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/fixmap.h>
21#include <asm/pgtable.h>
22
23struct addr_marker {
24	unsigned long start_address;
25	const char *name;
26};
27
28static struct addr_marker address_markers[] = {
29	{ MODULES_VADDR,	"Modules" },
30	{ PAGE_OFFSET,		"Kernel Mapping" },
31	{ 0,			"vmalloc() Area" },
32	{ VMALLOC_END,		"vmalloc() End" },
33	{ FIXADDR_START,	"Fixmap Area" },
34	{ CONFIG_VECTORS_BASE,	"Vectors" },
35	{ CONFIG_VECTORS_BASE + PAGE_SIZE * 2, "Vectors End" },
36	{ -1,			NULL },
37};
38
39struct pg_state {
40	struct seq_file *seq;
41	const struct addr_marker *marker;
42	unsigned long start_address;
43	unsigned level;
44	u64 current_prot;
45};
46
47struct prot_bits {
48	u64		mask;
49	u64		val;
50	const char	*set;
51	const char	*clear;
52};
53
54static const struct prot_bits pte_bits[] = {
55	{
56		.mask	= L_PTE_USER,
57		.val	= L_PTE_USER,
58		.set	= "USR",
59		.clear	= "   ",
60	}, {
61		.mask	= L_PTE_RDONLY,
62		.val	= L_PTE_RDONLY,
63		.set	= "ro",
64		.clear	= "RW",
65	}, {
66		.mask	= L_PTE_XN,
67		.val	= L_PTE_XN,
68		.set	= "NX",
69		.clear	= "x ",
70	}, {
71		.mask	= L_PTE_SHARED,
72		.val	= L_PTE_SHARED,
73		.set	= "SHD",
74		.clear	= "   ",
75	}, {
76		.mask	= L_PTE_MT_MASK,
77		.val	= L_PTE_MT_UNCACHED,
78		.set	= "SO/UNCACHED",
79	}, {
80		.mask	= L_PTE_MT_MASK,
81		.val	= L_PTE_MT_BUFFERABLE,
82		.set	= "MEM/BUFFERABLE/WC",
83	}, {
84		.mask	= L_PTE_MT_MASK,
85		.val	= L_PTE_MT_WRITETHROUGH,
86		.set	= "MEM/CACHED/WT",
87	}, {
88		.mask	= L_PTE_MT_MASK,
89		.val	= L_PTE_MT_WRITEBACK,
90		.set	= "MEM/CACHED/WBRA",
91#ifndef CONFIG_ARM_LPAE
92	}, {
93		.mask	= L_PTE_MT_MASK,
94		.val	= L_PTE_MT_MINICACHE,
95		.set	= "MEM/MINICACHE",
96#endif
97	}, {
98		.mask	= L_PTE_MT_MASK,
99		.val	= L_PTE_MT_WRITEALLOC,
100		.set	= "MEM/CACHED/WBWA",
101	}, {
102		.mask	= L_PTE_MT_MASK,
103		.val	= L_PTE_MT_DEV_SHARED,
104		.set	= "DEV/SHARED",
105#ifndef CONFIG_ARM_LPAE
106	}, {
107		.mask	= L_PTE_MT_MASK,
108		.val	= L_PTE_MT_DEV_NONSHARED,
109		.set	= "DEV/NONSHARED",
110#endif
111	}, {
112		.mask	= L_PTE_MT_MASK,
113		.val	= L_PTE_MT_DEV_WC,
114		.set	= "DEV/WC",
115	}, {
116		.mask	= L_PTE_MT_MASK,
117		.val	= L_PTE_MT_DEV_CACHED,
118		.set	= "DEV/CACHED",
119	},
120};
121
122static const struct prot_bits section_bits[] = {
123#ifdef CONFIG_ARM_LPAE
124	{
125		.mask	= PMD_SECT_USER,
126		.val	= PMD_SECT_USER,
127		.set	= "USR",
128	}, {
129		.mask	= L_PMD_SECT_RDONLY,
130		.val	= L_PMD_SECT_RDONLY,
131		.set	= "ro",
132		.clear	= "RW",
133#elif __LINUX_ARM_ARCH__ >= 6
134	{
135		.mask	= PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
136		.val	= PMD_SECT_APX | PMD_SECT_AP_WRITE,
137		.set	= "    ro",
138	}, {
139		.mask	= PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
140		.val	= PMD_SECT_AP_WRITE,
141		.set	= "    RW",
142	}, {
143		.mask	= PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
144		.val	= PMD_SECT_AP_READ,
145		.set	= "USR ro",
146	}, {
147		.mask	= PMD_SECT_APX | PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
148		.val	= PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
149		.set	= "USR RW",
150#else /* ARMv4/ARMv5  */
151	/* These are approximate */
152	{
153		.mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
154		.val    = 0,
155		.set    = "    ro",
156	}, {
157		.mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
158		.val    = PMD_SECT_AP_WRITE,
159		.set    = "    RW",
160	}, {
161		.mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
162		.val    = PMD_SECT_AP_READ,
163		.set    = "USR ro",
164	}, {
165		.mask   = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
166		.val    = PMD_SECT_AP_READ | PMD_SECT_AP_WRITE,
167		.set    = "USR RW",
168#endif
169	}, {
170		.mask	= PMD_SECT_XN,
171		.val	= PMD_SECT_XN,
172		.set	= "NX",
173		.clear	= "x ",
174	}, {
175		.mask	= PMD_SECT_S,
176		.val	= PMD_SECT_S,
177		.set	= "SHD",
178		.clear	= "   ",
179	},
180};
181
182struct pg_level {
183	const struct prot_bits *bits;
184	size_t num;
185	u64 mask;
186};
187
188static struct pg_level pg_level[] = {
189	{
190	}, { /* pgd */
191	}, { /* pud */
192	}, { /* pmd */
193		.bits	= section_bits,
194		.num	= ARRAY_SIZE(section_bits),
195	}, { /* pte */
