summaryrefslogtreecommitdiffstats
path: root/arch/x86/mm/dump_pagetables.c
blob: 64229dad7eab6ce868957491431b62b51a2bee95 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Debug helper to dump the current kernel pagetables of the system
 * so that we can see what the various memory ranges are set to.
 *
 * (C) Copyright 2008 Intel Corporation
 *
 * Author: Arjan van de Ven <arjan@linux.intel.com>
 */

#include <linux/debugfs.h>
#include <linux/kasan.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/highmem.h>
#include <linux/pci.h>
#include <linux/ptdump.h>

#include <asm/e820/types.h>
#include <asm/pgtable.h>

/*
 * The dumper groups pagetable entries of the same type into one, and for
 * that it needs to keep some state when walking, and flush this state
 * when a "break" in the continuity is found.
 */
struct pg_state {
	struct ptdump_state ptdump;
	int level;
	pgprotval_t current_prot;
	pgprotval_t effective_prot;
	pgprotval_t prot_levels[5];
	unsigned long start_address;
	const struct addr_marker *marker;
	unsigned long lines;
	bool to_dmesg;
	bool check_wx;
	unsigned long wx_pages;
	struct seq_file *seq;
};

struct addr_marker {
	unsigned long start_address;
	const char *name;
	unsigned long max_lines;
};

/* Address space markers hints */

#ifdef CONFIG_X86_64

enum address_markers_idx {
	USER_SPACE_NR = 0,
	KERNEL_SPACE_NR,
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	LDT_NR,
#endif
	LOW_KERNEL_NR,
	VMALLOC_START_NR,
	VMEMMAP_START_NR,
#ifdef CONFIG_KASAN
	KASAN_SHADOW_START_NR,
	KASAN_SHADOW_END_NR,
#endif
	CPU_ENTRY_AREA_NR,
#ifdef CONFIG_X86_ESPFIX64
	ESPFIX_START_NR,
#endif
#ifdef CONFIG_EFI
	EFI_END_NR,
#endif
	HIGH_KERNEL_NR,
	MODULES_VADDR_NR,
	MODULES_END_NR,
	FIXADDR_START_NR,
	END_OF_SPACE_NR,
};

static struct addr_marker address_markers[] = {
	[USER_SPACE_NR]		= { 0,			"User Space" },
	[KERNEL_SPACE_NR]	= { (1UL << 63),	"Kernel Space" },
	[LOW_KERNEL_NR]		= { 0UL,		"Low Kernel Mapping" },
	[VMALLOC_START_NR]	= { 0UL,		"vmalloc() Area" },
	[VMEMMAP_START_NR]	= { 0UL,		"Vmemmap" },
#ifdef CONFIG_KASAN
	/*
	 * These fields get initialized with the (dynamic)
	 * KASAN_SHADOW_{START,END} values in pt_dump_init().
	 */
	[KASAN_SHADOW_START_NR]	= { 0UL,		"KASAN shadow" },
	[KASAN_SHADOW_END_NR]	= { 0UL,		"KASAN shadow end" },
#endif
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	[LDT_NR]		= { 0UL,		"LDT remap" },
#endif
	[CPU_ENTRY_AREA_NR]	= { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
#ifdef CONFIG_X86_ESPFIX64
	[ESPFIX_START_NR]	= { ESPFIX_BASE_ADDR,	"ESPfix Area", 16 },
#endif
#ifdef CONFIG_EFI
	[EFI_END_NR]		= { EFI_VA_END,		"EFI Runtime Services" },
#endif
	[HIGH_KERNEL_NR]	= { __START_KERNEL_map,	"High Kernel Mapping" },
	[MODULES_VADDR_NR]	= { MODULES_VADDR,	"Modules" },
	[MODULES_END_NR]	= { MODULES_END,	"End Modules" },
	[FIXADDR_START_NR]	= { FIXADDR_START,	"Fixmap Area" },
	[END_OF_SPACE_NR]	= { -1,			NULL }
};

#define INIT_PGD	((pgd_t *) &init_top_pgt)

#else /* CONFIG_X86_64 */

enum address_markers_idx {
	USER_SPACE_NR = 0,
	KERNEL_SPACE_NR,
	VMALLOC_START_NR,
	VMALLOC_END_NR,
#ifdef CONFIG_HIGHMEM
	PKMAP_BASE_NR,
#endif
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	LDT_NR,
#endif
	CPU_ENTRY_AREA_NR,
	FIXADDR_START_NR,
	END_OF_SPACE_NR,
};

static struct addr_marker address_markers[] = {
	[USER_SPACE_NR]		= { 0,			"User Space" },
	[KERNEL_SPACE_NR]	= { PAGE_OFFSET,	"Kernel Mapping" },
	[VMALLOC_START_NR]	= { 0UL,		"vmalloc() Area" },
	[VMALLOC_END_NR]	= { 0UL,		"vmalloc() End" },
#ifdef CONFIG_HIGHMEM
	[PKMAP_BASE_NR]		= { 0UL,		"Persistent kmap() Area" },
#endif
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	[LDT_NR]		= { 0UL,		"LDT remap" },
#endif
	[CPU_ENTRY_AREA_NR]	= { 0UL,		"CPU entry area" },
	[FIXADDR_START_NR]	= { 0UL,		"Fixmap area" },
	[END_OF_SPACE_NR]	= { -1,			NULL }
};

