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
22DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
23
24static 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
40void __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
102void __init kasan_early_init(void) { }
103
104void __init kasan_late_init(void) { }
105