caller must call global_flush_tlb() after this.
 203  */
 204 int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 205 {
 206         int err = 0, kernel_map = 0, i;
 207
 208         if (address >= __START_KERNEL_map &&
 209                         address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
 210
 211                 address = (unsigned long)__va(__pa(address));
 212                 kernel_map = 1;
 213         }
 214
 215         down_write(&init_mm.mmap_sem);
 216         for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
 217                 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
 218
 219                 if (!kernel_map || pte_present(pfn_pte(0, prot))) {
 220                         err = __change_page_attr(address, pfn, prot,
 221                                                 PAGE_KERNEL);
 222                         if (err)
 223                                 break;
 224                 }
 225                 /* Handle kernel mapping too which aliases part of the
 226                  * lowmem */
 227                 if (__pa(address) < KERNEL_TEXT_SIZE) {
 228                         unsigned long addr2;
 229                         pgprot_t prot2;
 230
 231                         addr2 = __START_KERNEL_map + __pa(address);
 232                         /* Make sure the kernel mappings stay executable */
 233                         prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 234                         err = __change_page_attr(addr2, pfn, prot2,
 235                                                  PAGE_KERNEL_EXEC);
 236                 }
 237         }
 238         up_write(&init_mm.mmap_sem);
 239
 240         return err;
 241 }
 242
 243 /* Don't call this for MMIO areas that may not have a mem_map entry */
 244 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 245 {
 246         unsigned long addr = (unsigned long)page_address(page);
 247
 248         return change_page_attr_addr(addr, numpages, prot);
 249 }
 250 EXPORT_SYMBOL(change_page_attr);
 251
 252 void global_flush_tlb(void)
 253 {
 254         struct page *pg, *next;
 255         struct list_head l;
 256
 257         /*
 258          * Write-protect the semaphore, to exclude two contexts
 259          * doing a list_replace_init() call in parallel and to
 260          * exclude new additions to the deferred_pages list:
 261          */
 262         down_write(&init_mm.mmap_sem);
 263         list_replace_init(&deferred_pages, &l);
 264         up_write(&init_mm.mmap_sem);
 265
 266         flush_map(&l);
 267
 268         list_for_each_entry_safe(pg, next, &l, lru) {
 269                 list_del(&pg->lru);
 270                 clear_bit(PG_arch_1, &pg->flags);
 271                 if (page_private(pg) != 0)
 272                         continue;
 273                 ClearPagePrivate(pg);
 274                 __free_page(pg);
 275         }
 276 }
 277 EXPORT_SYMBOL(global_flush_tlb);