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_P4D_FOLDED
17 #define __pgd_none(early, pgd) (0)
18 #else
19 #define __pgd_none(early, pgd) (early ? (pgd_val(pgd) == 0) : \
20 (__pa(pgd_val(pgd)) == (unsigned long)__pa(kasan_early_shadow_p4d)))
21 #endif
22
23 #ifdef __PAGETABLE_PUD_FOLDED
24 #define __p4d_none(early, p4d) (0)
25 #else
26 #define __p4d_none(early, p4d) (early ? (p4d_val(p4d) == 0) : \
27 (__pa(p4d_val(p4d)) == (unsigned long)__pa(kasan_early_shadow_pud)))
28 #endif
29
30 #ifdef __PAGETABLE_PMD_FOLDED
31 #define __pud_none(early, pud) (0)
32 #else
33 #define __pud_none(early, pud) (early ? (pud_val(pud) == 0) : \
34 (__pa(pud_val(pud)) == (unsigned long)__pa(kasan_early_shadow_pmd)))
35 #endif
36
37 #define __pmd_none(early, pmd) (early ? (pmd_val(pmd) == 0) : \
38 (__pa(pmd_val(pmd)) == (unsigned long)__pa(kasan_early_shadow_pte)))
39
40 #define __pte_none(early, pte) (early ? pte_none(pte) : \
41 ((pte_val(pte) & _PFN_MASK) == (unsigned long)__pa(kasan_early_shadow_page)))
42
kasan_mem_to_shadow(const void * addr)43 void *kasan_mem_to_shadow(const void *addr)
44 {
45 if (!kasan_enabled()) {
46 return (void *)(kasan_early_shadow_page);
47 } else {
48 unsigned long maddr = (unsigned long)addr;
49 unsigned long xrange = (maddr >> XRANGE_SHIFT) & 0xffff;
50 unsigned long offset = 0;
51
52 if (maddr >= FIXADDR_START)
53 return (void *)(kasan_early_shadow_page);
54
55 maddr &= XRANGE_SHADOW_MASK;
56 switch (xrange) {
57 case XKPRANGE_CC_SEG:
58 offset = XKPRANGE_CC_SHADOW_OFFSET;
59 break;
60 case XKPRANGE_UC_SEG:
61 offset = XKPRANGE_UC_SHADOW_OFFSET;
62 break;
63 case XKPRANGE_WC_SEG:
64 offset = XKPRANGE_WC_SHADOW_OFFSET;
65 break;
66 case XKVRANGE_VC_SEG:
67 offset = XKVRANGE_VC_SHADOW_OFFSET;
68 break;
69 default:
70 WARN_ON(1);
71 return NULL;
72 }
73
74 return (void *)((maddr >> KASAN_SHADOW_SCALE_SHIFT) + offset);
75 }
76 }
77
kasan_shadow_to_mem(const void * shadow_addr)78 const void *kasan_shadow_to_mem(const void *shadow_addr)
79 {
80 unsigned long addr = (unsigned long)shadow_addr;
81
82 if (unlikely(addr > KASAN_SHADOW_END) ||
83 unlikely(addr < KASAN_SHADOW_START)) {
84 WARN_ON(1);
85 return NULL;
86 }
87
88 if (addr >= XKVRANGE_VC_SHADOW_OFFSET)
89 return (void *)(((addr - XKVRANGE_VC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKVRANGE_VC_START);
90 else if (addr >= XKPRANGE_WC_SHADOW_OFFSET)
91 return (void *)(((addr - XKPRANGE_WC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_WC_START);
92 else if (addr >= XKPRANGE_UC_SHADOW_OFFSET)
93 return (void *)(((addr - XKPRANGE_UC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_UC_START);
94 else if (addr >= XKPRANGE_CC_SHADOW_OFFSET)
95 return (void *)(((addr - XKPRANGE_CC_SHADOW_OFFSET) << KASAN_SHADOW_SCALE_SHIFT) + XKPRANGE_CC_START);
96 else {
97 WARN_ON(1);
98 return NULL;
99 }
100 }
101
102 /*
103 * Alloc memory for shadow memory page table.
104 */
kasan_alloc_zeroed_page(int node)105 static phys_addr_t __init kasan_alloc_zeroed_page(int node)
106 {
107 void *p = memblock_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
108 __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, node);
109 if (!p)
110 panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%llx\n",
111 __func__, PAGE_SIZE, PAGE_SIZE, node, __pa(MAX_DMA_ADDRESS));
112
113 return __pa(p);
114 }
115
kasan_pte_offset(pmd_t * pmdp,unsigned long addr,int node,bool early)116 static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early)
117 {
118 if (__pmd_none(early, pmdp_get(pmdp))) {
119 phys_addr_t pte_phys = early ?
