1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2023 Loongson Technology Corporation Limited
4 */
5#define pr_fmt(fmt) "kasan: " fmt
6#include <linux/kasan.h>
7#include <linux/memblock.h>
8#include <linux/sched/task.h>
9
10#include <asm/tlbflush.h>
11#include <asm/pgalloc.h>
12#include <asm-generic/sections.h>
13
14static pgd_t kasan_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
15
16#ifdef __PAGETABLE_PUD_FOLDED
17#define __p4d_none(early, p4d) (0)
18#else
19#define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
20(__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
21#endif
22
23#ifdef __PAGETABLE_PMD_FOLDED
24#define __pud_none(early, pud) (0)
25#else
26#define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
27(__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
28#endif
29
30#define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
31(__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
32
33#define __pte_none(early, pte) (early ? pte_none(pte) : \
34((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
35
36bool kasan_early_stage = true;
37
38void *kasan_mem_to_shadow(const void *addr)
39{
40	if (!kasan_arch_is_ready()) {
41		return (void *)(kasan_early_shadow_page);
42	} else {
43		unsigned long maddr = (unsigned long)addr;
44		unsigned long xrange = (maddr >> XRANGE_SHIFT) & 0xffff;
45		unsigned long offset = 0;
46
47		if (maddr >= FIXADDR_START)
48			return (void *)(kasan_early_shadow_page);
49
50		maddr &= XRANGE_SHADOW_MASK;
51		switch (xrange) {
52		case XKPRANGE_CC_SEG:
53			offset = XKPRANGE_CC_SHADOW_OFFSET;
54			break;
55		case XKPRANGE_UC_SEG:
56			offset = XKPRANGE_UC_SHADOW_OFFSET;
57			break;
58		case XKVRANGE_VC_SEG:
59			offset = XKVRANGE_VC_SHADOW_OFFSET;
60			break;
61		default:
62			WARN_ON(1);
63			return NULL;
64		}
65
66		return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
67	}
68}
69
70const void *kasan_shadow_to_mem(const void *shadow_addr)
71{
72	unsigned long addr = (unsigned long)shadow_addr;
73
74	if (unlikely(addr > KASAN_SHADOW_END) ||
75		unlikely(addr < KASAN_SHADOW_START)) {
76		WARN_ON(1);
77		return NULL;
78	}
79
80	if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
81		return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
82	else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
83		return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
84	else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
85		return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
86	else {
87		WARN_ON(1);
88		return NULL;
89	}
90}
91
92/*
93 * Alloc memory for shadow memory page table.
94 */
95static phys_addr_t __init kasan_alloc_zeroed_page(int node)
96{
97	void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
98					__pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
99	if (!p)
100		panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
101			__func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
102
103	return __pa(p);
104}
105
106static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
107{
108	if (__pmd_none(early, READ_ONCE(*pmdp))) {
109		phys_addr_t pte_phys = early ?
110				__pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
111		if (!early)
112			memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
113		pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
114	}
115
116	return pte_offset_kernel(pmdp, addr);
117}
118
119static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
120{
121	if (__pud_none(early, READ_ONCE(*pudp))) {
122		phys_addr_t pmd_phys = early ?
123				__pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
124		if (!early)
125			memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
126		pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
127	}
128
129	return pmd_offset(pudp, addr);
130}
131
132static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
133{
134	if (__p4d_none(early, READ_ONCE(*p4dp))) {
135		phys_addr_t pud_phys = early ?
136			__pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
137		if (!early)
138			memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
139		p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
140	}
141
142	return pud_offset(p4dp, addr);
143}
144
145static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
146				      unsigned long end, int node, bool early)
147{
148	unsigned long next;
149	pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
150
151	do {
152		phys_addr_t page_phys = early ?
153					__pa_symbol(kasan_early_shadow_page)
154					      : kasan_alloc_zeroed_page(node);
155		next = addr + PAGE_SIZE;
156		set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
157	} while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep)));
158}
159
160static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
161				      unsigned long end, int node, bool early)
162{
163	unsigned long next;
164	pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
165
166	do {
167		next = pmd_addr_end(addr, end);
168		kasan_pte_populate(pmdp, addr, next, node, early);
169	} while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp)));
170}
171
172static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
173					    unsigned long end, int node, bool early)
174{
175	unsigned long next;
176	pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
177
178	do {
179		next = pud_addr_end(addr, end);
180		kasan_pmd_populate(pudp, addr, next, node, early);
181	} while (pudp++, addr = next, addr != end);
182}
183
184static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
185					    unsigned long end, int node, bool early)
186{
187	unsigned long next;
188	p4d_t *p4dp = p4d_offset(pgdp, addr);
189
190	do {
191		next = p4d_addr_end(addr, end);
192		kasan_pud_populate(p4dp, addr, next, node, early);
193	} while (p4dp++, addr = next, addr != end);
194}
195
196static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
197				      int node, bool early)
198{
199	unsigned long next;
200	pgd_t *pgdp;
201
202	pgdp = pgd_offset_k(addr);
203
204	do {
205		next = pgd_addr_end(addr, end);
206		kasan_p4d_populate(pgdp, addr, next, node, early);
207	} while (pgdp++, addr = next, addr != end);
208
209}
210
211/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
212static void __init kasan_map_populate(unsigned long start, unsigned long end,
213				      int node)
214{
215	kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
216}
217
218asmlinkage void __init kasan_early_init(void)
219{
220	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
221	BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
222}
223
224static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
225{
226	WRITE_ONCE(*pgdp, pgdval);
227}
228
229static void __init clear_pgds(unsigned long start, unsigned long end)
230{
231	/*
232	 * Remove references to kasan page tables from
233	 * swapper_pg_dir. pgd_clear() can't be used
234	 * here because it's nop on 2,3-level pagetable setups
235	 */
236	for (; start < end; start += PGDIR_SIZE)
237		kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
238}
239
240void __init kasan_init(void)
241{
242	u64 i;
243	phys_addr_t pa_start, pa_end;
244
245	/*
246	 * PGD was populated as invalid_pmd_table or invalid_pud_table
247	 * in pagetable_init() which depends on how many levels of page
248	 * table you are using, but we had to clean the gpd of kasan
249	 * shadow memory, as the pgd value is none-zero.
250	 * The assertion pgd_none is going to be false and the formal populate
251	 * afterwards is not going to create any new pgd at all.
252	 */
253	memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
254	csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
255	local_flush_tlb_all();
256
257	clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
258
259	/* Maps everything to a single page of zeroes */
260	kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
261
262	kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
263					kasan_mem_to_shadow((void *)KFENCE_AREA_END));
264
265	kasan_early_stage = false;
266
267	/* Populate the linear mapping */
268	for_each_mem_range(i, &pa_start, &pa_end) {
269		void *start = (void *)phys_to_virt(pa_start);
270		void *end   = (void *)phys_to_virt(pa_end);
271
272		if (start >= end)
273			break;
274
275		kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
276			(unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
277	}
278
279	/* Populate modules mapping */
280	kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
281		(unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
282	/*
283	 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
284	 * should make sure that it maps the zero page read-only.
285	 */
286	for (i = 0; i < PTRS_PER_PTE; i++)
287		set_pte(&kasan_early_shadow_pte[i],
288			pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
289
290	memset(kasan_early_shadow_page, 0, PAGE_SIZE);
291	csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
292	local_flush_tlb_all();
293
294	/* At this point kasan is fully initialized. Enable error messages */
295	init_task.kasan_depth = 0;
296	pr_info("KernelAddressSanitizer initialized.\n");
297}
298