arch/um/kernel/mem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   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 EXPORT_SYMBOL(highmem);
  35 int kmalloc_ok = 0;
  36
  37 /* Used during early boot */
  38 static unsigned long brk_end;
  39
  40 void __init mem_init(void)
  41 {
  42         /* clear the zero-page */
  43         memset(empty_zero_page, 0, PAGE_SIZE);
  44
  45         /* Map in the area just after the brk now that kmalloc is about
  46          * to be turned on.
  47          */
  48         brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
  49         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
  50         memblock_free(__pa(brk_end), uml_reserved - brk_end);
  51         uml_reserved = brk_end;
  52
  53         /* this will put all low memory onto the freelists */
  54         memblock_free_all();
  55         max_low_pfn = totalram_pages();
  56         max_pfn = max_low_pfn;
  57         mem_init_print_info(NULL);
  58         kmalloc_ok = 1;
  59 }
  60
  61 /*
  62  * Create a page table and place a pointer to it in a middle page
  63  * directory entry.
  64  */
  65 static void __init one_page_table_init(pmd_t *pmd)
  66 {
  67         if (pmd_none(*pmd)) {
  68                 pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
  69                                                           PAGE_SIZE);
  70                 if (!pte)
  71                         panic("%s: Failed to allocate %lu bytes align=%lx\n",
  72                               __func__, PAGE_SIZE, PAGE_SIZE);
  73
  74                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  75                                            (unsigned long) __pa(pte)));
  76                 if (pte != pte_offset_kernel(pmd, 0))
  77                         BUG();
  78         }
  79 }
  80
  81 static void __init one_md_table_init(pud_t *pud)
  82 {
  83 #ifdef CONFIG_3_LEVEL_PGTABLES
  84         pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
  85         if (!pmd_table)
  86                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
  87                       __func__, PAGE_SIZE, PAGE_SIZE);
  88
  89         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
  90         if (pmd_table != pmd_offset(pud, 0))
  91                 BUG();
  92 #endif
  93 }
  94
  95 static void __init fixrange_init(unsigned long start, unsigned long end,
  96                                  pgd_t *pgd_base)
  97 {
  98         pgd_t *pgd;
  99         pud_t *pud;
 100         pmd_t *pmd;
 101         int i, j;
 102         unsigned long vaddr;
 103
 104         vaddr = start;
 105         i = pgd_index(vaddr);
 106         j = pmd_index(vaddr);
 107         pgd = pgd_base + i;
 108
 109         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 110                 pud = pud_offset(pgd, vaddr);
 111                 if (pud_none(*pud))
 112                         one_md_table_init(pud);
 113                 pmd = pmd_offset(pud, vaddr);
 114                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 115                         one_page_table_init(pmd);
 116                         vaddr += PMD_SIZE;
 117                 }
 118                 j = 0;
 119         }
 120 }
 121
 122 static void __init fixaddr_user_init( void)
 123 {
 124 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 125         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 126         pgd_t *pgd;
 127         pud_t *pud;
 128         pmd_t *pmd;
 129         pte_t *pte;
 130         phys_t p;
 131         unsigned long v, vaddr = FIXADDR_USER_START;
 132
 133         if (!size)
 134                 return;
 135
 136         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 137         v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
 138         if (!v)
 139                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 140                       __func__, size, PAGE_SIZE);
 141
 142         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 143         p = __pa(v);
 144         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 145                       p += PAGE_SIZE) {
 146                 pgd = swapper_pg_dir + pgd_index(vaddr);
 147                 pud = pud_offset(pgd, vaddr);
 148                 pmd = pmd_offset(pud, vaddr);
 149                 pte = pte_offset_kernel(pmd, vaddr);
 150                 pte_set_val(*pte, p, PAGE_READONLY);
 151         }
 152 #endif
 153 }
 154
 155 void __init paging_init(void)
 156 {
 157         unsigned long zones_size[MAX_NR_ZONES], vaddr;
 158         int i;
 159
 160         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 161                                                                PAGE_SIZE);
 162         if (!empty_zero_page)
 163                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 164                       __func__, PAGE_SIZE, PAGE_SIZE);
 165
 166         for (i = 0; i < ARRAY_SIZE(zones_size); i++)
 167                 zones_size[i] = 0;
 168
 169         zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
 170                 (uml_physmem >> PAGE_SHIFT);
 171         free_area_init(zones_size);
 172
 173         /*
 174          * Fixed mappings, only the page table structure has to be
 175          * created - mappings will be set by set_fixmap():
 176          */
 177         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 178         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 179
 180         fixaddr_user_init();
 181 }
 182
 183 /*
 184  * This can't do anything because nothing in the kernel image can be freed
 185  * since it's not in kernel physical memory.
 186  */
 187
 188 void free_initmem(void)
 189 {
 190 }
 191
 192 /* Allocate and free page tables. */
 193
 194 pgd_t *pgd_alloc(struct mm_struct *mm)
 195 {
 196         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 197
 198         if (pgd) {
 199                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 200                 memcpy(pgd + USER_PTRS_PER_PGD,
 201                        swapper_pg_dir + USER_PTRS_PER_PGD,
 202                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 203         }
 204         return pgd;
 205 }
 206
 207 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 208 {
 209         free_page((unsigned long) pgd);
 210 }
 211
 212 #ifdef CONFIG_3_LEVEL_PGTABLES
 213 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 214 {
 215         pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
 216
 217         if (pmd)
 218                 memset(pmd, 0, PAGE_SIZE);
 219
 220         return pmd;
 221 }
 222 #endif
 223
 224 void *uml_kmalloc(int size, int flags)
 225 {
 226         return kmalloc(size, flags);
 227 }