#define INIT_PGD	(swapper_pg_dir)

#endif /* !CONFIG_X86_64 */

/* Multipliers for offsets within the PTEs */
#define PTE_LEVEL_MULT (PAGE_SIZE)
#define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
#define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
#define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
#define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)

#define pt_dump_seq_printf(m, to_dmesg, fmt, args...)		\
({								\
	if (to_dmesg)					\
		printk(KERN_INFO fmt, ##args);			\
	else							\
		if (m)						\
			seq_printf(m, fmt, ##args);		\
})

#define pt_dump_cont_printf(m, to_dmesg, fmt, args...)		\
({								\
	if (to_dmesg)					\
		printk(KERN_CONT fmt, ##args);			\
	else							\
		if (m)						\
			seq_printf(m, fmt, ##args);		\
})

/*
 * Print a readable form of a pgprot_t to the seq_file
 */
static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
{
	static const char * const level_name[] =
		{ "pgd", "p4d", "pud", "pmd", "pte" };

	if (!(pr & _PAGE_PRESENT)) {
		/* Not present */
		pt_dump_cont_printf(m, dmsg, "                              ");
	} else {
		if (pr & _PAGE_USER)
			pt_dump_cont_printf(m, dmsg, "USR ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");
		if (pr & _PAGE_RW)
			pt_dump_cont_printf(m, dmsg, "RW ");
		else
			pt_dump_cont_printf(m, dmsg, "ro ");
		if (pr & _PAGE_PWT)
			pt_dump_cont_printf(m, dmsg, "PWT ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");
		if (pr & _PAGE_PCD)
			pt_dump_cont_printf(m, dmsg, "PCD ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");

		/* Bit 7 has a different meaning on level 3 vs 4 */
		if (level <= 3 && pr & _PAGE_PSE)
			pt_dump_cont_printf(m, dmsg, "PSE ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");
		if ((level == 4 && pr & _PAGE_PAT) ||
		    ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
			pt_dump_cont_printf(m, dmsg, "PAT ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");
		if (pr & _PAGE_GLOBAL)
			pt_dump_cont_printf(m, dmsg, "GLB ");
		else
			pt_dump_cont_printf(m, dmsg, "    ");
		if (pr & _PAGE_NX)
			pt_dump_cont_printf(m, dmsg, "NX ");
		else
			pt_dump_cont_printf(m, dmsg, "x  ");
	}
	pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
}

static void note_wx(struct pg_state *st, unsigned long addr)
{
	unsigned long npages;

	npages = (addr - st->start_address) / PAGE_SIZE;

#ifdef CONFIG_PCI_BIOS
	/*
	 * If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
	 * Inform about it, but avoid the warning.
	 */
	if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
	    addr <= PAGE_OFFSET + BIOS_END) {
		pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
		return;
	}
#endif
	/* Account the WX pages */
	st->wx_pages += npages;
	WARN_ONCE(__supported_pte_mask & _PAGE_NX,
		  "x86/mm: Found insecure W+X mapping at address %pS\n",
		  (void *)st->start_address);
}

static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
{
	return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) |
	       ((prot1 | prot2) & _PAGE_NX);
}

/*
 * This function gets called on a break in a continuous series
 * of PTE entries; the next one is different so we need to
 * print what we collected so far.
 */
static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
		      unsigned long val)
{
	struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
	pgprotval_t new_prot, new_eff;
	pgprotval_t cur, eff;
	static const char units[] = "BKMGTPE";
	struct seq_file *m = st->seq;

	new_prot = val & PTE_FLAGS_MASK;

	if (level > 0) {
		new_eff = effective_prot(st->prot_levels[level - 1],
					 new_prot);
	} else {
		new_eff = new_prot;
	}

	if (level >= 0)
		st->prot_levels[level] = new_eff;

