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>
21 #include <linux/highmem.h>
23 #include <asm/pgtable.h>
26 * The dumper groups pagetable entries of the same type into one, and for
27 * that it needs to keep some state when walking, and flush this state
28 * when a "break" in the continuity is found.
32 pgprot_t current_prot;
33 pgprotval_t effective_prot;
34 unsigned long start_address;
35 unsigned long current_address;
36 const struct addr_marker *marker;
40 unsigned long wx_pages;
44 unsigned long start_address;
46 unsigned long max_lines;
49 /* Address space markers hints */
53 enum address_markers_idx {
57 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && defined(CONFIG_X86_5LEVEL)
63 KASAN_SHADOW_START_NR,
67 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && !defined(CONFIG_X86_5LEVEL)
70 #ifdef CONFIG_X86_ESPFIX64
83 static struct addr_marker address_markers[] = {
84 [USER_SPACE_NR] = { 0, "User Space" },
85 [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" },
86 [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" },
87 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
88 [VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
91 * These fields get initialized with the (dynamic)
92 * KASAN_SHADOW_{START,END} values in pt_dump_init().
94 [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
95 [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
97 #ifdef CONFIG_MODIFY_LDT_SYSCALL
98 [LDT_NR] = { 0UL, "LDT remap" },
100 [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
101 #ifdef CONFIG_X86_ESPFIX64
102 [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
105 [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" },
107 [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" },
108 [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" },
109 [MODULES_END_NR] = { MODULES_END, "End Modules" },
110 [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" },
111 [END_OF_SPACE_NR] = { -1, NULL }
114 #define INIT_PGD ((pgd_t *) &init_top_pgt)
116 #else /* CONFIG_X86_64 */
118 enum address_markers_idx {
123 #ifdef CONFIG_HIGHMEM
131 static struct addr_marker address_markers[] = {
132 [USER_SPACE_NR] = { 0, "User Space" },
133 [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" },
134 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
135 [VMALLOC_END_NR] = { 0UL, "vmalloc() End" },
136 #ifdef CONFIG_HIGHMEM
137 [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" },
139 [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" },
140 [FIXADDR_START_NR] = { 0UL, "Fixmap area" },
141 [END_OF_SPACE_NR] = { -1, NULL }
144 #define INIT_PGD (swapper_pg_dir)
146 #endif /* !CONFIG_X86_64 */
148 /* Multipliers for offsets within the PTEs */
149 #define PTE_LEVEL_MULT (PAGE_SIZE)
150 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
151 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
152 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
153 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
155 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
158 printk(KERN_INFO fmt, ##args); \
161 seq_printf(m, fmt, ##args); \
164 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
167 printk(KERN_CONT fmt, ##args); \
170 seq_printf(m, fmt, ##args); \
174 * Print a readable form of a pgprot_t to the seq_file
176 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
178 pgprotval_t pr = pgprot_val(prot);
179 static const char * const level_name[] =
180 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
182 if (!(pr & _PAGE_PRESENT)) {
184 pt_dump_cont_printf(m, dmsg, " ");
187 pt_dump_cont_printf(m, dmsg, "USR ");
189 pt_dump_cont_printf(m, dmsg, " ");
191 pt_dump_cont_printf(m, dmsg, "RW ");
193 pt_dump_cont_printf(m, dmsg, "ro ");
195 pt_dump_cont_printf(m, dmsg, "PWT ");
197 pt_dump_cont_printf(m, dmsg, " ");
199 pt_dump_cont_printf(m, dmsg, "PCD ");
201 pt_dump_cont_printf(m, dmsg, " ");
203 /* Bit 7 has a different meaning on level 3 vs 4 */
204 if (level <= 4 && pr & _PAGE_PSE)
205 pt_dump_cont_printf(m, dmsg, "PSE ");
207 pt_dump_cont_printf(m, dmsg, " ");
208 if ((level == 5 && pr & _PAGE_PAT) ||
209 ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
210 pt_dump_cont_printf(m, dmsg, "PAT ");
212 pt_dump_cont_printf(m, dmsg, " ");
213 if (pr & _PAGE_GLOBAL)
214 pt_dump_cont_printf(m, dmsg, "GLB ");
216 pt_dump_cont_printf(m, dmsg, " ");
218 pt_dump_cont_printf(m, dmsg, "NX ");
220 pt_dump_cont_printf(m, dmsg, "x ");
222 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
226 * On 64 bits, sign-extend the 48 bit address to 64 bit
228 static unsigned long normalize_addr(unsigned long u)
231 if (!IS_ENABLED(CONFIG_X86_64))
234 shift = 64 - (__VIRTUAL_MASK_SHIFT + 1);
235 return (signed long)(u << shift) >> shift;
239 * This function gets called on a break in a continuous series
240 * of PTE entries; the next one is different so we need to
241 * print what we collected so far.
