arch/x86/mm/pageattr_32.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/sections.h>
  15 #include <asm/uaccess.h>
  16 #include <asm/pgalloc.h>
  17
  18 pte_t *lookup_address(unsigned long address, int *level)
  19 {
  20         pgd_t *pgd = pgd_offset_k(address);
  21         pud_t *pud;
  22         pmd_t *pmd;
  23
  24         if (pgd_none(*pgd))
  25                 return NULL;
  26         pud = pud_offset(pgd, address);
  27         if (pud_none(*pud))
  28                 return NULL;
  29         pmd = pmd_offset(pud, address);
  30         if (pmd_none(*pmd))
  31                 return NULL;
  32         *level = 2;
  33         if (pmd_large(*pmd))
  34                 return (pte_t *)pmd;
  35         *level = 3;
  36
  37         return pte_offset_kernel(pmd, address);
  38 }
  39
  40 static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
  41 {
  42         struct page *page;
  43
  44         /* change init_mm */
  45         set_pte_atomic(kpte, pte);
  46         if (SHARED_KERNEL_PMD)
  47                 return;
  48
  49         for (page = pgd_list; page; page = (struct page *)page->index) {
  50                 pgd_t *pgd;
  51                 pud_t *pud;
  52                 pmd_t *pmd;
  53
  54                 pgd = (pgd_t *)page_address(page) + pgd_index(address);
  55                 pud = pud_offset(pgd, address);
  56                 pmd = pmd_offset(pud, address);
  57                 set_pte_atomic((pte_t *)pmd, pte);
  58         }
  59 }
  60
  61 static int split_large_page(pte_t *kpte, unsigned long address)
  62 {
  63         pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte));
  64         unsigned long flags;
  65         unsigned long addr;
  66         pte_t *pbase, *tmp;
  67         struct page *base;
  68         int i, level;
  69
  70         base = alloc_pages(GFP_KERNEL, 0);
  71         if (!base)
  72                 return -ENOMEM;
  73
  74         spin_lock_irqsave(&pgd_lock, flags);
  75         /*
  76          * Check for races, another CPU might have split this page
  77          * up for us already:
  78          */
  79         tmp = lookup_address(address, &level);
  80         if (tmp != kpte) {
  81                 WARN_ON_ONCE(1);
  82                 goto out_unlock;
  83         }
  84
  85         address = __pa(address);
  86         addr = address & LARGE_PAGE_MASK;
  87         pbase = (pte_t *)page_address(base);
  88         paravirt_alloc_pt(&init_mm, page_to_pfn(base));
  89
  90         for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE)
  91                 set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot));
  92
  93         /*
  94          * Install the new, split up pagetable:
  95          */
  96         __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
  97         base = NULL;
  98
  99 out_unlock:
 100         spin_unlock_irqrestore(&pgd_lock, flags);
 101
 102         if (base)
 103                 __free_pages(base, 0);
 104
 105         return 0;
 106 }
 107
 108 static int __change_page_attr(struct page *page, pgprot_t prot)
 109 {
 110         struct page *kpte_page;
 111         unsigned long address;
 112         int level, err = 0;
 113         pte_t *kpte;
 114
 115         BUG_ON(PageHighMem(page));
 116         address = (unsigned long)page_address(page);
 117
 118 repeat:
 119         kpte = lookup_address(address, &level);
 120         if (!kpte)
 121                 return -EINVAL;
 122
 123         kpte_page = virt_to_page(kpte);
 124         BUG_ON(PageLRU(kpte_page));
 125         BUG_ON(PageCompound(kpte_page));
 126
 127         /*
 128          * Better fail early if someone sets the kernel text to NX.
 129          * Does not cover __inittext
 130          */
 131         BUG_ON(address >= (unsigned long)&_text &&
 132                 address < (unsigned long)&_etext &&
 133                (pgprot_val(prot) & _PAGE_NX));
 134
 135         if (level == 3) {
 136                 set_pte_atomic(kpte, mk_pte(page, canon_pgprot(prot)));
 137         } else {
 138                 err = split_large_page(kpte, address);
 139                 if (!err)
 140                         goto repeat;
 141         }
 142         return err;
 143 }
 144
 145 /*
 146  * Change the page attributes of an page in the linear mapping.
 147  *
 148  * This should be used when a page is mapped with a different caching policy
 149  * than write-back somewhere - some CPUs do not like it when mappings with
 150  * different caching policies exist. This changes the page attributes of the
 151  * in kernel linear mapping too.
 152  *
 153  * The caller needs to ensure that there are no conflicting mappings elsewhere.
 154  * This function only deals with the kernel linear map.
 155  *
 156  * Caller must call global_flush_tlb() after this.
 157  */
 158 int change_page_attr(struct page *page, int numpages, pgprot_t prot)
 159 {
 160         int err = 0, i;
 161
 162         for (i = 0; i < numpages; i++, page++) {
 163                 err = __change_page_attr(page, prot);
 164                 if (err)
 165                         break;
 166         }
 167
 168         return err;
 169 }
 170 EXPORT_SYMBOL(change_page_attr);
 171
 172 int change_page_attr_addr(unsigned long addr, int numpages, pgprot_t prot)
 173 {
 174         int i;
 175         unsigned long pfn = (__pa(addr) >> PAGE_SHIFT);
 176
 177         for (i = 0; i < numpages; i++) {
 178                 if (!pfn_valid(pfn + i)) {
 179                         WARN_ON_ONCE(1);
 180                         break;
 181                 } else {
 182                         int level;
 183                         pte_t *pte = lookup_address(addr + i*PAGE_SIZE, &level);
 184                         BUG_ON(pte && pte_none(*pte));
 185                 }
 186         }
 187
 188         return change_page_attr(virt_to_page(addr), i, prot);
 189 }
 190
 191 static void flush_kernel_map(void *arg)
 192 {
 193         /*
 194          * Flush all to work around Errata in early athlons regarding
 195          * large page flushing.
 196          */
 197         __flush_tlb_all();
 198
 199         if (boot_cpu_data.x86_model >= 4)
 200                 wbinvd();
 201 }
 202
 203 void global_flush_tlb(void)
 204 {
 205         BUG_ON(irqs_disabled());
 206
 207         on_each_cpu(flush_kernel_map, NULL, 1, 1);
 208 }
 209 EXPORT_SYMBOL(global_flush_tlb);
 210
 211 #ifdef CONFIG_DEBUG_PAGEALLOC
 212 void kernel_map_pages(struct page *page, int numpages, int enable)
 213 {
 214         if (PageHighMem(page))
 215                 return;
 216         if (!enable) {
 217                 debug_check_no_locks_freed(page_address(page),
 218                                            numpages * PAGE_SIZE);
 219         }
 220
 221         /*
 222          * the return value is ignored - the calls cannot fail,
 223          * large pages are disabled at boot time.
 224          */
 225         change_page_attr(page, numpages, enable ? PAGE_KERNEL : __pgprot(0));
 226
 227         /*
 228          * we should perform an IPI and flush all tlbs,
 229          * but that can deadlock->flush only current cpu.
 230          */
 231         __flush_tlb_all();
 232 }
 233 #endif