LXR linux/arch/xtensa/mm/kasan

   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/bootmem.h>
  12#include <linux/init_task.h>
  13#include <linux/kasan.h>
  14#include <linux/kernel.h>
  15#include <linux/memblock.h>
  16#include <asm/initialize_mmu.h>
  17#include <asm/tlbflush.h>
  18#include <asm/traps.h>
  19
  20void __init kasan_early_init(void)
  21{
  22        unsigned long vaddr = KASAN_SHADOW_START;
  23        pgd_t *pgd = pgd_offset_k(vaddr);
  24        pmd_t *pmd = pmd_offset(pgd, vaddr);
  25        int i;
  26
  27        for (i = 0; i < PTRS_PER_PTE; ++i)
  28                set_pte(kasan_zero_pte + i,
  29                        mk_pte(virt_to_page(kasan_zero_page), 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_zero_pte));
  34        }
  35        early_trap_init();
  36}
  37
  38static 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_virt_alloc(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_alloc_base(PAGE_SIZE, PAGE_SIZE,
  56                                                    MEMBLOCK_ALLOC_ANYWHERE);
  57
  58                        set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
  59                }
  60        }
  61
  62        for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
  63                set_pmd(pmd + i, __pmd((unsigned long)pte));
  64
  65        local_flush_tlb_all();
  66        memset(start, 0, end - start);
  67}
  68
  69void __init kasan_init(void)
  70{
  71        int i;
  72
  73        BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
  74                     (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
  75        BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
  76
  77        /*
  78         * Replace shadow map pages that cover addresses from VMALLOC area
  79         * start to the end of KSEG with clean writable pages.
  80         */
  81        populate(kasan_mem_to_shadow((void *)VMALLOC_START),
  82                 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
  83
  84        /* Write protect kasan_zero_page and zero-initialize it again. */
  85        for (i = 0; i < PTRS_PER_PTE; ++i)
  86                set_pte(kasan_zero_pte + i,
  87                        mk_pte(virt_to_page(kasan_zero_page), PAGE_KERNEL_RO));
  88
  89        local_flush_tlb_all();
  90        memset(kasan_zero_page, 0, PAGE_SIZE);
  91
  92        /* At this point kasan is fully initialized. Enable error messages. */
  93        current->kasan_depth = 0;
  94        pr_info("KernelAddressSanitizer initialized\n");
  95}
  96