Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[muen/linux.git] / arch / x86 / mm / dump_pagetables.c
1 /*
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.
4  *
5  * (C) Copyright 2008 Intel Corporation
6  *
7  * Author: Arjan van de Ven <arjan@linux.intel.com>
8  *
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
12  * of the License.
13  */
14
15 #include <linux/debugfs.h>
16 #include <linux/kasan.h>
17 #include <linux/mm.h>
18 #include <linux/init.h>
19 #include <linux/sched.h>
20 #include <linux/seq_file.h>
21
22 #include <asm/pgtable.h>
23
24 /*
25  * The dumper groups pagetable entries of the same type into one, and for
26  * that it needs to keep some state when walking, and flush this state
27  * when a "break" in the continuity is found.
28  */
29 struct pg_state {
30         int level;
31         pgprot_t current_prot;
32         unsigned long start_address;
33         unsigned long current_address;
34         const struct addr_marker *marker;
35         unsigned long lines;
36         bool to_dmesg;
37         bool check_wx;
38         unsigned long wx_pages;
39 };
40
41 struct addr_marker {
42         unsigned long start_address;
43         const char *name;
44         unsigned long max_lines;
45 };
46
47 /* Address space markers hints */
48
49 #ifdef CONFIG_X86_64
50
51 enum address_markers_idx {
52         USER_SPACE_NR = 0,
53         KERNEL_SPACE_NR,
54         LOW_KERNEL_NR,
55 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && defined(CONFIG_X86_5LEVEL)
56         LDT_NR,
57 #endif
58         VMALLOC_START_NR,
59         VMEMMAP_START_NR,
60 #ifdef CONFIG_KASAN
61         KASAN_SHADOW_START_NR,
62         KASAN_SHADOW_END_NR,
63 #endif
64 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && !defined(CONFIG_X86_5LEVEL)
65         LDT_NR,
66 #endif
67         CPU_ENTRY_AREA_NR,
68 #ifdef CONFIG_X86_ESPFIX64
69         ESPFIX_START_NR,
70 #endif
71 #ifdef CONFIG_EFI
72         EFI_END_NR,
73 #endif
74         HIGH_KERNEL_NR,
75         MODULES_VADDR_NR,
76         MODULES_END_NR,
77         FIXADDR_START_NR,
78         END_OF_SPACE_NR,
79 };
80
81 static struct addr_marker address_markers[] = {
82         [USER_SPACE_NR]         = { 0,                  "User Space" },
83         [KERNEL_SPACE_NR]       = { (1UL << 63),        "Kernel Space" },
84         [LOW_KERNEL_NR]         = { 0UL,                "Low Kernel Mapping" },
85         [VMALLOC_START_NR]      = { 0UL,                "vmalloc() Area" },
86         [VMEMMAP_START_NR]      = { 0UL,                "Vmemmap" },
87 #ifdef CONFIG_KASAN
88         [KASAN_SHADOW_START_NR] = { KASAN_SHADOW_START, "KASAN shadow" },
89         [KASAN_SHADOW_END_NR]   = { KASAN_SHADOW_END,   "KASAN shadow end" },
90 #endif
91 #ifdef CONFIG_MODIFY_LDT_SYSCALL
92         [LDT_NR]                = { LDT_BASE_ADDR,      "LDT remap" },
93 #endif
94         [CPU_ENTRY_AREA_NR]     = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
95 #ifdef CONFIG_X86_ESPFIX64
96         [ESPFIX_START_NR]       = { ESPFIX_BASE_ADDR,   "ESPfix Area", 16 },
97 #endif
98 #ifdef CONFIG_EFI
99         [EFI_END_NR]            = { EFI_VA_END,         "EFI Runtime Services" },
100 #endif
101         [HIGH_KERNEL_NR]        = { __START_KERNEL_map, "High Kernel Mapping" },
102         [MODULES_VADDR_NR]      = { MODULES_VADDR,      "Modules" },
103         [MODULES_END_NR]        = { MODULES_END,        "End Modules" },
104         [FIXADDR_START_NR]      = { FIXADDR_START,      "Fixmap Area" },
105         [END_OF_SPACE_NR]       = { -1,                 NULL }
106 };
107
108 #else /* CONFIG_X86_64 */
109
110 enum address_markers_idx {
111         USER_SPACE_NR = 0,
112         KERNEL_SPACE_NR,
113         VMALLOC_START_NR,
114         VMALLOC_END_NR,
115 #ifdef CONFIG_HIGHMEM
116         PKMAP_BASE_NR,
117 #endif
118         CPU_ENTRY_AREA_NR,
119         FIXADDR_START_NR,
120         END_OF_SPACE_NR,
121 };
122
123 static struct addr_marker address_markers[] = {
124         [USER_SPACE_NR]         = { 0,                  "User Space" },
125         [KERNEL_SPACE_NR]       = { PAGE_OFFSET,        "Kernel Mapping" },
126         [VMALLOC_START_NR]      = { 0UL,                "vmalloc() Area" },
127         [VMALLOC_END_NR]        = { 0UL,                "vmalloc() End" },
128 #ifdef CONFIG_HIGHMEM
129         [PKMAP_BASE_NR]         = { 0UL,                "Persistent kmap() Area" },
130 #endif
