um/kernel/mem.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
0004  */
0005
0006 #include <linux/stddef.h>
0007 #include <linux/module.h>
0008 #include <linux/memblock.h>
0009 #include <linux/highmem.h>
0010 #include <linux/mm.h>
0011 #include <linux/swap.h>
0012 #include <linux/slab.h>
0013 #include <asm/fixmap.h>
0014 #include <asm/page.h>
0015 #include <as-layout.h>
0016 #include <init.h>
0017 #include <kern.h>
0018 #include <kern_util.h>
0019 #include <mem_user.h>
0020 #include <os.h>
0021 #include <linux/sched/task.h>
0022
0023 #ifdef CONFIG_KASAN
0024 int kasan_um_is_ready;
0025 void kasan_init(void)
0026 {
0027     /*
0028      * kasan_map_memory will map all of the required address space and
0029      * the host machine will allocate physical memory as necessary.
0030      */
0031     kasan_map_memory((void *)KASAN_SHADOW_START, KASAN_SHADOW_SIZE);
0032     init_task.kasan_depth = 0;
0033     kasan_um_is_ready = true;
0034 }
0035
0036 static void (*kasan_init_ptr)(void)
0037 __section(".kasan_init") __used
0038 = kasan_init;
0039 #endif
0040
0041 /* allocated in paging_init, zeroed in mem_init, and unchanged thereafter */
0042 unsigned long *empty_zero_page = NULL;
0043 EXPORT_SYMBOL(empty_zero_page);
0044
0045 /*
0046  * Initialized during boot, and readonly for initializing page tables
0047  * afterwards
0048  */
0049 pgd_t swapper_pg_dir[PTRS_PER_PGD];
0050
0051 /* Initialized at boot time, and readonly after that */
0052 unsigned long long highmem;
0053 EXPORT_SYMBOL(highmem);
0054 int kmalloc_ok = 0;
0055
0056 /* Used during early boot */
0057 static unsigned long brk_end;
0058
0059 void __init mem_init(void)
0060 {
0061     /* clear the zero-page */
0062     memset(empty_zero_page, 0, PAGE_SIZE);
0063
0064     /* Map in the area just after the brk now that kmalloc is about
0065      * to be turned on.
0066      */
0067     brk_end = (unsigned long) UML_ROUND_UP(sbrk(0));
0068     map_memory(brk_end, __pa(brk_end), uml_reserved - brk_end, 1, 1, 0);
0069     memblock_free((void *)brk_end, uml_reserved - brk_end);
0070     uml_reserved = brk_end;
0071
0072     /* this will put all low memory onto the freelists */
0073     memblock_free_all();
0074     max_low_pfn = totalram_pages();
0075     max_pfn = max_low_pfn;
0076     kmalloc_ok = 1;
0077 }
0078
0079 /*
0080  * Create a page table and place a pointer to it in a middle page
0081  * directory entry.
0082  */
0083 static void __init one_page_table_init(pmd_t *pmd)
0084 {
0085     if (pmd_none(*pmd)) {
0086         pte_t *pte = (pte_t *) memblock_alloc_low(PAGE_SIZE,
0087                               PAGE_SIZE);
0088         if (!pte)
0089             panic("%s: Failed to allocate %lu bytes align=%lx\n",
0090                   __func__, PAGE_SIZE, PAGE_SIZE);
0091
0092         set_pmd(pmd, __pmd(_KERNPG_TABLE +
0093                        (unsigned long) __pa(pte)));
0094         BUG_ON(pte != pte_offset_kernel(pmd, 0));
0095     }
0096 }
0097
0098 static void __init one_md_table_init(pud_t *pud)
0099 {
0100 #ifdef CONFIG_3_LEVEL_PGTABLES
0101     pmd_t *pmd_table = (pmd_t *) memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
0102     if (!pmd_table)
0103         panic("%s: Failed to allocate %lu bytes align=%lx\n",
0104               __func__, PAGE_SIZE, PAGE_SIZE);
0105
0106     set_pud(pud, __pud(_KERNPG_TABLE + (unsigned long) __pa(pmd_table)));
0107     BUG_ON(pmd_table != pmd_offset(pud, 0));
0108 #endif
0109 }
0110
0111 static void __init fixrange_init(unsigned long start, unsigned long end,
0112                  pgd_t *pgd_base)
0113 {
0114     pgd_t *pgd;
0115     p4d_t *p4d;
0116     pud_t *pud;
0117     pmd_t *pmd;
0118     int i, j;
0119     unsigned long vaddr;
0120
0121     vaddr = start;
0122     i = pgd_index(vaddr);
0123     j = pmd_index(vaddr);
0124     pgd = pgd_base + i;
0125
0126     for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
0127         p4d = p4d_offset(pgd, vaddr);
