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 * (C) Copyright 2008 Intel Corporation
6 *
7 * Author: Arjan van de Ven <arjan@linux.intel.com>
8 *
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; version 2
12 * of the License.
13 */
14
15 #include <linux/debugfs.h>
16 #include <linux/mm.h>
17 #include <linux/module.h>
18 #include <linux/seq_file.h>
19
20 #include <asm/pgtable.h>
21
22 /*
23 * The dumper groups pagetable entries of the same type into one, and for
24 * that it needs to keep some state when walking, and flush this state
25 * when a "break" in the continuity is found.
26 */
27 struct pg_state {
28 int level;
29 pgprot_t current_prot;
30 unsigned long start_address;
31 unsigned long current_address;
32 const struct addr_marker *marker;
33 };
34
35 struct addr_marker {
36 unsigned long start_address;
37 const char *name;
38 };
39
40 /* indices for address_markers; keep sync'd w/ address_markers below */
41 enum address_markers_idx {
42 USER_SPACE_NR = 0,
43 #ifdef CONFIG_X86_64
44 KERNEL_SPACE_NR,
45 LOW_KERNEL_NR,
46 VMALLOC_START_NR,
47 VMEMMAP_START_NR,
48 HIGH_KERNEL_NR,
49 MODULES_VADDR_NR,
50 MODULES_END_NR,
51 #else
52 KERNEL_SPACE_NR,
53 VMALLOC_START_NR,
54 VMALLOC_END_NR,
55 # ifdef CONFIG_HIGHMEM
56 PKMAP_BASE_NR,
57 # endif
58 FIXADDR_START_NR,
59 #endif
60 };
61
62 /* Address space markers hints */
63 static struct addr_marker address_markers[] = {
64 { 0, "User Space" },
65 #ifdef CONFIG_X86_64
66 { 0x8000000000000000UL, "Kernel Space" },
67 { PAGE_OFFSET, "Low Kernel Mapping" },
68 { VMALLOC_START, "vmalloc() Area" },
69 { VMEMMAP_START, "Vmemmap" },
70 { __START_KERNEL_map, "High Kernel Mapping" },
71 { MODULES_VADDR, "Modules" },
72 { MODULES_END, "End Modules" },
73 #else
74 { PAGE_OFFSET, "Kernel Mapping" },
75 { 0/* VMALLOC_START */, "vmalloc() Area" },
76 { 0/*VMALLOC_END*/, "vmalloc() End" },
77 # ifdef CONFIG_HIGHMEM
78 { 0/*PKMAP_BASE*/, "Persisent kmap() Area" },
79 # endif
80 { 0/*FIXADDR_START*/, "Fixmap Area" },
81 #endif
82 { -1, NULL } /* End of list */
83 };
84
85 /* Multipliers for offsets within the PTEs */
86 #define PTE_LEVEL_MULT (PAGE_SIZE)
87 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
88 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
89 #define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
90
91 /*
92 * Print a readable form of a pgprot_t to the seq_file
93 */
printk_prot(struct seq_file * m,pgprot_t prot,int level)94 static void printk_prot(struct seq_file *m, pgprot_t prot, int level)
95 {
96 pgprotval_t pr = pgprot_val(prot);
97 static const char * const level_name[] =
98 { "cr3", "pgd", "pud", "pmd", "pte" };
99
100 if (!pgprot_val(prot)) {
101 /* Not present */
102 seq_printf(m, " ");
103 } else {
104 if (pr & _PAGE_USER)
