xref: /openbmc/linux/arch/riscv/mm/kasan_init.c (revision ccc319dc)
1 // SPDX-License-Identifier: GPL-2.0
2 // Copyright (C) 2019 Andes Technology Corporation
3 
4 #include <linux/pfn.h>
5 #include <linux/init_task.h>
6 #include <linux/kasan.h>
7 #include <linux/kernel.h>
8 #include <linux/memblock.h>
9 #include <linux/pgtable.h>
10 #include <asm/tlbflush.h>
11 #include <asm/fixmap.h>
12 #include <asm/pgalloc.h>
13 
14 /*
15  * Kasan shadow region must lie at a fixed address across sv39, sv48 and sv57
16  * which is right before the kernel.
17  *
18  * For sv39, the region is aligned on PGDIR_SIZE so we only need to populate
19  * the page global directory with kasan_early_shadow_pmd.
20  *
21  * For sv48 and sv57, the region is not aligned on PGDIR_SIZE so the mapping
22  * must be divided as follows:
23  * - the first PGD entry, although incomplete, is populated with
24  *   kasan_early_shadow_pud/p4d
25  * - the PGD entries in the middle are populated with kasan_early_shadow_pud/p4d
26  * - the last PGD entry is shared with the kernel mapping so populated at the
27  *   lower levels pud/p4d
28  *
29  * In addition, when shallow populating a kasan region (for example vmalloc),
30  * this region may also not be aligned on PGDIR size, so we must go down to the
31  * pud level too.
32  */
33 
34 extern pgd_t early_pg_dir[PTRS_PER_PGD];
35 
36 static void __init kasan_populate_pte(pmd_t *pmd, unsigned long vaddr, unsigned long end)
37 {
38 	phys_addr_t phys_addr;
39 	pte_t *ptep, *base_pte;
40 
41 	if (pmd_none(*pmd))
42 		base_pte = memblock_alloc(PTRS_PER_PTE * sizeof(pte_t), PAGE_SIZE);
43 	else
44 		base_pte = (pte_t *)pmd_page_vaddr(*pmd);
45 
46 	ptep = base_pte + pte_index(vaddr);
47 
48 	do {
49 		if (pte_none(*ptep)) {
50 			phys_addr = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
51 			set_pte(ptep, pfn_pte(PFN_DOWN(phys_addr), PAGE_KERNEL));
52 		}
53 	} while (ptep++, vaddr += PAGE_SIZE, vaddr != end);
54 
55 	set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa(base_pte)), PAGE_TABLE));
56 }
57 
58 static void __init kasan_populate_pmd(pud_t *pud, unsigned long vaddr, unsigned long end)
59 {
60 	phys_addr_t phys_addr;
61 	pmd_t *pmdp, *base_pmd;
62 	unsigned long next;
63 
64 	if (pud_none(*pud)) {
65 		base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
66 	} else {
67 		base_pmd = (pmd_t *)pud_pgtable(*pud);
68 		if (base_pmd == lm_alias(kasan_early_shadow_pmd))
69 			base_pmd = memblock_alloc(PTRS_PER_PMD * sizeof(pmd_t), PAGE_SIZE);
70 	}
71 
72 	pmdp = base_pmd + pmd_index(vaddr);
73 
74 	do {
75 		next = pmd_addr_end(vaddr, end);
76 
77 		if (pmd_none(*pmdp) && IS_ALIGNED(vaddr, PMD_SIZE) && (next - vaddr) >= PMD_SIZE) {
78 			phys_addr = memblock_phys_alloc(PMD_SIZE, PMD_SIZE);
79 			if (phys_addr) {
80 				set_pmd(pmdp, pfn_pmd(PFN_DOWN(phys_addr), PAGE_KERNEL));
81 				continue;
82 			}
83 		}
84 
85 		kasan_populate_pte(pmdp, vaddr, next);
86 	} while (pmdp++, vaddr = next, vaddr != end);
87 
88 	/*
89 	 * Wait for the whole PGD to be populated before setting the PGD in
90 	 * the page table, otherwise, if we did set the PGD before populating
91 	 * it entirely, memblock could allocate a page at a physical address
92 	 * where KASAN is not populated yet and then we'd get a page fault.