196		.bits	= pte_bits,
197		.num	= ARRAY_SIZE(pte_bits),
198	},
199};
200
201static void dump_prot(struct pg_state *st, const struct prot_bits *bits, size_t num)
202{
203	unsigned i;
204
205	for (i = 0; i < num; i++, bits++) {
206		const char *s;
207
208		if ((st->current_prot & bits->mask) == bits->val)
209			s = bits->set;
210		else
211			s = bits->clear;
212
213		if (s)
214			seq_printf(st->seq, " %s", s);
215	}
216}
217
218static void note_page(struct pg_state *st, unsigned long addr, unsigned level, u64 val)
219{
220	static const char units[] = "KMGTPE";
221	u64 prot = val & pg_level[level].mask;
222
223	if (!st->level) {
224		st->level = level;
225		st->current_prot = prot;
226		seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
227	} else if (prot != st->current_prot || level != st->level ||
228		   addr >= st->marker[1].start_address) {
229		const char *unit = units;
230		unsigned long delta;
231
232		if (st->current_prot) {
233			seq_printf(st->seq, "0x%08lx-0x%08lx   ",
234				   st->start_address, addr);
235
236			delta = (addr - st->start_address) >> 10;
237			while (!(delta & 1023) && unit[1]) {
238				delta >>= 10;
239				unit++;
240			}
241			seq_printf(st->seq, "%9lu%c", delta, *unit);
242			if (pg_level[st->level].bits)
243				dump_prot(st, pg_level[st->level].bits, pg_level[st->level].num);
244			seq_printf(st->seq, "\n");
245		}
246
247		if (addr >= st->marker[1].start_address) {
248			st->marker++;
249			seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
250		}
251		st->start_address = addr;
252		st->current_prot = prot;
253		st->level = level;
254	}
255}
256
257static void walk_pte(struct pg_state *st, pmd_t *pmd, unsigned long start)
258{
259	pte_t *pte = pte_offset_kernel(pmd, 0);
260	unsigned long addr;
261	unsigned i;
262
263	for (i = 0; i < PTRS_PER_PTE; i++, pte++) {
264		addr = start + i * PAGE_SIZE;
265		note_page(st, addr, 4, pte_val(*pte));
266	}
267}
268
269static void walk_pmd(struct pg_state *st, pud_t *pud, unsigned long start)
270{
271	pmd_t *pmd = pmd_offset(pud, 0);
272	unsigned long addr;
273	unsigned i;
274
275	for (i = 0; i < PTRS_PER_PMD; i++, pmd++) {
276		addr = start + i * PMD_SIZE;
277		if (pmd_none(*pmd) || pmd_large(*pmd) || !pmd_present(*pmd))
278			note_page(st, addr, 3, pmd_val(*pmd));
279		else
280			walk_pte(st, pmd, addr);
281
282		if (SECTION_SIZE < PMD_SIZE && pmd_large(pmd[1]))
283			note_page(st, addr + SECTION_SIZE, 3, pmd_val(pmd[1]));
284	}
285}
286
287static void walk_pud(struct pg_state *st, pgd_t *pgd, unsigned long start)
288{
289	pud_t *pud = pud_offset(pgd, 0);
290	unsigned long addr;
291	unsigned i;
292
293	for (i = 0; i < PTRS_PER_PUD; i++, pud++) {
294		addr = start + i * PUD_SIZE;
295		if (!pud_none(*pud)) {
296			walk_pmd(st, pud, addr);
297		} else {
298			note_page(st, addr, 2, pud_val(*pud));
299		}
300	}
301}
302
303static void walk_pgd(struct seq_file *m)
304{
305	pgd_t *pgd = swapper_pg_dir;
306	struct pg_state st;
307	unsigned long addr;
308	unsigned i;
309
310	memset(&st, 0, sizeof(st));
311	st.seq = m;
312	st.marker = address_markers;
313
314	for (i = 0; i < PTRS_PER_PGD; i++, pgd++) {
315		addr = i * PGDIR_SIZE;
316		if (!pgd_none(*pgd)) {
317			walk_pud(&st, pgd, addr);
318		} else {
319			note_page(&st, addr, 1, pgd_val(*pgd));
320		}
321	}
322
323	note_page(&st, 0, 0, 0);
324}
325
326static int ptdump_show(struct seq_file *m, void *v)
327{
328	walk_pgd(m);
329	return 0;
330}
331
332static int ptdump_open(struct inode *inode, struct file *file)
333{
334	return single_open(file, ptdump_show, NULL);
335}
336
337static const struct file_operations ptdump_fops = {
338	.open		= ptdump_open,
339	.read		= seq_read,
340	.llseek		= seq_lseek,
341	.release	= single_release,
342};
343
344static int ptdump_init(void)
345{
346	struct dentry *pe;
347	unsigned i, j;
348
349	for (i = 0; i < ARRAY_SIZE(pg_level); i++)
350		if (pg_level[i].bits)
351			for (j = 0; j < pg_level[i].num; j++)
352				pg_level[i].mask |= pg_level[i].bits[j].mask;
353
354	address_markers[2].start_address = VMALLOC_START;
355
356	pe = debugfs_create_file("kernel_page_tables", 0400, NULL, NULL,
357				 &ptdump_fops);
358	return pe ? 0 : -ENOMEM;
359}
360__initcall(ptdump_init);
361