	/*
	 * If we have a "break" in the series, we need to flush the state that
	 * we have now. "break" is either changing perms, levels or
	 * address space marker.
	 */
	cur = st->current_prot;
	eff = st->effective_prot;

	if (st->level == -1) {
		/* First entry */
		st->current_prot = new_prot;
		st->effective_prot = new_eff;
		st->level = level;
		st->marker = address_markers;
		st->lines = 0;
		pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
				   st->marker->name);
	} else if (new_prot != cur || new_eff != eff || level != st->level ||
		   addr >= st->marker[1].start_address) {
		const char *unit = units;
		unsigned long delta;
		int width = sizeof(unsigned long) * 2;

		if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
			note_wx(st, addr);

		/*
		 * Now print the actual finished series
		 */
		if (!st->marker->max_lines ||
		    st->lines < st->marker->max_lines) {
			pt_dump_seq_printf(m, st->to_dmesg,
					   "0x%0*lx-0x%0*lx   ",
					   width, st->start_address,
					   width, addr);

			delta = addr - st->start_address;
			while (!(delta & 1023) && unit[1]) {
				delta >>= 10;
				unit++;
			}
			pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
					    delta, *unit);
			printk_prot(m, st->current_prot, st->level,
				    st->to_dmesg);
		}
		st->lines++;

		/*
		 * We print markers for special areas of address space,
		 * such as the start of vmalloc space etc.
		 * This helps in the interpretation.
		 */
		if (addr >= st->marker[1].start_address) {
			if (st->marker->max_lines &&
			    st->lines > st->marker->max_lines) {
				unsigned long nskip =
					st->lines - st->marker->max_lines;
				pt_dump_seq_printf(m, st->to_dmesg,
						   "... %lu entr%s skipped ... \n",
						   nskip,
						   nskip == 1 ? "y" : "ies");
			}
			st->marker++;
			st->lines = 0;
			pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
					   st->marker->name);
		}

		st->start_address = addr;
		st->current_prot = new_prot;
		st->effective_prot = new_eff;
		st->level = level;
	}
}

static void ptdump_walk_pgd_level_core(struct seq_file *m,
				       struct mm_struct *mm, pgd_t *pgd,
				       bool checkwx, bool dmesg)
{
	const struct ptdump_range ptdump_ranges[] = {
#ifdef CONFIG_X86_64

#define normalize_addr_shift (64 - (__VIRTUAL_MASK_SHIFT + 1))
#define normalize_addr(u) ((signed long)((u) << normalize_addr_shift) >> \
			   normalize_addr_shift)

	{0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
	{normalize_addr(PTRS_PER_PGD * PGD_LEVEL_MULT / 2), ~0UL},
#else
	{0, ~0UL},
#endif
	{0, 0}
};

	struct pg_state st = {
		.ptdump = {
			.note_page	= note_page,
			.range		= ptdump_ranges
		},
		.level = -1,
		.to_dmesg	= dmesg,
		.check_wx	= checkwx,
		.seq		= m
	};

	ptdump_walk_pgd(&st.ptdump, mm, pgd);

	if (!checkwx)
		return;
	if (st.wx_pages)
		pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
			st.wx_pages);
	else
		pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
}

void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
{
	ptdump_walk_pgd_level_core(m, mm, mm->pgd, false, true);
}

void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
				   bool user)
{
	pgd_t *pgd = mm->pgd;
#ifdef CONFIG_PAGE_TABLE_ISOLATION
	if (user && boot_cpu_has(X86_FEATURE_PTI))
		pgd = kernel_to_user_pgdp(pgd);
#endif
	ptdump_walk_pgd_level_core(m, mm, pgd, false, false);
}
EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);

void ptdump_walk_user_pgd_level_checkwx(void)
{
#ifdef CONFIG_PAGE_TABLE_ISOLATION
	pgd_t *pgd = INIT_PGD;

	if (!(__supported_pte_mask & _PAGE_NX) ||
	    !boot_cpu_has(X86_FEATURE_PTI))
		return;

	pr_info("x86/mm: Checking user space page tables\n");
	pgd = kernel_to_user_pgdp(pgd);
	ptdump_walk_pgd_level_core(NULL, &init_mm, pgd, true, false);
#endif
}

void ptdump_walk_pgd_level_checkwx(void)
{
	ptdump_walk_pgd_level_core(NULL, &init_mm, INIT_PGD, true, false);
}

static int __init pt_dump_init(void)
{
	/*
	 * Various markers are not compile-time constants, so assign them
	 * here.
	 */
#ifdef CONFIG_X86_64
	address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
	address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
	address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
#ifdef CONFIG_MODIFY_LDT_SYSCALL
	address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
#endif
#ifdef CONFIG_KASAN
	address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
	address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
#endif
#endif
#ifdef CONFIG_X86_32
	address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
	address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
# ifdef CONFIG_HIGHMEM
	address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
# endif
	address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
	address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
# ifdef CONFIG_MODIFY_LDT_SYSCALL
	address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
# endif
#endif
	return 0;
}
__initcall(pt_dump_init);