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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2019 SiFive
4 */
5
6#include <linux/efi.h>
7#include <linux/init.h>
8#include <linux/debugfs.h>
9#include <linux/seq_file.h>
10#include <linux/ptdump.h>
11
12#include <asm/ptdump.h>
13#include <linux/pgtable.h>
14#include <asm/kasan.h>
15
16#define pt_dump_seq_printf(m, fmt, args...) \
17({ \
18 if (m) \
19 seq_printf(m, fmt, ##args); \
20})
21
22#define pt_dump_seq_puts(m, fmt) \
23({ \
24 if (m) \
25 seq_printf(m, fmt); \
26})
27
28/*
29 * The page dumper groups page table entries of the same type into a single
30 * description. It uses pg_state to track the range information while
31 * iterating over the pte entries. When the continuity is broken it then
32 * dumps out a description of the range.
33 */
34struct pg_state {
35 struct ptdump_state ptdump;
36 struct seq_file *seq;
37 const struct addr_marker *marker;
38 unsigned long start_address;
39 unsigned long start_pa;
40 unsigned long last_pa;
41 int level;
42 u64 current_prot;
43 bool check_wx;
44 unsigned long wx_pages;
45};
46
47/* Address marker */
48struct addr_marker {
49 unsigned long start_address;
50 const char *name;
51};
52
53/* Private information for debugfs */
54struct ptd_mm_info {
55 struct mm_struct *mm;
56 const struct addr_marker *markers;
57 unsigned long base_addr;
58 unsigned long end;
59};
60
61enum address_markers_idx {
62#ifdef CONFIG_KASAN
63 KASAN_SHADOW_START_NR,
64 KASAN_SHADOW_END_NR,
65#endif
66 FIXMAP_START_NR,
67 FIXMAP_END_NR,
68 PCI_IO_START_NR,
69 PCI_IO_END_NR,
70#ifdef CONFIG_SPARSEMEM_VMEMMAP
71 VMEMMAP_START_NR,
72 VMEMMAP_END_NR,
73#endif
74 VMALLOC_START_NR,
75 VMALLOC_END_NR,
76 PAGE_OFFSET_NR,
77#ifdef CONFIG_64BIT
78 MODULES_MAPPING_NR,
79 KERNEL_MAPPING_NR,
80#endif
81 END_OF_SPACE_NR
82};
83
84static struct addr_marker address_markers[] = {
85#ifdef CONFIG_KASAN
86 {0, "Kasan shadow start"},
87 {0, "Kasan shadow end"},
88#endif
89 {0, "Fixmap start"},
90 {0, "Fixmap end"},
91 {0, "PCI I/O start"},
92 {0, "PCI I/O end"},
93#ifdef CONFIG_SPARSEMEM_VMEMMAP
94 {0, "vmemmap start"},
95 {0, "vmemmap end"},
96#endif
97 {0, "vmalloc() area"},
98 {0, "vmalloc() end"},
99 {0, "Linear mapping"},
100#ifdef CONFIG_64BIT
101 {0, "Modules/BPF mapping"},
102 {0, "Kernel mapping"},
103#endif
104 {-1, NULL},
105};
106
107static struct ptd_mm_info kernel_ptd_info = {
108 .mm = &init_mm,
109 .markers = address_markers,
110 .base_addr = 0,
111 .end = ULONG_MAX,
112};
113
114#ifdef CONFIG_EFI
115static struct addr_marker efi_addr_markers[] = {
116 { 0, "UEFI runtime start" },
117 { SZ_1G, "UEFI runtime end" },
118 { -1, NULL }
119};
120
121static struct ptd_mm_info efi_ptd_info = {
122 .mm = &efi_mm,
123 .markers = efi_addr_markers,
124 .base_addr = 0,
125 .end = SZ_2G,
126};
127#endif
128
129/* Page Table Entry */
130struct prot_bits {
131 u64 mask;
132 u64 val;
133 const char *set;
134 const char *clear;
135};
136
137static const struct prot_bits pte_bits[] = {
138 {
139 .mask = _PAGE_SOFT,
140 .val = _PAGE_SOFT,
141 .set = "RSW",
142 .clear = " ",
143 }, {
144 .mask = _PAGE_DIRTY,
145 .val = _PAGE_DIRTY,
146 .set = "D",
147 .clear = ".",
148 }, {