131         [CPU_ENTRY_AREA_NR]     = { 0UL,                "CPU entry area" },
132         [FIXADDR_START_NR]      = { 0UL,                "Fixmap area" },
133         [END_OF_SPACE_NR]       = { -1,                 NULL }
134 };
135
136 #endif /* !CONFIG_X86_64 */
137
138 /* Multipliers for offsets within the PTEs */
139 #define PTE_LEVEL_MULT (PAGE_SIZE)
140 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
141 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
142 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
143 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
144
145 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...)           \
146 ({                                                              \
147         if (to_dmesg)                                   \
148                 printk(KERN_INFO fmt, ##args);                  \
149         else                                                    \
150                 if (m)                                          \
151                         seq_printf(m, fmt, ##args);             \
152 })
153
154 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...)          \
155 ({                                                              \
156         if (to_dmesg)                                   \
157                 printk(KERN_CONT fmt, ##args);                  \
158         else                                                    \
159                 if (m)                                          \
160                         seq_printf(m, fmt, ##args);             \
161 })
162
163 /*
164  * Print a readable form of a pgprot_t to the seq_file
165  */
166 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
167 {
168         pgprotval_t pr = pgprot_val(prot);
169         static const char * const level_name[] =
170                 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
171
172         if (!(pr & _PAGE_PRESENT)) {
173                 /* Not present */
174                 pt_dump_cont_printf(m, dmsg, "                              ");
175         } else {
176                 if (pr & _PAGE_USER)
177                         pt_dump_cont_printf(m, dmsg, "USR ");
178                 else
179                         pt_dump_cont_printf(m, dmsg, "    ");
180                 if (pr & _PAGE_RW)
181                         pt_dump_cont_printf(m, dmsg, "RW ");
182                 else
183                         pt_dump_cont_printf(m, dmsg, "ro ");
184                 if (pr & _PAGE_PWT)
185                         pt_dump_cont_printf(m, dmsg, "PWT ");
186                 else
187                         pt_dump_cont_printf(m, dmsg, "    ");
188                 if (pr & _PAGE_PCD)
189                         pt_dump_cont_printf(m, dmsg, "PCD ");
190                 else
191                         pt_dump_cont_printf(m, dmsg, "    ");
192
193                 /* Bit 7 has a different meaning on level 3 vs 4 */
194                 if (level <= 4 && pr & _PAGE_PSE)
195                         pt_dump_cont_printf(m, dmsg, "PSE ");
196                 else
197                         pt_dump_cont_printf(m, dmsg, "    ");
198                 if ((level == 5 && pr & _PAGE_PAT) ||
199                     ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
200                         pt_dump_cont_printf(m, dmsg, "PAT ");
201                 else
202                         pt_dump_cont_printf(m, dmsg, "    ");
203                 if (pr & _PAGE_GLOBAL)
204                         pt_dump_cont_printf(m, dmsg, "GLB ");
205                 else
206                         pt_dump_cont_printf(m, dmsg, "    ");
207                 if (pr & _PAGE_NX)
208                         pt_dump_cont_printf(m, dmsg, "NX ");
209                 else
210                         pt_dump_cont_printf(m, dmsg, "x  ");
211         }
212         pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
213 }
214
215 /*
216  * On 64 bits, sign-extend the 48 bit address to 64 bit
217  */
218 static unsigned long normalize_addr(unsigned long u)
219 {
220         int shift;
221         if (!IS_ENABLED(CONFIG_X86_64))
222                 return u;
223
224         shift = 64 - (__VIRTUAL_MASK_SHIFT + 1);
225         return (signed long)(u << shift) >> shift;
226 }
227
228 /*
229  * This function gets called on a break in a continuous series
230  * of PTE entries; the next one is different so we need to
231  * print what we collected so far.
