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         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                 pte = virt_to_kpte(vaddr);
 146                 pte_set_val(*pte, p, PAGE_READONLY);
 147         }
 148 #endif
 149 }
 150
 151 void __init paging_init(void)
 152 {
 153         unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 154         unsigned long vaddr;
 155
 156         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 157                                                                PAGE_SIZE);
 158         if (!empty_zero_page)
 159                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 160                       __func__, PAGE_SIZE, PAGE_SIZE);
 161
 162         max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
 163         free_area_init(max_zone_pfn);
 164
 165         /*
 166          * Fixed mappings, only the page table structure has to be
 167          * created - mappings will be set by set_fixmap():
 168          */
 169         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 170         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 171
 172         fixaddr_user_init();
 173 }
 174
 175 /*
 176  * This can't do anything because nothing in the kernel image can be freed
 177  * since it's not in kernel physical memory.
 178  */
 179
 180 void free_initmem(void)
 181 {
 182 }
 183
 184 /* Allocate and free page tables. */
 185
 186 pgd_t *pgd_alloc(struct mm_struct *mm)
 187 {
 188         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 189
 190         if (pgd) {
 191                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 192                 memcpy(pgd + USER_PTRS_PER_PGD,
 193                        swapper_pg_dir + USER_PTRS_PER_PGD,
 194                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 195         }
 196         return pgd;
 197 }
 198
 199 void *uml_kmalloc(int size, int flags)
 200 {
 201         return kmalloc(size, flags);
 202 }