149 .mask = _PAGE_ACCESSED,
150 .val = _PAGE_ACCESSED,
151 .set = "A",
152 .clear = ".",
153 }, {
154 .mask = _PAGE_GLOBAL,
155 .val = _PAGE_GLOBAL,
156 .set = "G",
157 .clear = ".",
158 }, {
159 .mask = _PAGE_USER,
160 .val = _PAGE_USER,
161 .set = "U",
162 .clear = ".",
163 }, {
164 .mask = _PAGE_EXEC,
165 .val = _PAGE_EXEC,
166 .set = "X",
167 .clear = ".",
168 }, {
169 .mask = _PAGE_WRITE,
170 .val = _PAGE_WRITE,
171 .set = "W",
172 .clear = ".",
173 }, {
174 .mask = _PAGE_READ,
175 .val = _PAGE_READ,
176 .set = "R",
177 .clear = ".",
178 }, {
179 .mask = _PAGE_PRESENT,
180 .val = _PAGE_PRESENT,
181 .set = "V",
182 .clear = ".",
183 }
184};
185
186/* Page Level */
187struct pg_level {
188 const char *name;
189 u64 mask;
190};
191
192static struct pg_level pg_level[] = {
193 { /* pgd */
194 .name = "PGD",
195 }, { /* p4d */
196 .name = (CONFIG_PGTABLE_LEVELS > 4) ? "P4D" : "PGD",
197 }, { /* pud */
198 .name = (CONFIG_PGTABLE_LEVELS > 3) ? "PUD" : "PGD",
199 }, { /* pmd */
200 .name = (CONFIG_PGTABLE_LEVELS > 2) ? "PMD" : "PGD",
201 }, { /* pte */
202 .name = "PTE",
203 },
204};
205
206static void dump_prot(struct pg_state *st)
207{
208 unsigned int i;
209
210 for (i = 0; i < ARRAY_SIZE(pte_bits); i++) {
211 const char *s;
212
213 if ((st->current_prot & pte_bits[i].mask) == pte_bits[i].val)
214 s = pte_bits[i].set;
215 else
216 s = pte_bits[i].clear;
217
218 if (s)
219 pt_dump_seq_printf(st->seq, " %s", s);
220 }
221}
222
223#ifdef CONFIG_64BIT
224#define ADDR_FORMAT "0x%016lx"
225#else
226#define ADDR_FORMAT "0x%08lx"
227#endif
228static void dump_addr(struct pg_state *st, unsigned long addr)
229{
230 static const char units[] = "KMGTPE";
231 const char *unit = units;
232 unsigned long delta;
233
234 pt_dump_seq_printf(st->seq, ADDR_FORMAT "-" ADDR_FORMAT " ",
235 st->start_address, addr);
236
237 pt_dump_seq_printf(st->seq, " " ADDR_FORMAT " ", st->start_pa);
238 delta = (addr - st->start_address) >> 10;
239
240 while (!(delta & 1023) && unit[1]) {
241 delta >>= 10;
242 unit++;
243 }
244
245 pt_dump_seq_printf(st->seq, "%9lu%c %s", delta, *unit,
246 pg_level[st->level].name);
247}
248
249static void note_prot_wx(struct pg_state *st, unsigned long addr)
250{
251 if (!st->check_wx)
252 return;
253
254 if ((st->current_prot & (_PAGE_WRITE | _PAGE_EXEC)) !=
255 (_PAGE_WRITE | _PAGE_EXEC))
256 return;
257
258 WARN_ONCE(1, "riscv/mm: Found insecure W+X mapping at address %p/%pS\n",
259 (void *)st->start_address, (void *)st->start_address);
260
261 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
262}
263
264static void note_page(struct ptdump_state *pt_st, unsigned long addr,
265 int level, u64 val)
266{
267 struct pg_state *st = container_of(pt_st, struct pg_state, ptdump);
268 u64 pa = PFN_PHYS(pte_pfn(__pte(val)));
269 u64 prot = 0;
270
271 if (level >= 0)
272 prot = val & pg_level[level].mask;
273
274 if (st->level == -1) {
275 st->level = level;
276 st->current_prot = prot;
277 st->start_address = addr;
278 st->start_pa = pa;
279 st->last_pa = pa;
280 pt_dump_seq_printf(st->seq, "---[ %s ]---\n", st->marker->name);
281 } else if (prot != st->current_prot ||
282 level != st->level || addr >= st->marker[1].start_address) {
