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         p4d_t *p4d = p4d_offset(pgd, vaddr);
  24         pud_t *pud = pud_offset(p4d, vaddr);
  25         pmd_t *pmd = pmd_offset(pud, vaddr);
  26         int i;
  27
  28         for (i = 0; i < PTRS_PER_PTE; ++i)
  29                 set_pte(kasan_early_shadow_pte + i,
  30                         mk_pte(virt_to_page(kasan_early_shadow_page),
  31                                 PAGE_KERNEL));
  32
  33         for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
  34                 BUG_ON(!pmd_none(*pmd));
  35                 set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
  36         }
  37         early_trap_init();
  38 }
  39
  40 static void __init populate(void *start, void *end)
  41 {
  42         unsigned long n_pages = (end - start) / PAGE_SIZE;
  43         unsigned long n_pmds = n_pages / PTRS_PER_PTE;
  44         unsigned long i, j;
  45         unsigned long vaddr = (unsigned long)start;
  46         pgd_t *pgd = pgd_offset_k(vaddr);
  47         p4d_t *p4d = p4d_offset(pgd, vaddr);
  48         pud_t *pud = pud_offset(p4d, vaddr);
  49         pmd_t *pmd = pmd_offset(pud, vaddr);
  50         pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
  51
  52         if (!pte)
  53                 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  54                       __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
  55
  56         pr_debug("%s: %p - %p\n", __func__, start, end);
  57
  58         for (i = j = 0; i < n_pmds; ++i) {
  59                 int k;
  60
  61                 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
  62                         phys_addr_t phys =
  63                                 memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
  64                                                           0,
  65                                                           MEMBLOCK_ALLOC_ANYWHERE);
  66
  67                         if (!phys)
  68                                 panic("Failed to allocate page table page\n");
  69
  70                         set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
  71                 }
  72         }
  73
  74         for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
  75                 set_pmd(pmd + i, __pmd((unsigned long)pte));
  76
  77         local_flush_tlb_all();
  78         memset(start, 0, end - start);
  79 }
  80
  81 void __init kasan_init(void)
  82 {
  83         int i;
  84
  85         BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
  86                      (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
  87         BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
  88
  89         /*
  90          * Replace shadow map pages that cover addresses from VMALLOC area
  91          * start to the end of KSEG with clean writable pages.
  92          */
  93         populate(kasan_mem_to_shadow((void *)VMALLOC_START),
  94                  kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
  95
  96         /*
  97          * Write protect kasan_early_shadow_page and zero-initialize it again.
  98          */
  99         for (i = 0; i < PTRS_PER_PTE; ++i)
 100                 set_pte(kasan_early_shadow_pte + i,
 101                         mk_pte(virt_to_page(kasan_early_shadow_page),
 102                                 PAGE_KERNEL_RO));
 103
 104         local_flush_tlb_all();
 105         memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 106
 107         /* At this point kasan is fully initialized. Enable error messages. */
 108         current->kasan_depth = 0;
 109         pr_info("KernelAddressSanitizer initialized\n");
 110 }