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
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>
22 #include <linux/pci.h>
24 #include <asm/e820/types.h>
25 #include <asm/pgtable.h>
28 * The dumper groups pagetable entries of the same type into one, and for
29 * that it needs to keep some state when walking, and flush this state
30 * when a "break" in the continuity is found.
34 pgprot_t current_prot;
35 pgprotval_t effective_prot;
36 unsigned long start_address;
37 unsigned long current_address;
38 const struct addr_marker *marker;
42 unsigned long wx_pages;
46 unsigned long start_address;
48 unsigned long max_lines;
51 /* Address space markers hints */
55 enum address_markers_idx {
59 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && defined(CONFIG_X86_5LEVEL)
65 KASAN_SHADOW_START_NR,
69 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && !defined(CONFIG_X86_5LEVEL)
72 #ifdef CONFIG_X86_ESPFIX64
85 static struct addr_marker address_markers[] = {
86 [USER_SPACE_NR] = { 0, "User Space" },
87 [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" },
88 [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" },
89 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
90 [VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
93 * These fields get initialized with the (dynamic)
94 * KASAN_SHADOW_{START,END} values in pt_dump_init().
96 [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
97 [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
99 #ifdef CONFIG_MODIFY_LDT_SYSCALL
100 [LDT_NR] = { 0UL, "LDT remap" },
102 [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
103 #ifdef CONFIG_X86_ESPFIX64
104 [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
107 [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" },
109 [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" },
110 [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" },
111 [MODULES_END_NR] = { MODULES_END, "End Modules" },
112 [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" },
113 [END_OF_SPACE_NR] = { -1, NULL }
116 #define INIT_PGD ((pgd_t *) &init_top_pgt)
118 #else /* CONFIG_X86_64 */
120 enum address_markers_idx {
125 #ifdef CONFIG_HIGHMEM
128 #ifdef CONFIG_MODIFY_LDT_SYSCALL
136 static struct addr_marker address_markers[] = {
137 [USER_SPACE_NR] = { 0, "User Space" },
138 [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" },
139 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
140 [VMALLOC_END_NR] = { 0UL, "vmalloc() End" },
141 #ifdef CONFIG_HIGHMEM
142 [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" },
144 #ifdef CONFIG_MODIFY_LDT_SYSCALL
145 [LDT_NR] = { 0UL, "LDT remap" },
147 [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" },
148 [FIXADDR_START_NR] = { 0UL, "Fixmap area" },
149 [END_OF_SPACE_NR] = { -1, NULL }
152 #define INIT_PGD (swapper_pg_dir)
154 #endif /* !CONFIG_X86_64 */
156 /* Multipliers for offsets within the PTEs */
157 #define PTE_LEVEL_MULT (PAGE_SIZE)
158 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
159 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
160 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
161 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
163 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
166 printk(KERN_INFO fmt, ##args); \
169 seq_printf(m, fmt, ##args); \
172 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
175 printk(KERN_CONT fmt, ##args); \
178 seq_printf(m, fmt, ##args); \
182 * Print a readable form of a pgprot_t to the seq_file
184 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
186 pgprotval_t pr = pgprot_val(prot);
187 static const char * const level_name[] =
188 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
190 if (!(pr & _PAGE_PRESENT)) {
192 pt_dump_cont_printf(m, dmsg, " ");
195 pt_dump_cont_printf(m, dmsg, "USR ");
197 pt_dump_cont_printf(m, dmsg, " ");
199 pt_dump_cont_printf(m, dmsg, "RW ");
201 pt_dump_cont_printf(m, dmsg, "ro ");
203 pt_dump_cont_printf(m, dmsg, "PWT ");
205 pt_dump_cont_printf(m, dmsg, " ");
207 pt_dump_cont_printf(m, dmsg, "PCD ");
209 pt_dump_cont_printf(m, dmsg, " ");
211 /* Bit 7 has a different meaning on level 3 vs 4 */
212 if (level <= 4 && pr & _PAGE_PSE)
213 pt_dump_cont_printf(m, dmsg, "PSE ");
215 pt_dump_cont_printf(m, dmsg, " ");
216 if ((level == 5 && pr & _PAGE_PAT) ||
217 ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
218 pt_dump_cont_printf(m, dmsg, "PAT ");
220 pt_dump_cont_printf(m, dmsg, " ");
221 if (pr & _PAGE_GLOBAL)
222 pt_dump_cont_printf(m, dmsg, "GLB ");
224 pt_dump_cont_printf(m, dmsg, " ");
226 pt_dump_cont_printf(m, dmsg, "NX ");
228 pt_dump_cont_printf(m, dmsg, "x ");
230 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
234 * On 64 bits, sign-extend the 48 bit address to 64 bit
236 static unsigned long normalize_addr(unsigned long u)
239 if (!IS_ENABLED(CONFIG_X86_64))
242 shift = 64 - (__VIRTUAL_MASK_SHIFT + 1);
243 return (signed long)(u << shift) >> shift;
246 static void note_wx(struct pg_state *st)
248 unsigned long npages;
250 npages = (st->current_address - st->start_address) / PAGE_SIZE;
252 #ifdef CONFIG_PCI_BIOS
254 * If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
255 * Inform about it, but avoid the warning.
