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;
38 unsigned long start_address;
40 unsigned long max_lines;
43 /* indices for address_markers; keep sync'd w/ address_markers below */
44 enum address_markers_idx {
51 # ifdef CONFIG_X86_ESPFIX64
61 # ifdef CONFIG_HIGHMEM
68 /* Address space markers hints */
69 static struct addr_marker address_markers[] = {
72 { 0x8000000000000000UL, "Kernel Space" },
73 { PAGE_OFFSET, "Low Kernel Mapping" },
74 { VMALLOC_START, "vmalloc() Area" },
75 { VMEMMAP_START, "Vmemmap" },
76 # ifdef CONFIG_X86_ESPFIX64
77 { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
79 { __START_KERNEL_map, "High Kernel Mapping" },
80 { MODULES_VADDR, "Modules" },
81 { MODULES_END, "End Modules" },
83 { PAGE_OFFSET, "Kernel Mapping" },
84 { 0/* VMALLOC_START */, "vmalloc() Area" },
85 { 0/*VMALLOC_END*/, "vmalloc() End" },
86 # ifdef CONFIG_HIGHMEM
87 { 0/*PKMAP_BASE*/, "Persisent kmap() Area" },
89 { 0/*FIXADDR_START*/, "Fixmap Area" },
91 { -1, NULL } /* End of list */
94 /* Multipliers for offsets within the PTEs */
95 #define PTE_LEVEL_MULT (PAGE_SIZE)
96 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
97 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
98 #define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
100 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
103 printk(KERN_INFO fmt, ##args); \
106 seq_printf(m, fmt, ##args); \
109 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
112 printk(KERN_CONT fmt, ##args); \
115 seq_printf(m, fmt, ##args); \
119 * Print a readable form of a pgprot_t to the seq_file
121 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
123 pgprotval_t pr = pgprot_val(prot);
124 static const char * const level_name[] =
125 { "cr3", "pgd", "pud", "pmd", "pte" };
127 if (!pgprot_val(prot)) {
129 pt_dump_cont_printf(m, dmsg, " ");
132 pt_dump_cont_printf(m, dmsg, "USR ");
134 pt_dump_cont_printf(m, dmsg, " ");
136 pt_dump_cont_printf(m, dmsg, "RW ");
138 pt_dump_cont_printf(m, dmsg, "ro ");
140 pt_dump_cont_printf(m, dmsg, "PWT ");
142 pt_dump_cont_printf(m, dmsg, " ");
144 pt_dump_cont_printf(m, dmsg, "PCD ");
146 pt_dump_cont_printf(m, dmsg, " ");
148 /* Bit 9 has a different meaning on level 3 vs 4 */
151 pt_dump_cont_printf(m, dmsg, "PSE ");
153 pt_dump_cont_printf(m, dmsg, " ");
156 pt_dump_cont_printf(m, dmsg, "pat ");
158 pt_dump_cont_printf(m, dmsg, " ");
160 if (pr & _PAGE_GLOBAL)
161 pt_dump_cont_printf(m, dmsg, "GLB ");
163 pt_dump_cont_printf(m, dmsg, " ");
165 pt_dump_cont_printf(m, dmsg, "NX ");
167 pt_dump_cont_printf(m, dmsg, "x ");
169 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
173 * On 64 bits, sign-extend the 48 bit address to 64 bit
175 static unsigned long normalize_addr(unsigned long u)
178 return (signed long)(u << 16) >> 16;
185 * This function gets called on a break in a continuous series
186 * of PTE entries; the next one is different so we need to
187 * print what we collected so far.
189 static void note_page(struct seq_file *m, struct pg_state *st,
190 pgprot_t new_prot, int level)
192 pgprotval_t prot, cur;
193 static const char units[] = "BKMGTPE";
196 * If we have a "break" in the series, we need to flush the state that
197 * we have now. "break" is either changing perms, levels or
198 * address space marker.
