1 // SPDX-License-Identifier: GPL-2.0-only
3 * Debug helper to dump the current kernel pagetables of the system
4 * so that we can see what the various memory ranges are set to.
6 * (C) Copyright 2008 Intel Corporation
8 * Author: Arjan van de Ven <arjan@linux.intel.com>
11 #include <linux/debugfs.h>
12 #include <linux/kasan.h>
14 #include <linux/init.h>
15 #include <linux/sched.h>
16 #include <linux/seq_file.h>
17 #include <linux/highmem.h>
18 #include <linux/pci.h>
19 #include <linux/ptdump.h>
21 #include <asm/e820/types.h>
24 * The dumper groups pagetable entries of the same type into one, and for
25 * that it needs to keep some state when walking, and flush this state
26 * when a "break" in the continuity is found.
29 struct ptdump_state ptdump;
31 pgprotval_t current_prot;
32 pgprotval_t effective_prot;
33 pgprotval_t prot_levels[5];
34 unsigned long start_address;
35 const struct addr_marker *marker;
39 unsigned long wx_pages;
44 unsigned long start_address;
46 unsigned long max_lines;
49 /* Address space markers hints */
53 enum address_markers_idx {
56 #ifdef CONFIG_MODIFY_LDT_SYSCALL
63 KASAN_SHADOW_START_NR,
67 #ifdef CONFIG_X86_ESPFIX64
80 static struct addr_marker address_markers[] = {
81 [USER_SPACE_NR] = { 0, "User Space" },
82 [KERNEL_SPACE_NR] = { (1UL << 63), "Kernel Space" },
83 [LOW_KERNEL_NR] = { 0UL, "Low Kernel Mapping" },
84 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
85 [VMEMMAP_START_NR] = { 0UL, "Vmemmap" },
88 * These fields get initialized with the (dynamic)
89 * KASAN_SHADOW_{START,END} values in pt_dump_init().
91 [KASAN_SHADOW_START_NR] = { 0UL, "KASAN shadow" },
92 [KASAN_SHADOW_END_NR] = { 0UL, "KASAN shadow end" },
94 #ifdef CONFIG_MODIFY_LDT_SYSCALL
95 [LDT_NR] = { 0UL, "LDT remap" },
97 [CPU_ENTRY_AREA_NR] = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
98 #ifdef CONFIG_X86_ESPFIX64
99 [ESPFIX_START_NR] = { ESPFIX_BASE_ADDR, "ESPfix Area", 16 },
102 [EFI_END_NR] = { EFI_VA_END, "EFI Runtime Services" },
104 [HIGH_KERNEL_NR] = { __START_KERNEL_map, "High Kernel Mapping" },
105 [MODULES_VADDR_NR] = { MODULES_VADDR, "Modules" },
106 [MODULES_END_NR] = { MODULES_END, "End Modules" },
107 [FIXADDR_START_NR] = { FIXADDR_START, "Fixmap Area" },
108 [END_OF_SPACE_NR] = { -1, NULL }
111 #define INIT_PGD ((pgd_t *) &init_top_pgt)
113 #else /* CONFIG_X86_64 */
115 enum address_markers_idx {
120 #ifdef CONFIG_HIGHMEM
123 #ifdef CONFIG_MODIFY_LDT_SYSCALL
131 static struct addr_marker address_markers[] = {
132 [USER_SPACE_NR] = { 0, "User Space" },
133 [KERNEL_SPACE_NR] = { PAGE_OFFSET, "Kernel Mapping" },
134 [VMALLOC_START_NR] = { 0UL, "vmalloc() Area" },
135 [VMALLOC_END_NR] = { 0UL, "vmalloc() End" },
136 #ifdef CONFIG_HIGHMEM
137 [PKMAP_BASE_NR] = { 0UL, "Persistent kmap() Area" },
139 #ifdef CONFIG_MODIFY_LDT_SYSCALL
140 [LDT_NR] = { 0UL, "LDT remap" },
142 [CPU_ENTRY_AREA_NR] = { 0UL, "CPU entry area" },
143 [FIXADDR_START_NR] = { 0UL, "Fixmap area" },
144 [END_OF_SPACE_NR] = { -1, NULL }
147 #define INIT_PGD (swapper_pg_dir)
149 #endif /* !CONFIG_X86_64 */
151 /* Multipliers for offsets within the PTEs */
152 #define PTE_LEVEL_MULT (PAGE_SIZE)
153 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
154 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
