arch/x86/mm/kasan_init_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define DISABLE_BRANCH_PROFILING
   3 #define pr_fmt(fmt) "kasan: " fmt
   4 #include <linux/bootmem.h>
   5 #include <linux/kasan.h>
   6 #include <linux/kdebug.h>
   7 #include <linux/mm.h>
   8 #include <linux/sched.h>
   9 #include <linux/sched/task.h>
  10 #include <linux/vmalloc.h>
  11
  12 #include <asm/e820/types.h>
  13 #include <asm/tlbflush.h>
  14 #include <asm/sections.h>
  15 #include <asm/pgtable.h>
  16
  17 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  18
  19 static int __init map_range(struct range *range)
  20 {
  21         unsigned long start;
  22         unsigned long end;
  23
  24         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
  25         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
  26
  27         return vmemmap_populate(start, end, NUMA_NO_NODE);
  28 }
  29
  30 static void __init clear_pgds(unsigned long start,
  31                         unsigned long end)
  32 {
  33         pgd_t *pgd;
  34
  35         for (; start < end; start += PGDIR_SIZE) {
  36                 pgd = pgd_offset_k(start);
  37                 /*
  38                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
  39                  * instead.
  40                  */
  41                 if (CONFIG_PGTABLE_LEVELS < 5)
  42                         p4d_clear(p4d_offset(pgd, start));
  43                 else
  44                         pgd_clear(pgd);
  45         }
  46 }
  47
  48 static void __init kasan_map_early_shadow(pgd_t *pgd)
  49 {
  50         int i;
  51         unsigned long start = KASAN_SHADOW_START;
  52         unsigned long end = KASAN_SHADOW_END;
  53
  54         for (i = pgd_index(start); start < end; i++) {
  55                 switch (CONFIG_PGTABLE_LEVELS) {
  56                 case 4:
  57                         pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) |
  58                                         _KERNPG_TABLE);
  59                         break;
  60                 case 5:
  61                         pgd[i] = __pgd(__pa_nodebug(kasan_zero_p4d) |
  62                                         _KERNPG_TABLE);
  63                         break;
  64                 default:
  65                         BUILD_BUG();
  66                 }
  67                 start += PGDIR_SIZE;
  68         }
  69 }
  70
  71 #ifdef CONFIG_KASAN_INLINE
  72 static int kasan_die_handler(struct notifier_block *self,
  73                              unsigned long val,
  74                              void *data)
  75 {
  76         if (val == DIE_GPF) {
  77                 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
  78                 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
  79         }
  80         return NOTIFY_OK;
  81 }
  82
  83 static struct notifier_block kasan_die_notifier = {
  84         .notifier_call = kasan_die_handler,
  85 };
  86 #endif
  87
  88 void __init kasan_early_init(void)
  89 {
  90         int i;
  91         pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL | _PAGE_ENC;
  92         pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
  93         pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
  94         p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
  95
  96         for (i = 0; i < PTRS_PER_PTE; i++)
  97                 kasan_zero_pte[i] = __pte(pte_val);
  98
  99         for (i = 0; i < PTRS_PER_PMD; i++)
 100                 kasan_zero_pmd[i] = __pmd(pmd_val);
 101
 102         for (i = 0; i < PTRS_PER_PUD; i++)
 103                 kasan_zero_pud[i] = __pud(pud_val);
 104
 105         for (i = 0; CONFIG_PGTABLE_LEVELS >= 5 && i < PTRS_PER_P4D; i++)
 106                 kasan_zero_p4d[i] = __p4d(p4d_val);
 107
 108         kasan_map_early_shadow(early_top_pgt);
 109         kasan_map_early_shadow(init_top_pgt);
 110 }
 111
 112 void __init kasan_init(void)
 113 {
 114         int i;
 115
 116 #ifdef CONFIG_KASAN_INLINE
 117         register_die_notifier(&kasan_die_notifier);
 118 #endif
 119
 120         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 121         load_cr3(early_top_pgt);
 122         __flush_tlb_all();
 123
 124         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
 125
 126         kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
 127                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 128
 129         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 130                 if (pfn_mapped[i].end == 0)
 131                         break;
 132
 133                 if (map_range(&pfn_mapped[i]))
 134                         panic("kasan: unable to allocate shadow!");
 135         }
 136         kasan_populate_zero_shadow(
 137                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 138                 kasan_mem_to_shadow((void *)__START_KERNEL_map));
 139
 140         vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
 141                         (unsigned long)kasan_mem_to_shadow(_end),
 142                         NUMA_NO_NODE);
 143
 144         kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 145                         (void *)KASAN_SHADOW_END);
 146
 147         load_cr3(init_top_pgt);
 148         __flush_tlb_all();
 149
 150         /*
 151          * kasan_zero_page has been used as early shadow memory, thus it may
 152          * contain some garbage. Now we can clear and write protect it, since
 153          * after the TLB flush no one should write to it.
 154          */
 155         memset(kasan_zero_page, 0, PAGE_SIZE);
 156         for (i = 0; i < PTRS_PER_PTE; i++) {
 157                 pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO | _PAGE_ENC);
 158                 set_pte(&kasan_zero_pte[i], pte);
 159         }
 160         /* Flush TLBs again to be sure that write protection applied. */
 161         __flush_tlb_all();
 162
 163         init_task.kasan_depth = 0;
 164         pr_info("KernelAddressSanitizer initialized\n");
 165 }