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1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* | |
3 | * Copyright (C) 2019 SiFive | |
4 | */ | |
5 | ||
6 | #include <linux/init.h> | |
7 | #include <linux/debugfs.h> | |
8 | #include <linux/seq_file.h> | |
9 | #include <linux/ptdump.h> | |
10 | ||
11 | #include <asm/ptdump.h> | |
12 | #include <asm/pgtable.h> | |
13 | #include <asm/kasan.h> | |
14 | ||
15 | #define pt_dump_seq_printf(m, fmt, args...) \ | |
16 | ({ \ | |
17 | if (m) \ | |
18 | seq_printf(m, fmt, ##args); \ | |
19 | }) | |
20 | ||
21 | #define pt_dump_seq_puts(m, fmt) \ | |
22 | ({ \ | |
23 | if (m) \ | |
24 | seq_printf(m, fmt); \ | |
25 | }) | |
26 | ||
27 | /* | |
28 | * The page dumper groups page table entries of the same type into a single | |
29 | * description. It uses pg_state to track the range information while | |
30 | * iterating over the pte entries. When the continuity is broken it then | |
31 | * dumps out a description of the range. | |
32 | */ | |
33 | struct pg_state { | |
34 | struct ptdump_state ptdump; | |
35 | struct seq_file *seq; | |
36 | const struct addr_marker *marker; | |
37 | unsigned long start_address; | |
38 | unsigned long start_pa; | |
39 | unsigned long last_pa; | |
40 | int level; | |
41 | u64 current_prot; | |
42 | bool check_wx; | |
43 | unsigned long wx_pages; | |
44 | }; | |
45 | ||
46 | /* Address marker */ | |
47 | struct addr_marker { | |
48 | unsigned long start_address; | |
49 | const char *name; | |
50 | }; | |
51 | ||
52 | static struct addr_marker address_markers[] = { | |
53 | #ifdef CONFIG_KASAN | |
54 | {KASAN_SHADOW_START, "Kasan shadow start"}, | |
55 | {KASAN_SHADOW_END, "Kasan shadow end"}, | |
56 | #endif | |
57 | {FIXADDR_START, "Fixmap start"}, | |
58 | {FIXADDR_TOP, "Fixmap end"}, | |
59 | {PCI_IO_START, "PCI I/O start"}, | |
60 | {PCI_IO_END, "PCI I/O end"}, | |
61 | #ifdef CONFIG_SPARSEMEM_VMEMMAP | |
62 | {VMEMMAP_START, "vmemmap start"}, | |
63 | {VMEMMAP_END, "vmemmap end"}, | |
64 | #endif | |
65 | {VMALLOC_START, "vmalloc() area"}, | |
66 | {VMALLOC_END, "vmalloc() end"}, | |
67 | {PAGE_OFFSET, "Linear mapping"}, | |
68 | {-1, NULL}, | |
69 | }; | |
70 | ||
71 | /* Page Table Entry */ | |
72 | struct prot_bits { | |
73 | u64 mask; | |
74 | u64 val; | |
75 | const char *set; | |
76 | const char *clear; | |
77 | }; | |
78 | ||
79 | static const struct prot_bits pte_bits[] = { | |
80 | { | |
81 | .mask = _PAGE_SOFT, | |
82 | .val = _PAGE_SOFT, | |
83 | .set = "RSW", | |
84 | .clear = " ", | |
85 | }, { | |
86 | .mask = _PAGE_DIRTY, | |
87 | .val = _PAGE_DIRTY, | |
88 | .set = "D", | |
89 | .clear = ".", | |
90 | }, { | |
91 | .mask = _PAGE_ACCESSED, | |
92 | .val = _PAGE_ACCESSED, | |
93 | .set = "A", | |
94 | .clear = ".", | |
95 | }, { | |
96 | .mask = _PAGE_GLOBAL, | |
97 | .val = _PAGE_GLOBAL, | |
98 | .set = "G", | |
99 | .clear = ".", | |
100 | }, { | |
101 | .mask = _PAGE_USER, | |
102 | .val = _PAGE_USER, | |
103 | .set = "U", | |
104 | .clear = ".", | |
105 | }, { | |
106 | .mask = _PAGE_EXEC, | |
