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1/*
2 * Debug helper to dump the current kernel pagetables of the system
3 * so that we can see what the various memory ranges are set to.
4 *
5 * Derived from x86 implementation:
6 * (C) Copyright 2008 Intel Corporation
7 *
8 * Author: Arjan van de Ven <arjan@linux.intel.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; version 2
13 * of the License.
14 */
15#include <linux/debugfs.h>
16#include <linux/fs.h>
17#include <linux/mm.h>
18#include <linux/seq_file.h>
19
20#include <asm/domain.h>
21#include <asm/fixmap.h>
22#include <asm/memory.h>
23#include <asm/pgtable.h>
24#include <asm/ptdump.h>
25
26static struct addr_marker address_markers[] = {
27 { MODULES_VADDR, "Modules" },
28 { PAGE_OFFSET, "Kernel Mapping" },
29 { 0, "vmalloc() Area" },
30 { VMALLOC_END, "vmalloc() End" },
31 { FIXADDR_START, "Fixmap Area" },
32 { VECTORS_BASE, "Vectors" },
33 { VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
34 { -1, NULL },
35};
36
37#define pt_dump_seq_printf(m, fmt, args...) \
38({ \
39 if (m) \
40 seq_printf(m, fmt, ##args); \
41})
42
43#define pt_dump_seq_puts(m, fmt) \
44({ \
45 if (m) \
46 seq_printf(m, fmt); \
47})
48
49struct pg_state {
50 struct seq_file *seq;
51 const struct addr_marker *marker;
52 unsigned long start_address;
53 unsigned level;
54 u64 current_prot;
55 bool check_wx;
56 unsigned long wx_pages;
57 const char *current_domain;
58};
59
60struct prot_bits {
61 u64 mask;
62 u64 val;
63 const char *set;
64 const char *clear;
65 bool ro_bit;
66 bool nx_bit;
67};
68
69static const struct prot_bits pte_bits[] = {
70 {
71 .mask = L_PTE_USER,
72 .val = L_PTE_USER,
73 .set = "USR",
74 .clear = " ",
75 }, {
76 .mask = L_PTE_RDONLY,
77 .val = L_PTE_RDONLY,
78 .set = "ro",
79 .clear = "RW",
80 .ro_bit = true,
81 }, {
82 .mask = L_PTE_XN,
83 .val = L_PTE_XN,
84 .set = "NX",
85 .clear = "x ",
86 .nx_bit = true,
87 }, {
88 .mask = L_PTE_SHARED,
89 .val = L_PTE_SHARED,
90 .set = "SHD",
91 .clear = " ",
92 }, {
93 .mask = L_PTE_MT_MASK,
94 .val = L_PTE_MT_UNCACHED,
95 .set = "SO/UNCACHED",
96 }, {
97 .mask = L_PTE_MT_MASK,
98 .val = L_PTE_MT_BUFFERABLE,
99 .set = "MEM/BUFFERABLE/WC",
100 }, {
101 .mask = L_PTE_MT_MASK,
102 .val = L_PTE_MT_WRITETHROUGH,
103 .set = "MEM/CACHED/WT",
104 }, {
105 .mask = L_PTE_MT_MASK,
106 .val = L_PTE_MT_WRITEBACK,
107 .set = "MEM/CACHED/WBRA",
108#ifndef CONFIG_ARM_LPAE
109 }, {
110 .mask = L_PTE_MT_MASK,
111 .val = L_PTE_MT_MINICACHE,
112 .set = "MEM/MINICACHE",
113#endif
114 }, {
115 .mask = L_PTE_MT_MASK,
116 .val = L_PTE_MT_WRITEALLOC,
117 .set = "MEM/CACHED/WBWA",
118 }, {
119 .mask = L_PTE_MT_MASK,
120 .val = L_PTE_MT_DEV_SHARED,
121 .set = "DEV/SHARED",
122#ifndef CONFIG_ARM_LPAE
123 }, {
124 .mask = L_PTE_MT_MASK,
125 .val = L_PTE_MT_DEV_NONSHARED,
126 .set = "DEV/NONSHARED",
127#endif
128 }, {
129 .mask = L_PTE_MT_MASK,
130 .val = L_PTE_MT_DEV_WC,
131 .set = "DEV/WC",
132 }, {
133 .mask = L_PTE_MT_MASK,
134 .val = L_PTE_MT_DEV_CACHED,
135 .set = "DEV/CACHED",
136 },
137};
138
139static const struct prot_bits section_bits[] = {
140#ifdef CONFIG_ARM_LPAE
141 {
142 .mask = PMD_SECT_USER,
143 .val = PMD_SECT_USER,
144 .set = "USR",
145 }, {
146 .mask = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
147 .val = L_PMD_SECT_RDONLY | PMD_SECT_AP2,
148 .set = "ro",
149 .clear = "RW",
150 .ro_bit = true,
151#elif __LINUX_ARM_ARCH__ >= 6
152 {
153 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
154 .val = PMD_SECT_APX | PMD_SECT_AP_WRITE,
155 .set = " ro",
156 .ro_bit = true,
157 }, {
158 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
159 .val = PMD_SECT_AP_WRITE,
160 .set = " RW",
161 }, {
162 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