232  */
233 static void note_page(struct seq_file *m, struct pg_state *st,
234                       pgprot_t new_prot, int level)
235 {
236         pgprotval_t prot, cur;
237         static const char units[] = "BKMGTPE";
238
239         /*
240          * If we have a "break" in the series, we need to flush the state that
241          * we have now. "break" is either changing perms, levels or
242          * address space marker.
243          */
244         prot = pgprot_val(new_prot);
245         cur = pgprot_val(st->current_prot);
246
247         if (!st->level) {
248                 /* First entry */
249                 st->current_prot = new_prot;
250                 st->level = level;
251                 st->marker = address_markers;
252                 st->lines = 0;
253                 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
254                                    st->marker->name);
255         } else if (prot != cur || level != st->level ||
256                    st->current_address >= st->marker[1].start_address) {
257                 const char *unit = units;
258                 unsigned long delta;
259                 int width = sizeof(unsigned long) * 2;
260                 pgprotval_t pr = pgprot_val(st->current_prot);
261
262                 if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) {
263                         WARN_ONCE(1,
264                                   "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
265                                   (void *)st->start_address,
266                                   (void *)st->start_address);
267                         st->wx_pages += (st->current_address -
268                                          st->start_address) / PAGE_SIZE;
269                 }
270
271                 /*
272                  * Now print the actual finished series
273                  */
274                 if (!st->marker->max_lines ||
275                     st->lines < st->marker->max_lines) {
276                         pt_dump_seq_printf(m, st->to_dmesg,
277                                            "0x%0*lx-0x%0*lx   ",
278                                            width, st->start_address,
279                                            width, st->current_address);
280
281                         delta = st->current_address - st->start_address;
282                         while (!(delta & 1023) && unit[1]) {
283                                 delta >>= 10;
284                                 unit++;
285                         }
286                         pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
287                                             delta, *unit);
288                         printk_prot(m, st->current_prot, st->level,
289                                     st->to_dmesg);
290                 }
291                 st->lines++;
292
293                 /*
294                  * We print markers for special areas of address space,
295                  * such as the start of vmalloc space etc.
296                  * This helps in the interpretation.
297                  */
298                 if (st->current_address >= st->marker[1].start_address) {
299                         if (st->marker->max_lines &&
300                             st->lines > st->marker->max_lines) {
301                                 unsigned long nskip =
302                                         st->lines - st->marker->max_lines;
303                                 pt_dump_seq_printf(m, st->to_dmesg,
304                                                    "... %lu entr%s skipped ... \n",
305                                                    nskip,
306                                                    nskip == 1 ? "y" : "ies");
307                         }
308                         st->marker++;
309                         st->lines = 0;
310                         pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
311                                            st->marker->name);
312                 }
313
314                 st->start_address = st->current_address;
315                 st->current_prot = new_prot;
316                 st->level = level;
317         }
318 }
319
320 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, unsigned long P)
321 {
322         int i;
323         pte_t *start;
324         pgprotval_t prot;
325
326         start = (pte_t *)pmd_page_vaddr(addr);
327         for (i = 0; i < PTRS_PER_PTE; i++) {
328                 prot = pte_flags(*start);
329                 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
330                 note_page(m, st, __pgprot(prot), 5);
331                 start++;
332         }
333 }
334 #ifdef CONFIG_KASAN
335
336 /*
337  * This is an optimization for KASAN=y case. Since all kasan page tables
338  * eventually point to the kasan_zero_page we could call note_page()
339  * right away without walking through lower level page tables. This saves
340  * us dozens of seconds (minutes for 5-level config) while checking for
341  * W+X mapping or reading kernel_page_tables debugfs file.
