arch/arm64/mm/kasan_init.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * This file contains kasan initialization code for ARM64.
   4  *
   5  * Copyright (c) 2015 Samsung Electronics Co., Ltd.
   6  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
   7  */
   8
   9 #define pr_fmt(fmt) "kasan: " fmt
  10 #include <linux/kasan.h>
  11 #include <linux/kernel.h>
  12 #include <linux/sched/task.h>
  13 #include <linux/memblock.h>
  14 #include <linux/start_kernel.h>
  15 #include <linux/mm.h>
  16
  17 #include <asm/mmu_context.h>
  18 #include <asm/kernel-pgtable.h>
  19 #include <asm/page.h>
  20 #include <asm/pgalloc.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/sections.h>
  23 #include <asm/tlbflush.h>
  24
  25 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
  26
  27 /*
  28  * The p*d_populate functions call virt_to_phys implicitly so they can't be used
  29  * directly on kernel symbols (bm_p*d). All the early functions are called too
  30  * early to use lm_alias so __p*d_populate functions must be used to populate
  31  * with the physical address from __pa_symbol.
  32  */
  33
  34 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
  35 {
  36         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
  37                                               __pa(MAX_DMA_ADDRESS),
  38                                               MEMBLOCK_ALLOC_KASAN, node);
  39         if (!p)
  40                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  41                       __func__, PAGE_SIZE, PAGE_SIZE, node,
  42                       __pa(MAX_DMA_ADDRESS));
  43
  44         return __pa(p);
  45 }
  46
  47 static phys_addr_t __init kasan_alloc_raw_page(int node)
  48 {
  49         void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
  50                                                 __pa(MAX_DMA_ADDRESS),
  51                                                 MEMBLOCK_ALLOC_KASAN, node);
  52         if (!p)
  53                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  54                       __func__, PAGE_SIZE, PAGE_SIZE, node,
  55                       __pa(MAX_DMA_ADDRESS));
  56
  57         return __pa(p);
  58 }
  59
  60 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
  61                                       bool early)
  62 {
  63         if (pmd_none(READ_ONCE(*pmdp))) {
  64                 phys_addr_t pte_phys = early ?
  65                                 __pa_symbol(kasan_early_shadow_pte)
  66                                         : kasan_alloc_zeroed_page(node);
  67                 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
  68         }
  69
  70         return early ? pte_offset_kimg(pmdp, addr)
  71                      : pte_offset_kernel(pmdp, addr);
  72 }
  73
  74 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
  75                                       bool early)
  76 {
  77         if (pud_none(READ_ONCE(*pudp))) {
  78                 phys_addr_t pmd_phys = early ?
  79                                 __pa_symbol(kasan_early_shadow_pmd)
  80                                         : kasan_alloc_zeroed_page(node);
  81                 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
  82         }
  83
  84         return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
  85 }
  86
  87 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
  88                                       bool early)
  89 {
  90         if (pgd_none(READ_ONCE(*pgdp))) {
  91                 phys_addr_t pud_phys = early ?
  92                                 __pa_symbol(kasan_early_shadow_pud)
  93                                         : kasan_alloc_zeroed_page(node);
  94                 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
  95         }
  96
  97         return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
  98 }
  99
 100 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 101                                       unsigned long end, int node, bool early)
 102 {
 103         unsigned long next;
 104         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
 105
 106         do {
 107                 phys_addr_t page_phys = early ?
