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