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.
5 * (C) Copyright 2008 Intel Corporation
7 * Author: Arjan van de Ven <arjan@linux.intel.com>
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
15 #include <linux/debugfs.h>
16 #include <linux/kasan.h>
18 #include <linux/init.h>
19 #include <linux/sched.h>
20 #include <linux/seq_file.h>
22 #include <asm/pgtable.h>
25 * The dumper groups pagetable entries of the same type into one, and for
26 * that it needs to keep some state when walking, and flush this state
27 * when a "break" in the continuity is found.
31 pgprot_t current_prot
;
32 unsigned long start_address
;
33 unsigned long current_address
;
34 const struct addr_marker
*marker
;
38 unsigned long wx_pages
;
42 unsigned long start_address
;
44 unsigned long max_lines
;
47 /* indices for address_markers; keep sync'd w/ address_markers below */
48 enum address_markers_idx
{
56 KASAN_SHADOW_START_NR
,
59 # ifdef CONFIG_X86_ESPFIX64
69 # ifdef CONFIG_HIGHMEM
76 /* Address space markers hints */
77 static struct addr_marker address_markers
[] = {
80 { 0x8000000000000000UL
, "Kernel Space" },
81 { 0/* PAGE_OFFSET */, "Low Kernel Mapping" },
82 { 0/* VMALLOC_START */, "vmalloc() Area" },
83 { 0/* VMEMMAP_START */, "Vmemmap" },
85 { KASAN_SHADOW_START
, "KASAN shadow" },
86 { KASAN_SHADOW_END
, "KASAN shadow end" },
88 # ifdef CONFIG_X86_ESPFIX64
89 { ESPFIX_BASE_ADDR
, "ESPfix Area", 16 },
92 { EFI_VA_END
, "EFI Runtime Services" },
94 { __START_KERNEL_map
, "High Kernel Mapping" },
95 { MODULES_VADDR
, "Modules" },
96 { MODULES_END
, "End Modules" },
98 { PAGE_OFFSET
, "Kernel Mapping" },
99 { 0/* VMALLOC_START */, "vmalloc() Area" },
100 { 0/*VMALLOC_END*/, "vmalloc() End" },
101 # ifdef CONFIG_HIGHMEM
102 { 0/*PKMAP_BASE*/, "Persistent kmap() Area" },
104 { 0/*FIXADDR_START*/, "Fixmap Area" },
106 { -1, NULL
} /* End of list */
109 /* Multipliers for offsets within the PTEs */
110 #define PTE_LEVEL_MULT (PAGE_SIZE)
111 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
112 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
113 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
114 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
116 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
119 printk(KERN_INFO fmt, ##args); \
122 seq_printf(m, fmt, ##args); \
125 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
128 printk(KERN_CONT fmt, ##args); \
131 seq_printf(m, fmt, ##args); \
135 * Print a readable form of a pgprot_t to the seq_file
137 static void printk_prot(struct seq_file
*m
, pgprot_t prot
, int level
, bool dmsg
)
139 pgprotval_t pr
= pgprot_val(prot
);
140 static const char * const level_name
[] =
141 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
143 if (!pgprot_val(prot
)) {
145 pt_dump_cont_printf(m
, dmsg
, " ");
148 pt_dump_cont_printf(m
, dmsg
, "USR ");
150 pt_dump_cont_printf(m
, dmsg
, " ");
152 pt_dump_cont_printf(m
, dmsg
, "RW ");
154 pt_dump_cont_printf(m
, dmsg
, "ro ");
156 pt_dump_cont_printf(m
, dmsg
, "PWT ");
158 pt_dump_cont_printf(m
, dmsg
, " ");
160 pt_dump_cont_printf(m
, dmsg
, "PCD ");
162 pt_dump_cont_printf(m
, dmsg
, " ");
164 /* Bit 7 has a different meaning on level 3 vs 4 */
165 if (level
<= 4 && pr
& _PAGE_PSE
)
166 pt_dump_cont_printf(m
, dmsg
, "PSE ");
168 pt_dump_cont_printf(m
, dmsg
, " ");
169 if ((level
== 5 && pr
& _PAGE_PAT
) ||
170 ((level
== 4 || level
== 3) && pr
& _PAGE_PAT_LARGE
))
171 pt_dump_cont_printf(m
, dmsg
, "PAT ");
173 pt_dump_cont_printf(m
, dmsg
, " ");
174 if (pr
& _PAGE_GLOBAL
)
175 pt_dump_cont_printf(m
, dmsg
, "GLB ");
177 pt_dump_cont_printf(m
, dmsg
, " ");
179 pt_dump_cont_printf(m
, dmsg
, "NX ");
181 pt_dump_cont_printf(m
, dmsg
, "x ");
183 pt_dump_cont_printf(m
, dmsg
, "%s\n", level_name
[level
]);
187 * On 64 bits, sign-extend the 48 bit address to 64 bit
189 static unsigned long normalize_addr(unsigned long u
)
192 if (!IS_ENABLED(CONFIG_X86_64
))
195 shift
= 64 - (__VIRTUAL_MASK_SHIFT
+ 1);
196 return (signed long)(u
<< shift
) >> shift
;
200 * This function gets called on a break in a continuous series
201 * of PTE entries; the next one is different so we need to
202 * print what we collected so far.
