summaryrefslogtreecommitdiff
path: root/arch/x86/mm/kasan_init_64.c
blob: 0493c17b8a516f4212bc21fe5e32d0bce466c24f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
#define pr_fmt(fmt) "kasan: " fmt
#include <linux/bootmem.h>
#include <linux/kasan.h>
#include <linux/kdebug.h>
#include <linux/mm.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>

#include <asm/tlbflush.h>
#include <asm/sections.h>

extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];

static int __init map_range(struct range *range)
{
	unsigned long start;
	unsigned long end;

	start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
	end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));

	/*
	 * end + 1 here is intentional. We check several shadow bytes in advance
	 * to slightly speed up fastpath. In some rare cases we could cross
	 * boundary of mapped shadow, so we just map some more here.
	 */
	return vmemmap_populate(start, end + 1, NUMA_NO_NODE);
}

static void __init clear_pgds(unsigned long start,
			unsigned long end)
{
	for (; start < end; start += PGDIR_SIZE)
		pgd_clear(pgd_offset_k(start));
}

static void __init kasan_map_early_shadow(pgd_t *pgd)
{
	int i;
	unsigned long start = KASAN_SHADOW_START;
	unsigned long end = KASAN_SHADOW_END;

	for (i = pgd_index(start); start < end; i++) {
		pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud)
				| _KERNPG_TABLE);
		start += PGDIR_SIZE;
	}
}

#ifdef CONFIG_KASAN_INLINE
static int kasan_die_handler(struct notifier_block *self,
			     unsigned long val,
			     void *data)
{
	if (val == DIE_GPF) {
		pr_emerg("CONFIG_KASAN_INLINE enabled\n");
		pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
	}
	return NOTIFY_OK;
}

static struct notifier_block kasan_die_notifier = {
	.notifier_call = kasan_die_handler,
};
#endif

void __init kasan_early_init(void)
{
	int i;
	pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL;
	pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
	pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;

	for (i = 0; i < PTRS_PER_PTE; i++)
		kasan_zero_pte[i] = __pte(pte_val);

	for (i = 0; i < PTRS_PER_PMD; i++)
		kasan_zero_pmd[i] = __pmd(pmd_val);

	for (i = 0; i < PTRS_PER_PUD; i++)
		kasan_zero_pud[i] = __pud(pud_val);

	kasan_map_early_shadow(early_level4_pgt);
	kasan_map_early_shadow(init_level4_pgt);
}

void __init kasan_init(void)
{
	int i;

#ifdef CONFIG_KASAN_INLINE
	register_die_notifier(&kasan_die_notifier);
#endif

	memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt));
	load_cr3(early_level4_pgt);
	__flush_tlb_all();

	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);

	kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
			kasan_mem_to_shadow((void *)PAGE_OFFSET));

	for (i = 0; i < E820_X_MAX; i++) {
		if (pfn_mapped[i].end == 0)
			break;

		if (map_range(&pfn_mapped[i]))
			panic("kasan: unable to allocate shadow!");
	}
	kasan_populate_zero_shadow(
		kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
		kasan_mem_to_shadow((void *)__START_KERNEL_map));

	vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
			(unsigned long)kasan_mem_to_shadow(_end),
			NUMA_NO_NODE);

	kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
			(void *)KASAN_SHADOW_END);

	load_cr3(init_level4_pgt);
	__flush_tlb_all();

	/*
	 * kasan_zero_page has been used as early shadow memory, thus it may
	 * contain some garbage. Now we can clear and write protect it, since
	 * after the TLB flush no one should write to it.
	 */
	memset(kasan_zero_page, 0, PAGE_SIZE);
	for (i = 0; i < PTRS_PER_PTE; i++) {
		pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO);
		set_pte(&kasan_zero_pte[i], pte);
	}
	/* Flush TLBs again to be sure that write protection applied. */
	__flush_tlb_all();

	init_task.kasan_depth = 0;
	pr_info("KernelAddressSanitizer initialized\n");
}