93 	 */
94 	set_pud(pud, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
95 }
96 
97 static void __init kasan_populate_pud(pgd_t *pgd,
98 				      unsigned long vaddr, unsigned long end,
99 				      bool early)
100 {
101 	phys_addr_t phys_addr;
102 	pud_t *pudp, *base_pud;
103 	unsigned long next;
104 
105 	if (early) {
106 		/*
107 		 * We can't use pgd_page_vaddr here as it would return a linear
108 		 * mapping address but it is not mapped yet, but when populating
109 		 * early_pg_dir, we need the physical address and when populating
110 		 * swapper_pg_dir, we need the kernel virtual address so use
111 		 * pt_ops facility.
112 		 */
113 		base_pud = pt_ops.get_pud_virt(pfn_to_phys(_pgd_pfn(*pgd)));
114 	} else if (pgd_none(*pgd)) {
115 		base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
116 	} else {
117 		base_pud = (pud_t *)pgd_page_vaddr(*pgd);
118 		if (base_pud == lm_alias(kasan_early_shadow_pud)) {
119 			base_pud = memblock_alloc(PTRS_PER_PUD * sizeof(pud_t), PAGE_SIZE);
120 			memcpy(base_pud, (void *)kasan_early_shadow_pud,
121 			       sizeof(pud_t) * PTRS_PER_PUD);
122 		}
123 	}
124 
125 	pudp = base_pud + pud_index(vaddr);
126 
127 	do {
128 		next = pud_addr_end(vaddr, end);
129 
130 		if (pud_none(*pudp) && IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE) {
131 			if (early) {
132 				phys_addr = __pa(((uintptr_t)kasan_early_shadow_pmd));
133 				set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_TABLE));
134 				continue;
135 			} else {
136 				phys_addr = memblock_phys_alloc(PUD_SIZE, PUD_SIZE);
137 				if (phys_addr) {
138 					set_pud(pudp, pfn_pud(PFN_DOWN(phys_addr), PAGE_KERNEL));
139 					continue;
140 				}
141 			}
142 		}
143 
144 		kasan_populate_pmd(pudp, vaddr, next);
145 	} while (pudp++, vaddr = next, vaddr != end);
146 
147 	/*
148 	 * Wait for the whole PGD to be populated before setting the PGD in
149 	 * the page table, otherwise, if we did set the PGD before populating
150 	 * it entirely, memblock could allocate a page at a physical address
151 	 * where KASAN is not populated yet and then we'd get a page fault.
152 	 */
153 	if (!early)
154 		set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
155 }
156 
157 static void __init kasan_populate_p4d(pgd_t *pgd,
158 				      unsigned long vaddr, unsigned long end,
159 				      bool early)
160 {
161 	phys_addr_t phys_addr;
162 	p4d_t *p4dp, *base_p4d;
163 	unsigned long next;
164 
165 	if (early) {
166 		/*
167 		 * We can't use pgd_page_vaddr here as it would return a linear
168 		 * mapping address but it is not mapped yet, but when populating
169 		 * early_pg_dir, we need the physical address and when populating
170 		 * swapper_pg_dir, we need the kernel virtual address so use
171 		 * pt_ops facility.
172 		 */
173 		base_p4d = pt_ops.get_p4d_virt(pfn_to_phys(_pgd_pfn(*pgd)));
174 	} else {
175 		base_p4d = (p4d_t *)pgd_page_vaddr(*pgd);
176 		if (base_p4d == lm_alias(kasan_early_shadow_p4d))
177 			base_p4d = memblock_alloc(PTRS_PER_PUD * sizeof(p4d_t), PAGE_SIZE);
178 	}
179 
180 	p4dp = base_p4d + p4d_index(vaddr);
181 
182 	do {
183 		next = p4d_addr_end(vaddr, end);
184 
185 		if (p4d_none(*p4dp) && IS_ALIGNED(vaddr, P4D_SIZE) && (next - vaddr) >= P4D_SIZE) {
186 			if (early) {
187 				phys_addr = __pa(((uintptr_t)kasan_early_shadow_pud));
188 				set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_TABLE));
189 				continue;
190 			} else {
191 				phys_addr = memblock_phys_alloc(P4D_SIZE, P4D_SIZE);
192 				if (phys_addr) {
193 					set_p4d(p4dp, pfn_p4d(PFN_DOWN(phys_addr), PAGE_KERNEL));
194 					continue;
195 				}
196 			}
197 		}
198 
199 		kasan_populate_pud((pgd_t *)p4dp, vaddr, next, early);
200 	} while (p4dp++, vaddr = next, vaddr != end);
201 
202 	/*
203 	 * Wait for the whole P4D to be populated before setting the P4D in
204 	 * the page table, otherwise, if we did set the P4D before populating
205 	 * it entirely, memblock could allocate a page at a physical address
206 	 * where KASAN is not populated yet and then we'd get a page fault.
