kasan_init.c

 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
18void __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
35static 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_or_panic(n_pages * sizeof(pte_t), PAGE_SIZE);
43
44	pr_debug("%s: %p - %p\n", __func__, start, end);
45
46	for (i = j = 0; i < n_pmds; ++i) {
47		int k;
48
49		for (k = 0; k < PTRS_PER_PTE; ++k, ++j) {
50			phys_addr_t phys =
51				memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE,
52							  0,
53							  MEMBLOCK_ALLOC_ANYWHERE);
54
55			if (!phys)
56				panic("Failed to allocate page table page\n");
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
69void __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	/*
85	 * Write protect kasan_early_shadow_page and zero-initialize it again.
86	 */
87	for (i = 0; i < PTRS_PER_PTE; ++i)
88		set_pte(kasan_early_shadow_pte + i,
89			mk_pte(virt_to_page(kasan_early_shadow_page),
90				PAGE_KERNEL_RO));
91
92	local_flush_tlb_all();
93	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
94
95	/* At this point kasan is fully initialized. Enable error messages. */
96	current->kasan_depth = 0;
97	kasan_init_generic();
98}