243 static void note_page(struct seq_file *m, struct pg_state *st,
244 pgprot_t new_prot, pgprotval_t new_eff, int level)
246 pgprotval_t prot, cur, eff;
247 static const char units[] = "BKMGTPE";
250 * If we have a "break" in the series, we need to flush the state that
251 * we have now. "break" is either changing perms, levels or
252 * address space marker.
254 prot = pgprot_val(new_prot);
255 cur = pgprot_val(st->current_prot);
256 eff = st->effective_prot;
260 st->current_prot = new_prot;
261 st->effective_prot = new_eff;
263 st->marker = address_markers;
265 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
267 } else if (prot != cur || new_eff != eff || level != st->level ||
268 st->current_address >= st->marker[1].start_address) {
269 const char *unit = units;
271 int width = sizeof(unsigned long) * 2;
273 if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX)) {
275 "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
276 (void *)st->start_address,
277 (void *)st->start_address);
278 st->wx_pages += (st->current_address -
279 st->start_address) / PAGE_SIZE;
283 * Now print the actual finished series
285 if (!st->marker->max_lines ||
286 st->lines < st->marker->max_lines) {
287 pt_dump_seq_printf(m, st->to_dmesg,
289 width, st->start_address,
290 width, st->current_address);
292 delta = st->current_address - st->start_address;
293 while (!(delta & 1023) && unit[1]) {
297 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
299 printk_prot(m, st->current_prot, st->level,
305 * We print markers for special areas of address space,
306 * such as the start of vmalloc space etc.
307 * This helps in the interpretation.
309 if (st->current_address >= st->marker[1].start_address) {
310 if (st->marker->max_lines &&
311 st->lines > st->marker->max_lines) {
312 unsigned long nskip =
313 st->lines - st->marker->max_lines;
314 pt_dump_seq_printf(m, st->to_dmesg,
315 "... %lu entr%s skipped ... \n",
317 nskip == 1 ? "y" : "ies");
321 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
325 st->start_address = st->current_address;
326 st->current_prot = new_prot;
327 st->effective_prot = new_eff;
332 static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
334 return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) |
335 ((prot1 | prot2) & _PAGE_NX);
338 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
339 pgprotval_t eff_in, unsigned long P)
343 pgprotval_t prot, eff;
345 for (i = 0; i < PTRS_PER_PTE; i++) {
346 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
347 pte = pte_offset_map(&addr, st->current_address);
348 prot = pte_flags(*pte);
349 eff = effective_prot(eff_in, prot);
350 note_page(m, st, __pgprot(prot), eff, 5);
357 * This is an optimization for KASAN=y case. Since all kasan page tables
358 * eventually point to the kasan_zero_page we could call note_page()
359 * right away without walking through lower level page tables. This saves
360 * us dozens of seconds (minutes for 5-level config) while checking for
361 * W+X mapping or reading kernel_page_tables debugfs file.
363 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
366 if (__pa(pt) == __pa(kasan_zero_pmd) ||
367 (pgtable_l5_enabled() && __pa(pt) == __pa(kasan_zero_p4d)) ||
368 __pa(pt) == __pa(kasan_zero_pud)) {
369 pgprotval_t prot = pte_flags(kasan_zero_pte[0]);
370 note_page(m, st, __pgprot(prot), 0, 5);
376 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
385 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
386 pgprotval_t eff_in, unsigned long P)
389 pmd_t *start, *pmd_start;
390 pgprotval_t prot, eff;
392 pmd_start = start = (pmd_t *)pud_page_vaddr(addr);
393 for (i = 0; i < PTRS_PER_PMD; i++) {
394 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
395 if (!pmd_none(*start)) {
396 prot = pmd_flags(*start);
397 eff = effective_prot(eff_in, prot);
398 if (pmd_large(*start) || !pmd_present(*start)) {
399 note_page(m, st, __pgprot(prot), eff, 4);
400 } else if (!kasan_page_table(m, st, pmd_start)) {
401 walk_pte_level(m, st, *start, eff,
402 P + i * PMD_LEVEL_MULT);
405 note_page(m, st, __pgprot(0), 0, 4);
411 #define walk_pmd_level(m,s,a,e,p) walk_pte_level(m,s,__pmd(pud_val(a)),e,p)
412 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
413 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
418 static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr,
419 pgprotval_t eff_in, unsigned long P)
422 pud_t *start, *pud_start;
423 pgprotval_t prot, eff;
424 pud_t *prev_pud = NULL;
