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_NOLEAKTRACE, 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_NOLEAKTRACE,
53 node);
54 if (!p)
55 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
56 __func__, PAGE_SIZE, PAGE_SIZE, node,
57 __pa(MAX_DMA_ADDRESS));
58
59 return __pa(p);
60 }
61
kasan_pte_offset(pmd_t * pmdp,unsigned long addr,int node,bool early)62 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
63 bool early)
64 {
65 if (pmd_none(READ_ONCE(*pmdp))) {
66 phys_addr_t pte_phys = early ?
67 __pa_symbol(kasan_early_shadow_pte)
68 : kasan_alloc_zeroed_page(node);
69 __pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
70 }
71
72 return early ? pte_offset_kimg(pmdp, addr)
73 : pte_offset_kernel(pmdp, addr);
74 }
75
kasan_pmd_offset(pud_t * pudp,unsigned long addr,int node,bool early)76 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
77 bool early)
78 {
79 if (pud_none(READ_ONCE(*pudp))) {
80 phys_addr_t pmd_phys = early ?
81 __pa_symbol(kasan_early_shadow_pmd)
82 : kasan_alloc_zeroed_page(node);
83 __pud_populate(pudp, pmd_phys, PUD_TYPE_TABLE);
84 }
85
86 return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
87 }
88
kasan_pud_offset(p4d_t * p4dp,unsigned long addr,int node,bool early)89 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node,
90 bool early)
91 {
92 if (p4d_none(READ_ONCE(*p4dp))) {
93 phys_addr_t pud_phys = early ?
94 __pa_symbol(kasan_early_shadow_pud)
95 : kasan_alloc_zeroed_page(node);
96 __p4d_populate(p4dp, pud_phys, P4D_TYPE_TABLE);
97 }
98
99 return early ? pud_offset_kimg(p4dp, addr) : pud_offset(p4dp, addr);
100 }
101
kasan_pte_populate(pmd_t * pmdp,unsigned long addr,unsigned long end,int node,bool early)102 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
103 unsigned long end, int node, bool early)
104 {
105 unsigned long next;
106 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
107
108 do {
109 phys_addr_t page_phys = early ?
110 __pa_symbol(kasan_early_shadow_page)
111 : kasan_alloc_raw_page(node);
112 if (!early)
113 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
114 next = addr + PAGE_SIZE;
115 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
116 } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
117 }
118
kasan_pmd_populate(pud_t * pudp,unsigned long addr,unsigned long end,int node,bool early)119 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
120 unsigned long end, int node, bool early)
121 {
122 unsigned long next;
123 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
124
125 do {
126 next = pmd_addr_end(addr, end);
127 kasan_pte_populate(pmdp, addr, next, node, early);
128 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
129 }
130
kasan_pud_populate(p4d_t * p4dp,unsigned long addr,unsigned long end,int node,bool early)131 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
132 unsigned long end, int node, bool early)
133 {
134 unsigned long next;
135 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
136
137 do {
138 next = pud_addr_end(addr, end);
139 kasan_pmd_populate(pudp, addr, next, node, early);
140 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
141 }
142
kasan_p4d_populate(pgd_t * pgdp,unsigned long addr,unsigned long end,int node,bool early)143 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
144 unsigned long end, int node, bool early)
145 {
146 unsigned long next;
147 p4d_t *p4dp = p4d_offset(pgdp, addr);
148
149 do {
150 next = p4d_addr_end(addr, end);
151 kasan_pud_populate(p4dp, addr, next, node, early);
152 } while (p4dp++, addr = next, addr != end);
153 }
154
kasan_pgd_populate(unsigned long addr,unsigned long end,int node,bool early)155 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
156 int node, bool early)
157 {
158 unsigned long next;
159 pgd_t *pgdp;
160
161 pgdp = pgd_offset_k(addr);
162 do {
163 next = pgd_addr_end(addr, end);
164 kasan_p4d_populate(pgdp, addr, next, node, early);
165 } while (pgdp++, addr = next, addr != end);
166 }
167
168 /* The early shadow maps everything to a single page of zeroes */
kasan_early_init(void)169 asmlinkage void __init kasan_early_init(void)
170 {
171 BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
172 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
173 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), PGDIR_SIZE));
174 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), PGDIR_SIZE));
175 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
176 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
177 true);
178 }
179
180 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
kasan_map_populate(unsigned long start,unsigned long end,int node)181 static void __init kasan_map_populate(unsigned long start, unsigned long end,
182 int node)
183 {
184 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
185 }
186
187 /*
188 * Copy the current shadow region into a new pgdir.
