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
  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         free_bootmem(__pa(brk_end), uml_reserved - brk_end);
  50         uml_reserved = brk_end;
  51
  52         /* this will put all low memory onto the freelists */
  53         free_all_bootmem();
  54         max_low_pfn = totalram_pages;
  55         max_pfn = totalram_pages;
  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 *) alloc_bootmem_low_pages(PAGE_SIZE);
  68                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  69                                            (unsigned long) __pa(pte)));
  70                 if (pte != pte_offset_kernel(pmd, 0))
  71                         BUG();
  72         }
  73 }
  74
  75 static void __init one_md_table_init(pud_t *pud)
  76 {
  77 #ifdef CONFIG_3_LEVEL_PGTABLES
  78         pmd_t *pmd_table = (pmd_t *) alloc_bootmem_low_pages(PAGE_SIZE);
  79         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
  80         if (pmd_table != pmd_offset(pud, 0))
  81                 BUG();
  82 #endif
  83 }
  84
  85 static void __init fixrange_init(unsigned long start, unsigned long end,
  86                                  pgd_t *pgd_base)
  87 {
  88         pgd_t *pgd;
  89         pud_t *pud;
  90         pmd_t *pmd;
  91         int i, j;
  92         unsigned long vaddr;
  93
  94         vaddr = start;
  95         i = pgd_index(vaddr);
  96         j = pmd_index(vaddr);
  97         pgd = pgd_base + i;
  98
  99         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 100                 pud = pud_offset(pgd, vaddr);
 101                 if (pud_none(*pud))
 102                         one_md_table_init(pud);
 103                 pmd = pmd_offset(pud, vaddr);
 104                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 105                         one_page_table_init(pmd);
 106                         vaddr += PMD_SIZE;
 107                 }
 108                 j = 0;
 109         }
 110 }
 111
 112 static void __init fixaddr_user_init( void)
 113 {
 114 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 115         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 116         pgd_t *pgd;
 117         pud_t *pud;
 118         pmd_t *pmd;
 119         pte_t *pte;
 120         phys_t p;
 121         unsigned long v, vaddr = FIXADDR_USER_START;
 122
 123         if (!size)
 124                 return;
 125
 126         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 127         v = (unsigned long) alloc_bootmem_low_pages(size);
 128         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 129         p = __pa(v);
 130         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 131                       p += PAGE_SIZE) {
 132                 pgd = swapper_pg_dir + pgd_index(vaddr);
 133                 pud = pud_offset(pgd, vaddr);
 134                 pmd = pmd_offset(pud, vaddr);
 135                 pte = pte_offset_kernel(pmd, vaddr);
 136                 pte_set_val(*pte, p, PAGE_READONLY);
 137         }
 138 #endif
 139 }
 140
 141 void __init paging_init(void)
 142 {
 143         unsigned long zones_size[MAX_NR_ZONES], vaddr;
 144         int i;
 145
 146         empty_zero_page = (unsigned long *) alloc_bootmem_low_pages(PAGE_SIZE);
 147         for (i = 0; i < ARRAY_SIZE(zones_size); i++)
 148                 zones_size[i] = 0;
 149
 150         zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
 151                 (uml_physmem >> PAGE_SHIFT);
 152         free_area_init(zones_size);
 153
 154         /*
 155          * Fixed mappings, only the page table structure has to be
 156          * created - mappings will be set by set_fixmap():
 157          */
 158         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 159         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 160
 161         fixaddr_user_init();
 162 }
 163
 164 /*
 165  * This can't do anything because nothing in the kernel image can be freed
 166  * since it's not in kernel physical memory.
 167  */
 168
 169 void free_initmem(void)
 170 {
 171 }
 172
 173 #ifdef CONFIG_BLK_DEV_INITRD
 174 void free_initrd_mem(unsigned long start, unsigned long end)
 175 {
 176         free_reserved_area((void *)start, (void *)end, -1, "initrd");
 177 }
 178 #endif
 179
 180 /* Allocate and free page tables. */
 181
 182 pgd_t *pgd_alloc(struct mm_struct *mm)
 183 {
 184         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 185
 186         if (pgd) {
 187                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 188                 memcpy(pgd + USER_PTRS_PER_PGD,
 189                        swapper_pg_dir + USER_PTRS_PER_PGD,
 190                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 191         }
 192         return pgd;
 193 }
 194
 195 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 196 {
 197         free_page((unsigned long) pgd);
 198 }
 199
 200 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 201 {
 202         pte_t *pte;
 203
 204         pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
 205         return pte;
 206 }
 207
 208 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
 209 {
 210         struct page *pte;
 211
 212         pte = alloc_page(GFP_KERNEL|__GFP_ZERO);
 213         if (!pte)
 214                 return NULL;
 215         if (!pgtable_page_ctor(pte)) {
 216                 __free_page(pte);
 217                 return NULL;
 218         }
 219         return pte;
 220 }
 221
 222 #ifdef CONFIG_3_LEVEL_PGTABLES
 223 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 224 {
 225         pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
 226
 227         if (pmd)
 228                 memset(pmd, 0, PAGE_SIZE);
 229
 230         return pmd;
 231 }
 232 #endif
 233
 234 void *uml_kmalloc(int size, int flags)
 235 {
 236         return kmalloc(size, flags);
 237 }