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
|
// SPDX-License-Identifier: GPL-2.0
#include <linux/seq_file.h>
#include <linux/debugfs.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kasan.h>
#include <asm/kasan.h>
#include <asm/sections.h>
#include <asm/pgtable.h>
static unsigned long max_addr;
struct addr_marker {
unsigned long start_address;
const char *name;
};
enum address_markers_idx {
IDENTITY_NR = 0,
KERNEL_START_NR,
KERNEL_END_NR,
#ifdef CONFIG_KASAN
KASAN_SHADOW_START_NR,
KASAN_SHADOW_END_NR,
#endif
VMEMMAP_NR,
VMALLOC_NR,
MODULES_NR,
};
static struct addr_marker address_markers[] = {
[IDENTITY_NR] = {0, "Identity Mapping"},
[KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
[KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
#ifdef CONFIG_KASAN
[KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
[KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
#endif
[VMEMMAP_NR] = {0, "vmemmap Area"},
[VMALLOC_NR] = {0, "vmalloc Area"},
[MODULES_NR] = {0, "Modules Area"},
{ -1, NULL }
};
struct pg_state {
int level;
unsigned int current_prot;
unsigned long start_address;
unsigned long current_address;
const struct addr_marker *marker;
};
static void print_prot(struct seq_file *m, unsigned int pr, int level)
{
static const char * const level_name[] =
{ "ASCE", "PGD", "PUD", "PMD", "PTE" };
seq_printf(m, "%s ", level_name[level]);
if (pr & _PAGE_INVALID) {
seq_printf(m, "I\n");
return;
}
seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
}
static void note_page(struct seq_file *m, struct pg_state *st,
unsigned int new_prot, int level)
{
static const char units[] = "KMGTPE";
int width = sizeof(unsigned long) * 2;
const char *unit = units;
unsigned int prot, cur;
unsigned long delta;
/*
* 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.
*/
prot = new_prot;
cur = st->current_prot;
if (!st->level) {
/* First entry */
st->current_prot = new_prot;
st->level = level;
st->marker = address_markers;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
} else if (prot != cur || level != st->level ||
st->current_address >= st->marker[1].start_address) {
/* Print the actual finished series */
seq_printf(m, "0x%0*lx-0x%0*lx ",
width, st->start_address,
width, st->current_address);
delta = (st->current_address - st->start_address) >> 10;
while (!(delta & 0x3ff) && unit[1]) {
delta >>= 10;
unit++;
}
seq_printf(m, "%9lu%c ", delta, *unit);
print_prot(m, st->current_prot, st->level);
while (st->current_address >= st->marker[1].start_address) {
st->marker++;
seq_printf(m, "---[ %s ]---\n", st->marker->name);
}
st->start_address = st->current_address;
st->current_prot = new_prot;
st->level = level;
}
}
#ifdef CONFIG_KASAN
static void note_kasan_early_shadow_page(struct seq_file *m,
struct pg_state *st)
{
unsigned int prot;
prot = pte_val(*kasan_early_shadow_pte) &
(_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
note_page(m, st, prot, 4);
}
#endif
/*
* The actual page table walker functions. In order to keep the
* implementation of print_prot() short, we only check and pass
* _PAGE_INVALID and _PAGE_PROTECT flags to note_page() if a region,
* segment or page table entry is invalid or read-only.
* After all it's just a hint that the current level being walked
* contains an invalid or read-only entry.
