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
kasan_early_init(void)19 void __init kasan_early_init(void)
20 {
21 unsigned long vaddr = KASAN_SHADOW_START;
22 pgd_t *pgd = pgd_offset_k(vaddr);
23 pmd_t *pmd = pmd_offset(pgd, vaddr);
24 int i;
25
26 for (i = 0; i < PTRS_PER_PTE; ++i)
27 set_pte(kasan_early_shadow_pte + i,
28 mk_pte(virt_to_page(kasan_early_shadow_page),
29 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_early_shadow_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_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
47
48 if (!pte)
49 panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
50 __func__, n_pages * sizeof(pte_t), PAGE_SIZE);
51
52 pr_debug("%s: %p - %p\n", __func__, start, end);
53
54 for (i = j = 0; i < n_pmds; ++i) {
55 int k;
56
57 for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
58 phys_addr_t phys =
59 memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
60 0,
61 MEMBLOCK_ALLOC_ANYWHERE);
62
63 if (!phys)
64 panic("Failed to allocate page table page\n");
65
66 set_pte(pte + j, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL));
67 }
68 }
69
70 for (i = 0; i < n_pmds ; ++i, pte += PTRS_PER_PTE)
71 set_pmd(pmd + i, __pmd((unsigned long)pte));
72
73 local_flush_tlb_all();
74 memset(start, 0, end - start);
75 }
76
kasan_init(void)77 void __init kasan_init(void)
78 {
79 int i;
80
81 BUILD_BUG_ON(KASAN_SHADOW_OFFSET != KASAN_SHADOW_START -
82 (KASAN_START_VADDR >> KASAN_SHADOW_SCALE_SHIFT));
83 BUILD_BUG_ON(VMALLOC_START < KASAN_START_VADDR);
84
85 /*
86 * Replace shadow map pages that cover addresses from VMALLOC area
87 * start to the end of KSEG with clean writable pages.
88 */
89 populate(kasan_mem_to_shadow((void *)VMALLOC_START),
90 kasan_mem_to_shadow((void *)XCHAL_KSEG_BYPASS_VADDR));
91
92 /*
93 * Write protect kasan_early_shadow_page and zero-initialize it again.
94 */
95 for (i = 0; i < PTRS_PER_PTE; ++i)
96 set_pte(kasan_early_shadow_pte + i,
97 mk_pte(virt_to_page(kasan_early_shadow_page),
98 PAGE_KERNEL_RO));
99
100 local_flush_tlb_all();
101 memset(kasan_early_shadow_page, 0, PAGE_SIZE);
102
103 /* At this point kasan is fully initialized. Enable error messages. */
104 current->kasan_depth = 0;
105 pr_info("KernelAddressSanitizer initialized\n");
106 }
107