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((void *)start, (void *)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_late_init(void) { }
103