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
26static 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
35static 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
48static 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
62static 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
76static 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
89static 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
102static 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
115static 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
132static 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
144static 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
156static 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
168static 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 */
191static 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 */
199asmlinkage 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 */
228static 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 */
237static 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 */
256static 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 */
270static 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 */
281static 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
289static 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
300static 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
377static void __init kasan_init_depth(void)
378{
379	init_task.kasan_depth = 0;
380}
381
382#ifdef CONFIG_KASAN_VMALLOC
383void __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
398void __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