arch/um/kernel/mem.c

   1 /*
   2  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <linux/stddef.h>
   7 #include <linux/module.h>
   8 #include <linux/bootmem.h>
   9 #include <linux/highmem.h>
  10 #include <linux/mm.h>
  11 #include <linux/swap.h>
  12 #include <linux/slab.h>
  13 #include <asm/fixmap.h>
  14 #include <asm/page.h>
  15 #include <as-layout.h>
  16 #include <init.h>
  17 #include <kern.h>
  18 #include <kern_util.h>
  19 #include <mem_user.h>
  20 #include <os.h>
  21
  22 /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
  23 unsigned long *empty_zero_page = NULL;
  24 EXPORT_SYMBOL(empty_zero_page);
  25 /* allocated in paging_init and unchanged thereafter */
  26 static unsigned long *empty_bad_page = NULL;
  27
  28 /*
  29  * Initialized during boot, and readonly for initializing page tables
  30  * afterwards
  31  */
  32 pgd_t swapper_pg_dir[PTRS_PER_PGD];
  33
  34 /* Initialized at boot time, and readonly after that */
  35 unsigned long long highmem;
  36 int kmalloc_ok = 0;
  37
  38 /* Used during early boot */
  39 static unsigned long brk_end;
  40
  41 void __init mem_init(void)
  42 {
  43         /* clear the zero-page */
  44         memset(empty_zero_page, 0, PAGE_SIZE);
  45
  46         /* Map in the area just after the brk now that kmalloc is about
  47          * to be turned on.
  48          */
  49         brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
  50         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
  51         free_bootmem(__pa(brk_end), uml_reserved - brk_end);
  52         uml_reserved = brk_end;
  53
  54         /* this will put all low memory onto the freelists */
  55         free_all_bootmem();
  56         max_low_pfn = totalram_pages;
  57         max_pfn = totalram_pages;
  58         mem_init_print_info(NULL);
  59         kmalloc_ok = 1;
  60 }
  61
  62 /*
  63  * Create a page table and place a pointer to it in a middle page
  64  * directory entry.
  65  */
  66 static void __init one_page_table_init(pmd_t *pmd)
  67 {
  68         if (pmd_none(*pmd)) {
  69                 pte_t *pte = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
  70                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  71                                            (unsigned long) __pa(pte)));
  72                 if (pte != pte_offset_kernel(pmd, 0))
  73                         BUG();
  74         }
  75 }
  76
  77 static void __init one_md_table_init(pud_t *pud)
  78 {
  79 #ifdef CONFIG_3_LEVEL_PGTABLES
  80         pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
  81         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
  82         if (pmd_table != pmd_offset(pud, 0))
  83                 BUG();
  84 #endif
  85 }
  86
  87 static void __init fixrange_init(unsigned long start, unsigned long end,
  88                                  pgd_t *pgd_base)
  89 {
  90         pgd_t *pgd;
  91         pud_t *pud;
  92         pmd_t *pmd;
  93         int i, j;
  94         unsigned long vaddr;
  95
  96         vaddr = start;
  97         i = pgd_index(vaddr);
  98         j = pmd_index(vaddr);
  99         pgd = pgd_base + i;
 100
 101         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 102                 pud = pud_offset(pgd, vaddr);
 103                 if (pud_none(*pud))
 104                         one_md_table_init(pud);
 105                 pmd = pmd_offset(pud, vaddr);
 106                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 107                         one_page_table_init(pmd);
 108                         vaddr += PMD_SIZE;
 109                 }
 110                 j = 0;
 111         }
 112 }
 113
 114 static void __init fixaddr_user_init( void)
 115 {
 116 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 117         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 118         pgd_t *pgd;
 119         pud_t *pud;
 120         pmd_t *pmd;
 121         pte_t *pte;
 122         phys_t p;
 123         unsigned long v, vaddr = FIXADDR_USER_START;
 124
 125         if (!size)
 126                 return;
 127
 128         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 129         v = (unsigned long) alloc_bootmem_low_pages(size);
 130         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 131         p = __pa(v);
 132         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 133                       p += PAGE_SIZE) {
 134                 pgd = swapper_pg_dir + pgd_index(vaddr);
 135                 pud = pud_offset(pgd, vaddr);
 136                 pmd = pmd_offset(pud, vaddr);
 137                 pte = pte_offset_kernel(pmd, vaddr);
 138                 pte_set_val(*pte, p, PAGE_READONLY);
 139         }
 140 #endif
 141 }
 142
 143 void __init paging_init(void)
 144 {
 145         unsigned long zones_size[MAX_NR_ZONES], vaddr;
 146         int i;
 147
 148         empty_zero_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
 149         empty_bad_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
 150         for (i = 0; i < ARRAY_SIZE(zones_size); i++)
 151                 zones_size[i] = 0;
 152
 153         zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
 154                 (uml_physmem >> PAGE_SHIFT);
 155         free_area_init(zones_size);
 156
 157         /*
 158          * Fixed mappings, only the page table structure has to be
 159          * created - mappings will be set by set_fixmap():
 160          */
 161         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 162         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 163
 164         fixaddr_user_init();
 165 }
 166
 167 /*
 168  * This can't do anything because nothing in the kernel image can be freed
 169  * since it's not in kernel physical memory.
 170  */
 171
 172 void free_initmem(void)
 173 {
 174 }
 175
 176 #ifdef CONFIG_BLK_DEV_INITRD
 177 void free_initrd_mem(unsigned long start, unsigned long end)
 178 {
 179         free_reserved_area((void *)start, (void *)end, -1, "initrd");
 180 }
 181 #endif
 182
 183 /* Allocate and free page tables. */
 184
 185 pgd_t *pgd_alloc(struct mm_struct *mm)
 186 {
 187         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 188
 189         if (pgd) {
 190                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 191                 memcpy(pgd + USER_PTRS_PER_PGD,
 192                        swapper_pg_dir + USER_PTRS_PER_PGD,
 193                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 194         }
 195         return pgd;
 196 }
 197
 198 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 199 {
 200         free_page((unsigned long) pgd);
 201 }
 202
 203 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 204 {
 205         pte_t *pte;
 206
 207         pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
 208         return pte;
 209 }
 210
 211 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 212 {
 213         struct page *pte;
 214
 215         pte = alloc_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
 216         if (!pte)
 217                 return NULL;
 218         if (!pgtable_page_ctor(pte)) {
 219                 __free_page(pte);
 220                 return NULL;
 221         }
 222         return pte;
 223 }
 224
 225 #ifdef CONFIG_3_LEVEL_PGTABLES
 226 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 227 {
 228         pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
 229
 230         if (pmd)
 231                 memset(pmd, 0, PAGE_SIZE);
 232
 233         return pmd;
 234 }
 235 #endif
 236
 237 void *uml_kmalloc(int size, int flags)
 238 {
 239         return kmalloc(size, flags);
 240 }