163 .val = PMD_SECT_AP_READ,
164 .set = "USR ro",
165 }, {
166 .mask = PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
167 .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
168 .set = "USR RW",
169#else /* ARMv4/ARMv5 */
170 /* These are approximate */
171 {
172 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
173 .val = 0,
174 .set = " ro",
175 .ro_bit = true,
176 }, {
177 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
178 .val = PMD_SECT_AP_WRITE,
179 .set = " RW",
180 }, {
181 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
182 .val = PMD_SECT_AP_READ,
183 .set = "USR ro",
184 }, {
185 .mask = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
186 .val = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
187 .set = "USR RW",
188#endif
189 }, {
190 .mask = PMD_SECT_XN,
191 .val = PMD_SECT_XN,
192 .set = "NX",
193 .clear = "x ",
194 .nx_bit = true,
195 }, {
196 .mask = PMD_SECT_S,
197 .val = PMD_SECT_S,
198 .set = "SHD",
199 .clear = " ",
200 },
201};
202
203struct pg_level {
204 const struct prot_bits *bits;
205 size_t num;
206 u64 mask;
207 const struct prot_bits *ro_bit;
208 const struct prot_bits *nx_bit;
209};
210
211static struct pg_level pg_level[] = {
212 {
213 }, { /* pgd */
214 }, { /* pud */
215 }, { /* pmd */
216 .bits = section_bits,
217 .num = ARRAY_SIZE(section_bits),
218 }, { /* pte */
219 .bits = pte_bits,
220 .num = ARRAY_SIZE(pte_bits),
221 },
222};
223
224static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num)
225{
226 unsigned i;
227
228 for (i = 0; i < num; i++, bits++) {
229 const char *s;
230
231 if ((st->current_prot & bits->mask) == bits->val)
232 s = bits->set;
233 else
234 s = bits->clear;
235
236 if (s)
237 pt_dump_seq_printf(st->seq, " %s", s);
238 }
239}
240
241static void note_prot_wx(struct pg_state *st, unsigned long addr)
242{
243 if (!st->check_wx)
244 return;
245 if ((st->current_prot & pg_level[st->level].ro_bit->mask) ==
246 pg_level[st->level].ro_bit->val)
247 return;
248 if ((st->current_prot & pg_level[st->level].nx_bit->mask) ==
249 pg_level[st->level].nx_bit->val)
250 return;
251
252 WARN_ONCE(1, "arm/mm: Found insecure W+X mapping at address %pS\n",
253 (void *)st->start_address);
254
255 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
256}
257
258static void note_page(struct pg_state *st, unsigned long addr,
259 unsigned int level, u64 val, const char *domain)
260{
261 static const char units[] = "KMGTPE";
262 u64 prot = val & pg_level[level].mask;
263
264 if (!st->level) {
265 st->level = level;
266 st->current_prot = prot;
267 st->current_domain = domain;
268 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
269 } else if (prot != st->current_prot || level != st->level ||
270 domain != st->current_domain ||
271 addr >= st->marker[1].start_address) {
272 const char *unit = units;
273 unsigned long delta;
274
275 if (st->current_prot) {
276 note_prot_wx(st, addr);
277 pt_dump_seq_printf(st->seq, "0x%08lx-0x%08lx ",
278 st->start_address, addr);
279
280 delta = (addr - st->start_address) >> 10;
281 while (!(delta & 1023) && unit[1]) {
282 delta >>= 10;
283 unit++;
284 }
285 pt_dump_seq_printf(st->seq, "%9lu%c", delta, *unit);
286 if (st->current_domain)
287 pt_dump_seq_printf(st->seq, " %s",
288 st->current_domain);
289 if (pg_level[st->level].bits)
290 dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num);
291 pt_dump_seq_printf(st->seq, "\n");
292 }
293
294 if (addr >= st->marker[1].start_address) {
295 st->marker++;
296 pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
297 st->marker->name);
298 }
299 st->start_address = addr;
300 st->current_prot = prot;
301 st->current_domain = domain;
302 st->level = level;
303 }
304}
305