0128         pud = pud_offset(p4d, vaddr);
0129         if (pud_none(*pud))
0130             one_md_table_init(pud);
0131         pmd = pmd_offset(pud, vaddr);
0132         for (; (j < PTRS_PER_PMD) && (vaddr < end); pmd++, j++) {
0133             one_page_table_init(pmd);
0134             vaddr += PMD_SIZE;
0135         }
0136         j = 0;
0137     }
0138 }
0139
0140 static void __init fixaddr_user_init( void)
0141 {
0142 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
0143     long size = FIXADDR_USER_END - FIXADDR_USER_START;
0144     pte_t *pte;
0145     phys_t p;
0146     unsigned long v, vaddr = FIXADDR_USER_START;
0147
0148     if (!size)
0149         return;
0150
0151     fixrange_init( FIXADDR_USER_START, FIXADDR_USER_END, swapper_pg_dir);
0152     v = (unsigned long) memblock_alloc_low(size, PAGE_SIZE);
0153     if (!v)
0154         panic("%s: Failed to allocate %lu bytes align=%lx\n",
0155               __func__, size, PAGE_SIZE);
0156
0157     memcpy((void *) v , (void *) FIXADDR_USER_START, size);
0158     p = __pa(v);
0159     for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
0160               p += PAGE_SIZE) {
0161         pte = virt_to_kpte(vaddr);
0162         pte_set_val(*pte, p, PAGE_READONLY);
0163     }
0164 #endif
0165 }
0166
0167 void __init paging_init(void)
0168 {
0169     unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
0170     unsigned long vaddr;
0171
0172     empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
0173                                    PAGE_SIZE);
0174     if (!empty_zero_page)
0175         panic("%s: Failed to allocate %lu bytes align=%lx\n",
0176               __func__, PAGE_SIZE, PAGE_SIZE);
0177
0178     max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
0179     free_area_init(max_zone_pfn);
0180
0181     /*
0182      * Fixed mappings, only the page table structure has to be
0183      * created - mappings will be set by set_fixmap():
0184      */
0185     vaddr = __fix_to_virt(__end_of_fixed_addresses - 1) & PMD_MASK;
0186     fixrange_init(vaddr, FIXADDR_TOP, swapper_pg_dir);
0187
0188     fixaddr_user_init();
0189 }
0190
0191 /*
0192  * This can't do anything because nothing in the kernel image can be freed
0193  * since it's not in kernel physical memory.
0194  */
0195
0196 void free_initmem(void)
0197 {
0198 }
0199
0200 /* Allocate and free page tables. */
0201
0202 pgd_t *pgd_alloc(struct mm_struct *mm)
0203 {
0204     pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL);
0205
0206     if (pgd) {
0207         memset(pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));
0208         memcpy(pgd + USER_PTRS_PER_PGD,
0209                swapper_pg_dir + USER_PTRS_PER_PGD,
0210                (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
0211     }
0212     return pgd;
0213 }
0214
0215 void *uml_kmalloc(int size, int flags)
0216 {
0217     return kmalloc(size, flags);
0218 }
0219
0220 static const pgprot_t protection_map[16] = {
0221     [VM_NONE]                   = PAGE_NONE,
0222     [VM_READ]                   = PAGE_READONLY,
0223     [VM_WRITE]                  = PAGE_COPY,
0224     [VM_WRITE | VM_READ]                = PAGE_COPY,
0225     [VM_EXEC]                   = PAGE_READONLY,
0226     [VM_EXEC | VM_READ]             = PAGE_READONLY,
0227     [VM_EXEC | VM_WRITE]                = PAGE_COPY,
0228     [VM_EXEC | VM_WRITE | VM_READ]          = PAGE_COPY,
0229     [VM_SHARED]                 = PAGE_NONE,
0230     [VM_SHARED | VM_READ]               = PAGE_READONLY,
0231     [VM_SHARED | VM_WRITE]              = PAGE_SHARED,
0232     [VM_SHARED | VM_WRITE | VM_READ]        = PAGE_SHARED,
0233     [VM_SHARED | VM_EXEC]               = PAGE_READONLY,
0234     [VM_SHARED | VM_EXEC | VM_READ]         = PAGE_READONLY,
0235     [VM_SHARED | VM_EXEC | VM_WRITE]        = PAGE_SHARED,
0236     [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ]  = PAGE_SHARED
0237 };
0238 DECLARE_VM_GET_PAGE_PROT