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b886d83c | 1 | // SPDX-License-Identifier: GPL-2.0-only |
8eb07b18 RG |
2 | /* |
3 | * Copyright 2016, Rashmica Gupta, IBM Corp. | |
4 | * | |
5 | * This traverses the kernel pagetables and dumps the | |
6 | * information about the used sections of memory to | |
7 | * /sys/kernel/debug/kernel_pagetables. | |
8 | * | |
9 | * Derived from the arm64 implementation: | |
10 | * Copyright (c) 2014, The Linux Foundation, Laura Abbott. | |
11 | * (C) Copyright 2008 Intel Corporation, Arjan van de Ven. | |
8eb07b18 RG |
12 | */ |
13 | #include <linux/debugfs.h> | |
14 | #include <linux/fs.h> | |
bfb9956a | 15 | #include <linux/hugetlb.h> |
8eb07b18 RG |
16 | #include <linux/io.h> |
17 | #include <linux/mm.h> | |
462951cd | 18 | #include <linux/highmem.h> |
e0847283 | 19 | #include <linux/ptdump.h> |
8eb07b18 RG |
20 | #include <linux/sched.h> |
21 | #include <linux/seq_file.h> | |
22 | #include <asm/fixmap.h> | |
8eb07b18 RG |
23 | #include <linux/const.h> |
24 | #include <asm/page.h> | |
6b789a26 | 25 | #include <asm/hugetlb.h> |
8eb07b18 | 26 | |
1e1c8b2c CL |
27 | #include <mm/mmu_decl.h> |
28 | ||
e66c3209 | 29 | #include "ptdump.h" |
97026b5a | 30 | |
8eb07b18 RG |
31 | /* |
32 | * To visualise what is happening, | |
33 | * | |
34 | * - PTRS_PER_P** = how many entries there are in the corresponding P** | |
35 | * - P**_SHIFT = how many bits of the address we use to index into the | |
36 | * corresponding P** | |
37 | * - P**_SIZE is how much memory we can access through the table - not the | |
38 | * size of the table itself. | |
39 | * P**={PGD, PUD, PMD, PTE} | |
40 | * | |
41 | * | |
42 | * Each entry of the PGD points to a PUD. Each entry of a PUD points to a | |
43 | * PMD. Each entry of a PMD points to a PTE. And every PTE entry points to | |
44 | * a page. | |
45 | * | |
46 | * In the case where there are only 3 levels, the PUD is folded into the | |
47 | * PGD: every PUD has only one entry which points to the PMD. | |
48 | * | |
49 | * The page dumper groups page table entries of the same type into a single | |
50 | * description. It uses pg_state to track the range information while | |
51 | * iterating over the PTE entries. When the continuity is broken it then | |
52 | * dumps out a description of the range - ie PTEs that are virtually contiguous | |
53 | * with the same PTE flags are chunked together. This is to make it clear how | |
54 | * different areas of the kernel virtual memory are used. | |
55 | * | |
56 | */ | |
57 | struct pg_state { | |
e0847283 | 58 | struct ptdump_state ptdump; |
8eb07b18 RG |
59 | struct seq_file *seq; |
60 | const struct addr_marker *marker; | |
61 | unsigned long start_address; | |
aaa22952 | 62 | unsigned long start_pa; |
cf98d2b6 | 63 | int level; |
8eb07b18 | 64 | u64 current_flags; |
453d87f6 RC |
65 | bool check_wx; |
66 | unsigned long wx_pages; | |
8eb07b18 RG |
67 | }; |
68 | ||
69 | struct addr_marker { | |
70 | unsigned long start_address; | |
71 | const char *name; | |
72 | }; | |
73 | ||
74 | static struct addr_marker address_markers[] = { | |
75 | { 0, "Start of kernel VM" }, | |
6ca05532 CL |
76 | #ifdef MODULES_VADDR |
77 | { 0, "modules start" }, | |
78 | { 0, "modules end" }, | |
79 | #endif | |
8eb07b18 RG |
80 | { 0, "vmalloc() Area" }, |
81 | { 0, "vmalloc() End" }, | |
6c01bbd2 | 82 | #ifdef CONFIG_PPC64 |
8eb07b18 RG |
83 | { 0, "isa I/O start" }, |
84 | { 0, "isa I/O end" }, | |
85 | { 0, "phb I/O start" }, | |