342  */
343 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
344                                 void *pt)
345 {
346         if (__pa(pt) == __pa(kasan_zero_pmd) ||
347 #ifdef CONFIG_X86_5LEVEL
348             __pa(pt) == __pa(kasan_zero_p4d) ||
349 #endif
350             __pa(pt) == __pa(kasan_zero_pud)) {
351                 pgprotval_t prot = pte_flags(kasan_zero_pte[0]);
352                 note_page(m, st, __pgprot(prot), 5);
353                 return true;
354         }
355         return false;
356 }
357 #else
358 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
359                                 void *pt)
360 {
361         return false;
362 }
363 #endif
364
365 #if PTRS_PER_PMD > 1
366
367 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, unsigned long P)
368 {
369         int i;
370         pmd_t *start, *pmd_start;
371         pgprotval_t prot;
372
373         pmd_start = start = (pmd_t *)pud_page_vaddr(addr);
374         for (i = 0; i < PTRS_PER_PMD; i++) {
375                 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
376                 if (!pmd_none(*start)) {
377                         if (pmd_large(*start) || !pmd_present(*start)) {
378                                 prot = pmd_flags(*start);
379                                 note_page(m, st, __pgprot(prot), 4);
380                         } else if (!kasan_page_table(m, st, pmd_start)) {
381                                 walk_pte_level(m, st, *start,
382                                                P + i * PMD_LEVEL_MULT);
383                         }
384                 } else
385                         note_page(m, st, __pgprot(0), 4);
386                 start++;
387         }
388 }
389
390 #else
391 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
392 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
393 #define pud_none(a)  pmd_none(__pmd(pud_val(a)))
394 #endif
395
396 #if PTRS_PER_PUD > 1
397
398 static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P)
399 {
400         int i;
401         pud_t *start, *pud_start;
402         pgprotval_t prot;
403         pud_t *prev_pud = NULL;
404
405         pud_start = start = (pud_t *)p4d_page_vaddr(addr);
406
407         for (i = 0; i < PTRS_PER_PUD; i++) {
408                 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
409                 if (!pud_none(*start)) {
410                         if (pud_large(*start) || !pud_present(*start)) {
411                                 prot = pud_flags(*start);
412                                 note_page(m, st, __pgprot(prot), 3);
413                         } else if (!kasan_page_table(m, st, pud_start)) {
414                                 walk_pmd_level(m, st, *start,
415                                                P + i * PUD_LEVEL_MULT);
416                         }
417                 } else
418                         note_page(m, st, __pgprot(0), 3);
419
420                 prev_pud = start;
421                 start++;
422         }
423 }
424
425 #else
426 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p)
427 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
428 #define p4d_none(a)  pud_none(__pud(p4d_val(a)))
429 #endif
430
431 #if PTRS_PER_P4D > 1
432
433 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P)
434 {
435         int i;
436         p4d_t *start, *p4d_start;
437         pgprotval_t prot;
438
439         p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
440
441         for (i = 0; i < PTRS_PER_P4D; i++) {
442                 st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
443                 if (!p4d_none(*start)) {
444                         if (p4d_large(*start) || !p4d_present(*start)) {
445                                 prot = p4d_flags(*start);
446                                 note_page(m, st, __pgprot(prot), 2);
447                         } else if (!kasan_page_table(m, st, p4d_start)) {
448                                 walk_pud_level(m, st, *start,
449                                                P + i * P4D_LEVEL_MULT);
450                         }
451                 } else
452                         note_page(m, st, __pgprot(0), 2);
453
454                 start++;
455         }
456 }
457
458 #else
459 #define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p)
460 #define pgd_large(a) p4d_large(__p4d(pgd_val(a)))
461 #define pgd_none(a)  p4d_none(__p4d(pgd_val(a)))
462 #endif
463
464 static inline bool is_hypervisor_range(int idx)
465 {
466 #ifdef CONFIG_X86_64
467         /*
468          * ffff800000000000 - ffff87ffffffffff is reserved for
469          * the hypervisor.
