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_PTE] __initdata __aligned(PAGE_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
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
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
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
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
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
102 static p4d_t *__init kasan_p4d_offset(pgd_t *pgdp, unsigned long addr, int node,
103 bool early)
104 {
105 if (pgd_none(READ_ONCE(*pgdp))) {
106 phys_addr_t p4d_phys = early ?
107 __pa_symbol(kasan_early_shadow_p4d)
108 : kasan_alloc_zeroed_page(node);
109 __pgd_populate(pgdp, p4d_phys, PGD_TYPE_TABLE);
110 }
111
112 return early ? p4d_offset_kimg(pgdp, addr) : p4d_offset(pgdp, addr);
113 }
114
115 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
116 unsigned long end, int node, bool early)
117 {
118 unsigned long next;
119 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
120
121 do {
122 phys_addr_t page_phys = early ?
123 __pa_symbol(kasan_early_shadow_page)
124 : kasan_alloc_raw_page(node);
125 if (!early)
126 memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
127 next = addr + PAGE_SIZE;
128 __set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
129 } while (ptep++, addr = next, addr != end && pte_none(__ptep_get(ptep)));
130 }
131
132 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
133 unsigned long end, int node, bool early)
134 {
135 unsigned long next;
136 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
137
138 do {
139 next = pmd_addr_end(addr, end);
140 kasan_pte_populate(pmdp, addr, next, node, early);
141 } while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
142 }
143
144 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
145 unsigned long end, int node, bool early)
146 {
147 unsigned long next;
148 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
149
150 do {
151 next = pud_addr_end(addr, end);
152 kasan_pmd_populate(pudp, addr, next, node, early);
153 } while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
154 }
155
156 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
157 unsigned long end, int node, bool early)
158 {
159 unsigned long next;
160 p4d_t *p4dp = kasan_p4d_offset(pgdp, addr, node, early);
161
162 do {
163 next = p4d_addr_end(addr, end);
164 kasan_pud_populate(p4dp, addr, next, node, early);
165 } while (p4dp++, addr = next, addr != end && p4d_none(READ_ONCE(*p4dp)));
166 }
167
168 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
169 int node, bool early)
170 {
171 unsigned long next;
172 pgd_t *pgdp;
173
174 pgdp = pgd_offset_k(addr);
175 do {
176 next = pgd_addr_end(addr, end);
177 kasan_p4d_populate(pgdp, addr, next, node, early);
178 } while (pgdp++, addr = next, addr != end);
179 }
180
181 #if defined(CONFIG_ARM64_64K_PAGES) || CONFIG_PGTABLE_LEVELS > 4
182 #define SHADOW_ALIGN P4D_SIZE
183 #else
184 #define SHADOW_ALIGN PUD_SIZE
185 #endif
186
187 /*
188 * Return whether 'addr' is aligned to the size covered by a root level
189 * descriptor.
190 */
191 static bool __init root_level_aligned(u64 addr)
192 {
193 int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 1) * (PAGE_SHIFT - 3);
194
195 return (addr % (PAGE_SIZE << shift)) == 0;
196 }
197
198 /* The early shadow maps everything to a single page of zeroes */
199 asmlinkage void __init kasan_early_init(void)
200 {
201 BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
202 KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
203 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS), SHADOW_ALIGN));
204 BUILD_BUG_ON(!IS_ALIGNED(_KASAN_SHADOW_START(VA_BITS_MIN), SHADOW_ALIGN));
205 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, SHADOW_ALIGN));
206
207 if (!root_level_aligned(KASAN_SHADOW_START)) {
208 /*
209 * The start address is misaligned, and so the next level table
210 * will be shared with the linear region. This can happen with
211 * 4 or 5 level paging, so install a generic pte_t[] as the
212 * next level. This prevents the kasan_pgd_populate call below
213 * from inserting an entry that refers to the shared KASAN zero
214 * shadow pud_t[]/p4d_t[], which could end up getting corrupted
215 * when the linear region is mapped.
