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 }
103
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