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
kasan_early_init(void)20 void __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
populate(void * start,void * end)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_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
kasan_init(void)69 void __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