200 prot = pgprot_val(new_prot) & PTE_FLAGS_MASK;
201 cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
205 st->current_prot = new_prot;
207 st->marker = address_markers;
209 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
211 } else if (prot != cur || level != st->level ||
212 st->current_address >= st->marker[1].start_address) {
213 const char *unit = units;
215 int width = sizeof(unsigned long) * 2;
218 * Now print the actual finished series
220 if (!st->marker->max_lines ||
221 st->lines < st->marker->max_lines) {
222 pt_dump_seq_printf(m, st->to_dmesg,
224 width, st->start_address,
225 width, st->current_address);
227 delta = st->current_address - st->start_address;
228 while (!(delta & 1023) && unit[1]) {
232 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
234 printk_prot(m, st->current_prot, st->level,
240 * We print markers for special areas of address space,
241 * such as the start of vmalloc space etc.
242 * This helps in the interpretation.
244 if (st->current_address >= st->marker[1].start_address) {
245 if (st->marker->max_lines &&
246 st->lines > st->marker->max_lines) {
247 unsigned long nskip =
248 st->lines - st->marker->max_lines;
249 pt_dump_seq_printf(m, st->to_dmesg,
250 "... %lu entr%s skipped ... \n",
252 nskip == 1 ? "y" : "ies");
256 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
260 st->start_address = st->current_address;
261 st->current_prot = new_prot;
266 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
272 start = (pte_t *) pmd_page_vaddr(addr);
273 for (i = 0; i < PTRS_PER_PTE; i++) {
274 pgprot_t prot = pte_pgprot(*start);
276 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
277 note_page(m, st, prot, 4);
284 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
290 start = (pmd_t *) pud_page_vaddr(addr);
291 for (i = 0; i < PTRS_PER_PMD; i++) {
292 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
293 if (!pmd_none(*start)) {
294 pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
296 if (pmd_large(*start) || !pmd_present(*start))
297 note_page(m, st, __pgprot(prot), 3);
299 walk_pte_level(m, st, *start,
300 P + i * PMD_LEVEL_MULT);
302 note_page(m, st, __pgprot(0), 3);
308 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
309 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
310 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
315 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
321 start = (pud_t *) pgd_page_vaddr(addr);
323 for (i = 0; i < PTRS_PER_PUD; i++) {
324 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
325 if (!pud_none(*start)) {
326 pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
328 if (pud_large(*start) || !pud_present(*start))
329 note_page(m, st, __pgprot(prot), 2);
331 walk_pmd_level(m, st, *start,
332 P + i * PUD_LEVEL_MULT);
334 note_page(m, st, __pgprot(0), 2);
341 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
342 #define pgd_large(a) pud_large(__pud(pgd_val(a)))
343 #define pgd_none(a) pud_none(__pud(pgd_val(a)))
346 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
349 pgd_t *start = (pgd_t *) &init_level4_pgt;
351 pgd_t *start = swapper_pg_dir;
354 struct pg_state st = {};
361 for (i = 0; i < PTRS_PER_PGD; i++) {
362 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
363 if (!pgd_none(*start)) {
364 pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
366 if (pgd_large(*start) || !pgd_present(*start))
367 note_page(m, &st, __pgprot(prot), 1);
369 walk_pud_level(m, &st, *start,
372 note_page(m, &st, __pgprot(0), 1);
377 /* Flush out the last page */
378 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
379 note_page(m, &st, __pgprot(0), 0);
382 static int ptdump_show(struct seq_file *m, void *v)
384 ptdump_walk_pgd_level(m, NULL);
388 static int ptdump_open(struct inode *inode, struct file *filp)
390 return single_open(filp, ptdump_show, NULL);
393 static const struct file_operations ptdump_fops = {
397 .release = single_release,
400 static int pt_dump_init(void)
405 /* Not a compile-time constant on x86-32 */
406 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
407 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
408 # ifdef CONFIG_HIGHMEM
409 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
411 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
414 pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
422 __initcall(pt_dump_init);
423 MODULE_LICENSE("GPL");
424 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
425 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");