204 static void note_page(struct seq_file
*m
, struct pg_state
*st
,
205 pgprot_t new_prot
, int level
)
207 pgprotval_t prot
, cur
;
208 static const char units
[] = "BKMGTPE";
211 * If we have a "break" in the series, we need to flush the state that
212 * we have now. "break" is either changing perms, levels or
213 * address space marker.
215 prot
= pgprot_val(new_prot
);
216 cur
= pgprot_val(st
->current_prot
);
220 st
->current_prot
= new_prot
;
222 st
->marker
= address_markers
;
224 pt_dump_seq_printf(m
, st
->to_dmesg
, "---[ %s ]---\n",
226 } else if (prot
!= cur
|| level
!= st
->level
||
227 st
->current_address
>= st
->marker
[1].start_address
) {
228 const char *unit
= units
;
230 int width
= sizeof(unsigned long) * 2;
231 pgprotval_t pr
= pgprot_val(st
->current_prot
);
233 if (st
->check_wx
&& (pr
& _PAGE_RW
) && !(pr
& _PAGE_NX
)) {
235 "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
236 (void *)st
->start_address
,
237 (void *)st
->start_address
);
238 st
->wx_pages
+= (st
->current_address
-
239 st
->start_address
) / PAGE_SIZE
;
243 * Now print the actual finished series
245 if (!st
->marker
->max_lines
||
246 st
->lines
< st
->marker
->max_lines
) {
247 pt_dump_seq_printf(m
, st
->to_dmesg
,
249 width
, st
->start_address
,
250 width
, st
->current_address
);
252 delta
= st
->current_address
- st
->start_address
;
253 while (!(delta
& 1023) && unit
[1]) {
257 pt_dump_cont_printf(m
, st
->to_dmesg
, "%9lu%c ",
259 printk_prot(m
, st
->current_prot
, st
->level
,
265 * We print markers for special areas of address space,
266 * such as the start of vmalloc space etc.
267 * This helps in the interpretation.
269 if (st
->current_address
>= st
->marker
[1].start_address
) {
270 if (st
->marker
->max_lines
&&
271 st
->lines
> st
->marker
->max_lines
) {
272 unsigned long nskip
=
273 st
->lines
- st
->marker
->max_lines
;
274 pt_dump_seq_printf(m
, st
->to_dmesg
,
275 "... %lu entr%s skipped ... \n",
277 nskip
== 1 ? "y" : "ies");
281 pt_dump_seq_printf(m
, st
->to_dmesg
, "---[ %s ]---\n",
285 st
->start_address
= st
->current_address
;
286 st
->current_prot
= new_prot
;
291 static void walk_pte_level(struct seq_file
*m
, struct pg_state
*st
, pmd_t addr
, unsigned long P
)
297 start
= (pte_t
*)pmd_page_vaddr(addr
);
298 for (i
= 0; i
< PTRS_PER_PTE
; i
++) {
299 prot
= pte_flags(*start
);
300 st
->current_address
= normalize_addr(P
+ i
* PTE_LEVEL_MULT
);
301 note_page(m
, st
, __pgprot(prot
), 5);
308 * This is an optimization for KASAN=y case. Since all kasan page tables
309 * eventually point to the kasan_zero_page we could call note_page()
310 * right away without walking through lower level page tables. This saves
311 * us dozens of seconds (minutes for 5-level config) while checking for
312 * W+X mapping or reading kernel_page_tables debugfs file.