257 if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
258 st->current_address <= PAGE_OFFSET + BIOS_END) {
259 pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
263 /* Account the WX pages */
264 st->wx_pages += npages;
265 WARN_ONCE(1, "x86/mm: Found insecure W+X mapping at address %pS\n",
266 (void *)st->start_address);
270 * This function gets called on a break in a continuous series
271 * of PTE entries; the next one is different so we need to
272 * print what we collected so far.
274 static void note_page(struct seq_file *m, struct pg_state *st,
275 pgprot_t new_prot, pgprotval_t new_eff, int level)
277 pgprotval_t prot, cur, eff;
278 static const char units[] = "BKMGTPE";
281 * If we have a "break" in the series, we need to flush the state that
282 * we have now. "break" is either changing perms, levels or
283 * address space marker.
285 prot = pgprot_val(new_prot);
286 cur = pgprot_val(st->current_prot);
287 eff = st->effective_prot;
291 st->current_prot = new_prot;
292 st->effective_prot = new_eff;
294 st->marker = address_markers;
296 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
298 } else if (prot != cur || new_eff != eff || level != st->level ||
299 st->current_address >= st->marker[1].start_address) {
300 const char *unit = units;
302 int width = sizeof(unsigned long) * 2;
304 if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
308 * Now print the actual finished series
310 if (!st->marker->max_lines ||
311 st->lines < st->marker->max_lines) {
312 pt_dump_seq_printf(m, st->to_dmesg,
314 width, st->start_address,
315 width, st->current_address);
317 delta = st->current_address - st->start_address;
318 while (!(delta & 1023) && unit[1]) {
322 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
324 printk_prot(m, st->current_prot, st->level,
330 * We print markers for special areas of address space,
331 * such as the start of vmalloc space etc.
332 * This helps in the interpretation.
334 if (st->current_address >= st->marker[1].start_address) {
335 if (st->marker->max_lines &&
336 st->lines > st->marker->max_lines) {
337 unsigned long nskip =
338 st->lines - st->marker->max_lines;
339 pt_dump_seq_printf(m, st->to_dmesg,
340 "... %lu entr%s skipped ... \n",
342 nskip == 1 ? "y" : "ies");
346 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
350 st->start_address = st->current_address;
351 st->current_prot = new_prot;
352 st->effective_prot = new_eff;
357 static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2)
359 return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) |
360 ((prot1 | prot2) & _PAGE_NX);
363 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
364 pgprotval_t eff_in, unsigned long P)
368 pgprotval_t prot, eff;
370 for (i = 0; i < PTRS_PER_PTE; i++) {
371 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
372 pte = pte_offset_map(&addr, st->current_address);
373 prot = pte_flags(*pte);
374 eff = effective_prot(eff_in, prot);
375 note_page(m, st, __pgprot(prot), eff, 5);
382 * This is an optimization for KASAN=y case. Since all kasan page tables
383 * eventually point to the kasan_zero_page we could call note_page()
384 * right away without walking through lower level page tables. This saves
385 * us dozens of seconds (minutes for 5-level config) while checking for
386 * W+X mapping or reading kernel_page_tables debugfs file.