155 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
156 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
158 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...) \
161 printk(KERN_INFO fmt, ##args); \
164 seq_printf(m, fmt, ##args); \
167 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...) \
170 printk(KERN_CONT fmt, ##args); \
173 seq_printf(m, fmt, ##args); \
177 * Print a readable form of a pgprot_t to the seq_file
179 static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
181 static const char * const level_name[] =
182 { "pgd", "p4d", "pud", "pmd", "pte" };
184 if (!(pr & _PAGE_PRESENT)) {
186 pt_dump_cont_printf(m, dmsg, " ");
189 pt_dump_cont_printf(m, dmsg, "USR ");
191 pt_dump_cont_printf(m, dmsg, " ");
193 pt_dump_cont_printf(m, dmsg, "RW ");
195 pt_dump_cont_printf(m, dmsg, "ro ");
197 pt_dump_cont_printf(m, dmsg, "PWT ");
199 pt_dump_cont_printf(m, dmsg, " ");
201 pt_dump_cont_printf(m, dmsg, "PCD ");
203 pt_dump_cont_printf(m, dmsg, " ");
205 /* Bit 7 has a different meaning on level 3 vs 4 */
206 if (level <= 3 && pr & _PAGE_PSE)
207 pt_dump_cont_printf(m, dmsg, "PSE ");
209 pt_dump_cont_printf(m, dmsg, " ");
210 if ((level == 4 && pr & _PAGE_PAT) ||
211 ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
212 pt_dump_cont_printf(m, dmsg, "PAT ");
214 pt_dump_cont_printf(m, dmsg, " ");
215 if (pr & _PAGE_GLOBAL)
216 pt_dump_cont_printf(m, dmsg, "GLB ");
218 pt_dump_cont_printf(m, dmsg, " ");
220 pt_dump_cont_printf(m, dmsg, "NX ");
222 pt_dump_cont_printf(m, dmsg, "x ");
224 pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
227 static void note_wx(struct pg_state *st, unsigned long addr)
229 unsigned long npages;
231 npages = (addr - st->start_address) / PAGE_SIZE;
233 #ifdef CONFIG_PCI_BIOS
235 * If PCI BIOS is enabled, the PCI BIOS area is forced to WX.
236 * Inform about it, but avoid the warning.
238 if (pcibios_enabled && st->start_address >= PAGE_OFFSET + BIOS_BEGIN &&
239 addr <= PAGE_OFFSET + BIOS_END) {
240 pr_warn_once("x86/mm: PCI BIOS W+X mapping %lu pages\n", npages);
244 /* Account the WX pages */
245 st->wx_pages += npages;
246 WARN_ONCE(__supported_pte_mask & _PAGE_NX,
247 "x86/mm: Found insecure W+X mapping at address %pS\n",
248 (void *)st->start_address);
251 static void effective_prot(struct ptdump_state *pt_st, int level, u64 val)
253 struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
254 pgprotval_t prot = val & PTE_FLAGS_MASK;
255 pgprotval_t effective;
258 pgprotval_t higher_prot = st->prot_levels[level - 1];
260 effective = (higher_prot & prot & (_PAGE_USER | _PAGE_RW)) |
261 ((higher_prot | prot) & _PAGE_NX);
266 st->prot_levels[level] = effective;
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 ptdump_state *pt_st, unsigned long addr, int level,
277 struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
278 pgprotval_t new_prot, new_eff;
279 pgprotval_t cur, eff;
280 static const char units[] = "BKMGTPE";
281 struct seq_file *m = st->seq;
283 new_prot = val & PTE_FLAGS_MASK;
287 new_eff = st->prot_levels[level];
290 * If we have a "break" in the series, we need to flush the state that
291 * we have now. "break" is either changing perms, levels or
292 * address space marker.