189 */
kasan_copy_shadow(pgd_t * pgdir)190 void __init kasan_copy_shadow(pgd_t *pgdir)
191 {
192 pgd_t *pgdp, *pgdp_new, *pgdp_end;
193
194 pgdp = pgd_offset_k(KASAN_SHADOW_START);
195 pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
196 pgdp_new = pgd_offset_pgd(pgdir, KASAN_SHADOW_START);
197 do {
198 set_pgd(pgdp_new, READ_ONCE(*pgdp));
199 } while (pgdp++, pgdp_new++, pgdp != pgdp_end);
200 }
201
clear_pgds(unsigned long start,unsigned long end)202 static void __init clear_pgds(unsigned long start,
203 unsigned long end)
204 {
205 /*
206 * Remove references to kasan page tables from
207 * swapper_pg_dir. pgd_clear() can't be used
208 * here because it's nop on 2,3-level pagetable setups
209 */
210 for (; start < end; start += PGDIR_SIZE)
211 set_pgd(pgd_offset_k(start), __pgd(0));
212 }
213
kasan_init_shadow(void)214 static void __init kasan_init_shadow(void)
215 {
216 u64 kimg_shadow_start, kimg_shadow_end;
217 u64 mod_shadow_start;
218 u64 vmalloc_shadow_end;
219 phys_addr_t pa_start, pa_end;
220 u64 i;
221
222 kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK;
223 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END));
224
225 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
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), idmap_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 BUILD_BUG_ON(VMALLOC_START != MODULES_END);
249 kasan_populate_early_shadow((void *)vmalloc_shadow_end,
250 (void *)KASAN_SHADOW_END);
251
252 for_each_mem_range(i, &pa_start, &pa_end) {
253 void *start = (void *)__phys_to_virt(pa_start);
254 void *end = (void *)__phys_to_virt(pa_end);
255
256 if (start >= end)
257 break;
258
259 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
260 (unsigned long)kasan_mem_to_shadow(end),
261 early_pfn_to_nid(virt_to_pfn(start)));
262 }
263
264 /*
265 * KAsan may reuse the contents of kasan_early_shadow_pte directly,
266 * so we should make sure that it maps the zero page read-only.
267 */
268 for (i = 0; i < PTRS_PER_PTE; i++)
269 set_pte(&kasan_early_shadow_pte[i],
270 pfn_pte(sym_to_pfn(kasan_early_shadow_page),
271 PAGE_KERNEL_RO));
272
273 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
274 cpu_replace_ttbr1(lm_alias(swapper_pg_dir), idmap_pg_dir);
275 }
276
kasan_init_depth(void)277 static void __init kasan_init_depth(void)
278 {
279 init_task.kasan_depth = 0;
280 }
281
282 #ifdef CONFIG_KASAN_VMALLOC
kasan_populate_early_vm_area_shadow(void * start,unsigned long size)283 void __init kasan_populate_early_vm_area_shadow(void *start, unsigned long size)
284 {
285 unsigned long shadow_start, shadow_end;
286
287 if (!is_vmalloc_or_module_addr(start))
288 return;
289
290 shadow_start = (unsigned long)kasan_mem_to_shadow(start);
291 shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
292 shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
293 shadow_end = ALIGN(shadow_end, PAGE_SIZE);
294 kasan_map_populate(shadow_start, shadow_end, NUMA_NO_NODE);
295 }
296 #endif
297
kasan_init(void)298 void __init kasan_init(void)
299 {
300 kasan_init_shadow();
301 kasan_init_depth();
302 #if defined(CONFIG_KASAN_GENERIC)
303 /* CONFIG_KASAN_SW_TAGS also requires kasan_init_sw_tags(). */
304 pr_info("KernelAddressSanitizer initialized (generic)\n");
305 #endif
306 }
307
308 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
309