388 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
391 if (__pa(pt) == __pa(kasan_zero_pmd) ||
392 (pgtable_l5_enabled() && __pa(pt) == __pa(kasan_zero_p4d)) ||
393 __pa(pt) == __pa(kasan_zero_pud)) {
394 pgprotval_t prot = pte_flags(kasan_zero_pte[0]);
395 note_page(m, st, __pgprot(prot), 0, 5);
401 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
410 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
411 pgprotval_t eff_in, unsigned long P)
414 pmd_t *start, *pmd_start;
415 pgprotval_t prot, eff;
417 pmd_start = start = (pmd_t *)pud_page_vaddr(addr);
418 for (i = 0; i < PTRS_PER_PMD; i++) {
419 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
420 if (!pmd_none(*start)) {
421 prot = pmd_flags(*start);
422 eff = effective_prot(eff_in, prot);
423 if (pmd_large(*start) || !pmd_present(*start)) {
424 note_page(m, st, __pgprot(prot), eff, 4);
425 } else if (!kasan_page_table(m, st, pmd_start)) {
426 walk_pte_level(m, st, *start, eff,
427 P + i * PMD_LEVEL_MULT);
430 note_page(m, st, __pgprot(0), 0, 4);
436 #define walk_pmd_level(m,s,a,e,p) walk_pte_level(m,s,__pmd(pud_val(a)),e,p)
437 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
438 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
443 static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr,
444 pgprotval_t eff_in, unsigned long P)
447 pud_t *start, *pud_start;
448 pgprotval_t prot, eff;
449 pud_t *prev_pud = NULL;
451 pud_start = start = (pud_t *)p4d_page_vaddr(addr);
453 for (i = 0; i < PTRS_PER_PUD; i++) {
454 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
455 if (!pud_none(*start)) {
456 prot = pud_flags(*start);
457 eff = effective_prot(eff_in, prot);
458 if (pud_large(*start) || !pud_present(*start)) {
459 note_page(m, st, __pgprot(prot), eff, 3);
460 } else if (!kasan_page_table(m, st, pud_start)) {
461 walk_pmd_level(m, st, *start, eff,
462 P + i * PUD_LEVEL_MULT);
465 note_page(m, st, __pgprot(0), 0, 3);
473 #define walk_pud_level(m,s,a,e,p) walk_pmd_level(m,s,__pud(p4d_val(a)),e,p)
474 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
475 #define p4d_none(a) pud_none(__pud(p4d_val(a)))
478 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
479 pgprotval_t eff_in, unsigned long P)
482 p4d_t *start, *p4d_start;
483 pgprotval_t prot, eff;
485 if (PTRS_PER_P4D == 1)
486 return walk_pud_level(m, st, __p4d(pgd_val(addr)), eff_in, P);
488 p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
490 for (i = 0; i < PTRS_PER_P4D; i++) {
491 st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
492 if (!p4d_none(*start)) {
493 prot = p4d_flags(*start);
494 eff = effective_prot(eff_in, prot);
495 if (p4d_large(*start) || !p4d_present(*start)) {
496 note_page(m, st, __pgprot(prot), eff, 2);
497 } else if (!kasan_page_table(m, st, p4d_start)) {
498 walk_pud_level(m, st, *start, eff,
499 P + i * P4D_LEVEL_MULT);
502 note_page(m, st, __pgprot(0), 0, 2);
508 #define pgd_large(a) (pgtable_l5_enabled() ? pgd_large(a) : p4d_large(__p4d(pgd_val(a))))
509 #define pgd_none(a) (pgtable_l5_enabled() ? pgd_none(a) : p4d_none(__p4d(pgd_val(a))))
511 static inline bool is_hypervisor_range(int idx)
515 * ffff800000000000 - ffff87ffffffffff is reserved for
518 return (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
519 (idx < pgd_index(__PAGE_OFFSET));
525 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
526 bool checkwx, bool dmesg)
528 pgd_t *start = INIT_PGD;
529 pgprotval_t prot, eff;
531 struct pg_state st = {};
538 st.check_wx = checkwx;
542 for (i = 0; i < PTRS_PER_PGD; i++) {
543 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
544 if (!pgd_none(*start) && !is_hypervisor_range(i)) {
545 prot = pgd_flags(*start);
546 #ifdef CONFIG_X86_PAE
547 eff = _PAGE_USER | _PAGE_RW;
551 if (pgd_large(*start) || !pgd_present(*start)) {
552 note_page(m, &st, __pgprot(prot), eff, 1);
554 walk_p4d_level(m, &st, *start, eff,
558 note_page(m, &st, __pgprot(0), 0, 1);
564 /* Flush out the last page */
565 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
566 note_page(m, &st, __pgprot(0), 0, 0);
570 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
573 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
576 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
578 ptdump_walk_pgd_level_core(m, pgd, false, true);
581 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
583 #ifdef CONFIG_PAGE_TABLE_ISOLATION
584 if (user && static_cpu_has(X86_FEATURE_PTI))
585 pgd = kernel_to_user_pgdp(pgd);
587 ptdump_walk_pgd_level_core(m, pgd, false, false);
589 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
591 void ptdump_walk_user_pgd_level_checkwx(void)
593 #ifdef CONFIG_PAGE_TABLE_ISOLATION
594 pgd_t *pgd = INIT_PGD;
596 if (!(__supported_pte_mask & _PAGE_NX) ||
597 !static_cpu_has(X86_FEATURE_PTI))
600 pr_info("x86/mm: Checking user space page tables\n");
601 pgd = kernel_to_user_pgdp(pgd);
602 ptdump_walk_pgd_level_core(NULL, pgd, true, false);
606 void ptdump_walk_pgd_level_checkwx(void)
608 ptdump_walk_pgd_level_core(NULL, NULL, true, false);
611 static int __init pt_dump_init(void)
614 * Various markers are not compile-time constants, so assign them
618 address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
619 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
620 address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
621 #ifdef CONFIG_MODIFY_LDT_SYSCALL
622 address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
625 address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
626 address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
630 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
631 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
632 # ifdef CONFIG_HIGHMEM
633 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
635 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
636 address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
637 # ifdef CONFIG_MODIFY_LDT_SYSCALL
638 address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
643 __initcall(pt_dump_init);