105 seq_printf(m, "USR ");
106 else
107 seq_printf(m, " ");
108 if (pr & _PAGE_RW)
109 seq_printf(m, "RW ");
110 else
111 seq_printf(m, "ro ");
112 if (pr & _PAGE_PWT)
113 seq_printf(m, "PWT ");
114 else
115 seq_printf(m, " ");
116 if (pr & _PAGE_PCD)
117 seq_printf(m, "PCD ");
118 else
119 seq_printf(m, " ");
120
121 /* Bit 9 has a different meaning on level 3 vs 4 */
122 if (level <= 3) {
123 if (pr & _PAGE_PSE)
124 seq_printf(m, "PSE ");
125 else
126 seq_printf(m, " ");
127 } else {
128 if (pr & _PAGE_PAT)
129 seq_printf(m, "pat ");
130 else
131 seq_printf(m, " ");
132 }
133 if (pr & _PAGE_GLOBAL)
134 seq_printf(m, "GLB ");
135 else
136 seq_printf(m, " ");
137 if (pr & _PAGE_NX)
138 seq_printf(m, "NX ");
139 else
140 seq_printf(m, "x ");
141 }
142 seq_printf(m, "%s\n", level_name[level]);
143 }
144
145 /*
146 * On 64 bits, sign-extend the 48 bit address to 64 bit
147 */
normalize_addr(unsigned long u)148 static unsigned long normalize_addr(unsigned long u)
149 {
150 #ifdef CONFIG_X86_64
151 return (signed long)(u << 16) >> 16;
152 #else
153 return u;
154 #endif
155 }
156
157 /*
158 * This function gets called on a break in a continuous series
159 * of PTE entries; the next one is different so we need to
160 * print what we collected so far.
161 */
note_page(struct seq_file * m,struct pg_state * st,pgprot_t new_prot,int level)162 static void note_page(struct seq_file *m, struct pg_state *st,
163 pgprot_t new_prot, int level)
164 {
165 pgprotval_t prot, cur;
166 static const char units[] = "KMGTPE";
167
168 /*
169 * If we have a "break" in the series, we need to flush the state that
170 * we have now. "break" is either changing perms, levels or
171 * address space marker.
172 */
173 prot = pgprot_val(new_prot) & PTE_FLAGS_MASK;
174 cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
175
176 if (!st->level) {
177 /* First entry */
178 st->current_prot = new_prot;
179 st->level = level;
180 st->marker = address_markers;
181 seq_printf(m, "---[ %s ]---\n", st->marker->name);
182 } else if (prot != cur || level != st->level ||
183 st->current_address >= st->marker[1].start_address) {
184 const char *unit = units;
185 unsigned long delta;
186 int width = sizeof(unsigned long) * 2;
187
188 /*
189 * Now print the actual finished series
190 */
191 seq_printf(m, "0x%0*lx-0x%0*lx ",
192 width, st->start_address,
193 width, st->current_address);
194
195 delta = (st->current_address - st->start_address) >> 10;
196 while (!(delta & 1023) && unit[1]) {
197 delta >>= 10;
198 unit++;
199 }
200 seq_printf(m, "%9lu%c ", delta, *unit);
201 printk_prot(m, st->current_prot, st->level);
202
203 /*
204 * We print markers for special areas of address space,
205 * such as the start of vmalloc space etc.
206 * This helps in the interpretation.
