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 #include <linux/sched/task.h>
  22
  23 #ifdef CONFIG_KASAN
  24 int kasan_um_is_ready;
  25 void kasan_init(void)
  26 {
  27         /*
  28          * kasan_map_memory will map all of the required address space and
  29          * the host machine will allocate physical memory as necessary.
  30          */
  31         kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE);
  32         init_task.kasan_depth = 0;
  33         kasan_um_is_ready = true;
  34 }
  35
  36 static void (*kasan_init_ptr)(void)
  37 __section(".kasan_init") __used
  38 = kasan_init;
  39 #endif
  40
  41 /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
  42 unsigned long *empty_zero_page = NULL;
  43 EXPORT_SYMBOL(empty_zero_page);
  44
  45 /*
  46  * Initialized during boot, and readonly for initializing page tables
  47  * afterwards
  48  */
  49 pgd_t swapper_pg_dir[PTRS_PER_PGD];
  50
  51 /* Initialized at boot time, and readonly after that */
  52 unsigned long long highmem;
  53 EXPORT_SYMBOL(highmem);
  54 int kmalloc_ok = 0;
  55
  56 /* Used during early boot */
  57 static unsigned long brk_end;
  58
  59 void __init mem_init(void)
  60 {
  61         /* clear the zero-page */
  62         memset(empty_zero_page, 0, PAGE_SIZE);
  63
  64         /* Map in the area just after the brk now that kmalloc is about
  65          * to be turned on.
  66          */
  67         brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
  68         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
  69         memblock_free((void *)brk_end, uml_reserved - brk_end);
  70         uml_reserved = brk_end;
  71
  72         /* this will put all low memory onto the freelists */
  73         memblock_free_all();
  74         max_low_pfn = totalram_pages();
  75         max_pfn = max_low_pfn;
  76         kmalloc_ok = 1;
  77 }
  78
  79 /*
  80  * Create a page table and place a pointer to it in a middle page
  81  * directory entry.
  82  */
  83 static void __init one_page_table_init(pmd_t *pmd)
  84 {
  85         if (pmd_none(*pmd)) {
  86                 pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
  87                                                           PAGE_SIZE);
  88                 if (!pte)
  89                         panic("%s: Failed to allocate %lu bytes align=%lx\n",
  90                               __func__, PAGE_SIZE, PAGE_SIZE);
  91
  92                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  93                                            (unsigned long) __pa(pte)));
  94                 BUG_ON(pte != pte_offset_kernel(pmd, 0));
  95         }
  96 }
  97
  98 static void __init one_md_table_init(pud_t *pud)
  99 {
 100 #ifdef CONFIG_3_LEVEL_PGTABLES
 101         pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
 102         if (!pmd_table)
 103                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 104                       __func__, PAGE_SIZE, PAGE_SIZE);
 105
 106         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
 107         BUG_ON(pmd_table != pmd_offset(pud, 0));
 108 #endif
 109 }
 110
 111 static void __init fixrange_init(unsigned long start, unsigned long end,
 112                                  pgd_t *pgd_base)
 113 {
 114         pgd_t *pgd;
 115         p4d_t *p4d;
 116         pud_t *pud;
 117         pmd_t *pmd;
 118         int i, j;
 119         unsigned long vaddr;
 120
 121         vaddr = start;
 122         i = pgd_index(vaddr);
 123         j = pmd_index(vaddr);
 124         pgd = pgd_base + i;
 125
 126         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 127                 p4d = p4d_offset(pgd, vaddr);
 128                 pud = pud_offset(p4d, vaddr);
 129                 if (pud_none(*pud))
 130                         one_md_table_init(pud);
 131                 pmd = pmd_offset(pud, vaddr);
 132                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 133                         one_page_table_init(pmd);
 134                         vaddr += PMD_SIZE;
 135                 }
 136                 j = 0;
 137         }
 138 }
 139
 140 static void __init fixaddr_user_init( void)
 141 {
 142 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 143         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 144         pte_t *pte;
 145         phys_t p;
 146         unsigned long v, vaddr = FIXADDR_USER_START;
 147
 148         if (!size)
 149                 return;
 150
 151         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 152         v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
 153         if (!v)
 154                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 155                       __func__, size, PAGE_SIZE);
 156
 157         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 158         p = __pa(v);
 159         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 160                       p += PAGE_SIZE) {
 161                 pte = virt_to_kpte(vaddr);
 162                 pte_set_val(*pte, p, PAGE_READONLY);
 163         }
 164 #endif
 165 }
 166
 167 void __init paging_init(void)
 168 {
 169         unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 170         unsigned long vaddr;
 171
 172         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 173                                                                PAGE_SIZE);
 174         if (!empty_zero_page)
 175                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 176                       __func__, PAGE_SIZE, PAGE_SIZE);
 177
 178         max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
 179         free_area_init(max_zone_pfn);
 180
 181         /*
 182          * Fixed mappings, only the page table structure has to be
 183          * created - mappings will be set by set_fixmap():
 184          */
 185         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 186         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 187
 188         fixaddr_user_init();
 189 }
 190
 191 /*
 192  * This can't do anything because nothing in the kernel image can be freed
 193  * since it's not in kernel physical memory.
 194  */
 195
 196 void free_initmem(void)
 197 {
 198 }
 199
 200 /* Allocate and free page tables. */
 201
 202 pgd_t *pgd_alloc(struct mm_struct *mm)
 203 {
 204         pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
 205
 206         if (pgd) {
 207                 memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
 208                 memcpy(pgd + USER_PTRS_PER_PGD,
 209                        swapper_pg_dir + USER_PTRS_PER_PGD,
 210                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 211         }
 212         return pgd;
 213 }
 214
 215 void *uml_kmalloc(int size, int flags)
 216 {
 217         return kmalloc(size, flags);
 218 }
 219
 220 static const pgprot_t protection_map[16] = {
 221         [VM_NONE]                                       = PAGE_NONE,
 222         [VM_READ]                                       = PAGE_READONLY,
 223         [VM_WRITE]                                      = PAGE_COPY,
 224         [VM_WRITE | VM_READ]                            = PAGE_COPY,
 225         [VM_EXEC]                                       = PAGE_READONLY,
 226         [VM_EXEC | VM_READ]                             = PAGE_READONLY,
 227         [VM_EXEC | VM_WRITE]                            = PAGE_COPY,
 228         [VM_EXEC | VM_WRITE | VM_READ]                  = PAGE_COPY,
 229         [VM_SHARED]                                     = PAGE_NONE,
 230         [VM_SHARED | VM_READ]                           = PAGE_READONLY,
 231         [VM_SHARED | VM_WRITE]                          = PAGE_SHARED,
 232         [VM_SHARED | VM_WRITE | VM_READ]                = PAGE_SHARED,
 233         [VM_SHARED | VM_EXEC]                           = PAGE_READONLY,
 234         [VM_SHARED | VM_EXEC | VM_READ]                 = PAGE_READONLY,
 235         [VM_SHARED | VM_EXEC | VM_WRITE]                = PAGE_SHARED,
 236         [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]      = PAGE_SHARED
 237 };
 238 DECLARE_VM_GET_PAGE_PROT