86 | { 0, "phb I/O end" }, | |
87 | { 0, "I/O remap start" }, | |
88 | { 0, "I/O remap end" }, | |
89 | { 0, "vmemmap start" }, | |
6c01bbd2 CL |
90 | #else |
91 | { 0, "Early I/O remap start" }, | |
92 | { 0, "Early I/O remap end" }, | |
6c01bbd2 CL |
93 | #ifdef CONFIG_HIGHMEM |
94 | { 0, "Highmem PTEs start" }, | |
95 | { 0, "Highmem PTEs end" }, | |
96 | #endif | |
97 | { 0, "Fixmap start" }, | |
98 | { 0, "Fixmap end" }, | |
b4abe38f CL |
99 | #endif |
100 | #ifdef CONFIG_KASAN | |
101 | { 0, "kasan shadow mem start" }, | |
102 | { 0, "kasan shadow mem end" }, | |
6c01bbd2 | 103 | #endif |
8eb07b18 RG |
104 | { -1, NULL }, |
105 | }; | |
106 | ||
e0847283 CL |
107 | static struct ptdump_range ptdump_range[] __ro_after_init = { |
108 | {TASK_SIZE_MAX, ~0UL}, | |
109 | {0, 0} | |
110 | }; | |
111 | ||
5f18cbdb RC |
112 | #define pt_dump_seq_printf(m, fmt, args...) \ |
113 | ({ \ | |
114 | if (m) \ | |
115 | seq_printf(m, fmt, ##args); \ | |
116 | }) | |
117 | ||
118 | #define pt_dump_seq_putc(m, c) \ | |
119 | ({ \ | |
120 | if (m) \ | |
121 | seq_putc(m, c); \ | |
122 | }) | |
123 | ||
6b30830e CL |
124 | void pt_dump_size(struct seq_file *m, unsigned long size) |
125 | { | |
126 | static const char units[] = "KMGTPE"; | |
127 | const char *unit = units; | |
128 | ||
129 | /* Work out what appropriate unit to use */ | |
130 | while (!(size & 1023) && unit[1]) { | |
131 | size >>= 10; | |
132 | unit++; | |
133 | } | |
134 | pt_dump_seq_printf(m, "%9lu%c ", size, *unit); | |
135 | } | |
136 | ||
8eb07b18 RG |
137 | static void dump_flag_info(struct pg_state *st, const struct flag_info |
138 | *flag, u64 pte, int num) | |
139 | { | |
140 | unsigned int i; | |
141 | ||
142 | for (i = 0; i < num; i++, flag++) { | |
143 | const char *s = NULL; | |
144 | u64 val; | |
145 | ||
146 | /* flag not defined so don't check it */ | |
147 | if (flag->mask == 0) | |
148 | continue; | |
149 | /* Some 'flags' are actually values */ | |
150 | if (flag->is_val) { | |
151 | val = pte & flag->val; | |
152 | if (flag->shift) | |
153 | val = val >> flag->shift; | |
5f18cbdb | 154 | pt_dump_seq_printf(st->seq, " %s:%llx", flag->set, val); |
8eb07b18 RG |
155 | } else { |
156 | if ((pte & flag->mask) == flag->val) | |
157 | s = flag->set; | |
158 | else | |
159 | s = flag->clear; | |
160 | if (s) | |
5f18cbdb | 161 | pt_dump_seq_printf(st->seq, " %s", s); |
8eb07b18 RG |
162 | } |
163 | st->current_flags &= ~flag->mask; | |
164 | } | |
165 | if (st->current_flags != 0) | |
5f18cbdb | 166 | pt_dump_seq_printf(st->seq, " unknown flags:%llx", st->current_flags); |
8eb07b18 RG |
167 | } |
168 | ||
169 | static void dump_addr(struct pg_state *st, unsigned long addr) | |
170 | { | |
78a18dbf | 171 | #ifdef CONFIG_PPC64 |
cabe8138 | 172 | #define REG "0x%016lx" |
78a18dbf | 173 | #else |
cabe8138 | 174 | #define REG "0x%08lx" |
78a18dbf | 175 | #endif |
aaa22952 | 176 | |
5f18cbdb | 177 | pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1); |
6ca6512c CL |
178 | pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa); |
179 | pt_dump_size(st->seq, (addr - st->start_address) >> 10); | |
8eb07b18 RG |
180 | } |
181 | ||
453d87f6 RC |
182 | static void note_prot_wx(struct pg_state *st, unsigned long addr) |
183 | { | |
d80ae83f CL |
184 | pte_t pte = __pte(st->current_flags); |
185 | ||
f3a2ac05 | 186 | if (!IS_ENABLED(CONFIG_PPC_DEBUG_WX) || !st->check_wx) |
453d87f6 RC |
187 | return; |
188 | ||
d80ae83f | 189 | if (!pte_write(pte) || !pte_exec(pte)) |
453d87f6 RC |
190 | return; |
