1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * This file contains kasan initialization code for ARM64.
4 *
5 * Copyright (c) 2015 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 */
8
9 #define pr_fmt(fmt) "kasan: " fmt
10 #include <linux/kasan.h>
11 #include <linux/kernel.h>
12 #include <linux/sched/task.h>
13 #include <linux/memblock.h>
14 #include <linux/start_kernel.h>
15 #include <linux/mm.h>
16
17 #include <asm/mmu_context.h>
18 #include <asm/kernel-pgtable.h>
19 #include <asm/page.h>
20 #include <asm/pgalloc.h>
21 #include <asm/sections.h>
22 #include <asm/tlbflush.h>
23
24 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
25
26 static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
27
28 /*
29 * The p*d_populate functions call virt_to_phys implicitly so they can't be used
30 * directly on kernel symbols (bm_p*d). All the early functions are called too
31 * early to use lm_alias so __p*d_populate functions must be used to populate
32 * with the physical address from __pa_symbol.
33 */
34
kasan_alloc_zeroed_page(int node)35 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
36 {
37 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
38 __pa(MAX_DMA_ADDRESS),
39 MEMBLOCK_ALLOC_KASAN, node);
40 if (!p)
41 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
42 __func__, PAGE_SIZE, PAGE_SIZE, node,
43 __pa(MAX_DMA_ADDRESS));
44
45 return __pa(p);
46 }
47
kasan_alloc_raw_page(int node)48 static phys_addr_t __init kasan_alloc_raw_page(int node)
49 {
50 void *p = memblock_alloc_try_nid_raw(PAGE_SIZE, PAGE_SIZE,
51 __pa(MAX_DMA_ADDRESS),
52 MEMBLOCK_ALLOC_KASAN, node);
53 if (!p)
54 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
55 __func__, PAGE_SIZE, PAGE_SIZE, node,
56 __pa(MAX_DMA_ADDRESS));
57
58 return __pa(p);
59 }
60
kasan_pte_offset(pmd_t * pmdp,unsigned long addr,int node,bool early)61 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
62 bool early)
63 {
64 if (pmd_none(READ_ONCE(*pmdp))) {
65 phys_addr_t pte_phys = early ?
66 __pa_symbol(kasan_early_shadow_pte)
67 : kasan_alloc_zeroed_page(node);
68 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
69 }
70
71 return early ? pte_offset_kimg(pmdp, addr)
72 : pte_offset_kernel(pmdp, addr);
73 }
74
kasan_pmd_offset(pud_t * pudp,unsigned long addr,int node,bool early)75 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
76 bool early)
77 {
78 if (pud_none(READ_ONCE(*pudp))) {
79 phys_addr_t pmd_phys = early ?
80 __pa_symbol(kasan_early_shadow_pmd)
81 : kasan_alloc_zeroed_page(node);
82 __pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE);
83 }
84
85 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
86 }
87
kasan_pud_offset(p4d_t * p4dp,unsigned long addr,int node,bool early)88 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
89 bool early)
90 {
91 if (p4d_none(READ_ONCE(*p4dp))) {
92 phys_addr_t pud_phys = early ?
93 __pa_symbol(kasan_early_shadow_pud)
94 : kasan_alloc_zeroed_page(node);
95 __p4d_populate(p4dp, pud_phys, P4D_TYPE_TABLE);
96 }
97
98 return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr);
99 }
100
kasan_pte_populate(pmd_t * pmdp,unsigned long addr,unsigned long end,int node,bool early)101 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
102 unsigned long end, int node, bool early)
103 {
104 unsigned long next;
105 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
106
107 do {
108 phys_addr_t page_phys = early ?
109 __pa_symbol(kasan_early_shadow_page)
110 : kasan_alloc_raw_page(node);
111 if (!early)
112 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
113 next = addr + PAGE_SIZE;
114 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
115 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
116 }
117
kasan_pmd_populate(pud_t * pudp,unsigned long addr,unsigned long end,int node,bool early)118 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
119 unsigned long end, int node, bool early)
120 {
121 unsigned long next;
122 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
123
124 do {
125 next = pmd_addr_end(addr, end);
126 kasan_pte_populate(pmdp, addr, next, node, early);
127 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
128 }
129
kasan_pud_populate(p4d_t * p4dp,unsigned long addr,unsigned long end,int node,bool early)130 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
131 unsigned long end, int node, bool early)
132 {
133 unsigned long next;
134 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
135
136 do {
137 next = pud_addr_end(addr, end);
138 kasan_pmd_populate(pudp, addr, next, node, early);
139 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
140 }
141
kasan_p4d_populate(pgd_t * pgdp,unsigned long addr,unsigned long end,int node,bool early)142 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
143 unsigned long end, int node, bool early)
144 {
145 unsigned long next;
146 p4d_t *p4dp = p4d_offset(pgdp, addr);
147
148 do {
149 next = p4d_addr_end(addr, end);
150 kasan_pud_populate(p4dp, addr, next, node, early);
151 } while (p4dp++, addr = next, addr != end);
152 }
153
kasan_pgd_populate(unsigned long addr,unsigned long end,int node,bool early)154 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
155 int node, bool early)
156 {
157 unsigned long next;
158 pgd_t *pgdp;
159
160 pgdp = pgd_offset_k(addr);
161 do {
162 next = pgd_addr_end(addr, end);
163 kasan_p4d_populate(pgdp, addr, next, node, early);
164 } while (pgdp++, addr = next, addr != end);
165 }
166
167 /* The early shadow maps everything to a single page of zeroes */
kasan_early_init(void)168 asmlinkage void __init kasan_early_init(void)
169 {
170 BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
171 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
172 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE));
173 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE));
174 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
175 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
176 true);
177 }
178
179 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
kasan_map_populate(unsigned long start,unsigned long end,int node)180 static void __init kasan_map_populate(unsigned long start, unsigned long end,
181 int node)
182 {
183 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
184 }
185
186 /*
187 * Copy the current shadow region into a new pgdir.