283 if (st->current_prot) {
284 note_prot_wx(st, addr);
285 dump_addr(st, addr);
286 dump_prot(st);
287 pt_dump_seq_puts(st->seq, "\n");
288 }
289
290 while (addr >= st->marker[1].start_address) {
291 st->marker++;
292 pt_dump_seq_printf(st->seq, "---[ %s ]---\n",
293 st->marker->name);
294 }
295
296 st->start_address = addr;
297 st->start_pa = pa;
298 st->last_pa = pa;
299 st->current_prot = prot;
300 st->level = level;
301 } else {
302 st->last_pa = pa;
303 }
304}
305
306static void ptdump_walk(struct seq_file *s, struct ptd_mm_info *pinfo)
307{
308 struct pg_state st = {
309 .seq = s,
310 .marker = pinfo->markers,
311 .level = -1,
312 .ptdump = {
313 .note_page = note_page,
314 .range = (struct ptdump_range[]) {
315 {pinfo->base_addr, pinfo->end},
316 {0, 0}
317 }
318 }
319 };
320
321 ptdump_walk_pgd(&st.ptdump, pinfo->mm, NULL);
322}
323
324void ptdump_check_wx(void)
325{
326 struct pg_state st = {
327 .seq = NULL,
328 .marker = (struct addr_marker[]) {
329 {0, NULL},
330 {-1, NULL},
331 },
332 .level = -1,
333 .check_wx = true,
334 .ptdump = {
335 .note_page = note_page,
336 .range = (struct ptdump_range[]) {
337 {KERN_VIRT_START, ULONG_MAX},
338 {0, 0}
339 }
340 }
341 };
342
343 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
344
345 if (st.wx_pages)
346 pr_warn("Checked W+X mappings: failed, %lu W+X pages found\n",
347 st.wx_pages);
348 else
349 pr_info("Checked W+X mappings: passed, no W+X pages found\n");
350}
351
352static int ptdump_show(struct seq_file *m, void *v)
353{
354 ptdump_walk(m, m->private);
355
356 return 0;
357}
358
359DEFINE_SHOW_ATTRIBUTE(ptdump);
360
361static int __init ptdump_init(void)
362{
363 unsigned int i, j;
364
365#ifdef CONFIG_KASAN
366 address_markers[KASAN_SHADOW_START_NR].start_address = KASAN_SHADOW_START;
367 address_markers[KASAN_SHADOW_END_NR].start_address = KASAN_SHADOW_END;
368#endif
369 address_markers[FIXMAP_START_NR].start_address = FIXADDR_START;
370 address_markers[FIXMAP_END_NR].start_address = FIXADDR_TOP;
371 address_markers[PCI_IO_START_NR].start_address = PCI_IO_START;
372 address_markers[PCI_IO_END_NR].start_address = PCI_IO_END;
373#ifdef CONFIG_SPARSEMEM_VMEMMAP
374 address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
375 address_markers[VMEMMAP_END_NR].start_address = VMEMMAP_END;
376#endif
377 address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
378 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
379 address_markers[PAGE_OFFSET_NR].start_address = PAGE_OFFSET;
380#ifdef CONFIG_64BIT
381 address_markers[MODULES_MAPPING_NR].start_address = MODULES_VADDR;
382 address_markers[KERNEL_MAPPING_NR].start_address = kernel_map.virt_addr;
383#endif
384
385 kernel_ptd_info.base_addr = KERN_VIRT_START;
386
387 for (i = 0; i < ARRAY_SIZE(pg_level); i++)
388 for (j = 0; j < ARRAY_SIZE(pte_bits); j++)
389 pg_level[i].mask |= pte_bits[j].mask;
390
391 debugfs_create_file("kernel_page_tables", 0400, NULL, &kernel_ptd_info,
392 &ptdump_fops);
393#ifdef CONFIG_EFI
394 if (efi_enabled(EFI_RUNTIME_SERVICES))
395 debugfs_create_file("efi_page_tables", 0400, NULL, &efi_ptd_info,
396 &ptdump_fops);
397#endif
398
399 return 0;
400}
401
402device_initcall(ptdump_init);