207 	 */
208 	if (!early)
209 		set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(base_p4d)), PAGE_TABLE));
210 }
211 
212 #define kasan_early_shadow_pgd_next			(pgtable_l5_enabled ?	\
213 				(uintptr_t)kasan_early_shadow_p4d :		\
214 							(pgtable_l4_enabled ?	\
215 				(uintptr_t)kasan_early_shadow_pud :		\
216 				(uintptr_t)kasan_early_shadow_pmd))
217 #define kasan_populate_pgd_next(pgdp, vaddr, next, early)			\
218 		(pgtable_l5_enabled ?						\
219 		kasan_populate_p4d(pgdp, vaddr, next, early) :			\
220 		(pgtable_l4_enabled ?						\
221 			kasan_populate_pud(pgdp, vaddr, next, early) :		\
222 			kasan_populate_pmd((pud_t *)pgdp, vaddr, next)))
223 
224 static void __init kasan_populate_pgd(pgd_t *pgdp,
225 				      unsigned long vaddr, unsigned long end,
226 				      bool early)
227 {
228 	phys_addr_t phys_addr;
229 	unsigned long next;
230 
231 	do {
232 		next = pgd_addr_end(vaddr, end);
233 
234 		if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE) {
235 			if (early) {
236 				phys_addr = __pa((uintptr_t)kasan_early_shadow_pgd_next);
237 				set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_TABLE));
238 				continue;
239 			} else if (pgd_page_vaddr(*pgdp) ==
240 				   (unsigned long)lm_alias(kasan_early_shadow_pgd_next)) {
241 				/*
242 				 * pgdp can't be none since kasan_early_init
243 				 * initialized all KASAN shadow region with
244 				 * kasan_early_shadow_pud: if this is still the
245 				 * case, that means we can try to allocate a
246 				 * hugepage as a replacement.
247 				 */
248 				phys_addr = memblock_phys_alloc(PGDIR_SIZE, PGDIR_SIZE);
249 				if (phys_addr) {
250 					set_pgd(pgdp, pfn_pgd(PFN_DOWN(phys_addr), PAGE_KERNEL));
251 					continue;
252 				}
253 			}
254 		}
255 
256 		kasan_populate_pgd_next(pgdp, vaddr, next, early);
257 	} while (pgdp++, vaddr = next, vaddr != end);
258 }
259 
260 asmlinkage void __init kasan_early_init(void)
261 {
262 	uintptr_t i;
263 
264 	BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
265 		KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
266 
267 	for (i = 0; i < PTRS_PER_PTE; ++i)
268 		set_pte(kasan_early_shadow_pte + i,
269 			pfn_pte(virt_to_pfn(kasan_early_shadow_page), PAGE_KERNEL));
270 
271 	for (i = 0; i < PTRS_PER_PMD; ++i)
272 		set_pmd(kasan_early_shadow_pmd + i,
273 			pfn_pmd(PFN_DOWN
274 				(__pa((uintptr_t)kasan_early_shadow_pte)),
275 				PAGE_TABLE));
276 
277 	if (pgtable_l4_enabled) {
278 		for (i = 0; i < PTRS_PER_PUD; ++i)
279 			set_pud(kasan_early_shadow_pud + i,
280 				pfn_pud(PFN_DOWN
281 					(__pa(((uintptr_t)kasan_early_shadow_pmd))),
282 					PAGE_TABLE));
283 	}
284 
285 	if (pgtable_l5_enabled) {
286 		for (i = 0; i < PTRS_PER_P4D; ++i)
287 			set_p4d(kasan_early_shadow_p4d + i,
288 				pfn_p4d(PFN_DOWN
289 					(__pa(((uintptr_t)kasan_early_shadow_pud))),
