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(va: vaddr);
22 int i;
23
24 for (i = 0; i < PTRS_PER_PTE; ++i)
25 set_pte(ptep: kasan_early_shadow_pte + i,
26 pte: 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(pmdp: pmd, pmd: __pmd(val: (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(va: 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 start: 0,
53 MEMBLOCK_ALLOC_ANYWHERE);
54
55 if (!phys)
56 panic(fmt: "Failed to allocate page table page\n");
57
58 set_pte(ptep: pte + j, pte: 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(pmdp: pmd + i, pmd: __pmd(val: (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(ptep: kasan_early_shadow_pte + i,
89 pte: 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}
99

source code of linux/arch/xtensa/mm/kasan_init.c