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_NOLEAKTRACE, 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_NOLEAKTRACE,
  53                                                 node);
  54         if (!p)
  55                 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
  56                       __func__, PAGE_SIZE, PAGE_SIZE, node,
  57                       __pa(MAX_DMA_ADDRESS));
  58
  59         return __pa(p);
  60 }
  61
  62 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
  63                                       bool early)
  64 {
  65         if (pmd_none(READ_ONCE(*pmdp))) {
  66                 phys_addr_t pte_phys = early ?
  67                                 __pa_symbol(kasan_early_shadow_pte)
  68                                         : kasan_alloc_zeroed_page(node);
  69                 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
  70         }
  71
  72         return early ? pte_offset_kimg(pmdp, addr)
  73                      : pte_offset_kernel(pmdp, addr);
  74 }
  75
  76 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
  77                                       bool early)
  78 {
  79         if (pud_none(READ_ONCE(*pudp))) {
  80                 phys_addr_t pmd_phys = early ?
  81                                 __pa_symbol(kasan_early_shadow_pmd)
  82                                         : kasan_alloc_zeroed_page(node);
  83                 __pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE);
  84         }
  85
  86         return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
  87 }
  88
  89 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
  90                                       bool early)
  91 {
  92         if (p4d_none(READ_ONCE(*p4dp))) {
  93                 phys_addr_t pud_phys = early ?
  94                                 __pa_symbol(kasan_early_shadow_pud)
  95                                         : kasan_alloc_zeroed_page(node);
  96                 __p4d_populate(p4dp, pud_phys, P4D_TYPE_TABLE);
  97         }
  98
  99         return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr);
 100 }
 101
 102 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
 103                                       unsigned long end, int node, bool early)
 104 {
 105         unsigned long next;
 106         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
 107
 108         do {
 109                 phys_addr_t page_phys = early ?
 110                                 __pa_symbol(kasan_early_shadow_page)
 111                                         : kasan_alloc_raw_page(node);
 112                 if (!early)
 113                         memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
 114                 next = addr + PAGE_SIZE;
 115                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
 116         } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
 117 }
 118
 119 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
 120                                       unsigned long end, int node, bool early)
 121 {
 122         unsigned long next;
 123         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
 124
 125         do {
 126                 next = pmd_addr_end(addr, end);
 127                 kasan_pte_populate(pmdp, addr, next, node, early);
 128         } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
 129 }
 130
 131 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
 132                                       unsigned long end, int node, bool early)
 133 {
 134         unsigned long next;
 135         pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
 136
 137         do {
 138                 next = pud_addr_end(addr, end);
 139                 kasan_pmd_populate(pudp, addr, next, node, early);
 140         } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
 141 }
 142
 143 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
 144                                       unsigned long end, int node, bool early)
 145 {
 146         unsigned long next;
 147         p4d_t *p4dp = p4d_offset(pgdp, addr);
 148
 149         do {
 150                 next = p4d_addr_end(addr, end);
 151                 kasan_pud_populate(p4dp, addr, next, node, early);
 152         } while (p4dp++, addr = next, addr != end);
 153 }
 154
 155 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
 156                                       int node, bool early)
 157 {
 158         unsigned long next;
 159         pgd_t *pgdp;
 160
 161         pgdp = pgd_offset_k(addr);
 162         do {
 163                 next = pgd_addr_end(addr, end);
 164                 kasan_p4d_populate(pgdp, addr, next, node, early);
 165         } while (pgdp++, addr = next, addr != end);
 166 }
 167
 168 /* The early shadow maps everything to a single page of zeroes */
 169 asmlinkage void __init kasan_early_init(void)
 170 {
 171         BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
 172                 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
 173         /*
 174          * We cannot check the actual value of KASAN_SHADOW_START during build,
 175          * as it depends on vabits_actual. As a best-effort approach, check
 176          * potential values calculated based on VA_BITS and VA_BITS_MIN.