290 					PAGE_TABLE));
291 	}
292 
293 	kasan_populate_pgd(early_pg_dir + pgd_index(KASAN_SHADOW_START),
294 			   KASAN_SHADOW_START, KASAN_SHADOW_END, true);
295 
296 	local_flush_tlb_all();
297 }
298 
299 void __init kasan_swapper_init(void)
300 {
301 	kasan_populate_pgd(pgd_offset_k(KASAN_SHADOW_START),
302 			   KASAN_SHADOW_START, KASAN_SHADOW_END, true);
303 
304 	local_flush_tlb_all();
305 }
306 
307 static void __init kasan_populate(void *start, void *end)
308 {
309 	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
310 	unsigned long vend = PAGE_ALIGN((unsigned long)end);
311 
312 	kasan_populate_pgd(pgd_offset_k(vaddr), vaddr, vend, false);
313 
314 	local_flush_tlb_all();
315 	memset(start, KASAN_SHADOW_INIT, end - start);
316 }
317 
318 static void __init kasan_shallow_populate_pmd(pgd_t *pgdp,
319 					      unsigned long vaddr, unsigned long end)
320 {
321 	unsigned long next;
322 	pmd_t *pmdp, *base_pmd;
323 	bool is_kasan_pte;
324 
325 	base_pmd = (pmd_t *)pgd_page_vaddr(*pgdp);
326 	pmdp = base_pmd + pmd_index(vaddr);
327 
328 	do {
329 		next = pmd_addr_end(vaddr, end);
330 		is_kasan_pte = (pmd_pgtable(*pmdp) == lm_alias(kasan_early_shadow_pte));
331 
332 		if (is_kasan_pte)
333 			pmd_clear(pmdp);
334 	} while (pmdp++, vaddr = next, vaddr != end);
335 }
336 
337 static void __init kasan_shallow_populate_pud(pgd_t *pgdp,
338 					      unsigned long vaddr, unsigned long end)
339 {
340 	unsigned long next;
341 	pud_t *pudp, *base_pud;
342 	pmd_t *base_pmd;
343 	bool is_kasan_pmd;
344 
345 	base_pud = (pud_t *)pgd_page_vaddr(*pgdp);
346 	pudp = base_pud + pud_index(vaddr);
347 
348 	do {
349 		next = pud_addr_end(vaddr, end);
350 		is_kasan_pmd = (pud_pgtable(*pudp) == lm_alias(kasan_early_shadow_pmd));
351 
352 		if (!is_kasan_pmd)
353 			continue;
354 
355 		base_pmd = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
356 		set_pud(pudp, pfn_pud(PFN_DOWN(__pa(base_pmd)), PAGE_TABLE));
357 
358 		if (IS_ALIGNED(vaddr, PUD_SIZE) && (next - vaddr) >= PUD_SIZE)
359 			continue;
360 
361 		memcpy(base_pmd, (void *)kasan_early_shadow_pmd, PAGE_SIZE);
362 		kasan_shallow_populate_pmd((pgd_t *)pudp, vaddr, next);
363 	} while (pudp++, vaddr = next, vaddr != end);
364 }
365 
366 static void __init kasan_shallow_populate_p4d(pgd_t *pgdp,
367 					      unsigned long vaddr, unsigned long end)
368 {
369 	unsigned long next;
370 	p4d_t *p4dp, *base_p4d;
371 	pud_t *base_pud;
372 	bool is_kasan_pud;
373 
374 	base_p4d = (p4d_t *)pgd_page_vaddr(*pgdp);
375 	p4dp = base_p4d + p4d_index(vaddr);
376 
377 	do {
378 		next = p4d_addr_end(vaddr, end);
379 		is_kasan_pud = (p4d_pgtable(*p4dp) == lm_alias(kasan_early_shadow_pud));
380 
381 		if (!is_kasan_pud)
382 			continue;
383 
384 		base_pud = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
385 		set_p4d(p4dp, pfn_p4d(PFN_DOWN(__pa(base_pud)), PAGE_TABLE));