470          */
471         return  (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
472                 (idx <  pgd_index(__PAGE_OFFSET));
473 #else
474         return false;
475 #endif
476 }
477
478 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
479                                        bool checkwx, bool dmesg)
480 {
481 #ifdef CONFIG_X86_64
482         pgd_t *start = (pgd_t *) &init_top_pgt;
483 #else
484         pgd_t *start = swapper_pg_dir;
485 #endif
486         pgprotval_t prot;
487         int i;
488         struct pg_state st = {};
489
490         if (pgd) {
491                 start = pgd;
492                 st.to_dmesg = dmesg;
493         }
494
495         st.check_wx = checkwx;
496         if (checkwx)
497                 st.wx_pages = 0;
498
499         for (i = 0; i < PTRS_PER_PGD; i++) {
500                 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
501                 if (!pgd_none(*start) && !is_hypervisor_range(i)) {
502                         if (pgd_large(*start) || !pgd_present(*start)) {
503                                 prot = pgd_flags(*start);
504                                 note_page(m, &st, __pgprot(prot), 1);
505                         } else {
506                                 walk_p4d_level(m, &st, *start,
507                                                i * PGD_LEVEL_MULT);
508                         }
509                 } else
510                         note_page(m, &st, __pgprot(0), 1);
511
512                 cond_resched();
513                 start++;
514         }
515
516         /* Flush out the last page */
517         st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
518         note_page(m, &st, __pgprot(0), 0);
519         if (!checkwx)
520                 return;
521         if (st.wx_pages)
522                 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
523                         st.wx_pages);
524         else
525                 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
526 }
527
528 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
529 {
530         ptdump_walk_pgd_level_core(m, pgd, false, true);
531 }
532
533 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
534 {
535 #ifdef CONFIG_PAGE_TABLE_ISOLATION
536         if (user && static_cpu_has(X86_FEATURE_PTI))
537                 pgd = kernel_to_user_pgdp(pgd);
538 #endif
539         ptdump_walk_pgd_level_core(m, pgd, false, false);
540 }
541 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
542
543 static void ptdump_walk_user_pgd_level_checkwx(void)
544 {
545 #ifdef CONFIG_PAGE_TABLE_ISOLATION
546         pgd_t *pgd = (pgd_t *) &init_top_pgt;
547
548         if (!static_cpu_has(X86_FEATURE_PTI))
549                 return;
550
551         pr_info("x86/mm: Checking user space page tables\n");
552         pgd = kernel_to_user_pgdp(pgd);
553         ptdump_walk_pgd_level_core(NULL, pgd, true, false);
554 #endif
555 }
556
557 void ptdump_walk_pgd_level_checkwx(void)
558 {
559         ptdump_walk_pgd_level_core(NULL, NULL, true, false);
560         ptdump_walk_user_pgd_level_checkwx();
561 }
562
563 static int __init pt_dump_init(void)
564 {
565         /*
566          * Various markers are not compile-time constants, so assign them
567          * here.
568          */
569 #ifdef CONFIG_X86_64
570         address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
571         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
572         address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
573 #endif
574 #ifdef CONFIG_X86_32
575         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
576         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
577 # ifdef CONFIG_HIGHMEM
578         address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
579 # endif
580         address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
581         address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
582 #endif
583         return 0;
584 }
585 __initcall(pt_dump_init);