1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (c) 2014, The Linux Foundation. All rights reserved.
4 * Debug helper to dump the current kernel pagetables of the system
5 * so that we can see what the various memory ranges are set to.
7 * Derived from x86 and arm implementation:
8 * (C) Copyright 2008 Intel Corporation
10 * Author: Arjan van de Ven <arjan@linux.intel.com>
12 #include <linux/debugfs.h>
13 #include <linux/errno.h>
16 #include <linux/init.h>
18 #include <linux/sched.h>
19 #include <linux/seq_file.h>
21 #include <asm/fixmap.h>
22 #include <asm/kasan.h>
23 #include <asm/memory.h>
24 #include <asm/pgtable.h>
25 #include <asm/pgtable-hwdef.h>
26 #include <asm/ptdump.h>
28 static const struct addr_marker address_markers[] = {
30 { KASAN_SHADOW_START, "Kasan shadow start" },
31 { KASAN_SHADOW_END, "Kasan shadow end" },
33 { MODULES_VADDR, "Modules start" },
34 { MODULES_END, "Modules end" },
35 { VMALLOC_START, "vmalloc() area" },
36 { VMALLOC_END, "vmalloc() end" },
37 { FIXADDR_START, "Fixmap start" },
38 { FIXADDR_TOP, "Fixmap end" },
39 { PCI_IO_START, "PCI I/O start" },
40 { PCI_IO_END, "PCI I/O end" },
41 #ifdef CONFIG_SPARSEMEM_VMEMMAP
42 { VMEMMAP_START, "vmemmap start" },
43 { VMEMMAP_START + VMEMMAP_SIZE, "vmemmap end" },
45 { PAGE_OFFSET, "Linear mapping" },
49 #define pt_dump_seq_printf(m, fmt, args...) \
52 seq_printf(m, fmt, ##args); \
55 #define pt_dump_seq_puts(m, fmt) \
62 * The page dumper groups page table entries of the same type into a single
63 * description. It uses pg_state to track the range information while
64 * iterating over the pte entries. When the continuity is broken it then
65 * dumps out a description of the range.
69 const struct addr_marker *marker;
70 unsigned long start_address;
74 unsigned long wx_pages;
75 unsigned long uxn_pages;
85 static const struct prot_bits pte_bits[] = {
127 .mask = PTE_TABLE_BIT,
128 .val = PTE_TABLE_BIT,
136 .mask = PTE_ATTRINDX_MASK,
137 .val = PTE_ATTRINDX(MT_DEVICE_nGnRnE),
138 .set = "DEVICE/nGnRnE",
140 .mask = PTE_ATTRINDX_MASK,
141 .val = PTE_ATTRINDX(MT_DEVICE_nGnRE),
142 .set = "DEVICE/nGnRE",
144 .mask = PTE_ATTRINDX_MASK,
145 .val = PTE_ATTRINDX(MT_DEVICE_GRE),
148 .mask = PTE_ATTRINDX_MASK,
149 .val = PTE_ATTRINDX(MT_NORMAL_NC),
150 .set = "MEM/NORMAL-NC",
152 .mask = PTE_ATTRINDX_MASK,
153 .val = PTE_ATTRINDX(MT_NORMAL),
159 const struct prot_bits *bits;
165 static struct pg_level pg_level[] = {
170 .num = ARRAY_SIZE(pte_bits),
172 .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
174 .num = ARRAY_SIZE(pte_bits),
176 .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
178 .num = ARRAY_SIZE(pte_bits),
182 .num = ARRAY_SIZE(pte_bits),
186 static void dump_prot(struct pg_state *st, const struct prot_bits *bits,
191 for (i = 0; i < num; i++, bits++) {
194 if ((st->current_prot & bits->mask) == bits->val)
200 pt_dump_seq_printf(st->seq, " %s", s);
204 static void note_prot_uxn(struct pg_state *st, unsigned long addr)
209 if ((st->current_prot & PTE_UXN) == PTE_UXN)
212 WARN_ONCE(1, "arm64/mm: Found non-UXN mapping at address %p/%pS\n",
213 (void *)st->start_address, (void *)st->start_address);
215 st->uxn_pages += (addr - st->start_address) / PAGE_SIZE;
218 static void note_prot_wx(struct pg_state *st, unsigned long addr)
222 if ((st->current_prot & PTE_RDONLY) == PTE_RDONLY)
224 if ((st->current_prot & PTE_PXN) == PTE_PXN)
227 WARN_ONCE(1, "arm64/mm: Found insecure W+X mapping at address %p/%pS\n",
228 (void *)st->start_address, (void *)st->start_address);
230 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
233 static void note_page(struct pg_state *st, unsigned long addr, unsigned level,
