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         p4d_t *p4d;
 100         pud_t *pud;
 101         pmd_t *pmd;
 102         int i, j;
 103         unsigned long vaddr;
 104
 105         vaddr = start;
 106         i = pgd_index(vaddr);
 107         j = pmd_index(vaddr);
 108         pgd = pgd_base + i;
 109
 110         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 111                 p4d = p4d_offset(pgd, vaddr);
 112                 pud = pud_offset(p4d, vaddr);
 113                 if (pud_none(*pud))
 114                         one_md_table_init(pud);
 115                 pmd = pmd_offset(pud, vaddr);
 116                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 117                         one_page_table_init(pmd);
 118                         vaddr += PMD_SIZE;
 119                 }
 120                 j = 0;
 121         }
 122 }
 123
 124 static void __init fixaddr_user_init( void)
 125 {
 126 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 127         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 128         pgd_t *pgd;
 129         p4d_t *p4d;
 130         pud_t *pud;
 131         pmd_t *pmd;
 132         pte_t *pte;
 133         phys_t p;
 134         unsigned long v, vaddr = FIXADDR_USER_START;
 135
 136         if (!size)
 137                 return;
 138
 139         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 140         v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
 141         if (!v)
 142                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 143                       __func__, size, PAGE_SIZE);
 144
 145         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 146         p = __pa(v);
 147         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 148                       p += PAGE_SIZE) {
 149                 pgd = swapper_pg_dir + pgd_index(vaddr);
 150                 p4d = p4d_offset(pgd, vaddr);
 151                 pud = pud_offset(p4d, vaddr);
 152                 pmd = pmd_offset(pud, vaddr);
 153                 pte = pte_offset_kernel(pmd, vaddr);
 154                 pte_set_val(*pte, p, PAGE_READONLY);
 155         }
 156 #endif
 157 }
 158
 159 void __init paging_init(void)
 160 {
 161         unsigned long zones_size[MAX_NR_ZONES], vaddr;
 162         int i;
 163
 164         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 165                                                                PAGE_SIZE);
 166         if (!empty_zero_page)
 167                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 168                       __func__, PAGE_SIZE, PAGE_SIZE);
 169
 170         for (i = 0; i < ARRAY_SIZE(zones_size); i++)
 171                 zones_size[i] = 0;
 172
 173         zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
 174                 (uml_physmem >> PAGE_SHIFT);
 175         free_area_init(zones_size);
 176
 177         /*
 178          * Fixed mappings, only the page table structure has to be
 179          * created - mappings will be set by set_fixmap():
 180          */
 181         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 182         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 183
 184         fixaddr_user_init();
 185 }
 186
 187 /*
 188  * This can't do anything because nothing in the kernel image can be freed
 189  * since it's not in kernel physical memory.
 190  */
 191
 192 void free_initmem(void)
 193 {
 194 }
 195
 196 /* Allocate and free page tables. */
 197
 198 pgd_t *pgd_alloc(struct mm_struct *mm)
 199 {
 200         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 201
 202         if (pgd) {
 203                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 204                 memcpy(pgd + USER_PTRS_PER_PGD,
 205                        swapper_pg_dir + USER_PTRS_PER_PGD,
 206                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 207         }
 208         return pgd;
 209 }
 210
 211 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
 212 {
 213         free_page((unsigned long) pgd);
 214 }
 215
 216 #ifdef CONFIG_3_LEVEL_PGTABLES
 217 pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 218 {
 219         pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
 220
 221         if (pmd)
 222                 memset(pmd, 0, PAGE_SIZE);
 223
 224         return pmd;
 225 }
 226 #endif
 227
 228 void *uml_kmalloc(int size, int flags)
 229 {
 230         return kmalloc(size, flags);
 231 }