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>
17 #include <linux/module.h>
18 #include <linux/seq_file.h>
20 #include <asm/pgtable.h>
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.
29 pgprot_t current_prot;
30 unsigned long start_address;
31 unsigned long current_address;
32 const struct addr_marker *marker;
36 unsigned long wx_pages;
40 unsigned long start_address;
42 unsigned long max_lines;
45 /* indices for address_markers; keep sync'd w/ address_markers below */
46 enum address_markers_idx {
53 # ifdef CONFIG_X86_ESPFIX64
63 # ifdef CONFIG_HIGHMEM
70 /* Address space markers hints */
71 static struct addr_marker address_markers[] = {
74 { 0x8000000000000000UL, "Kernel Space" },
75 { PAGE_OFFSET, "Low Kernel Mapping" },
76 { VMALLOC_START, "vmalloc() Area" },
77 { VMEMMAP_START, "Vmemmap" },
78 # ifdef CONFIG_X86_ESPFIX64
79 { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
82 { EFI_VA_END, "EFI Runtime Services" },
84 { __START_KERNEL_map, "High Kernel Mapping" },
85 { MODULES_VADDR, "Modules" },
86 { MODULES_END, "End Modules" },
88 { PAGE_OFFSET, "Kernel Mapping" },
89 { 0/* VMALLOC_START */, "vmalloc() Area" },
90 { 0/*VMALLOC_END*/, "vmalloc() End" },
91 # ifdef CONFIG_HIGHMEM
92 { 0/*PKMAP_BASE*/, "Persistent kmap() Area" },
94 { 0/*FIXADDR_START*/, "Fixmap Area" },
96 { -1, NULL } /* End of list */
99 /* Multipliers for offsets within the PTEs */
100 #define PTE_LEVEL_MULT (PAGE_SIZE)
101 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
102 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
103 #define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
105 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
108 printk(KERN_INFO fmt, ##args); \
111 seq_printf(m, fmt, ##args); \
114 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
117 printk(KERN_CONT fmt, ##args); \
120 seq_printf(m, fmt, ##args); \
124 * Print a readable form of a pgprot_t to the seq_file
126 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
128 pgprotval_t pr = pgprot_val(prot);
129 static const char * const level_name[] =
130 { "cr3", "pgd", "pud", "pmd", "pte" };
132 if (!pgprot_val(prot)) {
134 pt_dump_cont_printf(m, dmsg, " ");
137 pt_dump_cont_printf(m, dmsg, "USR ");
139 pt_dump_cont_printf(m, dmsg, " ");
141 pt_dump_cont_printf(m, dmsg, "RW ");
143 pt_dump_cont_printf(m, dmsg, "ro ");
145 pt_dump_cont_printf(m, dmsg, "PWT ");
147 pt_dump_cont_printf(m, dmsg, " ");
149 pt_dump_cont_printf(m, dmsg, "PCD ");
151 pt_dump_cont_printf(m, dmsg, " ");
153 /* Bit 7 has a different meaning on level 3 vs 4 */
154 if (level <= 3 && pr & _PAGE_PSE)
155 pt_dump_cont_printf(m, dmsg, "PSE ");
157 pt_dump_cont_printf(m, dmsg, " ");
158 if ((level == 4 && pr & _PAGE_PAT) ||
159 ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
160 pt_dump_cont_printf(m, dmsg, "PAT ");
162 pt_dump_cont_printf(m, dmsg, " ");
163 if (pr & _PAGE_GLOBAL)
164 pt_dump_cont_printf(m, dmsg, "GLB ");
166 pt_dump_cont_printf(m, dmsg, " ");
168 pt_dump_cont_printf(m, dmsg, "NX ");
170 pt_dump_cont_printf(m, dmsg, "x ");
172 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
176 * On 64 bits, sign-extend the 48 bit address to 64 bit
178 static unsigned long normalize_addr(unsigned long u)
181 return (signed long)(u << 16) >> 16;
188 * This function gets called on a break in a continuous series
189 * of PTE entries; the next one is different so we need to
190 * print what we collected so far.
192 static void note_page(struct seq_file *m, struct pg_state *st,
193 pgprot_t new_prot, int level)
195 pgprotval_t prot, cur;
196 static const char units[] = "BKMGTPE";
199 * If we have a "break" in the series, we need to flush the state that
200 * we have now. "break" is either changing perms, levels or
201 * address space marker.