 108                                 __pa_symbol(kasan_early_shadow_page)
 109                                         : kasan_alloc_raw_page(node);
 110                 if (!early)
 111                         memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
 112                 next = addr + PAGE_SIZE;
 113                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 114         } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
 115 }
 116
 117 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 118                                       unsigned long end, int node, bool early)
 119 {
 120         unsigned long next;
 121         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 122
 123         do {
 124                 next = pmd_addr_end(addr, end);
 125                 kasan_pte_populate(pmdp, addr, next, node, early);
 126         } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
 127 }
 128
 129 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
 130                                       unsigned long end, int node, bool early)
 131 {
 132         unsigned long next;
 133         pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
 134
 135         do {
 136                 next = pud_addr_end(addr, end);
 137                 kasan_pmd_populate(pudp, addr, next, node, early);
 138         } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
 139 }
 140
 141 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 142                                       int node, bool early)
 143 {
 144         unsigned long next;
 145         pgd_t *pgdp;
 146
 147         pgdp = pgd_offset_k(addr);
 148         do {
 149                 next = pgd_addr_end(addr, end);
 150                 kasan_pud_populate(pgdp, addr, next, node, early);
 151         } while (pgdp++, addr = next, addr != end);
 152 }
 153
 154 /* The early shadow maps everything to a single page of zeroes */
 155 asmlinkage void __init kasan_early_init(void)
 156 {
 157         BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
 158                 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
 159         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE));
 160         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE));
 161         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 162         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
 163                            true);
 164 }
 165
 166 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 167 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 168                                       int node)
 169 {
 170         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 171 }
 172
 173 /*
 174  * Copy the current shadow region into a new pgdir.
 175  */
 176 void __init kasan_copy_shadow(pgd_t *pgdir)
 177 {
 178         pgd_t *pgdp, *pgdp_new, *pgdp_end;
 179
 180         pgdp = pgd_offset_k(KASAN_SHADOW_START);
 181         pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
 182         pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
 183         do {
 184                 set_pgd(pgdp_new, READ_ONCE(*pgdp));
 185         } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
 186 }
 187
 188 static void __init clear_pgds(unsigned long start,
 189                         unsigned long end)
 190 {
 191         /*
 192          * Remove references to kasan page tables from
 193          * swapper_pg_dir. pgd_clear() can't be used
 194          * here because it's nop on 2,3-level pagetable setups
 195          */
 196         for (; start < end; start += PGDIR_SIZE)
 197                 set_pgd(pgd_offset_k(start), __pgd(0));
 198 }
 199
 200 void __init kasan_init(void)
 201 {
 202         u64 kimg_shadow_start, kimg_shadow_end;
 203         u64 mod_shadow_start, mod_shadow_end;
 204         struct memblock_region *reg;
 205         int i;
 206
 207         kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
 208         kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
 209
 210         mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
 211         mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
 212
 213         /*
 214          * We are going to perform proper setup of shadow memory.
 215          * At first we should unmap early shadow (clear_pgds() call below).
 216          * However, instrumented code couldn't execute without shadow memory.
 217          * tmp_pg_dir used to keep early shadow mapped until full shadow
 218          * setup will be finished.
 219          */
 220         memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
 221         dsb(ishst);
 222         cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
 223
 224         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 225
 226         kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
 227                            early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
 228
 229         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
 230                                    (void *)mod_shadow_start);
 231         kasan_populate_early_shadow((void *)kimg_shadow_end,
 232                                    (void *)KASAN_SHADOW_END);
 233
 234         if (kimg_shadow_start > mod_shadow_end)
 235                 kasan_populate_early_shadow((void *)mod_shadow_end,
 236                                             (void *)kimg_shadow_start);
 237
 238         for_each_memblock(memory, reg) {
 239                 void *start = (void *)__phys_to_virt(reg->base);
 240                 void *end = (void *)__phys_to_virt(reg->base + reg->size);
 241
 242                 if (start >= end)
 243                         break;
 244
 245                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 246                                    (unsigned long)kasan_mem_to_shadow(end),
 247                                    early_pfn_to_nid(virt_to_pfn(start)));
 248         }
 249
 250         /*
 251          * KAsan may reuse the contents of kasan_early_shadow_pte directly,
 252          * so we should make sure that it maps the zero page read-only.
 253          */
 254         for (i = 0; i < PTRS_PER_PTE; i++)
 255                 set_pte(&kasan_early_shadow_pte[i],
 256                         pfn_pte(sym_to_pfn(kasan_early_shadow_page),
 257                                 PAGE_KERNEL_RO));
 258
 259         memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 260         cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 261
 262         /* At this point kasan is fully initialized. Enable error messages */
 263         init_task.kasan_depth = 0;
 264         pr_info("KernelAddressSanitizer initialized\n");
 265 }