1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/cpufeature.h>
4 #include <linux/set_memory.h>
5 #include <linux/ptdump.h>
6 #include <linux/seq_file.h>
7 #include <linux/debugfs.h>
8 #include <linux/sort.h>
9 #include <linux/mm.h>
10 #include <linux/kfence.h>
11 #include <linux/kasan.h>
12 #include <asm/kasan.h>
13 #include <asm/abs_lowcore.h>
14 #include <asm/nospec-branch.h>
15 #include <asm/sections.h>
16 #include <asm/maccess.h>
17
18 static unsigned long max_addr;
19
20 struct addr_marker {
21 int is_start;
22 unsigned long start_address;
23 unsigned long size;
24 const char *name;
25 };
26
27 static struct addr_marker *markers;
28 static unsigned int markers_cnt;
29
30 struct pg_state {
31 struct ptdump_state ptdump;
32 struct seq_file *seq;
33 int level;
34 unsigned int current_prot;
35 bool check_wx;
36 unsigned long wx_pages;
37 unsigned long start_address;
38 const struct addr_marker *marker;
39 };
40
41 #define pt_dump_seq_printf(m, fmt, args...) \
42 ({ \
43 struct seq_file *__m = (m); \
44 \
45 if (__m) \
46 seq_printf(__m, fmt, ##args); \
47 })
48
49 #define pt_dump_seq_puts(m, fmt) \
50 ({ \
51 struct seq_file *__m = (m); \
52 \
53 if (__m) \
54 seq_printf(__m, fmt); \
55 })
56
print_prot(struct seq_file * m,unsigned int pr,int level)57 static void print_prot(struct seq_file *m, unsigned int pr, int level)
58 {
59 static const char * const level_name[] =
60 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
61
62 pt_dump_seq_printf(m, "%s ", level_name[level]);
63 if (pr & _PAGE_INVALID) {
64 pt_dump_seq_printf(m, "I\n");
65 return;
66 }
67 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
68 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
69 }
70
note_prot_wx(struct pg_state * st,unsigned long addr)71 static void note_prot_wx(struct pg_state *st, unsigned long addr)
72 {
73 if (!st->check_wx)
74 return;
75 if (st->current_prot & _PAGE_INVALID)
76 return;
77 if (st->current_prot & _PAGE_PROTECT)
78 return;
79 if (st->current_prot & _PAGE_NOEXEC)
80 return;
81 /*
82 * The first lowcore page is W+X if spectre mitigations are using
83 * trampolines or the BEAR enhancements facility is not installed,
84 * in which case we have two lpswe instructions in lowcore that need
85 * to be executable.
86 */
87 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !cpu_has_bear()))
88 return;
89 WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX),
90 "s390/mm: Found insecure W+X mapping at address %pS\n",
91 (void *)st->start_address);
92 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
93 }
94
note_page_update_state(struct pg_state * st,unsigned long addr,unsigned int prot,int level)95 static void note_page_update_state(struct pg_state *st, unsigned long addr, unsigned int prot, int level)
96 {
97 struct seq_file *m = st->seq;
98
99 while (addr >= st->marker[1].start_address) {
100 st->marker++;
101 pt_dump_seq_printf(m, "---[ %s %s ]---\n", st->marker->name,
102 st->marker->is_start ? "Start" : "End");
103 }
104 st->start_address = addr;
105 st->current_prot = prot;
106 st->level = level;
107 }
108
note_page(struct ptdump_state * pt_st,unsigned long addr,int level,u64 val)109 static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
110 {
111 int width = sizeof(unsigned long) * 2;
112 static const char units[] = "KMGTPE";
113 const char *unit = units;
114 unsigned long delta;
115 struct pg_state *st;
116 struct seq_file *m;
117 unsigned int prot;
118
119 st = container_of(pt_st, struct pg_state, ptdump);
120 m = st->seq;
121 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
122 if (level == 4 && (val & _PAGE_INVALID))
123 prot = _PAGE_INVALID;
124 /* For pmd_none() & friends val gets passed as zero. */
125 if (level != 4 && !val)
126 prot = _PAGE_INVALID;
127 /* Final flush from generic code. */
128 if (level == -1)
129 addr = max_addr;
130 if (st->level == -1) {
131 pt_dump_seq_puts(m, "---[ Kernel Virtual Address Space ]---\n");
132 note_page_update_state(st, addr, prot, level);
133 } else if (prot != st->current_prot || level != st->level ||
134 addr >= st->marker[1].start_address) {
135 note_prot_wx(st, addr);