314 static inline bool kasan_page_table(struct seq_file
*m
, struct pg_state
*st
,
317 if (__pa(pt
) == __pa(kasan_zero_pmd
) ||
318 #ifdef CONFIG_X86_5LEVEL
319 __pa(pt
) == __pa(kasan_zero_p4d
) ||
321 __pa(pt
) == __pa(kasan_zero_pud
)) {
322 pgprotval_t prot
= pte_flags(kasan_zero_pte
[0]);
323 note_page(m
, st
, __pgprot(prot
), 5);
329 static inline bool kasan_page_table(struct seq_file
*m
, struct pg_state
*st
,
338 static void walk_pmd_level(struct seq_file
*m
, struct pg_state
*st
, pud_t addr
, unsigned long P
)
341 pmd_t
*start
, *pmd_start
;
344 pmd_start
= start
= (pmd_t
*)pud_page_vaddr(addr
);
345 for (i
= 0; i
< PTRS_PER_PMD
; i
++) {
346 st
->current_address
= normalize_addr(P
+ i
* PMD_LEVEL_MULT
);
347 if (!pmd_none(*start
)) {
348 if (pmd_large(*start
) || !pmd_present(*start
)) {
349 prot
= pmd_flags(*start
);
350 note_page(m
, st
, __pgprot(prot
), 4);
351 } else if (!kasan_page_table(m
, st
, pmd_start
)) {
352 walk_pte_level(m
, st
, *start
,
353 P
+ i
* PMD_LEVEL_MULT
);
356 note_page(m
, st
, __pgprot(0), 4);
362 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
363 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
364 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
369 static void walk_pud_level(struct seq_file
*m
, struct pg_state
*st
, p4d_t addr
, unsigned long P
)
372 pud_t
*start
, *pud_start
;
374 pud_t
*prev_pud
= NULL
;
376 pud_start
= start
= (pud_t
*)p4d_page_vaddr(addr
);
378 for (i
= 0; i
< PTRS_PER_PUD
; i
++) {
379 st
->current_address
= normalize_addr(P
+ i
* PUD_LEVEL_MULT
);
380 if (!pud_none(*start
)) {
381 if (pud_large(*start
) || !pud_present(*start
)) {
382 prot
= pud_flags(*start
);
383 note_page(m
, st
, __pgprot(prot
), 3);
384 } else if (!kasan_page_table(m
, st
, pud_start
)) {
385 walk_pmd_level(m
, st
, *start
,
386 P
+ i
* PUD_LEVEL_MULT
);
389 note_page(m
, st
, __pgprot(0), 3);
397 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p)
398 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
399 #define p4d_none(a) pud_none(__pud(p4d_val(a)))
404 static void walk_p4d_level(struct seq_file
*m
, struct pg_state
*st
, pgd_t addr
, unsigned long P
)
407 p4d_t
*start
, *p4d_start
;
410 p4d_start
= start
= (p4d_t
*)pgd_page_vaddr(addr
);
412 for (i
= 0; i
< PTRS_PER_P4D
; i
++) {
413 st
->current_address
= normalize_addr(P
+ i
* P4D_LEVEL_MULT
);
414 if (!p4d_none(*start
)) {
415 if (p4d_large(*start
) || !p4d_present(*start
)) {
416 prot
= p4d_flags(*start
);
417 note_page(m
, st
, __pgprot(prot
), 2);
418 } else if (!kasan_page_table(m
, st
, p4d_start
)) {
419 walk_pud_level(m
, st
, *start
,
420 P
+ i
* P4D_LEVEL_MULT
);
423 note_page(m
, st
, __pgprot(0), 2);
430 #define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p)
431 #define pgd_large(a) p4d_large(__p4d(pgd_val(a)))
432 #define pgd_none(a) p4d_none(__p4d(pgd_val(a)))
435 static inline bool is_hypervisor_range(int idx
)
439 * ffff800000000000 - ffff87ffffffffff is reserved for
442 return (idx
>= pgd_index(__PAGE_OFFSET
) - 16) &&
443 (idx
< pgd_index(__PAGE_OFFSET
));
449 static void ptdump_walk_pgd_level_core(struct seq_file
*m
, pgd_t
*pgd
,
453 pgd_t
*start
= (pgd_t
*) &init_top_pgt
;
455 pgd_t
*start
= swapper_pg_dir
;
459 struct pg_state st
= {};
466 st
.check_wx
= checkwx
;
470 for (i
= 0; i
< PTRS_PER_PGD
; i
++) {
471 st
.current_address
= normalize_addr(i
* PGD_LEVEL_MULT
);
472 if (!pgd_none(*start
) && !is_hypervisor_range(i
)) {
473 if (pgd_large(*start
) || !pgd_present(*start
)) {
474 prot
= pgd_flags(*start
);
475 note_page(m
, &st
, __pgprot(prot
), 1);
477 walk_p4d_level(m
, &st
, *start
,
481 note_page(m
, &st
, __pgprot(0), 1);
487 /* Flush out the last page */
488 st
.current_address
= normalize_addr(PTRS_PER_PGD
*PGD_LEVEL_MULT
);
489 note_page(m
, &st
, __pgprot(0), 0);
493 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
496 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
499 void ptdump_walk_pgd_level(struct seq_file
*m
, pgd_t
*pgd
)
501 ptdump_walk_pgd_level_core(m
, pgd
, false);
503 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level
);
505 void ptdump_walk_pgd_level_checkwx(void)
507 ptdump_walk_pgd_level_core(NULL
, NULL
, true);
510 static int __init
pt_dump_init(void)
513 * Various markers are not compile-time constants, so assign them
517 address_markers
[LOW_KERNEL_NR
].start_address
= PAGE_OFFSET
;
518 address_markers
[VMALLOC_START_NR
].start_address
= VMALLOC_START
;
519 address_markers
[VMEMMAP_START_NR
].start_address
= VMEMMAP_START
;
522 address_markers
[VMALLOC_START_NR
].start_address
= VMALLOC_START
;
523 address_markers
[VMALLOC_END_NR
].start_address
= VMALLOC_END
;
524 # ifdef CONFIG_HIGHMEM
525 address_markers
[PKMAP_BASE_NR
].start_address
= PKMAP_BASE
;
527 address_markers
[FIXADDR_START_NR
].start_address
= FIXADDR_START
;
532 __initcall(pt_dump_init
);