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/mm.h>
  10 #include <linux/swap.h>
  11 #include <linux/slab.h>
  12 #include <asm/fixmap.h>
  13 #include <asm/page.h>
  14 #include <asm/pgalloc.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 <um_malloc.h>
  22 #include <linux/sched/task.h>
  23
  24 #ifdef CONFIG_KASAN
  25 int kasan_um_is_ready;
  26 void kasan_init(void)
  27 {
  28         /*
  29          * kasan_map_memory will map all of the required address space and
  30          * the host machine will allocate physical memory as necessary.
  31          */
  32         kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE);
  33         init_task.kasan_depth = 0;
  34         kasan_um_is_ready = true;
  35 }
  36
  37 static void (*kasan_init_ptr)(void)
  38 __section(".kasan_init") __used
  39 = kasan_init;
  40 #endif
  41
  42 /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
  43 unsigned long *empty_zero_page = NULL;
  44 EXPORT_SYMBOL(empty_zero_page);
  45
  46 /*
  47  * Initialized during boot, and readonly for initializing page tables
  48  * afterwards
  49  */
  50 pgd_t swapper_pg_dir[PTRS_PER_PGD];
  51
  52 /* Initialized at boot time, and readonly after that */
  53 int kmalloc_ok = 0;
  54
  55 /* Used during early boot */
  56 static unsigned long brk_end;
  57
  58 void __init mem_init(void)
  59 {
  60         /* clear the zero-page */
  61         memset(empty_zero_page, 0, PAGE_SIZE);
  62
  63         /* Map in the area just after the brk now that kmalloc is about
  64          * to be turned on.
  65          */
  66         brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
  67         map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
  68         memblock_free((void *)brk_end, uml_reserved - brk_end);
  69         uml_reserved = brk_end;
  70
  71         /* this will put all low memory onto the freelists */
  72         memblock_free_all();
  73         max_pfn = max_low_pfn;
  74         kmalloc_ok = 1;
  75 }
  76
  77 /*
  78  * Create a page table and place a pointer to it in a middle page
  79  * directory entry.
  80  */
  81 static void __init one_page_table_init(pmd_t *pmd)
  82 {
  83         if (pmd_none(*pmd)) {
  84                 pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
  85                                                           PAGE_SIZE);
  86                 if (!pte)
  87                         panic("%s: Failed to allocate %lu bytes align=%lx\n",
  88                               __func__, PAGE_SIZE, PAGE_SIZE);
  89
  90                 set_pmd(pmd, __pmd(_KERNPG_TABLE +
  91                                            (unsigned long) __pa(pte)));
  92                 BUG_ON(pte != pte_offset_kernel(pmd, 0));
  93         }
  94 }
  95
  96 static void __init one_md_table_init(pud_t *pud)
  97 {
  98 #if CONFIG_PGTABLE_LEVELS > 2
  99         pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
 100         if (!pmd_table)
 101                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 102                       __func__, PAGE_SIZE, PAGE_SIZE);
 103
 104         set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
 105         BUG_ON(pmd_table != pmd_offset(pud, 0));
 106 #endif
 107 }
 108
 109 static void __init one_ud_table_init(p4d_t *p4d)
 110 {
 111 #if CONFIG_PGTABLE_LEVELS > 3
 112         pud_t *pud_table = (pud_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
 113         if (!pud_table)
 114                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 115                       __func__, PAGE_SIZE, PAGE_SIZE);
 116
 117         set_p4d(p4d, __p4d(_KERNPG_TABLE + (unsigned long) __pa(pud_table)));
 118         BUG_ON(pud_table != pud_offset(p4d, 0));
 119 #endif
 120 }
 121
 122 static void __init fixrange_init(unsigned long start, unsigned long end,
 123                                  pgd_t *pgd_base)
 124 {
 125         pgd_t *pgd;
 126         p4d_t *p4d;
 127         pud_t *pud;
 128         pmd_t *pmd;
 129         int i, j;
 130         unsigned long vaddr;
 131
 132         vaddr = start;
 133         i = pgd_index(vaddr);
 134         j = pmd_index(vaddr);
 135         pgd = pgd_base + i;
 136
 137         for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
 138                 p4d = p4d_offset(pgd, vaddr);
 139                 if (p4d_none(*p4d))
 140                         one_ud_table_init(p4d);