136 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
137 width, st->start_address,
138 width, addr);
139 delta = (addr - st->start_address) >> 10;
140 while (!(delta & 0x3ff) && unit[1]) {
141 delta >>= 10;
142 unit++;
143 }
144 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
145 print_prot(m, st->current_prot, st->level);
146 note_page_update_state(st, addr, prot, level);
147 }
148 }
149
note_page_pte(struct ptdump_state * pt_st,unsigned long addr,pte_t pte)150 static void note_page_pte(struct ptdump_state *pt_st, unsigned long addr, pte_t pte)
151 {
152 note_page(pt_st, addr, 4, pte_val(pte));
153 }
154
note_page_pmd(struct ptdump_state * pt_st,unsigned long addr,pmd_t pmd)155 static void note_page_pmd(struct ptdump_state *pt_st, unsigned long addr, pmd_t pmd)
156 {
157 note_page(pt_st, addr, 3, pmd_val(pmd));
158 }
159
note_page_pud(struct ptdump_state * pt_st,unsigned long addr,pud_t pud)160 static void note_page_pud(struct ptdump_state *pt_st, unsigned long addr, pud_t pud)
161 {
162 note_page(pt_st, addr, 2, pud_val(pud));
163 }
164
note_page_p4d(struct ptdump_state * pt_st,unsigned long addr,p4d_t p4d)165 static void note_page_p4d(struct ptdump_state *pt_st, unsigned long addr, p4d_t p4d)
166 {
167 note_page(pt_st, addr, 1, p4d_val(p4d));
168 }
169
note_page_pgd(struct ptdump_state * pt_st,unsigned long addr,pgd_t pgd)170 static void note_page_pgd(struct ptdump_state *pt_st, unsigned long addr, pgd_t pgd)
171 {
172 note_page(pt_st, addr, 0, pgd_val(pgd));
173 }
174
note_page_flush(struct ptdump_state * pt_st)175 static void note_page_flush(struct ptdump_state *pt_st)
176 {
177 pte_t pte_zero = {0};
178
179 note_page(pt_st, 0, -1, pte_val(pte_zero));
180 }
181
ptdump_check_wx(void)182 bool ptdump_check_wx(void)
183 {
184 struct pg_state st = {
185 .ptdump = {
186 .note_page_pte = note_page_pte,
187 .note_page_pmd = note_page_pmd,
188 .note_page_pud = note_page_pud,
189 .note_page_p4d = note_page_p4d,
190 .note_page_pgd = note_page_pgd,
191 .note_page_flush = note_page_flush,
192 .range = (struct ptdump_range[]) {
193 {.start = 0, .end = max_addr},
194 {.start = 0, .end = 0},
195 }
196 },
197 .seq = NULL,
198 .level = -1,
199 .current_prot = 0,
200 .check_wx = true,
201 .wx_pages = 0,
202 .start_address = 0,
203 .marker = (struct addr_marker[]) {
204 { .start_address = 0, .name = NULL},
205 { .start_address = -1, .name = NULL},
206 },
207 };
208
209 if (!cpu_has_nx())
210 return true;
211 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
212 if (st.wx_pages) {
213 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
214
215 return false;
216 } else {
217 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
218 (nospec_uses_trampoline() || !cpu_has_bear()) ?
219 "unexpected " : "");
220
221 return true;
222 }
223 }
224
225 #ifdef CONFIG_PTDUMP_DEBUGFS
ptdump_show(struct seq_file * m,void * v)226 static int ptdump_show(struct seq_file *m, void *v)
227 {
228 struct pg_state st = {
229 .ptdump = {
230 .note_page_pte = note_page_pte,
231 .note_page_pmd = note_page_pmd,
232 .note_page_pud = note_page_pud,
233 .note_page_p4d = note_page_p4d,
234 .note_page_pgd = note_page_pgd,
235 .note_page_flush = note_page_flush,
236 .range = (struct ptdump_range[]) {
237 {.start = 0, .end = max_addr},
238 {.start = 0, .end = 0},
239 }
240 },
241 .seq = m,
242 .level = -1,
243 .current_prot = 0,
244 .check_wx = false,
245 .wx_pages = 0,
246 .start_address = 0,
247 .marker = markers,
248 };
249
250 mutex_lock(&cpa_mutex);
251 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
252 mutex_unlock(&cpa_mutex);
253 return 0;
254 }
255 DEFINE_SHOW_ATTRIBUTE(ptdump);
256 #endif /* CONFIG_PTDUMP_DEBUGFS */
257
ptdump_cmp(const void * a,const void * b)258 static int ptdump_cmp(const void *a, const void *b)
259 {
260 const struct addr_marker *ama = a;
261 const struct addr_marker *amb = b;
262
263 if (ama->start_address > amb->start_address)
264 return 1;
265 if (ama->start_address < amb->start_address)
266 return -1;
267 /*
268 * If the start addresses of two markers are identical sort markers in an
269 * order that considers areas contained within other areas correctly.
