4b55b15707a33e5a5c7c202977845f86e847bda5
[sfrench/cifs-2.6.git] / arch / arm64 / mm / kasan_init.c
1 /*
2  * This file contains kasan initialization code for ARM64.
3  *
4  * Copyright (c) 2015 Samsung Electronics Co., Ltd.
5  * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License version 2 as
9  * published by the Free Software Foundation.
10  *
11  */
12
13 #define pr_fmt(fmt) "kasan: " fmt
14 #include <linux/kasan.h>
15 #include <linux/kernel.h>
16 #include <linux/sched/task.h>
17 #include <linux/memblock.h>
18 #include <linux/start_kernel.h>
19 #include <linux/mm.h>
20
21 #include <asm/mmu_context.h>
22 #include <asm/kernel-pgtable.h>
23 #include <asm/page.h>
24 #include <asm/pgalloc.h>
25 #include <asm/pgtable.h>
26 #include <asm/sections.h>
27 #include <asm/tlbflush.h>
28
29 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
30
31 /*
32  * The p*d_populate functions call virt_to_phys implicitly so they can't be used
33  * directly on kernel symbols (bm_p*d). All the early functions are called too
34  * early to use lm_alias so __p*d_populate functions must be used to populate
35  * with the physical address from __pa_symbol.
36  */
37
38 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
39 {
40         void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
41                                               __pa(MAX_DMA_ADDRESS),
42                                               MEMBLOCK_ALLOC_KASAN, node);
43         return __pa(p);
44 }
45
46 static phys_addr_t __init kasan_alloc_raw_page(int node)
47 {
48         void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
49                                                 __pa(MAX_DMA_ADDRESS),
50                                                 MEMBLOCK_ALLOC_KASAN, node);
51         return __pa(p);
52 }
53
54 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
55                                       bool early)
56 {
57         if (pmd_none(READ_ONCE(*pmdp))) {
58                 phys_addr_t pte_phys = early ?
59                                 __pa_symbol(kasan_early_shadow_pte)
60                                         : kasan_alloc_zeroed_page(node);
61                 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
62         }
63
64         return early ? pte_offset_kimg(pmdp, addr)
65                      : pte_offset_kernel(pmdp, addr);
66 }
67
68 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
69                                       bool early)
70 {
71         if (pud_none(READ_ONCE(*pudp))) {
72                 phys_addr_t pmd_phys = early ?
73                                 __pa_symbol(kasan_early_shadow_pmd)
74                                         : kasan_alloc_zeroed_page(node);
75                 __pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
76         }
77
78         return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
79 }
80
81 static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
82                                       bool early)
83 {
84         if (pgd_none(READ_ONCE(*pgdp))) {
85                 phys_addr_t pud_phys = early ?
86                                 __pa_symbol(kasan_early_shadow_pud)
87                                         : kasan_alloc_zeroed_page(node);
88                 __pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
89         }
90
91         return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
92 }
93
94 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
95                                       unsigned long end, int node, bool early)
96 {
97         unsigned long next;
98         pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
99
100         do {
101                 phys_addr_t page_phys = early ?
102                                 __pa_symbol(kasan_early_shadow_page)
103                                         : kasan_alloc_raw_page(node);
104                 if (!early)
105                         memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
106                 next = addr + PAGE_SIZE;
107                 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
108         } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
109 }
110
111 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
112                                       unsigned long end, int node, bool early)
113 {
114         unsigned long next;
115         pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
116
117         do {
118                 next = pmd_addr_end(addr, end);
119                 kasan_pte_populate(pmdp, addr, next, node, early);
120         } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
121 }
122
123 static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
124                                       unsigned long end, int node, bool early)
125 {
126         unsigned long next;
127         pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
128
129         do {
130                 next = pud_addr_end(addr, end);
131                 kasan_pmd_populate(pudp, addr, next, node, early);
132         } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
133 }
134
135 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
136                                       int node, bool early)
137 {
138         unsigned long next;
139         pgd_t *pgdp;
140
141         pgdp = pgd_offset_k(addr);
142         do {
143                 next = pgd_addr_end(addr, end);
144                 kasan_pud_populate(pgdp, addr, next, node, early);
145         } while (pgdp++, addr = next, addr != end);
146 }
147
148 /* The early shadow maps everything to a single page of zeroes */
149 asmlinkage void __init kasan_early_init(void)
150 {
151         BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
152                 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
153         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
154         BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
155         kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
156                            true);
157 }
158
159 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
160 static void __init kasan_map_populate(unsigned long start, unsigned long end,
161                                       int node)
162 {
163         kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
164 }
165
166 /*
167  * Copy the current shadow region into a new pgdir.