120 __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node);
121 if (!early)
122 memcpy(__va(pte_phys), kasan_early_shadow_pte, sizeof(kasan_early_shadow_pte));
123 pmd_populate_kernel(NULL, pmdp, (pte_t *)__va(pte_phys));
124 }
125
126 return pte_offset_kernel(pmdp, addr);
127 }
128
kasan_pmd_offset(pud_t * pudp,unsigned long addr,int node,bool early)129 static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early)
130 {
131 if (__pud_none(early, pudp_get(pudp))) {
132 phys_addr_t pmd_phys = early ?
133 __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node);
134 if (!early)
135 memcpy(__va(pmd_phys), kasan_early_shadow_pmd, sizeof(kasan_early_shadow_pmd));
136 pud_populate(&init_mm, pudp, (pmd_t *)__va(pmd_phys));
137 }
138
139 return pmd_offset(pudp, addr);
140 }
141
kasan_pud_offset(p4d_t * p4dp,unsigned long addr,int node,bool early)142 static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early)
143 {
144 if (__p4d_none(early, p4dp_get(p4dp))) {
145 phys_addr_t pud_phys = early ?
146 __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node);
147 if (!early)
148 memcpy(__va(pud_phys), kasan_early_shadow_pud, sizeof(kasan_early_shadow_pud));
149 p4d_populate(&init_mm, p4dp, (pud_t *)__va(pud_phys));
150 }
151
152 return pud_offset(p4dp, addr);
153 }
154
kasan_p4d_offset(pgd_t * pgdp,unsigned long addr,int node,bool early)155 static p4d_t *__init kasan_p4d_offset(pgd_t *pgdp, unsigned long addr, int node, bool early)
156 {
157 if (__pgd_none(early, pgdp_get(pgdp))) {
158 phys_addr_t p4d_phys = early ?
159 __pa_symbol(kasan_early_shadow_p4d) : kasan_alloc_zeroed_page(node);
160 if (!early)
161 memcpy(__va(p4d_phys), kasan_early_shadow_p4d, sizeof(kasan_early_shadow_p4d));
162 pgd_populate(&init_mm, pgdp, (p4d_t *)__va(p4d_phys));
163 }
164
165 return p4d_offset(pgdp, addr);
166 }
167
kasan_pte_populate(pmd_t * pmdp,unsigned long addr,unsigned long end,int node,bool early)168 static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
169 unsigned long end, int node, bool early)
170 {
171 unsigned long next;
172 pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
173
174 do {
175 phys_addr_t page_phys = early ?
176 __pa_symbol(kasan_early_shadow_page)
177 : kasan_alloc_zeroed_page(node);
178 next = addr + PAGE_SIZE;
179 set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
180 } while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep)));
181 }
182
kasan_pmd_populate(pud_t * pudp,unsigned long addr,unsigned long end,int node,bool early)183 static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
184 unsigned long end, int node, bool early)
185 {
186 unsigned long next;
187 pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
188
189 do {
190 next = pmd_addr_end(addr, end);
191 kasan_pte_populate(pmdp, addr, next, node, early);
192 } while (pmdp++, addr = next, addr != end && __pmd_none(early, pmdp_get(pmdp)));
193 }
194
kasan_pud_populate(p4d_t * p4dp,unsigned long addr,unsigned long end,int node,bool early)195 static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr,
196 unsigned long end, int node, bool early)
197 {
198 unsigned long next;
199 pud_t *pudp = kasan_pud_offset(p4dp, addr, node, early);
200
201 do {
202 next = pud_addr_end(addr, end);
203 kasan_pmd_populate(pudp, addr, next, node, early);
204 } while (pudp++, addr = next, addr != end && __pud_none(early, READ_ONCE(*pudp)));
205 }
206
kasan_p4d_populate(pgd_t * pgdp,unsigned long addr,unsigned long end,int node,bool early)207 static void __init kasan_p4d_populate(pgd_t *pgdp, unsigned long addr,
208 unsigned long end, int node, bool early)
209 {
210 unsigned long next;
211 p4d_t *p4dp = kasan_p4d_offset(pgdp, addr, node, early);
212
213 do {
214 next = p4d_addr_end(addr, end);
215 kasan_pud_populate(p4dp, addr, next, node, early);
216 } while (p4dp++, addr = next, addr != end && __p4d_none(early, READ_ONCE(*p4dp)));
217 }
218
kasan_pgd_populate(unsigned long addr,unsigned long end,int node,bool early)219 static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