270 */
271 if (ama->is_start && amb->is_start) {
272 if (ama->size > amb->size)
273 return -1;
274 if (ama->size < amb->size)
275 return 1;
276 return 0;
277 }
278 if (!ama->is_start && !amb->is_start) {
279 if (ama->size > amb->size)
280 return 1;
281 if (ama->size < amb->size)
282 return -1;
283 return 0;
284 }
285 if (ama->is_start)
286 return 1;
287 if (amb->is_start)
288 return -1;
289 return 0;
290 }
291
add_marker(unsigned long start,unsigned long end,const char * name)292 static int add_marker(unsigned long start, unsigned long end, const char *name)
293 {
294 size_t oldsize, newsize;
295
296 oldsize = markers_cnt * sizeof(*markers);
297 newsize = oldsize + 2 * sizeof(*markers);
298 if (!oldsize)
299 markers = kvmalloc(newsize, GFP_KERNEL);
300 else
301 markers = kvrealloc(markers, newsize, GFP_KERNEL);
302 if (!markers)
303 goto error;
304 markers[markers_cnt].is_start = 1;
305 markers[markers_cnt].start_address = start;
306 markers[markers_cnt].size = end - start;
307 markers[markers_cnt].name = name;
308 markers_cnt++;
309 markers[markers_cnt].is_start = 0;
310 markers[markers_cnt].start_address = end;
311 markers[markers_cnt].size = end - start;
312 markers[markers_cnt].name = name;
313 markers_cnt++;
314 return 0;
315 error:
316 markers_cnt = 0;
317 return -ENOMEM;
318 }
319
pt_dump_init(void)320 static int pt_dump_init(void)
321 {
322 #ifdef CONFIG_KFENCE
323 unsigned long kfence_start = (unsigned long)__kfence_pool;
324 #endif
325 unsigned long lowcore = (unsigned long)get_lowcore();
326 int rc;
327
328 /*
329 * Figure out the maximum virtual address being accessible with the
330 * kernel ASCE. We need this to keep the page table walker functions
331 * from accessing non-existent entries.
332 */
333 max_addr = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
334 max_addr = 1UL << (max_addr * 11 + 31);
335 /* start + end markers - must be added first */
336 rc = add_marker(0, -1UL, NULL);
337 rc |= add_marker((unsigned long)_stext, (unsigned long)_end, "Kernel Image");
338 rc |= add_marker(lowcore, lowcore + sizeof(struct lowcore), "Lowcore");
339 rc |= add_marker(__identity_base, __identity_base + ident_map_size, "Identity Mapping");
340 rc |= add_marker((unsigned long)__samode31, (unsigned long)__eamode31, "Amode31 Area");
341 rc |= add_marker(MODULES_VADDR, MODULES_END, "Modules Area");
342 rc |= add_marker(__abs_lowcore, __abs_lowcore + ABS_LOWCORE_MAP_SIZE, "Lowcore Area");
343 rc |= add_marker(__memcpy_real_area, __memcpy_real_area + MEMCPY_REAL_SIZE, "Real Memory Copy Area");
344 rc |= add_marker((unsigned long)vmemmap, (unsigned long)vmemmap + vmemmap_size, "vmemmap Area");
345 rc |= add_marker(VMALLOC_START, VMALLOC_END, "vmalloc Area");
346 #ifdef CONFIG_KFENCE
347 rc |= add_marker(kfence_start, kfence_start + KFENCE_POOL_SIZE, "KFence Pool");
348 #endif
349 #ifdef CONFIG_KMSAN
350 rc |= add_marker(KMSAN_VMALLOC_SHADOW_START, KMSAN_VMALLOC_SHADOW_END, "Kmsan vmalloc Shadow");
351 rc |= add_marker(KMSAN_VMALLOC_ORIGIN_START, KMSAN_VMALLOC_ORIGIN_END, "Kmsan vmalloc Origins");
352 rc |= add_marker(KMSAN_MODULES_SHADOW_START, KMSAN_MODULES_SHADOW_END, "Kmsan Modules Shadow");
353 rc |= add_marker(KMSAN_MODULES_ORIGIN_START, KMSAN_MODULES_ORIGIN_END, "Kmsan Modules Origins");
354 #endif
355 #ifdef CONFIG_KASAN
356 rc |= add_marker(KASAN_SHADOW_START, KASAN_SHADOW_END, "Kasan Shadow");
357 #endif
358 if (rc)
359 goto error;
360 sort(&markers[1], markers_cnt - 1, sizeof(*markers), ptdump_cmp, NULL);
361 #ifdef CONFIG_PTDUMP_DEBUGFS
362 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
363 #endif /* CONFIG_PTDUMP_DEBUGFS */
364 return 0;
365 error:
366 kvfree(markers);
367 return -ENOMEM;
368 }
369 device_initcall(pt_dump_init);
370