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;
37 unsigned long start_address;
41 /* indices for address_markers; keep sync'd w/ address_markers below */
42 enum address_markers_idx {
56 # ifdef CONFIG_HIGHMEM
63 /* Address space markers hints */
64 static struct addr_marker address_markers[] = {
67 { 0x8000000000000000UL, "Kernel Space" },
68 { PAGE_OFFSET, "Low Kernel Mapping" },
69 { VMALLOC_START, "vmalloc() Area" },
70 { VMEMMAP_START, "Vmemmap" },
71 { __START_KERNEL_map, "High Kernel Mapping" },
72 { MODULES_VADDR, "Modules" },
73 { MODULES_END, "End Modules" },
75 { PAGE_OFFSET, "Kernel Mapping" },
76 { 0/* VMALLOC_START */, "vmalloc() Area" },
77 { 0/*VMALLOC_END*/, "vmalloc() End" },
78 # ifdef CONFIG_HIGHMEM
79 { 0/*PKMAP_BASE*/, "Persisent kmap() Area" },
81 { 0/*FIXADDR_START*/, "Fixmap Area" },
83 { -1, NULL } /* End of list */
86 /* Multipliers for offsets within the PTEs */
87 #define PTE_LEVEL_MULT (PAGE_SIZE)
88 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
89 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
90 #define PGD_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
92 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
95 printk(KERN_INFO fmt, ##args); \
98 seq_printf(m, fmt, ##args); \
101 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
104 printk(KERN_CONT fmt, ##args); \
107 seq_printf(m, fmt, ##args); \
111 * Print a readable form of a pgprot_t to the seq_file
113 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
115 pgprotval_t pr = pgprot_val(prot);
116 static const char * const level_name[] =
117 { "cr3", "pgd", "pud", "pmd", "pte" };
119 if (!pgprot_val(prot)) {
121 pt_dump_cont_printf(m, dmsg, " ");
124 pt_dump_cont_printf(m, dmsg, "USR ");
126 pt_dump_cont_printf(m, dmsg, " ");
128 pt_dump_cont_printf(m, dmsg, "RW ");
130 pt_dump_cont_printf(m, dmsg, "ro ");
132 pt_dump_cont_printf(m, dmsg, "PWT ");
134 pt_dump_cont_printf(m, dmsg, " ");
136 pt_dump_cont_printf(m, dmsg, "PCD ");
138 pt_dump_cont_printf(m, dmsg, " ");
140 /* Bit 9 has a different meaning on level 3 vs 4 */
143 pt_dump_cont_printf(m, dmsg, "PSE ");
145 pt_dump_cont_printf(m, dmsg, " ");
148 pt_dump_cont_printf(m, dmsg, "pat ");
150 pt_dump_cont_printf(m, dmsg, " ");
152 if (pr & _PAGE_GLOBAL)
153 pt_dump_cont_printf(m, dmsg, "GLB ");
155 pt_dump_cont_printf(m, dmsg, " ");
157 pt_dump_cont_printf(m, dmsg, "NX ");
159 pt_dump_cont_printf(m, dmsg, "x ");
161 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
165 * On 64 bits, sign-extend the 48 bit address to 64 bit
167 static unsigned long normalize_addr(unsigned long u)
170 return (signed long)(u << 16) >> 16;
177 * This function gets called on a break in a continuous series
178 * of PTE entries; the next one is different so we need to
179 * print what we collected so far.
181 static void note_page(struct seq_file *m, struct pg_state *st,
182 pgprot_t new_prot, int level)
184 pgprotval_t prot, cur;
185 static const char units[] = "KMGTPE";
188 * If we have a "break" in the series, we need to flush the state that
189 * we have now. "break" is either changing perms, levels or
190 * address space marker.
192 prot = pgprot_val(new_prot) & PTE_FLAGS_MASK;
193 cur = pgprot_val(st->current_prot) & PTE_FLAGS_MASK;
197 st->current_prot = new_prot;
199 st->marker = address_markers;
200 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
202 } else if (prot != cur || level != st->level ||
203 st->current_address >= st->marker[1].start_address) {
204 const char *unit = units;
206 int width = sizeof(unsigned long) * 2;
209 * Now print the actual finished series
211 pt_dump_seq_printf(m, st->to_dmesg, "0x%0*lx-0x%0*lx ",
212 width, st->start_address,
213 width, st->current_address);
215 delta = (st->current_address - st->start_address) >> 10;
216 while (!(delta & 1023) && unit[1]) {
220 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ", delta, *unit);
221 printk_prot(m, st->current_prot, st->level, st->to_dmesg);
224 * We print markers for special areas of address space,
225 * such as the start of vmalloc space etc.
226 * This helps in the interpretation.
228 if (st->current_address >= st->marker[1].start_address) {
230 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
234 st->start_address = st->current_address;
235 st->current_prot = new_prot;
240 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr,
246 start = (pte_t *) pmd_page_vaddr(addr);
247 for (i = 0; i < PTRS_PER_PTE; i++) {
248 pgprot_t prot = pte_pgprot(*start);
250 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
251 note_page(m, st, prot, 4);
258 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr,
264 start = (pmd_t *) pud_page_vaddr(addr);
265 for (i = 0; i < PTRS_PER_PMD; i++) {
266 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
267 if (!pmd_none(*start)) {
268 pgprotval_t prot = pmd_val(*start) & PTE_FLAGS_MASK;
270 if (pmd_large(*start) || !pmd_present(*start))
271 note_page(m, st, __pgprot(prot), 3);
273 walk_pte_level(m, st, *start,
274 P + i * PMD_LEVEL_MULT);
276 note_page(m, st, __pgprot(0), 3);
282 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
283 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
284 #define pud_none(a) pmd_none(__pmd(pud_val(a)))
289 static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr,
295 start = (pud_t *) pgd_page_vaddr(addr);
297 for (i = 0; i < PTRS_PER_PUD; i++) {
298 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
299 if (!pud_none(*start)) {
300 pgprotval_t prot = pud_val(*start) & PTE_FLAGS_MASK;
302 if (pud_large(*start) || !pud_present(*start))
303 note_page(m, st, __pgprot(prot), 2);
305 walk_pmd_level(m, st, *start,
306 P + i * PUD_LEVEL_MULT);
308 note_page(m, st, __pgprot(0), 2);
315 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(pgd_val(a)),p)
316 #define pgd_large(a) pud_large(__pud(pgd_val(a)))
317 #define pgd_none(a) pud_none(__pud(pgd_val(a)))
320 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
323 pgd_t *start = (pgd_t *) &init_level4_pgt;
325 pgd_t *start = swapper_pg_dir;
328 struct pg_state st = {};
335 for (i = 0; i < PTRS_PER_PGD; i++) {
336 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
337 if (!pgd_none(*start)) {
338 pgprotval_t prot = pgd_val(*start) & PTE_FLAGS_MASK;
340 if (pgd_large(*start) || !pgd_present(*start))
341 note_page(m, &st, __pgprot(prot), 1);
343 walk_pud_level(m, &st, *start,
346 note_page(m, &st, __pgprot(0), 1);
351 /* Flush out the last page */
352 st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
353 note_page(m, &st, __pgprot(0), 0);
356 static int ptdump_show(struct seq_file *m, void *v)
358 ptdump_walk_pgd_level(m, NULL);
362 static int ptdump_open(struct inode *inode, struct file *filp)
364 return single_open(filp, ptdump_show, NULL);
367 static const struct file_operations ptdump_fops = {
371 .release = single_release,
374 static int pt_dump_init(void)
379 /* Not a compile-time constant on x86-32 */
380 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
381 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
382 # ifdef CONFIG_HIGHMEM
383 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
385 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
388 pe = debugfs_create_file("kernel_page_tables", 0600, NULL, NULL,
396 __initcall(pt_dump_init);
397 MODULE_LICENSE("GPL");
398 MODULE_AUTHOR("Arjan van de Ven <arjan@linux.intel.com>");
399 MODULE_DESCRIPTION("Kernel debugging helper that dumps pagetables");