168  */
169 void __init kasan_copy_shadow(pgd_t *pgdir)
170 {
171         pgd_t *pgdp, *pgdp_new, *pgdp_end;
172
173         pgdp = pgd_offset_k(KASAN_SHADOW_START);
174         pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
175         pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
176         do {
177                 set_pgd(pgdp_new, READ_ONCE(*pgdp));
178         } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
179 }
180
181 static void __init clear_pgds(unsigned long start,
182                         unsigned long end)
183 {
184         /*
185          * Remove references to kasan page tables from
186          * swapper_pg_dir. pgd_clear() can't be used
187          * here because it's nop on 2,3-level pagetable setups
188          */
189         for (; start < end; start += PGDIR_SIZE)
190                 set_pgd(pgd_offset_k(start), __pgd(0));
191 }
192
193 void __init kasan_init(void)
194 {
195         u64 kimg_shadow_start, kimg_shadow_end;
196         u64 mod_shadow_start, mod_shadow_end;
197         struct memblock_region *reg;
198         int i;
199
200         kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
201         kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
202
203         mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
204         mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
205
206         /*
207          * We are going to perform proper setup of shadow memory.
208          * At first we should unmap early shadow (clear_pgds() call below).
209          * However, instrumented code couldn't execute without shadow memory.
210          * tmp_pg_dir used to keep early shadow mapped until full shadow
211          * setup will be finished.
212          */
213         memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
214         dsb(ishst);
215         cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
216
217         clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
218
219         kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
220                            early_pfn_to_nid(virt_to_pfn(lm_alias(_text))));
221
222         kasan_populate_early_shadow((void *)KASAN_SHADOW_START,
223                                     (void *)mod_shadow_start);
224         kasan_populate_early_shadow((void *)kimg_shadow_end,
225                                     kasan_mem_to_shadow((void *)PAGE_OFFSET));
226
227         if (kimg_shadow_start > mod_shadow_end)
228                 kasan_populate_early_shadow((void *)mod_shadow_end,
229                                             (void *)kimg_shadow_start);
230
231         for_each_memblock(memory, reg) {
232                 void *start = (void *)__phys_to_virt(reg->base);
233                 void *end = (void *)__phys_to_virt(reg->base + reg->size);
234
235                 if (start >= end)
236                         break;
237
238                 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
239                                    (unsigned long)kasan_mem_to_shadow(end),
240                                    early_pfn_to_nid(virt_to_pfn(start)));
241         }
242
243         /*
244          * KAsan may reuse the contents of kasan_early_shadow_pte directly,
245          * so we should make sure that it maps the zero page read-only.
246          */
247         for (i = 0; i < PTRS_PER_PTE; i++)
248                 set_pte(&kasan_early_shadow_pte[i],
249                         pfn_pte(sym_to_pfn(kasan_early_shadow_page),
250                                 PAGE_KERNEL_RO));
251
252         memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
253         cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
254
255         kasan_init_tags();
256
257         /* At this point kasan is fully initialized. Enable error messages */
258         init_task.kasan_depth = 0;
259         pr_info("KernelAddressSanitizer initialized\n");
260 }