220 int node, bool early)
221 {
222 unsigned long next;
223 pgd_t *pgdp;
224
225 pgdp = pgd_offset_k(addr);
226
227 do {
228 next = pgd_addr_end(addr, end);
229 kasan_p4d_populate(pgdp, addr, next, node, early);
230 } while (pgdp++, addr = next, addr != end);
231
232 }
233
234 /* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
kasan_map_populate(unsigned long start,unsigned long end,int node)235 static void __init kasan_map_populate(unsigned long start, unsigned long end,
236 int node)
237 {
238 kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
239 }
240
kasan_early_init(void)241 asmlinkage void __init kasan_early_init(void)
242 {
243 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
244 BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END + 1, PGDIR_SIZE));
245 }
246
kasan_set_pgd(pgd_t * pgdp,pgd_t pgdval)247 static inline void kasan_set_pgd(pgd_t *pgdp, pgd_t pgdval)
248 {
249 WRITE_ONCE(*pgdp, pgdval);
250 }
251
clear_pgds(unsigned long start,unsigned long end)252 static void __init clear_pgds(unsigned long start, unsigned long end)
253 {
254 /*
255 * Remove references to kasan page tables from
256 * swapper_pg_dir. pgd_clear() can't be used
257 * here because it's nop on 2,3-level pagetable setups
258 */
259 for (; start < end; start = pgd_addr_end(start, end))
260 kasan_set_pgd((pgd_t *)pgd_offset_k(start), __pgd(0));
261 }
262
kasan_init(void)263 void __init kasan_init(void)
264 {
265 u64 i;
266 phys_addr_t pa_start, pa_end;
267
268 /*
269 * If PGDIR_SIZE is too large for cpu_vabits, KASAN_SHADOW_END will
270 * overflow UINTPTR_MAX and then looks like a user space address.
271 * For example, PGDIR_SIZE of CONFIG_4KB_4LEVEL is 2^39, which is too
272 * large for Loongson-2K series whose cpu_vabits = 39.
273 */
274 if (KASAN_SHADOW_END < vm_map_base) {
275 pr_warn("PGDIR_SIZE too large for cpu_vabits, KernelAddressSanitizer disabled.\n");
276 return;
277 }
278
279 /*
280 * PGD was populated as invalid_pmd_table or invalid_pud_table
281 * in pagetable_init() which depends on how many levels of page
282 * table you are using, but we had to clean the gpd of kasan
283 * shadow memory, as the pgd value is none-zero.
284 * The assertion pgd_none is going to be false and the formal populate
285 * afterwards is not going to create any new pgd at all.
286 */
287 memcpy(kasan_pg_dir, swapper_pg_dir, sizeof(kasan_pg_dir));
288 csr_write64(__pa_symbol(kasan_pg_dir), LOONGARCH_CSR_PGDH);
289 local_flush_tlb_all();
290
291 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
292
293 /* Maps everything to a single page of zeroes */
294 kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE, true);
295
296 kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START),
297 kasan_mem_to_shadow((void *)KFENCE_AREA_END));
298
299 /* Enable KASAN here before kasan_mem_to_shadow(). */
300 kasan_init_generic();
301
302 /* Populate the linear mapping */
303 for_each_mem_range(i, &pa_start, &pa_end) {
304 void *start = (void *)phys_to_virt(pa_start);
305 void *end = (void *)phys_to_virt(pa_end);
306
307 if (start >= end)
308 break;
309
310 kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
311 (unsigned long)kasan_mem_to_shadow(end), NUMA_NO_NODE);
312 }
313
314 /* Populate modules mapping */
315 kasan_map_populate((unsigned long)kasan_mem_to_shadow((void *)MODULES_VADDR),
316 (unsigned long)kasan_mem_to_shadow((void *)MODULES_END), NUMA_NO_NODE);
317 /*
318 * KAsan may reuse the contents of kasan_early_shadow_pte directly, so we
319 * should make sure that it maps the zero page read-only.
320 */
321 for (i = 0; i < PTRS_PER_PTE; i++)
322 set_pte(&kasan_early_shadow_pte[i],
323 pfn_pte(__phys_to_pfn(__pa_symbol(kasan_early_shadow_page)), PAGE_KERNEL_RO));
324
325 memset(kasan_early_shadow_page, 0, PAGE_SIZE);
326 csr_write64(__pa_symbol(swapper_pg_dir), LOONGARCH_CSR_PGDH);
327 local_flush_tlb_all();
328
329 /* At this point kasan is fully initialized. Enable error messages */
330 init_task.kasan_depth = 0;
331 }
332