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/sections.h>
  22 #include <asm/tlbflush.h>
  23
  24 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
  25
  26 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
  27
  28 /*
  29  * The p*d_populate functions call virt_to_phys implicitly so they can't be used
  30  * directly on kernel symbols (bm_p*d). All the early functions are called too
  31  * early to use lm_alias so __p*d_populate functions must be used to populate
  32  * with the physical address from __pa_symbol.
  33  */
  34
  35 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
  36 {
  37         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
  38                                               __pa(MAX_DMA_ADDRESS),
  39                                               MEMBLOCK_ALLOC_KASAN, node);
  40         if (!p)
  41                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  42                       __func__, PAGE_SIZE, PAGE_SIZE, node,
  43                       __pa(MAX_DMA_ADDRESS));
  44
  45         return __pa(p);
  46 }
  47
  48 static phys_addr_t __init kasan_alloc_raw_page(int node)
  49 {
  50         void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
  51                                                 __pa(MAX_DMA_ADDRESS),
  52                                                 MEMBLOCK_ALLOC_KASAN, node);
  53         if (!p)
  54                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  55                       __func__, PAGE_SIZE, PAGE_SIZE, node,
  56                       __pa(MAX_DMA_ADDRESS));
  57
  58         return __pa(p);
  59 }
  60
  61 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
  62                                       bool early)
  63 {
  64         if (pmd_none(READ_ONCE(*pmdp))) {
  65                 phys_addr_t pte_phys = early ?
  66                                 __pa_symbol(kasan_early_shadow_pte)
  67                                         : kasan_alloc_zeroed_page(node);
  68                 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
  69         }
  70
  71         return early ? pte_offset_kimg(pmdp, addr)
  72                      : pte_offset_kernel(pmdp, addr);
  73 }
  74
  75 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
  76                                       bool early)
  77 {
  78         if (pud_none(READ_ONCE(*pudp))) {
  79                 phys_addr_t pmd_phys = early ?
  80                                 __pa_symbol(kasan_early_shadow_pmd)
  81                                         : kasan_alloc_zeroed_page(node);
  82                 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
  83         }
  84
  85         return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
  86 }
  87
  88 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
  89                                       bool early)
  90 {
  91         if (p4d_none(READ_ONCE(*p4dp))) {
  92                 phys_addr_t pud_phys = early ?
  93                                 __pa_symbol(kasan_early_shadow_pud)
  94                                         : kasan_alloc_zeroed_page(node);
  95                 __p4d_populate(p4dp, pud_phys, PMD_TYPE_TABLE);
  96         }
  97
  98         return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr);
  99 }
 100
 101 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 102                                       unsigned long end, int node, bool early)
 103 {
 104         unsigned long next;
 105         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
 106
 107         do {
 108                 phys_addr_t page_phys = early ?
 109                                 __pa_symbol(kasan_early_shadow_page)
 110                                         : kasan_alloc_raw_page(node);
 111                 if (!early)
 112                         memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
 113                 next = addr + PAGE_SIZE;
 114                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 115         } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
 116 }
 117
 118 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 119                                       unsigned long end, int node, bool early)
 120 {
 121         unsigned long next;
 122         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 123
 124         do {
 125                 next = pmd_addr_end(addr, end);
 126                 kasan_pte_populate(pmdp, addr, next, node, early);
 127         } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
 128 }
 129
 130 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 131                                       unsigned long end, int node, bool early)
 132 {
 133         unsigned long next;
 134         pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 135
 136         do {
 137                 next = pud_addr_end(addr, end);
 138                 kasan_pmd_populate(pudp, addr, next, node, early);
 139         } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
 140 }
 141
 142 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
 143                                       unsigned long end, int node, bool early)
 144 {
 145         unsigned long next;
 146         p4d_t *p4dp = p4d_offset(pgdp, addr);
 147
 148         do {
 149                 next = p4d_addr_end(addr, end);
 150                 kasan_pud_populate(p4dp, addr, next, node, early);
 151         } while (p4dp++, addr = next, addr != end);
 152 }
 153
 154 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 155                                       int node, bool early)
 156 {
 157         unsigned long next;
 158         pgd_t *pgdp;
 159
 160         pgdp = pgd_offset_k(addr);
 161         do {
 162                 next = pgd_addr_end(addr, end);
 163                 kasan_p4d_populate(pgdp, addr, next, node, early);
 164         } while (pgdp++, addr = next, addr != end);
 165 }
 166
 167 /* The early shadow maps everything to a single page of zeroes */
 168 asmlinkage void __init kasan_early_init(void)
 169 {
 170         BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
 171                 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
 172         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE));
 173         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE));
 174         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 175         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
 176                            true);
 177 }
 178
 179 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 180 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 181                                       int node)
 182 {
 183         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 184 }
 185
 186 /*
 187  * Copy the current shadow region into a new pgdir.