 141                 pud = pud_offset(p4d, vaddr);
 142                 if (pud_none(*pud))
 143                         one_md_table_init(pud);
 144                 pmd = pmd_offset(pud, vaddr);
 145                 for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
 146                         one_page_table_init(pmd);
 147                         vaddr += PMD_SIZE;
 148                 }
 149                 j = 0;
 150         }
 151 }
 152
 153 static void __init fixaddr_user_init( void)
 154 {
 155 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 156         long size = FIXADDR_USER_END - FIXADDR_USER_START;
 157         pte_t *pte;
 158         phys_t p;
 159         unsigned long v, vaddr = FIXADDR_USER_START;
 160
 161         if (!size)
 162                 return;
 163
 164         fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
 165         v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
 166         if (!v)
 167                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 168                       __func__, size, PAGE_SIZE);
 169
 170         memcpy((void *) v , (void *) FIXADDR_USER_START, size);
 171         p = __pa(v);
 172         for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 173                       p += PAGE_SIZE) {
 174                 pte = virt_to_kpte(vaddr);
 175                 pte_set_val(*pte, p, PAGE_READONLY);
 176         }
 177 #endif
 178 }
 179
 180 void __init paging_init(void)
 181 {
 182         unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
 183         unsigned long vaddr;
 184
 185         empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 186                                                                PAGE_SIZE);
 187         if (!empty_zero_page)
 188                 panic("%s: Failed to allocate %lu bytes align=%lx\n",
 189                       __func__, PAGE_SIZE, PAGE_SIZE);
 190
 191         max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
 192         free_area_init(max_zone_pfn);
 193
 194         /*
 195          * Fixed mappings, only the page table structure has to be
 196          * created - mappings will be set by set_fixmap():
 197          */
 198         vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
 199         fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
 200
 201         fixaddr_user_init();
 202 }
 203
 204 /*
 205  * This can't do anything because nothing in the kernel image can be freed
 206  * since it's not in kernel physical memory.
 207  */
 208
 209 void free_initmem(void)
 210 {
 211 }
 212
 213 /* Allocate and free page tables. */
 214
 215 pgd_t *pgd_alloc(struct mm_struct *mm)
 216 {
 217         pgd_t *pgd = __pgd_alloc(mm, 0);
 218
 219         if (pgd)
 220                 memcpy(pgd + USER_PTRS_PER_PGD,
 221                        swapper_pg_dir + USER_PTRS_PER_PGD,
 222                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
 223
 224         return pgd;
 225 }
 226
 227 void *uml_kmalloc(int size, int flags)
 228 {
 229         return kmalloc(size, flags);
 230 }
 231
 232 static const pgprot_t protection_map[16] = {
 233         [VM_NONE]                                       = PAGE_NONE,
 234         [VM_READ]                                       = PAGE_READONLY,
 235         [VM_WRITE]                                      = PAGE_COPY,
 236         [VM_WRITE | VM_READ]                            = PAGE_COPY,
 237         [VM_EXEC]                                       = PAGE_READONLY,
 238         [VM_EXEC | VM_READ]                             = PAGE_READONLY,
 239         [VM_EXEC | VM_WRITE]                            = PAGE_COPY,
 240         [VM_EXEC | VM_WRITE | VM_READ]                  = PAGE_COPY,
 241         [VM_SHARED]                                     = PAGE_NONE,
 242         [VM_SHARED | VM_READ]                           = PAGE_READONLY,
 243         [VM_SHARED | VM_WRITE]                          = PAGE_SHARED,
 244         [VM_SHARED | VM_WRITE | VM_READ]                = PAGE_SHARED,
 245         [VM_SHARED | VM_EXEC]                           = PAGE_READONLY,
 246         [VM_SHARED | VM_EXEC | VM_READ]                 = PAGE_READONLY,
 247         [VM_SHARED | VM_EXEC | VM_WRITE]                = PAGE_SHARED,
 248         [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]      = PAGE_SHARED
 249 };
 250 DECLARE_VM_GET_PAGE_PROT