arch/xtensa/mm/kasan_init.c

   1 /*
   2  * Xtensa KASAN shadow map initialization
   3  *
   4  * This file is subject to the terms and conditions of the GNU General Public
   5  * License.  See the file "COPYING" in the main directory of this archive
   6  * for more details.
   7  *
   8  * Copyright (C) 2017 Cadence Design Systems Inc.
   9  */
  10
  11 #include <linux/memblock.h>
  12 #include <linux/init_task.h>
  13 #include <linux/kasan.h>
  14 #include <linux/kernel.h>
  15 #include <asm/initialize_mmu.h>
  16 #include <asm/tlbflush.h>
  17 #include <asm/traps.h>
  18
  19 void __init kasan_early_init(void)
  20 {
  21         unsigned long vaddr = KASAN_SHADOW_START;
  22         pgd_t *pgd = pgd_offset_k(vaddr);
  23         pmd_t *pmd = pmd_offset(pgd, vaddr);
  24         int i;
  25
  26         for (i = 0; i < PTRS_PER_PTE; ++i)
  27                 set_pte(kasan_early_shadow_pte + i,
  28                         mk_pte(virt_to_page(kasan_early_shadow_page),
  29                                 PAGE_KERNEL));
  30
  31         for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
  32                 BUG_ON(!pmd_none(*pmd));
  33                 set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
  34         }
  35         early_trap_init();
  36 }
  37
  38 static void __init populate(void *start, void *end)
  39 {
  40         unsigned long n_pages = (end - start) / PAGE_SIZE;
  41         unsigned long n_pmds = n_pages / PTRS_PER_PTE;
  42         unsigned long i, j;
  43         unsigned long vaddr = (unsigned long)start;
  44         pgd_t *pgd = pgd_offset_k(vaddr);
  45         pmd_t *pmd = pmd_offset(pgd, vaddr);
  46         pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
  47
  48         if (!pte)
  49                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  50                       __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
  51
  52         pr_debug("%s: %p - %p\n", __func__, start, end);
  53
  54         for (i = j = 0; i < n_pmds; ++i) {
  55                 int k;
  56
  57                 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
  58                         phys_addr_t phys =
  59                                 memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
  60
  61                         if (!phys)
  62                                 panic("Failed to allocate page table page\n");
  63
  64                         set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
  65                 }
  66         }
  67
  68         for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
  69                 set_pmd(pmd + i, __pmd((unsigned long)pte));
  70
  71         local_flush_tlb_all();
  72         memset(start, 0, end - start);
  73 }
  74
  75 void __init kasan_init(void)
  76 {
  77         int i;
  78
  79         BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
  80                      (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
  81         BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
  82
  83         /*
  84          * Replace shadow map pages that cover addresses from VMALLOC area
  85          * start to the end of KSEG with clean writable pages.
  86          */
  87         populate(kasan_mem_to_shadow((void *)VMALLOC_START),
  88                  kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
  89
  90         /*
  91          * Write protect kasan_early_shadow_page and zero-initialize it again.
  92          */
  93         for (i = 0; i < PTRS_PER_PTE; ++i)
  94                 set_pte(kasan_early_shadow_pte + i,
  95                         mk_pte(virt_to_page(kasan_early_shadow_page),
  96                                 PAGE_KERNEL_RO));
  97
  98         local_flush_tlb_all();
  99         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 100
 101         /* At this point kasan is fully initialized. Enable error messages. */
 102         current->kasan_depth = 0;
 103         pr_info("KernelAddressSanitizer initialized\n");
 104 }