294 cur = st->current_prot;
295 eff = st->effective_prot;
297 if (st->level == -1) {
299 st->current_prot = new_prot;
300 st->effective_prot = new_eff;
302 st->marker = address_markers;
304 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
306 } else if (new_prot != cur || new_eff != eff || level != st->level ||
307 addr >= st->marker[1].start_address) {
308 const char *unit = units;
310 int width = sizeof(unsigned long) * 2;
312 if (st->check_wx && (eff & _PAGE_RW) && !(eff & _PAGE_NX))
316 * Now print the actual finished series
318 if (!st->marker->max_lines ||
319 st->lines < st->marker->max_lines) {
320 pt_dump_seq_printf(m, st->to_dmesg,
322 width, st->start_address,
325 delta = addr - st->start_address;
326 while (!(delta & 1023) && unit[1]) {
330 pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
332 printk_prot(m, st->current_prot, st->level,
338 * We print markers for special areas of address space,
339 * such as the start of vmalloc space etc.
340 * This helps in the interpretation.
342 if (addr >= st->marker[1].start_address) {
343 if (st->marker->max_lines &&
344 st->lines > st->marker->max_lines) {
345 unsigned long nskip =
346 st->lines - st->marker->max_lines;
347 pt_dump_seq_printf(m, st->to_dmesg,
348 "... %lu entr%s skipped ... \n",
350 nskip == 1 ? "y" : "ies");
354 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
358 st->start_address = addr;
359 st->current_prot = new_prot;
360 st->effective_prot = new_eff;
365 static void ptdump_walk_pgd_level_core(struct seq_file *m,
366 struct mm_struct *mm, pgd_t *pgd,
367 bool checkwx, bool dmesg)
369 const struct ptdump_range ptdump_ranges[] = {
371 {0, PTRS_PER_PGD * PGD_LEVEL_MULT / 2},
372 {GUARD_HOLE_END_ADDR, ~0UL},
379 struct pg_state st = {
381 .note_page = note_page,
382 .effective_prot = effective_prot,
383 .range = ptdump_ranges
391 ptdump_walk_pgd(&st.ptdump, mm, pgd);
396 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
399 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
402 void ptdump_walk_pgd_level(struct seq_file *m, struct mm_struct *mm)
404 ptdump_walk_pgd_level_core(m, mm, mm->pgd, false, true);
407 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, struct mm_struct *mm,
410 pgd_t *pgd = mm->pgd;
411 #ifdef CONFIG_PAGE_TABLE_ISOLATION
412 if (user && boot_cpu_has(X86_FEATURE_PTI))
413 pgd = kernel_to_user_pgdp(pgd);
415 ptdump_walk_pgd_level_core(m, mm, pgd, false, false);
417 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
419 void ptdump_walk_user_pgd_level_checkwx(void)
421 #ifdef CONFIG_PAGE_TABLE_ISOLATION
422 pgd_t *pgd = INIT_PGD;
424 if (!(__supported_pte_mask & _PAGE_NX) ||
425 !boot_cpu_has(X86_FEATURE_PTI))
428 pr_info("x86/mm: Checking user space page tables\n");
429 pgd = kernel_to_user_pgdp(pgd);
430 ptdump_walk_pgd_level_core(NULL, &init_mm, pgd, true, false);
434 void ptdump_walk_pgd_level_checkwx(void)
436 ptdump_walk_pgd_level_core(NULL, &init_mm, INIT_PGD, true, false);
439 static int __init pt_dump_init(void)
442 * Various markers are not compile-time constants, so assign them
446 address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
447 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
448 address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
449 #ifdef CONFIG_MODIFY_LDT_SYSCALL
450 address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
453 address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
454 address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
458 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
459 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
460 # ifdef CONFIG_HIGHMEM
461 address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
463 address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
464 address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
465 # ifdef CONFIG_MODIFY_LDT_SYSCALL
466 address_markers[LDT_NR].start_address = LDT_BASE_ADDR;
471 __initcall(pt_dump_init);