1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * KASAN for 64-bit Book3S powerpc
4 *
5 * Copyright 2019-2022, Daniel Axtens, IBM Corporation.
6 */
7
8 /*
9 * ppc64 turns on virtual memory late in boot, after calling into generic code
10 * like the device-tree parser, so it uses this in conjunction with a hook in
11 * outline mode to avoid invalid access early in boot.
12 */
13
14 #define DISABLE_BRANCH_PROFILING
15
16 #include <linux/kasan.h>
17 #include <linux/printk.h>
18 #include <linux/sched/task.h>
19 #include <linux/memblock.h>
20 #include <asm/pgalloc.h>
21
22 DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
23
24 static void __init kasan_init_phys_region(void *start, void *end)
25 {
26 unsigned long k_start, k_end, k_cur;
27 void *va;
28
29 if (start >= end)
30 return;
31
32 k_start = ALIGN_DOWN((unsigned long)kasan_mem_to_shadow(start), PAGE_SIZE);
33 k_end = ALIGN((unsigned long)kasan_mem_to_shadow(end), PAGE_SIZE);
34
35 va = memblock_alloc(k_end - k_start, PAGE_SIZE);
36 for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE, va += PAGE_SIZE)
37 map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
38 }
39
40 void __init kasan_init(void)
41 {
42 /*
43 * We want to do the following things:
44 * 1) Map real memory into the shadow for all physical memblocks
45 * This takes us from c000... to c008...
46 * 2) Leave a hole over the shadow of vmalloc space. KASAN_VMALLOC
47 * will manage this for us.
48 * This takes us from c008... to c00a...
49 * 3) Map the 'early shadow'/zero page over iomap and vmemmap space.
50 * This takes us up to where we start at c00e...
51 */
52
53 void *k_start = kasan_mem_to_shadow((void *)RADIX_VMALLOC_END);
54 void *k_end = kasan_mem_to_shadow((void *)RADIX_VMEMMAP_END);
55 phys_addr_t start, end;
56 u64 i;
57 pte_t zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL);
58
59 if (!early_radix_enabled()) {
60 pr_warn("KASAN not enabled as it requires radix!");
61 return;
62 }
63
64 for_each_mem_range(i, &start, &end)
65 kasan_init_phys_region(phys_to_virt(start), phys_to_virt(end));
66
67 for (i = 0; i < PTRS_PER_PTE; i++)
68 __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
69 &kasan_early_shadow_pte[i], zero_pte, 0);
70
71 for (i = 0; i < PTRS_PER_PMD; i++)
72 pmd_populate_kernel(&init_mm, &kasan_early_shadow_pmd[i],
73 kasan_early_shadow_pte);
74
75 for (i = 0; i < PTRS_PER_PUD; i++)
76 pud_populate(&init_mm, &kasan_early_shadow_pud[i],
77 kasan_early_shadow_pmd);
78
79 /* map the early shadow over the iomap and vmemmap space */
80 kasan_populate_early_shadow(k_start, k_end);
81
82 /* mark early shadow region as RO and wipe it */
83 zero_pte = pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL_RO);
84 for (i = 0; i < PTRS_PER_PTE; i++)
85 __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
86 &kasan_early_shadow_pte[i], zero_pte, 0);
87
88 /*
89 * clear_page relies on some cache info that hasn't been set up yet.
90 * It ends up looping ~forever and blows up other data.
91 * Use memset instead.
92 */
93 memset(kasan_early_shadow_page, 0, PAGE_SIZE);
94
95 static_branch_inc(&powerpc_kasan_enabled_key);
96
97 /* Enable error messages */
98 init_task.kasan_depth = 0;
99 pr_info("KASAN init done\n");
100 }
101
102 void __init kasan_early_init(void) { }
103
104 void __init kasan_late_init(void) { }
105
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