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/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
  19void __init kasan_early_init(void)
  20{
  21        unsigned long vaddr = KASAN_SHADOW_START;
  22        pmd_t *pmd = pmd_off_k(vaddr);
  23        int i;
  24
  25        for (i = 0; i < PTRS_PER_PTE; ++i)
  26                set_pte(kasan_early_shadow_pte + i,
  27                        mk_pte(virt_to_page(kasan_early_shadow_page),
  28                                PAGE_KERNEL));
  29
  30        for (vaddr = 0; vaddr < KASAN_SHADOW_SIZE; vaddr += PMD_SIZE, ++pmd) {
  31                BUG_ON(!pmd_none(*pmd));
  32                set_pmd(pmd, __pmd((unsigned long)kasan_early_shadow_pte));
  33        }
  34        early_trap_init();
  35}
  36
  37static void __init populate(void *start, void *end)
  38{
  39        unsigned long n_pages = (end - start) / PAGE_SIZE;
  40        unsigned long n_pmds = n_pages / PTRS_PER_PTE;
  41        unsigned long i, j;
  42        unsigned long vaddr = (unsigned long)start;
  43        pmd_t *pmd = pmd_off_k(vaddr);
  44        pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
  45
  46        if (!pte)
  47                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
  48                      __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
  49
  50        pr_debug("%s: %p - %p\n", __func__, start, end);
  51
  52        for (i = j = 0; i < n_pmds; ++i) {
  53                int k;
  54
  55                for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
  56                        phys_addr_t phys =
  57                                memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
  58                                                          0,
  59                                                          MEMBLOCK_ALLOC_ANYWHERE);
  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
  75void __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}
 105