236 static const char units[] = "KMGTPE";
237 u64 prot = val & pg_level[level].mask;
241 st->current_prot = prot;
242 st->start_address = addr;
243 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
244 } else if (prot != st->current_prot || level != st->level ||
245 addr >= st->marker[1].start_address) {
246 const char *unit = units;
249 if (st->current_prot) {
250 note_prot_uxn(st, addr);
251 note_prot_wx(st, addr);
252 pt_dump_seq_printf(st->seq, "0x%016lx-0x%016lx ",
253 st->start_address, addr);
255 delta = (addr - st->start_address) >> 10;
256 while (!(delta & 1023) && unit[1]) {
260 pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
261 pg_level[st->level].name);
262 if (pg_level[st->level].bits)
263 dump_prot(st, pg_level[st->level].bits,
264 pg_level[st->level].num);
265 pt_dump_seq_puts(st->seq, "\n");
268 if (addr >= st->marker[1].start_address) {
270 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
273 st->start_address = addr;
274 st->current_prot = prot;
278 if (addr >= st->marker[1].start_address) {
280 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
285 static void walk_pte(struct pg_state *st, pmd_t *pmdp, unsigned long start,
288 unsigned long addr = start;
289 pte_t *ptep = pte_offset_kernel(pmdp, start);
292 note_page(st, addr, 4, READ_ONCE(pte_val(*ptep)));
293 } while (ptep++, addr += PAGE_SIZE, addr != end);
296 static void walk_pmd(struct pg_state *st, pud_t *pudp, unsigned long start,
299 unsigned long next, addr = start;
300 pmd_t *pmdp = pmd_offset(pudp, start);
303 pmd_t pmd = READ_ONCE(*pmdp);
304 next = pmd_addr_end(addr, end);
306 if (pmd_none(pmd) || pmd_sect(pmd)) {
307 note_page(st, addr, 3, pmd_val(pmd));
309 BUG_ON(pmd_bad(pmd));
310 walk_pte(st, pmdp, addr, next);
312 } while (pmdp++, addr = next, addr != end);
315 static void walk_pud(struct pg_state *st, pgd_t *pgdp, unsigned long start,
318 unsigned long next, addr = start;
319 pud_t *pudp = pud_offset(pgdp, start);
322 pud_t pud = READ_ONCE(*pudp);
323 next = pud_addr_end(addr, end);
325 if (pud_none(pud) || pud_sect(pud)) {
326 note_page(st, addr, 2, pud_val(pud));
328 BUG_ON(pud_bad(pud));
329 walk_pmd(st, pudp, addr, next);
331 } while (pudp++, addr = next, addr != end);
334 static void walk_pgd(struct pg_state *st, struct mm_struct *mm,
337 unsigned long end = (start < TASK_SIZE_64) ? TASK_SIZE_64 : 0;
338 unsigned long next, addr = start;
339 pgd_t *pgdp = pgd_offset(mm, start);
342 pgd_t pgd = READ_ONCE(*pgdp);
343 next = pgd_addr_end(addr, end);
346 note_page(st, addr, 1, pgd_val(pgd));
348 BUG_ON(pgd_bad(pgd));
349 walk_pud(st, pgdp, addr, next);
351 } while (pgdp++, addr = next, addr != end);
354 void ptdump_walk_pgd(struct seq_file *m, struct ptdump_info *info)
356 struct pg_state st = {
358 .marker = info->markers,
361 walk_pgd(&st, info->mm, info->base_addr);
363 note_page(&st, 0, 0, 0);
366 static void ptdump_initialize(void)
370 for (i = 0; i < ARRAY_SIZE(pg_level); i++)
371 if (pg_level[i].bits)
372 for (j = 0; j < pg_level[i].num; j++)
373 pg_level[i].mask |= pg_level[i].bits[j].mask;
376 static struct ptdump_info kernel_ptdump_info = {
378 .markers = address_markers,
379 .base_addr = VA_START,
382 void ptdump_check_wx(void)
384 struct pg_state st = {
386 .marker = (struct addr_marker[]) {
393 walk_pgd(&st, &init_mm, VA_START);
394 note_page(&st, 0, 0, 0);
395 if (st.wx_pages || st.uxn_pages)
396 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found, %lu non-UXN pages found\n",
397 st.wx_pages, st.uxn_pages);
399 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
402 static int ptdump_init(void)
405 ptdump_debugfs_register(&kernel_ptdump_info, "kernel_page_tables");
408 device_initcall(ptdump_init);