 177          */
 178         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE));
 179         BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE));
 180         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
 181         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
 182                            true);
 183 }
 184
 185 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
 186 static void __init kasan_map_populate(unsigned long start, unsigned long end,
 187                                       int node)
 188 {
 189         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
 190 }
 191
 192 static void __init clear_pgds(unsigned long start,
 193                         unsigned long end)
 194 {
 195         /*
 196          * Remove references to kasan page tables from
 197          * swapper_pg_dir. pgd_clear() can't be used
 198          * here because it's nop on 2,3-level pagetable setups
 199          */
 200         for (; start < end; start += PGDIR_SIZE)
 201                 set_pgd(pgd_offset_k(start), __pgd(0));
 202 }
 203
 204 static void __init kasan_init_shadow(void)
 205 {
 206         u64 kimg_shadow_start, kimg_shadow_end;
 207         u64 mod_shadow_start;
 208         u64 vmalloc_shadow_end;
 209         phys_addr_t pa_start, pa_end;
 210         u64 i;
 211
 212         kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK;
 213         kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END));
 214
 215         mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
 216
 217         vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END);
 218
 219         /*
 220          * We are going to perform proper setup of shadow memory.
 221          * At first we should unmap early shadow (clear_pgds() call below).
 222          * However, instrumented code couldn't execute without shadow memory.
 223          * tmp_pg_dir used to keep early shadow mapped until full shadow
 224          * setup will be finished.
 225          */
 226         memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
 227         dsb(ishst);
 228         cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
 229
 230         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 231
 232         kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
 233                            early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START))));
 234
 235         kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
 236                                    (void *)mod_shadow_start);
 237
 238         BUILD_BUG_ON(VMALLOC_START != MODULES_END);
 239         kasan_populate_early_shadow((void *)vmalloc_shadow_end,
 240                                     (void *)KASAN_SHADOW_END);
 241
 242         for_each_mem_range(i, &pa_start, &pa_end) {
 243                 void *start = (void *)__phys_to_virt(pa_start);
 244                 void *end = (void *)__phys_to_virt(pa_end);
 245
 246                 if (start >= end)
 247                         break;
 248
 249                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
 250                                    (unsigned long)kasan_mem_to_shadow(end),
 251                                    early_pfn_to_nid(virt_to_pfn(start)));
 252         }
 253
 254         /*
 255          * KAsan may reuse the contents of kasan_early_shadow_pte directly,
 256          * so we should make sure that it maps the zero page read-only.
 257          */
 258         for (i = 0; i < PTRS_PER_PTE; i++)
 259                 set_pte(&kasan_early_shadow_pte[i],
 260                         pfn_pte(sym_to_pfn(kasan_early_shadow_page),
 261                                 PAGE_KERNEL_RO));
 262
 263         memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
 264         cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
 265 }
 266
 267 static void __init kasan_init_depth(void)
 268 {
 269         init_task.kasan_depth = 0;
 270 }
 271
 272 #ifdef CONFIG_KASAN_VMALLOC
 273 void __init kasan_populate_early_vm_area_shadow(void *start, unsigned long size)
 274 {
 275         unsigned long shadow_start, shadow_end;
 276
 277         if (!is_vmalloc_or_module_addr(start))
 278                 return;
 279
 280         shadow_start = (unsigned long)kasan_mem_to_shadow(start);
 281         shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
 282         shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
 283         shadow_end = ALIGN(shadow_end, PAGE_SIZE);
 284         kasan_map_populate(shadow_start, shadow_end, NUMA_NO_NODE);
 285 }
 286 #endif
 287
 288 void __init kasan_init(void)
 289 {
 290         kasan_init_shadow();
 291         kasan_init_depth();
 292 #if defined(CONFIG_KASAN_GENERIC)
 293         /*
 294          * Generic KASAN is now fully initialized.
 295          * Software and Hardware Tag-Based modes still require
 296          * kasan_init_sw_tags() and kasan_init_hw_tags() correspondingly.
 297          */
 298         pr_info("KernelAddressSanitizer initialized (generic)\n");
 299 #endif
 300 }
 301
 302 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */