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
14 static 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
36 bool kasan_early_stage = true;
37
kasan_mem_to_shadow(const void * addr)38 void *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
kasan_shadow_to_mem(const void * shadow_addr)70 const 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 */
kasan_alloc_zeroed_page(int node)95 static 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
kasan_pte_offset(pmd_t * pmdp,unsigned long addr,int node,bool early)106 static 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
kasan_pmd_offset(pud_t * pudp,unsigned long addr,int node,bool early)119 static 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
kasan_pud_offset(p4d_t * p4dp,unsigned long addr,int node,bool early)132 static 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
kasan_pte_populate(pmd_t * pmdp,unsigned long addr,unsigned long end,int node,bool early)145 static 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
kasan_pmd_populate(pud_t * pudp,unsigned long addr,unsigned long end,int node,bool early)160 static 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
kasan_pud_populate(p4d_t * p4dp,unsigned long addr,unsigned long end,int node,bool early)172 static 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
kasan_p4d_populate(pgd_t * pgdp,unsigned long addr,unsigned long end,int node,bool early)184 static 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
kasan_pgd_populate(unsigned long addr,unsigned long end,int node,bool early)196 static 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 */
kasan_map_populate(unsigned long start,unsigned long end,int node)212 static 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
kasan_early_init(void)218 asmlinkage 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
kasan_set_pgd(pgd_t * pgdp,pgd_t pgdval)224 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
225 {
226 WRITE_ONCE(*pgdp, pgdval);
227 }
228
clear_pgds(unsigned long start,unsigned long end)229 static 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
kasan_init(void)240 void __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