426 pud_start = start = (pud_t *)p4d_page_vaddr(addr);
428 for (i = 0; i < PTRS_PER_PUD; i++) {
429 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
430 if (!pud_none(*start)) {
431 prot = pud_flags(*start);
432 eff = effective_prot(eff_in, prot);
433 if (pud_large(*start) || !pud_present(*start)) {
434 note_page(m, st, __pgprot(prot), eff, 3);
435 } else if (!kasan_page_table(m, st, pud_start)) {
436 walk_pmd_level(m, st, *start, eff,
437 P + i * PUD_LEVEL_MULT);
440 note_page(m, st, __pgprot(0), 0, 3);
448 #define walk_pud_level(m,s,a,e,p) walk_pmd_level(m,s,__pud(p4d_val(a)),e,p)
449 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
450 #define p4d_none(a) pud_none(__pud(p4d_val(a)))
453 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
454 pgprotval_t eff_in, unsigned long P)
457 p4d_t *start, *p4d_start;
458 pgprotval_t prot, eff;
460 if (PTRS_PER_P4D == 1)
461 return walk_pud_level(m, st, __p4d(pgd_val(addr)), eff_in, P);
463 p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
465 for (i = 0; i < PTRS_PER_P4D; i++) {
466 st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
467 if (!p4d_none(*start)) {
468 prot = p4d_flags(*start);
469 eff = effective_prot(eff_in, prot);
470 if (p4d_large(*start) || !p4d_present(*start)) {
471 note_page(m, st, __pgprot(prot), eff, 2);
472 } else if (!kasan_page_table(m, st, p4d_start)) {
473 walk_pud_level(m, st, *start, eff,
474 P + i * P4D_LEVEL_MULT);
477 note_page(m, st, __pgprot(0), 0, 2);
483 #define pgd_large(a) (pgtable_l5_enabled() ? pgd_large(a) : p4d_large(__p4d(pgd_val(a))))
484 #define pgd_none(a) (pgtable_l5_enabled() ? pgd_none(a) : p4d_none(__p4d(pgd_val(a))))
486 static inline bool is_hypervisor_range(int idx)
490 * ffff800000000000 - ffff87ffffffffff is reserved for
493 return (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
494 (idx < pgd_index(__PAGE_OFFSET));
500 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
501 bool checkwx, bool dmesg)
503 pgd_t *start = INIT_PGD;
504 pgprotval_t prot, eff;
506 struct pg_state st = {};
513 st.check_wx = checkwx;
517 for (i = 0; i < PTRS_PER_PGD; i++) {
518 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
519 if (!pgd_none(*start) && !is_hypervisor_range(i)) {
520 prot = pgd_flags(*start);
521 #ifdef CONFIG_X86_PAE
522 eff = _PAGE_USER | _PAGE_RW;
526 if (pgd_large(*start) || !pgd_present(*start)) {
527 note_page(m, &st, __pgprot(prot), eff, 1);
529 walk_p4d_level(m, &st, *start, eff,
533 note_page(m, &st, __pgprot(0), 0, 1);
539 /* Flush out the last page */
540 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
541 note_page(m, &st, __pgprot(0), 0, 0);
545 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
548 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
551 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
553 ptdump_walk_pgd_level_core(m, pgd, false, true);
556 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
558 #ifdef CONFIG_PAGE_TABLE_ISOLATION
559 if (user && static_cpu_has(X86_FEATURE_PTI))
560 pgd = kernel_to_user_pgdp(pgd);
562 ptdump_walk_pgd_level_core(m, pgd, false, false);
564 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
566 static void ptdump_walk_user_pgd_level_checkwx(void)
568 #ifdef CONFIG_PAGE_TABLE_ISOLATION
569 pgd_t *pgd = INIT_PGD;
571 if (!static_cpu_has(X86_FEATURE_PTI))
574 pr_info("x86/mm: Checking user space page tables\n");
575 pgd = kernel_to_user_pgdp(pgd);
576 ptdump_walk_pgd_level_core(NULL, pgd, true, false);
580 void ptdump_walk_pgd_level_checkwx(void)
582 ptdump_walk_pgd_level_core(NULL, NULL, true, false);
583 ptdump_walk_user_pgd_level_checkwx();
586 static int __init pt_dump_init(void)
589 * Various markers are not compile-time constants, so assign them
593 address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
594 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
595 address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
596 #ifdef CONFIG_MODIFY_LDT_SYSCALL
597 address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
600 address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
601 address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
605 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
606 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
607 # ifdef CONFIG_HIGHMEM
608 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
610 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
611 address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
615 __initcall(pt_dump_init);