306static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start,
307 const char *domain)
308{
309 pte_t *pte = pte_offset_kernel(pmd, 0);
310 unsigned long addr;
311 unsigned i;
312
313 for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
314 addr = start + i * PAGE_SIZE;
315 note_page(st, addr, 4, pte_val(*pte), domain);
316 }
317}
318
319static const char *get_domain_name(pmd_t *pmd)
320{
321#ifndef CONFIG_ARM_LPAE
322 switch (pmd_val(*pmd) & PMD_DOMAIN_MASK) {
323 case PMD_DOMAIN(DOMAIN_KERNEL):
324 return "KERNEL ";
325 case PMD_DOMAIN(DOMAIN_USER):
326 return "USER ";
327 case PMD_DOMAIN(DOMAIN_IO):
328 return "IO ";
329 case PMD_DOMAIN(DOMAIN_VECTORS):
330 return "VECTORS";
331 default:
332 return "unknown";
333 }
334#endif
335 return NULL;
336}
337
338static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
339{
340 pmd_t *pmd = pmd_offset(pud, 0);
341 unsigned long addr;
342 unsigned i;
343 const char *domain;
344
345 for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
346 addr = start + i * PMD_SIZE;
347 domain = get_domain_name(pmd);
348 if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd))
349 note_page(st, addr, 3, pmd_val(*pmd), domain);
350 else
351 walk_pte(st, pmd, addr, domain);
352
353 if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1])) {
354 addr += SECTION_SIZE;
355 pmd++;
356 domain = get_domain_name(pmd);
357 note_page(st, addr, 3, pmd_val(*pmd), domain);
358 }
359 }
360}
361
362static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
363{
364 pud_t *pud = pud_offset(pgd, 0);
365 unsigned long addr;
366 unsigned i;
367
368 for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
369 addr = start + i * PUD_SIZE;
370 if (!pud_none(*pud)) {
371 walk_pmd(st, pud, addr);
372 } else {
373 note_page(st, addr, 2, pud_val(*pud), NULL);
374 }
375 }
376}
377
378static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
379 unsigned long start)
380{
381 pgd_t *pgd = pgd_offset(mm, 0UL);
382 unsigned i;
383 unsigned long addr;
384
385 for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
386 addr = start + i * PGDIR_SIZE;
387 if (!pgd_none(*pgd)) {
388 walk_pud(st, pgd, addr);
389 } else {
390 note_page(st, addr, 1, pgd_val(*pgd), NULL);
391 }
392 }
393}
394
395void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
396{
397 struct pg_state st = {
398 .seq = m,
399 .marker = info->markers,
400 .check_wx = false,
401 };
402
403 walk_pgd(&st, info->mm, info->base_addr);
404 note_page(&st, 0, 0, 0, NULL);
405}
406
407static void ptdump_initialize(void)
408{
409 unsigned i, j;
410
411 for (i = 0; i < ARRAY_SIZE(pg_level); i++)
412 if (pg_level[i].bits)
413 for (j = 0; j < pg_level[i].num; j++) {
414 pg_level[i].mask |= pg_level[i].bits[j].mask;
415 if (pg_level[i].bits[j].ro_bit)
416 pg_level[i].ro_bit = &pg_level[i].bits[j];
417 if (pg_level[i].bits[j].nx_bit)
418 pg_level[i].nx_bit = &pg_level[i].bits[j];
419 }
420
421 address_markers[2].start_address = VMALLOC_START;
422}
423
424static struct ptdump_info kernel_ptdump_info = {
425 .mm = &init_mm,
426 .markers = address_markers,
427 .base_addr = 0,
428};
429
430void ptdump_check_wx(void)
431{
432 struct pg_state st = {
433 .seq = NULL,
434 .marker = (struct addr_marker[]) {
435 { 0, NULL},
436 { -1, NULL},
437 },
438 .check_wx = true,
439 };
440
441 walk_pgd(&st, &init_mm, 0);
442 note_page(&st, 0, 0, 0, NULL);
443 if (st.wx_pages)
444 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n",
445 st.wx_pages);
446 else
447 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
448}
449
450static int ptdump_init(void)
451{
452 ptdump_initialize();
453 return ptdump_debugfs_register(&kernel_ptdump_info,
454 "kernel_page_tables");
455}
456__initcall(ptdump_init);