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
  18 void __init kasan_early_init(void)
  19 {
  20         unsigned long vaddr = KASAN_SHADOW_START;
  21         pmd_t *pmd = pmd_off_k(vaddr);
  22         int i;
  23
  24         for (i = 0; i < PTRS_PER_PTE; ++i)
  25                 set_pte(kasan_early_shadow_pte + i,
  26                         mk_pte(virt_to_page(kasan_early_shadow_page),
  27                                 PAGE_KERNEL));
  28
  29         for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
  30                 BUG_ON(!pmd_none(*pmd));
  31                 set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
  32         }
  33 }
  34
  35 static void __init populate(void *start, void *end)
  36 {
  37         unsigned long n_pages = (end - start) / PAGE_SIZE;
  38         unsigned long n_pmds = n_pages / PTRS_PER_PTE;
  39         unsigned long i, j;
  40         unsigned long vaddr = (unsigned long)start;
  41         pmd_t *pmd = pmd_off_k(vaddr);
  42         pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
  43
  44         if (!pte)
  45                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  46                       __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
  47
  48         pr_debug("%s: %p - %p\n", __func__, start, end);
  49
  50         for (i = j = 0; i < n_pmds; ++i) {
  51                 int k;
  52
  53                 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
  54                         phys_addr_t phys =
  55                                 memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
  56                                                           0,
  57                                                           MEMBLOCK_ALLOC_ANYWHERE);
  58
  59                         if (!phys)
  60                                 panic("Failed to allocate page table page\n");
  61
  62                         set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
  63                 }
  64         }
  65
  66         for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
  67                 set_pmd(pmd + i, __pmd((unsigned long)pte));
  68
  69         local_flush_tlb_all();
  70         memset(start, 0, end - start);
  71 }
  72
  73 void __init kasan_init(void)
  74 {
  75         int i;
  76
  77         BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
  78                      (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
  79         BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
  80
  81         /*
  82          * Replace shadow map pages that cover addresses from VMALLOC area
  83          * start to the end of KSEG with clean writable pages.
  84          */
  85         populate(kasan_mem_to_shadow((void *)VMALLOC_START),
  86                  kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
  87
  88         /*
  89          * Write protect kasan_early_shadow_page and zero-initialize it again.
  90          */
  91         for (i = 0; i < PTRS_PER_PTE; ++i)
  92                 set_pte(kasan_early_shadow_pte + i,
  93                         mk_pte(virt_to_page(kasan_early_shadow_page),
  94                                 PAGE_KERNEL_RO));
  95
  96         local_flush_tlb_all();
  97         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
  98
  99         /* At this point kasan is fully initialized. Enable error messages. */
 100         current->kasan_depth = 0;
 101         pr_info("KernelAddressSanitizer initialized\n");
 102 }