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