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/memblock.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
  26 /*
  27  * Initialized during boot, and readonly for initializing page tables
  28  * afterwards
  29  */
  30 pgd_t swapper_pg_dir[PTRS_PER_PGD];
  31
  32 /* Initialized at boot time, and readonly after that */
  33 unsigned long long highmem;
  34 int kmalloc_ok = 0;
  35
  36 /* Used during early boot */
  37 static unsigned long brk_end;
  38
  39 void __init mem_init(void)
  40 {
  41         /* clear the zero-page */
  42         memset(empty_zero_page, 0, PAGE_SIZE);
  43
  44         /* Map in the area just after the brk now that kmalloc is about
  45          * to be turned on.
  46          */
  47         brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
  48         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
  49         memblock_free(__pa(brk_end), uml_reserved - brk_end);
  50         uml_reserved = brk_end;
  51
  52         /* this will put all low memory onto the freelists */
  53         memblock_free_all();
  54         max_low_pfn = totalram_pages();
  55         max_pfn = max_low_pfn;
  56         mem_init_print_info(NULL);
  57         kmalloc_ok = 1;
  58 }
  59
  60 /*
  61  * Create a page table and place a pointer to it in a middle page
  62  * directory entry.
  63  */
  64 static void __init one_page_table_init(pmd_t *pmd)
  65 {
  66         if (pmd_none(*pmd)) {
  67                 pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
  68                                                           PAGE_SIZE);
  69                 if (!pte)
  70                         panic("%s: Failed to allocate %lu bytes align=%lx\n",
  71                               __func__, PAGE_SIZE, PAGE_SIZE);
  72
  73                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  74                                            (unsigned long) __pa(pte)));
  75                 if (pte != pte_offset_kernel(pmd, 0))
  76                         BUG();
  77         }
  78 }
  79
  80 static void __init one_md_table_init(pud_t *pud)
  81 {
  82 #ifdef CONFIG_3_LEVEL_PGTABLES
  83         pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
  84         if (!pmd_table)
  85                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
  86                       __func__, PAGE_SIZE, PAGE_SIZE);
  87
  88         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
  89         if (pmd_table != pmd_offset(pud, 0))
  90                 BUG();
  91 #endif
  92 }
  93
  94 static void __init fixrange_init(unsigned long start, unsigned long end,
  95                                  pgd_t *pgd_base)
  96 {
  97         pgd_t *pgd;
  98         pud_t *pud;
  99         pmd_t *pmd;
 100         int i, j;
 101         unsigned long vaddr;
 102
 103         vaddr = start;
 104         i = pgd_index(vaddr);
 105         j = pmd_index(vaddr);
 106         pgd = pgd_base + i;
 107
 108         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 109                 pud = pud_offset(pgd, vaddr);
 110                 if (pud_none(*pud))
 111                         one_md_table_init(pud);
 112                 pmd = pmd_offset(pud, vaddr);
 113                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 114                         one_page_table_init(pmd);
 115                         vaddr += PMD_SIZE;
 116                 }
 117                 j = 0;
 118         }
 119 }
 120
 121 static void __init fixaddr_user_init( void)
 122 {
 123 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 124         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 125         pgd_t *pgd;
 126         pud_t *pud;
 127         pmd_t *pmd;
 128         pte_t *pte;
 129         phys_t p;
 130         unsigned long v, vaddr = FIXADDR_USER_START;
 131
 132         if (!size)
 133                 return;
 134
 135         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 136         v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
 137         if (!v)
 138                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 139                       __func__, size, PAGE_SIZE);
 140
 141         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 142         p = __pa(v);
 143         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 144                       p += PAGE_SIZE) {
 145                 pgd = swapper_pg_dir + pgd_index(vaddr);
 146                 pud = pud_offset(pgd, vaddr);
 147                 pmd = pmd_offset(pud, vaddr);
 148                 pte = pte_offset_kernel(pmd, vaddr);
 149                 pte_set_val(*pte, p, PAGE_READONLY);
 150         }
 151 #endif
 152 }
 153
 154 void __init paging_init(void)
 155 {
 156         unsigned long zones_size[MAX_NR_ZONES], vaddr;
 157         int i;
 158
 159         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 160                                                                PAGE_SIZE);
 161         if (!empty_zero_page)
 162                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 163                       __func__, PAGE_SIZE, PAGE_SIZE);
 164
 165         for (i = 0; i < ARRAY_SIZE(zones_size); i++)
 166                 zones_size[i] = 0;
 167
 168         zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
 169                 (uml_physmem >> PAGE_SHIFT);
 170         free_area_init(zones_size);
 171
 172         /*
 173          * Fixed mappings, only the page table structure has to be
 174          * created - mappings will be set by set_fixmap():
 175          */
 176         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 177         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 178
 179         fixaddr_user_init();
 180 }
 181
 182 /*
 183  * This can't do anything because nothing in the kernel image can be freed
 184  * since it's not in kernel physical memory.
 185  */
 186
 187 void free_initmem(void)
 188 {
 189 }
 190
 191 #ifdef CONFIG_BLK_DEV_INITRD
 192 void free_initrd_mem(unsigned long start, unsigned long end)
 193 {
 194         free_reserved_area((void *)start, (void *)end, -1, "initrd");
 195 }
 196 #endif
 197
 198 /* Allocate and free page tables. */
 199
 200 pgd_t *pgd_alloc(struct mm_struct *mm)
 201 {
 202         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 203
 204         if (pgd) {
 205                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 206                 memcpy(pgd + USER_PTRS_PER_PGD,
 207                        swapper_pg_dir + USER_PTRS_PER_PGD,
 208                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 209         }
 210         return pgd;
 211 }
 212
 213 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 214 {
 215         free_page((unsigned long) pgd);
 216 }
 217
 218 pte_t *pte_alloc_one_kernel(struct mm_struct *mm)
 219 {
 220         pte_t *pte;
 221
 222         pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
 223         return pte;
 224 }
 225
 226 pgtable_t pte_alloc_one(struct mm_struct *mm)
 227 {
 228         struct page *pte;
 229
 230         pte = alloc_page(GFP_KERNEL|__GFP_ZERO);
 231         if (!pte)
 232                 return NULL;
 233         if (!pgtable_page_ctor(pte)) {
 234                 __free_page(pte);
 235                 return NULL;
 236         }
 237         return pte;
 238 }
 239
 240 #ifdef CONFIG_3_LEVEL_PGTABLES
 241 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 242 {
 243         pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
 244
 245         if (pmd)
 246                 memset(pmd, 0, PAGE_SIZE);
 247
 248         return pmd;
 249 }
 250 #endif
 251
 252 void *uml_kmalloc(int size, int flags)
 253 {
 254         return kmalloc(size, flags);
 255 }