107 | .val = _PAGE_EXEC, | |
108 | .set = "X", | |
109 | .clear = ".", | |
110 | }, { | |
111 | .mask = _PAGE_WRITE, | |
112 | .val = _PAGE_WRITE, | |
113 | .set = "W", | |
114 | .clear = ".", | |
115 | }, { | |
116 | .mask = _PAGE_READ, | |
117 | .val = _PAGE_READ, | |
118 | .set = "R", | |
119 | .clear = ".", | |
120 | }, { | |
121 | .mask = _PAGE_PRESENT, | |
122 | .val = _PAGE_PRESENT, | |
123 | .set = "V", | |
124 | .clear = ".", | |
125 | } | |
126 | }; | |
127 | ||
128 | /* Page Level */ | |
129 | struct pg_level { | |
130 | const char *name; | |
131 | u64 mask; | |
132 | }; | |
133 | ||
134 | static struct pg_level pg_level[] = { | |
135 | { /* pgd */ | |
136 | .name = "PGD", | |
137 | }, { /* p4d */ | |
138 | .name = (CONFIG_PGTABLE_LEVELS > 4) ? "P4D" : "PGD", | |
139 | }, { /* pud */ | |
140 | .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD", | |
141 | }, { /* pmd */ | |
142 | .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD", | |
143 | }, { /* pte */ | |
144 | .name = "PTE", | |
145 | }, | |
146 | }; | |
147 | ||
148 | static void dump_prot(struct pg_state *st) | |
149 | { | |
150 | unsigned int i; | |
151 | ||
152 | for (i = 0; i < ARRAY_SIZE(pte_bits); i++) { | |
153 | const char *s; | |
154 | ||
155 | if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val) | |
156 | s = pte_bits[i].set; | |
157 | else | |
158 | s = pte_bits[i].clear; | |
159 | ||
160 | if (s) | |
161 | pt_dump_seq_printf(st->seq, " %s", s); | |
162 | } | |
163 | } | |
164 | ||
165 | #ifdef CONFIG_64BIT | |
166 | #define ADDR_FORMAT "0x%016lx" | |
167 | #else | |
168 | #define ADDR_FORMAT "0x%08lx" | |
169 | #endif | |
170 | static void dump_addr(struct pg_state *st, unsigned long addr) | |
171 | { | |
172 | static const char units[] = "KMGTPE"; | |
173 | const char *unit = units; | |
174 | unsigned long delta; | |
175 | ||
176 | pt_dump_seq_printf(st->seq, ADDR_FORMAT "-" ADDR_FORMAT " ", | |
177 | st->start_address, addr); | |
178 | ||
179 | pt_dump_seq_printf(st->seq, " " ADDR_FORMAT " ", st->start_pa); | |
180 | delta = (addr - st->start_address) >> 10; | |
181 | ||
182 | while (!(delta & 1023) && unit[1]) { | |
183 | delta >>= 10; | |
184 | unit++; | |
185 | } | |
186 | ||
187 | pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit, | |
188 | pg_level[st->level].name); | |
189 | } | |
190 | ||
191 | static void note_prot_wx(struct pg_state *st, unsigned long addr) | |
192 | { | |
193 | if (!st->check_wx) | |
194 | return; | |
195 | ||
196 | if ((st->current_prot & (_PAGE_WRITE | _PAGE_EXEC)) != | |
197 | (_PAGE_WRITE | _PAGE_EXEC)) | |
198 | return; | |
199 | ||
200 | WARN_ONCE(1, "riscv/mm: Found insecure W+X mapping at address %p/%pS\n", | |
201 | (void *)st->start_address, (void *)st->start_address); | |
202 | ||
203 | st->wx_pages += (addr - st->start_address) / PAGE_SIZE; | |
204 | } | |
205 | ||
206 | static void note_page(struct ptdump_state *pt_st, unsigned long addr, | |
99395ee3 | 207 | int level, u64 val) |
59c4da86 ZL |
208 | { |
209 | struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); | |