203 prot = pgprot_val(new_prot);
204 cur = pgprot_val(st->current_prot);
208 st->current_prot = new_prot;
210 st->marker = address_markers;
212 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
214 } else if (prot != cur || level != st->level ||
215 st->current_address >= st->marker[1].start_address) {
216 const char *unit = units;
218 int width = sizeof(unsigned long) * 2;
219 pgprotval_t pr = pgprot_val(st->current_prot);
221 if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) {
223 "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
224 (void *)st->start_address,
225 (void *)st->start_address);
226 st->wx_pages += (st->current_address -
227 st->start_address) / PAGE_SIZE;
231 * Now print the actual finished series
233 if (!st->marker->max_lines ||
234 st->lines < st->marker->max_lines) {
235 pt_dump_seq_printf(m, st->to_dmesg,
237 width, st->start_address,
238 width, st->current_address);
240 delta = st->current_address - st->start_address;
241 while (!(delta & 1023) && unit[1]) {
245 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
247 printk_prot(m, st->current_prot, st->level,
253 * We print markers for special areas of address space,
254 * such as the start of vmalloc space etc.
255 * This helps in the interpretation.
257 if (st->current_address >= st->marker[1].start_address) {
258 if (st->marker->max_lines &&
259 st->lines > st->marker->max_lines) {
260 unsigned long nskip =
261 st->lines - st->marker->max_lines;
262 pt_dump_seq_printf(m, st->to_dmesg,
263 "... %lu entr%s skipped ... \n",
265 nskip == 1 ? "y" : "ies");
269 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
273 st->start_address = st->current_address;
274 st->current_prot = new_prot;
279 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
286 start = (pte_t *) pmd_page_vaddr(addr);
287 for (i = 0; i < PTRS_PER_PTE; i++) {
288 prot = pte_flags(*start);
289 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
290 note_page(m, st, __pgprot(prot), 4);
297 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
304 start = (pmd_t *) pud_page_vaddr(addr);
305 for (i = 0; i < PTRS_PER_PMD; i++) {
306 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
307 if (!pmd_none(*start)) {
308 if (pmd_large(*start) || !pmd_present(*start)) {
309 prot = pmd_flags(*start);
310 note_page(m, st, __pgprot(prot), 3);
312 walk_pte_level(m, st, *start,
313 P + i * PMD_LEVEL_MULT);
316 note_page(m, st, __pgprot(0), 3);
322 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
323 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
324 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
329 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
336 start = (pud_t *) pgd_page_vaddr(addr);
338 for (i = 0; i < PTRS_PER_PUD; i++) {
339 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
340 if (!pud_none(*start)) {
341 if (pud_large(*start) || !pud_present(*start)) {
342 prot = pud_flags(*start);
343 note_page(m, st, __pgprot(prot), 2);
345 walk_pmd_level(m, st, *start,
346 P + i * PUD_LEVEL_MULT);
349 note_page(m, st, __pgprot(0), 2);
356 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
357 #define pgd_large(a) pud_large(__pud(pgd_val(a)))
358 #define pgd_none(a) pud_none(__pud(pgd_val(a)))
362 static inline bool is_hypervisor_range(int idx)
365 * ffff800000000000 - ffff87ffffffffff is reserved for
368 return paravirt_enabled() &&
369 (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
370 (idx < pgd_index(__PAGE_OFFSET));
373 static inline bool is_hypervisor_range(int idx) { return false; }
376 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
380 pgd_t *start = (pgd_t *) &init_level4_pgt;
382 pgd_t *start = swapper_pg_dir;
386 struct pg_state st = {};
393 st.check_wx = checkwx;
397 for (i = 0; i < PTRS_PER_PGD; i++) {
398 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
399 if (!pgd_none(*start) && !is_hypervisor_range(i)) {
400 if (pgd_large(*start) || !pgd_present(*start)) {
401 prot = pgd_flags(*start);
402 note_page(m, &st, __pgprot(prot), 1);
404 walk_pud_level(m, &st, *start,
408 note_page(m, &st, __pgprot(0), 1);
413 /* Flush out the last page */
414 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
415 note_page(m, &st, __pgprot(0), 0);
419 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
422 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
425 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
427 ptdump_walk_pgd_level_core(m, pgd, false);
430 void ptdump_walk_pgd_level_checkwx(void)
432 ptdump_walk_pgd_level_core(NULL, NULL, true);
435 #ifdef CONFIG_X86_PTDUMP
436 static int ptdump_show(struct seq_file *m, void *v)
438 ptdump_walk_pgd_level(m, NULL);
442 static int ptdump_open(struct inode *inode, struct file *filp)
444 return single_open(filp, ptdump_show, NULL);
447 static const struct file_operations ptdump_fops = {
451 .release = single_release,
455 static int pt_dump_init(void)
457 #ifdef CONFIG_X86_PTDUMP
462 /* Not a compile-time constant on x86-32 */
463 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
464 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
465 # ifdef CONFIG_HIGHMEM
466 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
468 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
471 #ifdef CONFIG_X86_PTDUMP
472 pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
481 __initcall(pt_dump_init);
482 MODULE_LICENSE("GPL");
483 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
484 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");