191 | ||
192 | WARN_ONCE(1, "powerpc/mm: Found insecure W+X mapping at address %p/%pS\n", | |
193 | (void *)st->start_address, (void *)st->start_address); | |
194 | ||
195 | st->wx_pages += (addr - st->start_address) / PAGE_SIZE; | |
196 | } | |
197 | ||
cf98d2b6 | 198 | static void note_page_update_state(struct pg_state *st, unsigned long addr, int level, u64 val) |
e54e30bc | 199 | { |
cf98d2b6 | 200 | u64 flag = level >= 0 ? val & pg_level[level].mask : 0; |
e54e30bc CL |
201 | u64 pa = val & PTE_RPN_MASK; |
202 | ||
203 | st->level = level; | |
204 | st->current_flags = flag; | |
205 | st->start_address = addr; | |
206 | st->start_pa = pa; | |
e54e30bc CL |
207 | |
208 | while (addr >= st->marker[1].start_address) { | |
209 | st->marker++; | |
210 | pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); | |
211 | } | |
212 | } | |
213 | ||
e0847283 | 214 | static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val) |
8eb07b18 | 215 | { |
cf98d2b6 | 216 | u64 flag = level >= 0 ? val & pg_level[level].mask : 0; |
e0847283 | 217 | struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); |
aaa22952 | 218 | |
8eb07b18 | 219 | /* At first no level is set */ |
cf98d2b6 | 220 | if (st->level == -1) { |
5f18cbdb | 221 | pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name); |
64b87b0c | 222 | note_page_update_state(st, addr, level, val); |
8eb07b18 RG |
223 | /* |
224 | * Dump the section of virtual memory when: | |
225 | * - the PTE flags from one entry to the next differs. | |
226 | * - we change levels in the tree. | |
227 | * - the address is in a different section of memory and is thus | |
228 | * used for a different purpose, regardless of the flags. | |
229 | */ | |
230 | } else if (flag != st->current_flags || level != st->level || | |
6ca6512c | 231 | addr >= st->marker[1].start_address) { |
8eb07b18 RG |
232 | |
233 | /* Check the PTE flags */ | |
234 | if (st->current_flags) { | |
453d87f6 | 235 | note_prot_wx(st, addr); |
8eb07b18 RG |
236 | dump_addr(st, addr); |
237 | ||
238 | /* Dump all the flags */ | |
239 | if (pg_level[st->level].flag) | |
240 | dump_flag_info(st, pg_level[st->level].flag, | |
241 | st->current_flags, | |
242 | pg_level[st->level].num); | |
243 | ||
5f18cbdb | 244 | pt_dump_seq_putc(st->seq, '\n'); |
8eb07b18 RG |
245 | } |
246 | ||
247 | /* | |
248 | * Address indicates we have passed the end of the | |
249 | * current section of virtual memory | |
250 | */ | |
64b87b0c | 251 | note_page_update_state(st, addr, level, val); |
8eb07b18 RG |
252 | } |
253 | } | |
254 | ||
8eb07b18 RG |
255 | static void populate_markers(void) |
256 | { | |
6c01bbd2 CL |
257 | int i = 0; |
258 | ||
b6be1bb7 | 259 | #ifdef CONFIG_PPC64 |
6c01bbd2 | 260 | address_markers[i++].start_address = PAGE_OFFSET; |
b6be1bb7 CL |
261 | #else |
262 | address_markers[i++].start_address = TASK_SIZE; | |
6ca05532 CL |
263 | #endif |
264 | #ifdef MODULES_VADDR | |
265 | address_markers[i++].start_address = MODULES_VADDR; | |
266 | address_markers[i++].start_address = MODULES_END; | |
b6be1bb7 | 267 | #endif |
6c01bbd2 CL |
268 | address_markers[i++].start_address = VMALLOC_START; |
269 | address_markers[i++].start_address = VMALLOC_END; | |
270 | #ifdef CONFIG_PPC64 | |
271 | address_markers[i++].start_address = ISA_IO_BASE; | |
272 | address_markers[i++].start_address = ISA_IO_END; | |
273 | address_markers[i++].start_address = PHB_IO_BASE; | |
274 | address_markers[i++].start_address = PHB_IO_END; | |
