xref: /openbmc/linux/arch/arm/mm/dump.c (revision be709d48) 
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 
26 static 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 
49 struct 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 
60 struct 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 
69 static 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 
139 static 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 
203 struct 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 
211 static 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 
224 static 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 
241 static 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 
258 static 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 
306 static 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 
319 static 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 
338 static 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 
362 static 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 
378 static 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 
395 void 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 
407 static 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 
424 static struct ptdump_info kernel_ptdump_info = {
425 	.mm = &init_mm,
426 	.markers = address_markers,
427 	.base_addr = 0,
428 };
429 
430 void 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 
450 static 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);
457