216 */
217 static pte_t tbl[PTRS_PER_PTE] __page_aligned_bss;
218 pgd_t *pgdp = pgd_offset_k(KASAN_SHADOW_START);
219
220 set_pgd(pgdp, __pgd(__pa_symbol(tbl) | PGD_TYPE_TABLE));
221 }
222
223 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
224 true);
225 }
226
227 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
228 static void __init kasan_map_populate(unsigned long start, unsigned long end,
229 int node)
230 {
231 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
232 }
233
234 /*
235 * Return the descriptor index of 'addr' in the root level table
236 */
237 static int __init root_level_idx(u64 addr)
238 {
239 /*
240 * On 64k pages, the TTBR1 range root tables are extended for 52-bit
241 * virtual addressing, and TTBR1 will simply point to the pgd_t entry
242 * that covers the start of the 48-bit addressable VA space if LVA is
243 * not implemented. This means we need to index the table as usual,
244 * instead of masking off bits based on vabits_actual.
245 */
246 u64 vabits = IS_ENABLED(CONFIG_ARM64_64K_PAGES) ? VA_BITS
247 : vabits_actual;
248 int shift = (ARM64_HW_PGTABLE_LEVELS(vabits) - 1) * (PAGE_SHIFT - 3);
249
250 return (addr & ~_PAGE_OFFSET(vabits)) >> (shift + PAGE_SHIFT);
251 }
252
253 /*
254 * Clone a next level table from swapper_pg_dir into tmp_pg_dir
255 */
256 static void __init clone_next_level(u64 addr, pgd_t *tmp_pg_dir, pud_t *pud)
257 {
258 int idx = root_level_idx(addr);
259 pgd_t pgd = READ_ONCE(swapper_pg_dir[idx]);
260 pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd));
261
262 memcpy(pud, pudp, PAGE_SIZE);
263 tmp_pg_dir[idx] = __pgd(__phys_to_pgd_val(__pa_symbol(pud)) |
264 PUD_TYPE_TABLE);
265 }
266
267 /*
268 * Return the descriptor index of 'addr' in the next level table
269 */
270 static int __init next_level_idx(u64 addr)
271 {
272 int shift = (ARM64_HW_PGTABLE_LEVELS(vabits_actual) - 2) * (PAGE_SHIFT - 3);
273
274 return (addr >> (shift + PAGE_SHIFT)) % PTRS_PER_PTE;
275 }
276
277 /*
278 * Dereference the table descriptor at 'pgd_idx' and clear the entries from
279 * 'start' to 'end' (exclusive) from the table.
280 */
281 static void __init clear_next_level(int pgd_idx, int start, int end)
282 {
283 pgd_t pgd = READ_ONCE(swapper_pg_dir[pgd_idx]);
284 pud_t *pudp = (pud_t *)__phys_to_kimg(__pgd_to_phys(pgd));
285
286 memset(&pudp[start], 0, (end - start) * sizeof(pud_t));
287 }
288
289 static void __init clear_shadow(u64 start, u64 end)
290 {
291 int l = root_level_idx(start), m = root_level_idx(end);
292
293 if (!root_level_aligned(start))
294 clear_next_level(l++, next_level_idx(start), PTRS_PER_PTE);
295 if (!root_level_aligned(end))
296 clear_next_level(m, 0, next_level_idx(end));
297 memset(&swapper_pg_dir[l], 0, (m - l) * sizeof(pgd_t));
298 }
299
300 static void __init kasan_init_shadow(void)
301 {
302 static pud_t pud[2][PTRS_PER_PUD] __initdata __aligned(PAGE_SIZE);
303 u64 kimg_shadow_start, kimg_shadow_end;
304 u64 mod_shadow_start;
305 u64 vmalloc_shadow_end;
306 phys_addr_t pa_start, pa_end;
307 u64 i;
308
309 kimg_shadow_start = (u64)kasan_mem_to_shadow(KERNEL_START) & PAGE_MASK;
310 kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(KERNEL_END));
311
312 mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
313
314 vmalloc_shadow_end = (u64)kasan_mem_to_shadow((void *)VMALLOC_END);
315
316 /*
317 * We are going to perform proper setup of shadow memory.