275 | address_markers[i++].start_address = IOREMAP_BASE; | |
276 | address_markers[i++].start_address = IOREMAP_END; | |
0034d395 | 277 | /* What is the ifdef about? */ |
4e003747 | 278 | #ifdef CONFIG_PPC_BOOK3S_64 |
0034d395 | 279 | address_markers[i++].start_address = H_VMEMMAP_START; |
8eb07b18 | 280 | #else |
6c01bbd2 CL |
281 | address_markers[i++].start_address = VMEMMAP_BASE; |
282 | #endif | |
283 | #else /* !CONFIG_PPC64 */ | |
284 | address_markers[i++].start_address = ioremap_bot; | |
285 | address_markers[i++].start_address = IOREMAP_TOP; | |
6c01bbd2 CL |
286 | #ifdef CONFIG_HIGHMEM |
287 | address_markers[i++].start_address = PKMAP_BASE; | |
288 | address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP); | |
8eb07b18 | 289 | #endif |
6c01bbd2 CL |
290 | address_markers[i++].start_address = FIXADDR_START; |
291 | address_markers[i++].start_address = FIXADDR_TOP; | |
b4abe38f CL |
292 | #ifdef CONFIG_KASAN |
293 | address_markers[i++].start_address = KASAN_SHADOW_START; | |
294 | address_markers[i++].start_address = KASAN_SHADOW_END; | |
295 | #endif | |
6c01bbd2 | 296 | #endif /* CONFIG_PPC64 */ |
8eb07b18 RG |
297 | } |
298 | ||
299 | static int ptdump_show(struct seq_file *m, void *v) | |
300 | { | |
301 | struct pg_state st = { | |
302 | .seq = m, | |
8eb07b18 | 303 | .marker = address_markers, |
cf98d2b6 | 304 | .level = -1, |
e0847283 CL |
305 | .ptdump = { |
306 | .note_page = note_page, | |
307 | .range = ptdump_range, | |
308 | } | |
8eb07b18 | 309 | }; |
0d923962 | 310 | |
8eb07b18 | 311 | /* Traverse kernel page tables */ |
e0847283 | 312 | ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); |
8eb07b18 RG |
313 | return 0; |
314 | } | |
315 | ||
11f27a7f | 316 | DEFINE_SHOW_ATTRIBUTE(ptdump); |
8eb07b18 RG |
317 | |
318 | static void build_pgtable_complete_mask(void) | |
319 | { | |
320 | unsigned int i, j; | |
321 | ||
322 | for (i = 0; i < ARRAY_SIZE(pg_level); i++) | |
323 | if (pg_level[i].flag) | |
324 | for (j = 0; j < pg_level[i].num; j++) | |
325 | pg_level[i].mask |= pg_level[i].flag[j].mask; | |
326 | } | |
327 | ||
e0847283 | 328 | #ifdef CONFIG_DEBUG_WX |
453d87f6 RC |
329 | void ptdump_check_wx(void) |
330 | { | |
331 | struct pg_state st = { | |
332 | .seq = NULL, | |
e0847283 CL |
333 | .marker = (struct addr_marker[]) { |
334 | { 0, NULL}, | |
335 | { -1, NULL}, | |
336 | }, | |
cf98d2b6 | 337 | .level = -1, |
453d87f6 | 338 | .check_wx = true, |
e0847283 CL |
339 | .ptdump = { |
340 | .note_page = note_page, | |
341 | .range = ptdump_range, | |
342 | } | |
453d87f6 RC |
343 | }; |
344 | ||
e0847283 | 345 | ptdump_walk_pgd(&st.ptdump, &init_mm, NULL); |
453d87f6 RC |
346 | |
347 | if (st.wx_pages) | |
348 | pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", | |
349 | st.wx_pages); | |
350 | else | |
351 | pr_info("Checked W+X mappings: passed, no W+X pages found\n"); | |
352 | } | |
353 | #endif | |
354 | ||
e0847283 | 355 | static int __init ptdump_init(void) |
8eb07b18 | 356 | { |
e0847283 CL |
357 | #ifdef CONFIG_PPC64 |
358 | if (!radix_enabled()) | |
359 | ptdump_range[0].start = KERN_VIRT_START; | |
360 | else | |
361 | ptdump_range[0].start = PAGE_OFFSET; | |
362 | #endif | |
363 | ||
8eb07b18 RG |
364 | populate_markers(); |
365 | build_pgtable_complete_mask(); | |
e0847283 CL |
366 | |
367 | if (IS_ENABLED(CONFIG_PTDUMP_DEBUGFS)) | |
368 | debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops); | |
369 | ||
f3c05201 | 370 | return 0; |
8eb07b18 RG |
371 | } |
372 | device_initcall(ptdump_init); |