386 
387 		if (IS_ALIGNED(vaddr, P4D_SIZE) && (next - vaddr) >= P4D_SIZE)
388 			continue;
389 
390 		memcpy(base_pud, (void *)kasan_early_shadow_pud, PAGE_SIZE);
391 		kasan_shallow_populate_pud((pgd_t *)p4dp, vaddr, next);
392 	} while (p4dp++, vaddr = next, vaddr != end);
393 }
394 
395 #define kasan_shallow_populate_pgd_next(pgdp, vaddr, next)			\
396 		(pgtable_l5_enabled ?						\
397 		kasan_shallow_populate_p4d(pgdp, vaddr, next) :			\
398 		(pgtable_l4_enabled ?						\
399 		kasan_shallow_populate_pud(pgdp, vaddr, next) :			\
400 		kasan_shallow_populate_pmd(pgdp, vaddr, next)))
401 
402 static void __init kasan_shallow_populate_pgd(unsigned long vaddr, unsigned long end)
403 {
404 	unsigned long next;
405 	void *p;
406 	pgd_t *pgd_k = pgd_offset_k(vaddr);
407 	bool is_kasan_pgd_next;
408 
409 	do {
410 		next = pgd_addr_end(vaddr, end);
411 		is_kasan_pgd_next = (pgd_page_vaddr(*pgd_k) ==
412 				     (unsigned long)lm_alias(kasan_early_shadow_pgd_next));
413 
414 		if (is_kasan_pgd_next) {
415 			p = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
416 			set_pgd(pgd_k, pfn_pgd(PFN_DOWN(__pa(p)), PAGE_TABLE));
417 		}
418 
419 		if (IS_ALIGNED(vaddr, PGDIR_SIZE) && (next - vaddr) >= PGDIR_SIZE)
420 			continue;
421 
422 		memcpy(p, (void *)kasan_early_shadow_pgd_next, PAGE_SIZE);
423 		kasan_shallow_populate_pgd_next(pgd_k, vaddr, next);
424 	} while (pgd_k++, vaddr = next, vaddr != end);
425 }
426 
427 static void __init kasan_shallow_populate(void *start, void *end)
428 {
429 	unsigned long vaddr = (unsigned long)start & PAGE_MASK;
430 	unsigned long vend = PAGE_ALIGN((unsigned long)end);
431 
432 	kasan_shallow_populate_pgd(vaddr, vend);
433 	local_flush_tlb_all();
434 }
435 
436 void __init kasan_init(void)
437 {
438 	phys_addr_t p_start, p_end;
439 	u64 i;
440 
441 	if (IS_ENABLED(CONFIG_KASAN_VMALLOC))
442 		kasan_shallow_populate(
443 			(void *)kasan_mem_to_shadow((void *)VMALLOC_START),
444 			(void *)kasan_mem_to_shadow((void *)VMALLOC_END));
445 
446 	/* Populate the linear mapping */
447 	for_each_mem_range(i, &p_start, &p_end) {
448 		void *start = (void *)__va(p_start);
449 		void *end = (void *)__va(p_end);
450 
451 		if (start >= end)
452 			break;
453 
454 		kasan_populate(kasan_mem_to_shadow(start), kasan_mem_to_shadow(end));
455 	}
456 
457 	/* Populate kernel, BPF, modules mapping */
458 	kasan_populate(kasan_mem_to_shadow((const void *)MODULES_VADDR),
459 		       kasan_mem_to_shadow((const void *)MODULES_VADDR + SZ_2G));
460 
461 	for (i = 0; i < PTRS_PER_PTE; i++)
462 		set_pte(&kasan_early_shadow_pte[i],
463 			mk_pte(virt_to_page(kasan_early_shadow_page),
464 			       __pgprot(_PAGE_PRESENT | _PAGE_READ |
465 					_PAGE_ACCESSED)));
466 
467 	memset(kasan_early_shadow_page, KASAN_SHADOW_INIT, PAGE_SIZE);
468 	init_task.kasan_depth = 0;
469 }
470