1/*
2 * Copyright (c) 2014, The Linux Foundation. All rights reserved.
3 * Debug helper to dump the current kernel pagetables of the system
4 * so that we can see what the various memory ranges are set to.
5 *
6 * Derived from x86 and arm implementation:
7 * (C) Copyright 2008 Intel Corporation
8 *
9 * Author: Arjan van de Ven <arjan@linux.intel.com>
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; version 2
14 * of the License.
15 */
16#include <linux/debugfs.h>
17#include <linux/errno.h>
18#include <linux/fs.h>
19#include <linux/io.h>
20#include <linux/init.h>
21#include <linux/mm.h>
22#include <linux/sched.h>
23#include <linux/seq_file.h>
24
25#include <asm/fixmap.h>
26#include <asm/memory.h>
27#include <asm/pgtable.h>
28#include <asm/pgtable-hwdef.h>
29
30#define LOWEST_ADDR	(UL(0xffffffffffffffff) << VA_BITS)
31
32struct addr_marker {
33	unsigned long start_address;
34	const char *name;
35};
36
37enum address_markers_idx {
38	VMALLOC_START_NR = 0,
39	VMALLOC_END_NR,
40#ifdef CONFIG_SPARSEMEM_VMEMMAP
41	VMEMMAP_START_NR,
42	VMEMMAP_END_NR,
43#endif
44	FIXADDR_START_NR,
45	FIXADDR_END_NR,
46	PCI_START_NR,
47	PCI_END_NR,
48	MODULES_START_NR,
49	MODUELS_END_NR,
50	KERNEL_SPACE_NR,
51};
52
53static struct addr_marker address_markers[] = {
54	{ VMALLOC_START,	"vmalloc() Area" },
55	{ VMALLOC_END,		"vmalloc() End" },
56#ifdef CONFIG_SPARSEMEM_VMEMMAP
57	{ 0,			"vmemmap start" },
58	{ 0,			"vmemmap end" },
59#endif
60	{ FIXADDR_START,	"Fixmap start" },
61	{ FIXADDR_TOP,		"Fixmap end" },
62	{ PCI_IO_START,		"PCI I/O start" },
63	{ PCI_IO_END,		"PCI I/O end" },
64	{ MODULES_VADDR,	"Modules start" },
65	{ MODULES_END,		"Modules end" },
66	{ PAGE_OFFSET,		"Kernel Mapping" },
67	{ -1,			NULL },
68};
69
70struct pg_state {
71	struct seq_file *seq;
72	const struct addr_marker *marker;
73	unsigned long start_address;
74	unsigned level;
75	u64 current_prot;
76};
77
78struct prot_bits {
79	u64		mask;
80	u64		val;
81	const char	*set;
82	const char	*clear;
83};
84
85static const struct prot_bits pte_bits[] = {
86	{
87		.mask	= PTE_USER,
88		.val	= PTE_USER,
89		.set	= "USR",
90		.clear	= "   ",
91	}, {
92		.mask	= PTE_RDONLY,
93		.val	= PTE_RDONLY,
94		.set	= "ro",
95		.clear	= "RW",
96	}, {
97		.mask	= PTE_PXN,
98		.val	= PTE_PXN,
99		.set	= "NX",
100		.clear	= "x ",
101	}, {
102		.mask	= PTE_SHARED,
103		.val	= PTE_SHARED,
104		.set	= "SHD",
105		.clear	= "   ",
106	}, {
107		.mask	= PTE_AF,
108		.val	= PTE_AF,
109		.set	= "AF",
110		.clear	= "  ",
111	}, {
112		.mask	= PTE_NG,
113		.val	= PTE_NG,
114		.set	= "NG",
115		.clear	= "  ",
116	}, {
117		.mask	= PTE_UXN,
118		.val	= PTE_UXN,
119		.set	= "UXN",
120	}, {
121		.mask	= PTE_ATTRINDX_MASK,
122		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRnE),
123		.set	= "DEVICE/nGnRnE",
124	}, {
125		.mask	= PTE_ATTRINDX_MASK,
126		.val	= PTE_ATTRINDX(MT_DEVICE_nGnRE),
127		.set	= "DEVICE/nGnRE",
128	}, {
129		.mask	= PTE_ATTRINDX_MASK,
130		.val	= PTE_ATTRINDX(MT_DEVICE_GRE),
131		.set	= "DEVICE/GRE",
132	}, {
133		.mask	= PTE_ATTRINDX_MASK,
134		.val	= PTE_ATTRINDX(MT_NORMAL_NC),
135		.set	= "MEM/NORMAL-NC",
136	}, {
137		.mask	= PTE_ATTRINDX_MASK,
138		.val	= PTE_ATTRINDX(MT_NORMAL),
139		.set	= "MEM/NORMAL",
140	}
141};
142
143struct pg_level {
144	const struct prot_bits *bits;
145	size_t num;
146	u64 mask;
147};
148
149static struct pg_level pg_level[] = {
150	{
151	}, { /* pgd */
152		.bits	= pte_bits,
153		.num	= ARRAY_SIZE(pte_bits),
154	}, { /* pud */
155		.bits	= pte_bits,
156		.num	= ARRAY_SIZE(pte_bits),
157	}, { /* pmd */
158		.bits	= pte_bits,
159		.num	= ARRAY_SIZE(pte_bits),
160	}, { /* pte */
161		.bits	= pte_bits,
162		.num	= ARRAY_SIZE(pte_bits),
163	},
164};
165
166static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
167			size_t num)
168{
169	unsigned i;
170
171	for (i = 0; i < num; i++, bits++) {
172		const char *s;
173
174		if ((st->current_prot & bits->mask) == bits->val)
175			s = bits->set;
176		else
177			s = bits->clear;
178
179		if (s)
180			seq_printf(st->seq, " %s", s);
181	}
182}
183
184static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