 188  */
 189 void __init kasan_copy_shadow(pgd_t *pgdir)
 190 {
 191         pgd_t *pgdp, *pgdp_new, *pgdp_end;
 192
 193         pgdp = pgd_offset_k(KASAN_SHADOW_START);
 194         pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
 195         pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START);
 196         do {
 197                 set_pgd(pgdp_new, READ_ONCE(*pgdp));
 198         } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
 199 }
 200
 201 static void __init clear_pgds(unsigned long start,
 202                         unsigned long end)
 203 {
 204         /*
 205          * Remove references to kasan page tables from
 206          * swapper_pg_dir. pgd_clear() can't be used
 207          * here because it's nop on 2,3-level pagetable setups
 208          */
 209         for (; start < end; start += PGDIR_SIZE)
 210                 set_pgd(pgd_offset_k(start), __pgd(0));
 211 }
 212
 213 static void __init kasan_init_shadow(void)
 214 {
 215         u64 kimg_shadow_start, kimg_shadow_end;
 216         u64 mod_shadow_start, mod_shadow_end;
 217         phys_addr_t pa_start, pa_end;
 218         u64 i;
 219
 220         kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
 221         kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
 222
 223         mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
 224         mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
 225
 226         /*
 227          * We are going to perform proper setup of shadow memory.
 228          * At first we should unmap early shadow (clear_pgds() call below).
 229          * However, instrumented code couldn't execute without shadow memory.
 230          * tmp_pg_dir used to keep early shadow mapped until full shadow
 231          * setup will be finished.
 232          */
 233         memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
 234         dsb(ishst);
 235         cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
 236
 237         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 238
 239         kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
 240                            early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
 241
 242         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
 243                                    (void *)mod_shadow_start);
 244         kasan_populate_early_shadow((void *)kimg_shadow_end,
 245                                    (void *)KASAN_SHADOW_END);
 246
 247         if (kimg_shadow_start > mod_shadow_end)
 248                 kasan_populate_early_shadow((void *)mod_shadow_end,
 249                                             (void *)kimg_shadow_start);
 250
 251         for_each_mem_range(i, &pa_start, &pa_end) {
 252                 void *start = (void *)__phys_to_virt(pa_start);
 253                 void *end = (void *)__phys_to_virt(pa_end);
 254
 255                 if (start >= end)
 256                         break;
 257
 258                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 259                                    (unsigned long)kasan_mem_to_shadow(end),
 260                                    early_pfn_to_nid(virt_to_pfn(start)));
 261         }
 262
 263         /*
 264          * KAsan may reuse the contents of kasan_early_shadow_pte directly,
 265          * so we should make sure that it maps the zero page read-only.
 266          */
 267         for (i = 0; i < PTRS_PER_PTE; i++)
 268                 set_pte(&kasan_early_shadow_pte[i],
 269                         pfn_pte(sym_to_pfn(kasan_early_shadow_page),
 270                                 PAGE_KERNEL_RO));
 271
 272         memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 273         cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 274 }
 275
 276 static void __init kasan_init_depth(void)
 277 {
 278         init_task.kasan_depth = 0;
 279 }
 280
 281 #else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS) */
 282
 283 static inline void __init kasan_init_shadow(void) { }
 284
 285 static inline void __init kasan_init_depth(void) { }
 286
 287 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
 288
 289 void __init kasan_init(void)
 290 {
 291         kasan_init_shadow();
 292         kasan_init_depth();
 293         pr_info("KernelAddressSanitizer initialized\n");
 294 }