210 | u64 pa = PFN_PHYS(pte_pfn(__pte(val))); | |
211 | u64 prot = 0; | |
212 | ||
213 | if (level >= 0) | |
214 | prot = val & pg_level[level].mask; | |
215 | ||
216 | if (st->level == -1) { | |
217 | st->level = level; | |
218 | st->current_prot = prot; | |
219 | st->start_address = addr; | |
220 | st->start_pa = pa; | |
221 | st->last_pa = pa; | |
222 | pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); | |
223 | } else if (prot != st->current_prot || | |
224 | level != st->level || addr >= st->marker[1].start_address) { | |
225 | if (st->current_prot) { | |
226 | note_prot_wx(st, addr); | |
227 | dump_addr(st, addr); | |
228 | dump_prot(st); | |
229 | pt_dump_seq_puts(st->seq, "\n"); | |
230 | } | |
231 | ||
232 | while (addr >= st->marker[1].start_address) { | |
233 | st->marker++; | |
234 | pt_dump_seq_printf(st->seq, "---[ %s ]---\n", | |
235 | st->marker->name); | |
236 | } | |
237 | ||
238 | st->start_address = addr; | |
239 | st->start_pa = pa; | |
240 | st->last_pa = pa; | |
241 | st->current_prot = prot; | |
242 | st->level = level; | |
243 | } else { | |
244 | st->last_pa = pa; | |
245 | } | |
246 | } | |
247 | ||
248 | static void ptdump_walk(struct seq_file *s) | |
249 | { | |
250 | struct pg_state st = { | |
251 | .seq = s, | |
252 | .marker = address_markers, | |
253 | .level = -1, | |
254 | .ptdump = { | |
255 | .note_page = note_page, | |
256 | .range = (struct ptdump_range[]) { | |
257 | {KERN_VIRT_START, ULONG_MAX}, | |
258 | {0, 0} | |
259 | } | |
260 | } | |
261 | }; | |
262 | ||
263 | ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); | |
264 | } | |
265 | ||
266 | void ptdump_check_wx(void) | |
267 | { | |
268 | struct pg_state st = { | |
269 | .seq = NULL, | |
270 | .marker = (struct addr_marker[]) { | |
271 | {0, NULL}, | |
272 | {-1, NULL}, | |
273 | }, | |
274 | .level = -1, | |
275 | .check_wx = true, | |
276 | .ptdump = { | |
277 | .note_page = note_page, | |
278 | .range = (struct ptdump_range[]) { | |
279 | {KERN_VIRT_START, ULONG_MAX}, | |
280 | {0, 0} | |
281 | } | |
282 | } | |
283 | }; | |
284 | ||
285 | ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); | |
286 | ||
287 | if (st.wx_pages) | |
288 | pr_warn("Checked W+X mappings: failed, %lu W+X pages found\n", | |
289 | st.wx_pages); | |
290 | else | |
291 | pr_info("Checked W+X mappings: passed, no W+X pages found\n"); | |
292 | } | |
293 | ||
294 | static int ptdump_show(struct seq_file *m, void *v) | |
295 | { | |
296 | ptdump_walk(m); | |
297 | ||
298 | return 0; | |
299 | } | |
300 | ||
301 | DEFINE_SHOW_ATTRIBUTE(ptdump); | |
302 | ||
303 | static int ptdump_init(void) | |
304 | { | |
305 | unsigned int i, j; | |
306 | ||
307 | for (i = 0; i < ARRAY_SIZE(pg_level); i++) | |
308 | for (j = 0; j < ARRAY_SIZE(pte_bits); j++) | |
309 | pg_level[i].mask |= pte_bits[j].mask; | |
310 | ||
311 | debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, | |
312 | &ptdump_fops); | |
313 | ||
314 | return 0; | |
315 | } | |
316 | ||
317 | device_initcall(ptdump_init); |