err.no Git - linux-2.6/blob - 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 void clflush_cache_range(void *addr, int size)
  13 {
  14         int i;
  15
  16         for (i = 0; i < size; i += boot_cpu_data.x86_clflush_size)
  17                 clflush(addr+i);
  18 }
  19
  20 #include <asm/processor.h>
  21 #include <asm/tlbflush.h>
  22 #include <asm/sections.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/pgalloc.h>
  25
  26 pte_t *lookup_address(unsigned long address, int *level)
  27 {
  28         pgd_t *pgd = pgd_offset_k(address);
  29         pud_t *pud;
  30         pmd_t *pmd;
  31
  32         if (pgd_none(*pgd))
  33                 return NULL;
  34         pud = pud_offset(pgd, address);
  35         if (pud_none(*pud))
  36                 return NULL;
  37         pmd = pmd_offset(pud, address);
  38         if (pmd_none(*pmd))
  39                 return NULL;
  40         *level = 3;
  41         if (pmd_large(*pmd))
  42                 return (pte_t *)pmd;
  43         *level = 4;
  44
  45         return pte_offset_kernel(pmd, address);
  46 }
  47
  48 static struct page *
  49 split_large_page(unsigned long address, pgprot_t ref_prot)
  50 {
  51         unsigned long addr;
  52         struct page *base;
  53         pte_t *pbase;
  54         int i;
  55
  56         base = alloc_pages(GFP_KERNEL, 0);
  57         if (!base)
  58                 return NULL;
  59
  60         address = __pa(address);
  61         addr = address & LARGE_PAGE_MASK;
  62         pbase = (pte_t *)page_address(base);
  63         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
  64                 pbase[i] = pfn_pte(addr >> PAGE_SHIFT, ref_prot);
  65
  66         return base;
  67 }
  68
  69 static int
  70 __change_page_attr(unsigned long address, unsigned long pfn, pgprot_t prot,
  71                    pgprot_t ref_prot)
  72 {
  73         struct page *kpte_page;
  74         pte_t *kpte;
  75         pgprot_t ref_prot2, oldprot;
  76         int level;
  77
  78 repeat:
  79         kpte = lookup_address(address, &level);
  80         if (!kpte)
  81                 return 0;
  82
  83         kpte_page = virt_to_page(kpte);
  84         oldprot = pte_pgprot(*kpte);
  85         BUG_ON(PageLRU(kpte_page));
  86         BUG_ON(PageCompound(kpte_page));
  87         ref_prot = canon_pgprot(ref_prot);
  88         prot = canon_pgprot(prot);
  89
  90         if (pgprot_val(prot) != pgprot_val(ref_prot)) {
  91                 if (level == 4) {
  92                         set_pte(kpte, pfn_pte(pfn, prot));
  93                 } else {
  94                         /*
  95                          * split_large_page will take the reference for this
  96                          * change_page_attr on the split page.
  97                          */
  98                         struct page *split;
  99
 100                         ref_prot2 = pte_pgprot(pte_clrhuge(*kpte));
 101                         split = split_large_page(address, ref_prot2);
 102                         if (!split)
 103                                 return -ENOMEM;
 104                         pgprot_val(ref_prot2) &= ~_PAGE_NX;
 105                         set_pte(kpte, mk_pte(split, ref_prot2));
 106                         goto repeat;
 107                 }
 108         } else {
 109                 if (level == 4) {
 110                         set_pte(kpte, pfn_pte(pfn, ref_prot));
 111                 } else
 112                         BUG();
 113         }
 114
 115         return 0;
 116 }
 117
 118 /**
 119  * change_page_attr_addr - Change page table attributes in linear mapping
 120  * @address: Virtual address in linear mapping.
 121  * @numpages: Number of pages to change
 122  * @prot:    New page table attribute (PAGE_*)
 123  *
 124  * Change page attributes of a page in the direct mapping. This is a variant
 125  * of change_page_attr() that also works on memory holes that do not have
 126  * mem_map entry (pfn_valid() is false).
 127  *
 128  * See change_page_attr() documentation for more details.
 129  */
 130
 131 int change_page_attr_addr(unsigned long address, int numpages, pgprot_t prot)
 132 {
 133         int err = 0, kernel_map = 0, i;
 134
 135         if (address >= __START_KERNEL_map &&
 136                         address < __START_KERNEL_map + KERNEL_TEXT_SIZE) {
 137
 138                 address = (unsigned long)__va(__pa(address));
 139                 kernel_map = 1;
 140         }
 141
 142         down_write(&init_mm.mmap_sem);
 143         for (i = 0; i < numpages; i++, address += PAGE_SIZE) {
 144                 unsigned long pfn = __pa(address) >> PAGE_SHIFT;
 145
 146                 if (!kernel_map || pte_present(pfn_pte(0, prot))) {
 147                         err = __change_page_attr(address, pfn, prot,
 148                                                 PAGE_KERNEL);
 149                         if (err)
 150                                 break;
 151                 }
 152                 /* Handle kernel mapping too which aliases part of the
 153                  * lowmem */
 154                 if (__pa(address) < KERNEL_TEXT_SIZE) {
 155                         unsigned long addr2;
 156                         pgprot_t prot2;
 157
 158                         addr2 = __START_KERNEL_map + __pa(address);
 159                         /* Make sure the kernel mappings stay executable */
 160                         prot2 = pte_pgprot(pte_mkexec(pfn_pte(0, prot)));
 161                         err = __change_page_attr(addr2, pfn, prot2,
 162                                                  PAGE_KERNEL_EXEC);
 163                 }
 164         }
 165         up_write(&init_mm.mmap_sem);
 166
 167         return err;
 168 }
 169
 170 /**
 171  * change_page_attr - Change page table attributes in the linear mapping.
 172  * @page: First page to change
 173  * @numpages: Number of pages to change
 174  * @prot: New protection/caching type (PAGE_*)
 175  *
 176  * Returns 0 on success, otherwise a negated errno.
 177  *
 178  * This should be used when a page is mapped with a different caching policy
 179  * than write-back somewhere - some CPUs do not like it when mappings with
 180  * different caching policies exist. This changes the page attributes of the
 181  * in kernel linear mapping too.
 182  *
 183  * Caller must call global_flush_tlb() later to make the changes active.
 184  *
 185  * The caller needs to ensure that there are no conflicting mappings elsewhere
 186  * (e.g. in user space) * This function only deals with the kernel linear map.
 187  *
 188  * For MMIO areas without mem_map use change_page_attr_addr() instead.
 189  */
 190 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 191 {
 192         unsigned long addr = (unsigned long)page_address(page);
 193
 194         return change_page_attr_addr(addr, numpages, prot);
 195 }
 196 EXPORT_SYMBOL(change_page_attr);
 197
 198 static void flush_kernel_map(void *arg)
 199 {
 200         /*
 201          * Flush all to work around Errata in early athlons regarding
 202          * large page flushing.
 203          */
 204         __flush_tlb_all();
 205
 206         if (boot_cpu_data.x86_model >= 4)
 207                 wbinvd();
 208 }
 209
 210 void global_flush_tlb(void)
 211 {
 212         BUG_ON(irqs_disabled());
 213
 214         on_each_cpu(flush_kernel_map, NULL, 1, 1);
 215 }
 216 EXPORT_SYMBOL(global_flush_tlb);