*/
static void walk_pte_level(struct seq_file *m, struct pg_state *st,
pmd_t *pmd, unsigned long addr)
{
unsigned int prot;
pte_t *pte;
int i;
for (i = 0; i < PTRS_PER_PTE && addr < max_addr; i++) {
st->current_address = addr;
pte = pte_offset_kernel(pmd, addr);
prot = pte_val(*pte) &
(_PAGE_PROTECT | _PAGE_INVALID | _PAGE_NOEXEC);
note_page(m, st, prot, 4);
addr += PAGE_SIZE;
}
}
static void walk_pmd_level(struct seq_file *m, struct pg_state *st,
pud_t *pud, unsigned long addr)
{
unsigned int prot;
pmd_t *pmd;
int i;
#ifdef CONFIG_KASAN
if ((pud_val(*pud) & PAGE_MASK) == __pa(kasan_early_shadow_pmd)) {
note_kasan_early_shadow_page(m, st);
return;
}
#endif
pmd = pmd_offset(pud, addr);
for (i = 0; i < PTRS_PER_PMD && addr < max_addr; i++, pmd++) {
st->current_address = addr;
if (!pmd_none(*pmd)) {
if (pmd_large(*pmd)) {
prot = pmd_val(*pmd) &
(_SEGMENT_ENTRY_PROTECT |
_SEGMENT_ENTRY_NOEXEC);
note_page(m, st, prot, 3);
} else
walk_pte_level(m, st, pmd, addr);
} else
note_page(m, st, _PAGE_INVALID, 3);
addr += PMD_SIZE;
}
}
static void walk_pud_level(struct seq_file *m, struct pg_state *st,
p4d_t *p4d, unsigned long addr)
{
unsigned int prot;
pud_t *pud;
int i;
#ifdef CONFIG_KASAN
if ((p4d_val(*p4d) & PAGE_MASK) == __pa(kasan_early_shadow_pud)) {
note_kasan_early_shadow_page(m, st);
return;
}
#endif
pud = pud_offset(p4d, addr);
for (i = 0; i < PTRS_PER_PUD && addr < max_addr; i++, pud++) {
st->current_address = addr;
if (!pud_none(*pud))
if (pud_large(*pud)) {
prot = pud_val(*pud) &
(_REGION_ENTRY_PROTECT |
_REGION_ENTRY_NOEXEC);
note_page(m, st, prot, 2);
} else
walk_pmd_level(m, st, pud, addr);
else
note_page(m, st, _PAGE_INVALID, 2);
addr += PUD_SIZE;
}
}
static void walk_p4d_level(struct seq_file *m, struct pg_state *st,
pgd_t *pgd, unsigned long addr)
{
p4d_t *p4d;
int i;
#ifdef CONFIG_KASAN
if ((pgd_val(*pgd) & PAGE_MASK) == __pa(kasan_early_shadow_p4d)) {
note_kasan_early_shadow_page(m, st);
return;
}
#endif
p4d = p4d_offset(pgd, addr);
for (i = 0; i < PTRS_PER_P4D && addr < max_addr; i++, p4d++) {
st->current_address = addr;
if (!p4d_none(*p4d))
walk_pud_level(m, st, p4d, addr);
else
note_page(m, st, _PAGE_INVALID, 2);
addr += P4D_SIZE;
}
}
static void walk_pgd_level(struct seq_file *m)
{
unsigned long addr = 0;
struct pg_state st;
pgd_t *pgd;
int i;
memset(&st, 0, sizeof(st));
for (i = 0; i < PTRS_PER_PGD && addr < max_addr; i++) {
st.current_address = addr;
pgd = pgd_offset_k(addr);
if (!pgd_none(*pgd))
walk_p4d_level(m, &st, pgd, addr);
else
note_page(m, &st, _PAGE_INVALID, 1);
addr += PGDIR_SIZE;
cond_resched();
}
/* Flush out the last page */
st.current_address = max_addr;
note_page(m, &st, 0, 0);
}
static int ptdump_show(struct seq_file *m, void *v)
{
walk_pgd_level(m);
return 0;
}
static int ptdump_open(struct inode *inode, struct file *filp)
{
return single_open(filp, ptdump_show, NULL);
}
static const struct file_operations ptdump_fops = {
.open = ptdump_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int pt_dump_init(void)
{
/*
* Figure out the maximum virtual address being accessible with the
* kernel ASCE. We need this to keep the page table walker functions
* from accessing non-existent entries.
*/
max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
max_addr = 1UL << (max_addr * 11 + 31);
address_markers[MODULES_NR].start_address = MODULES_VADDR;
address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
address_markers[VMALLOC_NR].start_address = VMALLOC_START;
debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
return 0;
}
device_initcall(pt_dump_init);
|