318 * At first we should unmap early shadow (clear_pgds() call below).
319 * However, instrumented code couldn't execute without shadow memory.
320 * tmp_pg_dir used to keep early shadow mapped until full shadow
321 * setup will be finished.
322 */
323 memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
324
325 /*
326 * If the start or end address of the shadow region is not aligned to
327 * the root level size, we have to allocate a temporary next-level table
328 * in each case, clone the next level of descriptors, and install the
329 * table into tmp_pg_dir. Note that with 5 levels of paging, the next
330 * level will in fact be p4d_t, but that makes no difference in this
331 * case.
332 */
333 if (!root_level_aligned(KASAN_SHADOW_START))
334 clone_next_level(KASAN_SHADOW_START, tmp_pg_dir, pud[0]);
335 if (!root_level_aligned(KASAN_SHADOW_END))
336 clone_next_level(KASAN_SHADOW_END, tmp_pg_dir, pud[1]);
337 dsb(ishst);
338 cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
339
340 clear_shadow(KASAN_SHADOW_START, KASAN_SHADOW_END);
341
342 kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
343 early_pfn_to_nid(virt_to_pfn(lm_alias(KERNEL_START))));
344
345 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)PAGE_END),
346 (void *)mod_shadow_start);
347
348 BUILD_BUG_ON(VMALLOC_START != MODULES_END);
349 kasan_populate_early_shadow((void *)vmalloc_shadow_end,
350 (void *)KASAN_SHADOW_END);
351
352 for_each_mem_range(i, &pa_start, &pa_end) {
353 void *start = (void *)__phys_to_virt(pa_start);
354 void *end = (void *)__phys_to_virt(pa_end);
355
356 if (start >= end)
357 break;
358
359 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
360 (unsigned long)kasan_mem_to_shadow(end),
361 early_pfn_to_nid(virt_to_pfn(start)));
362 }
363
364 /*
365 * KAsan may reuse the contents of kasan_early_shadow_pte directly,
366 * so we should make sure that it maps the zero page read-only.
367 */
368 for (i = 0; i < PTRS_PER_PTE; i++)
369 __set_pte(&kasan_early_shadow_pte[i],
370 pfn_pte(sym_to_pfn(kasan_early_shadow_page),
371 PAGE_KERNEL_RO));
372
373 memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
374 cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
375 }
376
377 static void __init kasan_init_depth(void)
378 {
379 init_task.kasan_depth = 0;
380 }
381
382 #ifdef CONFIG_KASAN_VMALLOC
383 void __init kasan_populate_early_vm_area_shadow(void *start, unsigned long size)
384 {
385 unsigned long shadow_start, shadow_end;
386
387 if (!is_vmalloc_or_module_addr(start))
388 return;
389
390 shadow_start = (unsigned long)kasan_mem_to_shadow(start);
391 shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE);
392 shadow_end = (unsigned long)kasan_mem_to_shadow(start + size);
393 shadow_end = ALIGN(shadow_end, PAGE_SIZE);
394 kasan_map_populate(shadow_start, shadow_end, NUMA_NO_NODE);
395 }
396 #endif
397
398 void __init kasan_init(void)
399 {
400 kasan_init_shadow();
401 kasan_init_depth();
402 #if defined(CONFIG_KASAN_GENERIC)
403 /*
404 * Generic KASAN is now fully initialized.
405 * Software and Hardware Tag-Based modes still require
406 * kasan_init_sw_tags() and kasan_init_hw_tags() correspondingly.
407 */
408 pr_info("KernelAddressSanitizer initialized (generic)\n");
409 #endif
410 }
411
412 #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
413
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