185				u64 val)
186{
187	static const char units[] = "KMGTPE";
188	u64 prot = val & pg_level[level].mask;
189
190	if (!st->level) {
191		st->level = level;
192		st->current_prot = prot;
193		st->start_address = addr;
194		seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
195	} else if (prot != st->current_prot || level != st->level ||
196		   addr >= st->marker[1].start_address) {
197		const char *unit = units;
198		unsigned long delta;
199
200		if (st->current_prot) {
201			seq_printf(st->seq, "0x%16lx-0x%16lx   ",
202				   st->start_address, addr);
203
204			delta = (addr - st->start_address) >> 10;
205			while (!(delta & 1023) && unit[1]) {
206				delta >>= 10;
207				unit++;
208			}
209			seq_printf(st->seq, "%9lu%c", delta, *unit);
210			if (pg_level[st->level].bits)
211				dump_prot(st, pg_level[st->level].bits,
212					  pg_level[st->level].num);
213			seq_puts(st->seq, "\n");
214		}
215
216		if (addr >= st->marker[1].start_address) {
217			st->marker++;
218			seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
219		}
220
221		st->start_address = addr;
222		st->current_prot = prot;
223		st->level = level;
224	}
225
226	if (addr >= st->marker[1].start_address) {
227		st->marker++;
228		seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
229	}
230
231}
232
233static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
234{
235	pte_t *pte = pte_offset_kernel(pmd, 0);
236	unsigned long addr;
237	unsigned i;
238
239	for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
240		addr = start + i * PAGE_SIZE;
241		note_page(st, addr, 4, pte_val(*pte));
242	}
243}
244
245static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
246{
247	pmd_t *pmd = pmd_offset(pud, 0);
248	unsigned long addr;
249	unsigned i;
250
251	for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
252		addr = start + i * PMD_SIZE;
253		if (pmd_none(*pmd) || pmd_sect(*pmd)) {
254			note_page(st, addr, 3, pmd_val(*pmd));
255		} else {
256			BUG_ON(pmd_bad(*pmd));
257			walk_pte(st, pmd, addr);
258		}
259	}
260}
261
262static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
263{
264	pud_t *pud = pud_offset(pgd, 0);
265	unsigned long addr;
266	unsigned i;
267
268	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
269		addr = start + i * PUD_SIZE;
270		if (pud_none(*pud) || pud_sect(*pud)) {
271			note_page(st, addr, 2, pud_val(*pud));
272		} else {
273			BUG_ON(pud_bad(*pud));
274			walk_pmd(st, pud, addr);
275		}
276	}
277}
278
279static void walk_pgd(struct pg_state *st, struct mm_struct *mm, unsigned long start)
280{
281	pgd_t *pgd = pgd_offset(mm, 0UL);
282	unsigned i;
283	unsigned long addr;
284
285	for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
286		addr = start + i * PGDIR_SIZE;
287		if (pgd_none(*pgd)) {
288			note_page(st, addr, 1, pgd_val(*pgd));
289		} else {
290			BUG_ON(pgd_bad(*pgd));
291			walk_pud(st, pgd, addr);
292		}
293	}
294}
295
296static int ptdump_show(struct seq_file *m, void *v)
297{
298	struct pg_state st = {
299		.seq = m,
300		.marker = address_markers,
301	};
302
303	walk_pgd(&st, &init_mm, LOWEST_ADDR);
304
305	note_page(&st, 0, 0, 0);
306	return 0;
307}
308
309static int ptdump_open(struct inode *inode, struct file *file)
310{
311	return single_open(file, ptdump_show, NULL);
312}
313
314static const struct file_operations ptdump_fops = {
315	.open		= ptdump_open,
316	.read		= seq_read,
317	.llseek		= seq_lseek,
318	.release	= single_release,
319};
320
321static int ptdump_init(void)
322{
323	struct dentry *pe;
324	unsigned i, j;
325
326	for (i = 0; i < ARRAY_SIZE(pg_level); i++)
327		if (pg_level[i].bits)
328			for (j = 0; j < pg_level[i].num; j++)
329				pg_level[i].mask |= pg_level[i].bits[j].mask;
330
331#ifdef CONFIG_SPARSEMEM_VMEMMAP
332	address_markers[VMEMMAP_START_NR].start_address =
333				(unsigned long)virt_to_page(PAGE_OFFSET);
334	address_markers[VMEMMAP_END_NR].start_address =
335				(unsigned long)virt_to_page(high_memory);
336#endif
337
338	pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
339				 &ptdump_fops);
340	return pe ? 0 : -ENOMEM;
341}
342device_initcall(ptdump_init);
343