207 */
208 if (st->current_address >= st->marker[1].start_address) {
209 st->marker++;
210 seq_printf(m, "---[ %s ]---\n", st->marker->name);
211 }
212
213 st->start_address = st->current_address;
214 st->current_prot = new_prot;
215 st->level = level;
216 }
217 }
218
walk_pte_level(struct seq_file * m,struct pg_state * st,pmd_t addr,unsigned long P)219 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
220 unsigned long P)
221 {
222 int i;
223 pte_t *start;
224
225 start = (pte_t *) pmd_page_vaddr(addr);
226 for (i = 0; i < PTRS_PER_PTE; i++) {
227 pgprot_t prot = pte_pgprot(*start);
228
229 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
230 note_page(m, st, prot, 4);
231 start++;
232 }
233 }
234
235 #if PTRS_PER_PMD > 1
236
walk_pmd_level(struct seq_file * m,struct pg_state * st,pud_t addr,unsigned long P)237 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
238 unsigned long P)
239 {
240 int i;
241 pmd_t *start;
242
243 start = (pmd_t *) pud_page_vaddr(addr);
244 for (i = 0; i < PTRS_PER_PMD; i++) {
245 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
246 if (!pmd_none(*start)) {
247 pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
248
249 if (pmd_large(*start) || !pmd_present(*start))
250 note_page(m, st, __pgprot(prot), 3);
251 else
252 walk_pte_level(m, st, *start,
253 P + i * PMD_LEVEL_MULT);
254 } else
255 note_page(m, st, __pgprot(0), 3);
256 start++;
257 }
258 }
259
260 #else
261 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
262 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
263 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
264 #endif
265
266 #if PTRS_PER_PUD > 1
267
walk_pud_level(struct seq_file * m,struct pg_state * st,pgd_t addr,unsigned long P)268 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
269 unsigned long P)
270 {
271 int i;
272 pud_t *start;
273
274 start = (pud_t *) pgd_page_vaddr(addr);
275
276 for (i = 0; i < PTRS_PER_PUD; i++) {
277 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
278 if (!pud_none(*start)) {
279 pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
280
281 if (pud_large(*start) || !pud_present(*start))
282 note_page(m, st, __pgprot(prot), 2);
283 else
284 walk_pmd_level(m, st, *start,
285 P + i * PUD_LEVEL_MULT);
286 } else
287 note_page(m, st, __pgprot(0), 2);
288
289 start++;
290 }
291 }
292
293 #else
294 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
295 #define pgd_large(a) pud_large(__pud(pgd_val(a)))
296 #define pgd_none(a) pud_none(__pud(pgd_val(a)))
297 #endif
298
walk_pgd_level(struct seq_file * m)299 static void walk_pgd_level(struct seq_file *m)
300 {
301 #ifdef CONFIG_X86_64
302 pgd_t *start = (pgd_t *) &init_level4_pgt;
303 #else
304 pgd_t *start = swapper_pg_dir;
305 #endif
306 int i;
307 struct pg_state st;
308
309 memset(&st, 0, sizeof(st));
310
311 for (i = 0; i < PTRS_PER_PGD; i++) {
312 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
313 if (!pgd_none(*start)) {
314 pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
315
316 if (pgd_large(*start) || !pgd_present(*start))
317 note_page(m, &st, __pgprot(prot), 1);
318 else
319 walk_pud_level(m, &st, *start,
320 i * PGD_LEVEL_MULT);
321 } else
322 note_page(m, &st, __pgprot(0), 1);
323
324 start++;
325 }
326
327 /* Flush out the last page */
328 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
329 note_page(m, &st, __pgprot(0), 0);
330 }
331
ptdump_show(struct seq_file * m,void * v)332 static int ptdump_show(struct seq_file *m, void *v)
333 {
334 walk_pgd_level(m);
335 return 0;
336 }
337
ptdump_open(struct inode * inode,struct file * filp)338 static int ptdump_open(struct inode *inode, struct file *filp)
339 {
340 return single_open(filp, ptdump_show, NULL);
341 }
342
343 static const struct file_operations ptdump_fops = {
344 .open = ptdump_open,
345 .read = seq_read,
346 .llseek = seq_lseek,
347 .release = single_release,
348 };
349
pt_dump_init(void)350 static int pt_dump_init(void)
351 {
352 struct dentry *pe;
353
354 #ifdef CONFIG_X86_32
355 /* Not a compile-time constant on x86-32 */
356 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
357 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
358 # ifdef CONFIG_HIGHMEM
359 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
360 # endif
361 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
362 #endif
363
364 pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
365 &ptdump_fops);
366 if (!pe)
367 return -ENOMEM;
368
369 return 0;
370 }
371
372 __initcall(pt_dump_init);
373 MODULE_LICENSE("GPL");
374 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
375 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");
376