188 */
kasan_copy_shadow(pgd_t * pgdir)189 void __init kasan_copy_shadow(pgd_t *pgdir)
190 {
191 pgd_t *pgdp, *pgdp_new, *pgdp_end;
192
193 pgdp = pgd_offset_k(KASAN_SHADOW_START);
194 pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
195 pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START);
196 do {
197 set_pgd(pgdp_new, READ_ONCE(*pgdp));
198 } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
199 }
200
clear_pgds(unsigned long start,unsigned long end)201 static void __init clear_pgds(unsigned long start,
202 unsigned long end)
203 {
204 /*
205 * Remove references to kasan page tables from
206 * swapper_pg_dir. pgd_clear() can't be used
207 * here because it's nop on 2,3-level pagetable setups
208 */
209 for (; start < end; start += PGDIR_SIZE)
210 set_pgd(pgd_offset_k(start), __pgd(0));
211 }
212
kasan_init_shadow(void)213 static void __init kasan_init_shadow(void)
214 {
215 u64 kimg_shadow_start, kimg_shadow_end;
216 u64 mod_shadow_start, mod_shadow_end;
217 u64 vmalloc_shadow_end;
218 phys_addr_t pa_start, pa_end;
219 u64 i;
220
221 kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK;
222 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END));
223
224 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
225 mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
226
227 vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END);
228
229 /*
230 * We are going to perform proper setup of shadow memory.
231 * At first we should unmap early shadow (clear_pgds() call below).
232 * However, instrumented code couldn't execute without shadow memory.
233 * tmp_pg_dir used to keep early shadow mapped until full shadow
234 * setup will be finished.
235 */
236 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
237 dsb(ishst);
238 cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
239
240 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
241
242 kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
243 early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START))));
244
245 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
246 (void *)mod_shadow_start);
247
248 if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
249 BUILD_BUG_ON(VMALLOC_START != MODULES_END);
250 kasan_populate_early_shadow((void *)vmalloc_shadow_end,
251 (void *)KASAN_SHADOW_END);
252 } else {
253 kasan_populate_early_shadow((void *)kimg_shadow_end,
254 (void *)KASAN_SHADOW_END);
255 if (kimg_shadow_start > mod_shadow_end)
256 kasan_populate_early_shadow((void *)mod_shadow_end,
257 (void *)kimg_shadow_start);
258 }
259
260 for_each_mem_range(i, &pa_start, &pa_end) {
261 void *start = (void *)__phys_to_virt(pa_start);
262 void *end = (void *)__phys_to_virt(pa_end);
263
264 if (start >= end)
265 break;
266
267 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
268 (unsigned long)kasan_mem_to_shadow(end),
269 early_pfn_to_nid(virt_to_pfn(start)));
270 }
271
272 /*
273 * KAsan may reuse the contents of kasan_early_shadow_pte directly,
274 * so we should make sure that it maps the zero page read-only.
275 */
276 for (i = 0; i < PTRS_PER_PTE; i++)
277 set_pte(&kasan_early_shadow_pte[i],
278 pfn_pte(sym_to_pfn(kasan_early_shadow_page),
279 PAGE_KERNEL_RO));
280
281 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
282 cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
283 }
284
kasan_init_depth(void)285 static void __init kasan_init_depth(void)
286 {
287 init_task.kasan_depth = 0;
288 }
289
kasan_init(void)290 void __init kasan_init(void)
291 {
292 kasan_init_shadow();
293 kasan_init_depth();
294 #if defined(CONFIG_KASAN_GENERIC)
295 /* CONFIG_KASAN_SW_TAGS also requires kasan_init_sw_tags(). */
296 pr_info("KernelAddressSanitizer initialized\n");
297 #endif
298 }
299
300 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
301