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
18static unsigned long max_addr;
19
20struct addr_marker {
21 int is_start;
22 unsigned long start_address;
23 unsigned long size;
24 const char *name;
25};
26
27static struct addr_marker *markers;
28static unsigned int markers_cnt;
29
30struct 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_puts(__m, fmt); \
55})
56
57static 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
71static 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
95static 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
109static 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, pr: st->current_prot, level: st->level);
146 note_page_update_state(st, addr, prot, level);
147 }
148}
149
150static void note_page_pte(struct ptdump_state *pt_st, unsigned long addr, pte_t pte)
151{
152 note_page(pt_st, addr, level: 4, val: pte_val(pte));
153}
154
155static void note_page_pmd(struct ptdump_state *pt_st, unsigned long addr, pmd_t pmd)
156{
157 note_page(pt_st, addr, level: 3, val: pmd_val(pmd));
158}
159
160static void note_page_pud(struct ptdump_state *pt_st, unsigned long addr, pud_t pud)
161{
162 note_page(pt_st, addr, level: 2, val: pud_val(pud));
163}
164
165static void note_page_p4d(struct ptdump_state *pt_st, unsigned long addr, p4d_t p4d)
166{
167 note_page(pt_st, addr, level: 1, val: p4d_val(p4d));
168}
169
170static void note_page_pgd(struct ptdump_state *pt_st, unsigned long addr, pgd_t pgd)
171{
172 note_page(pt_st, addr, level: 0, val: pgd_val(pgd));
173}
174
175static void note_page_flush(struct ptdump_state *pt_st)
176{
177 pte_t pte_zero = {0};
178
179 note_page(pt_st, addr: 0, level: -1, val: pte_val(pte: pte_zero));
180}
181
182bool 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: &st.ptdump, mm: &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
226static 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: &st.ptdump, mm: &init_mm, NULL);
252 mutex_unlock(lock: &cpa_mutex);
253 return 0;
254}
255DEFINE_SHOW_ATTRIBUTE(ptdump);
256#endif /* CONFIG_PTDUMP_DEBUGFS */
257
258static 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
292static int add_marker(unsigned long start, unsigned long end, const char *name)
293{
294 struct addr_marker *new;
295 size_t newsize;
296
297 newsize = (markers_cnt + 2) * sizeof(*markers);
298 new = kvrealloc(markers, newsize, GFP_KERNEL);
299 if (!new)
300 return -ENOMEM;
301 markers = new;
302 markers[markers_cnt].is_start = 1;
303 markers[markers_cnt].start_address = start;
304 markers[markers_cnt].size = end - start;
305 markers[markers_cnt].name = name;
306 markers_cnt++;
307 markers[markers_cnt].is_start = 0;
308 markers[markers_cnt].start_address = end;
309 markers[markers_cnt].size = end - start;
310 markers[markers_cnt].name = name;
311 markers_cnt++;
312 return 0;
313}
314
315static int pt_dump_init(void)
316{
317#ifdef CONFIG_KFENCE
318 unsigned long kfence_start = (unsigned long)__kfence_pool;
319#endif
320 unsigned long lowcore = (unsigned long)get_lowcore();
321 int rc;
322
323 /*
324 * Figure out the maximum virtual address being accessible with the
325 * kernel ASCE. We need this to keep the page table walker functions
326 * from accessing non-existent entries.
327 */
328 max_addr = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
329 max_addr = 1UL << (max_addr * 11 + 31);
330 /* start + end markers - must be added first */
331 rc = add_marker(start: 0, end: -1UL, NULL);
332 rc |= add_marker(start: (unsigned long)_stext, end: (unsigned long)_end, name: "Kernel Image");
333 rc |= add_marker(lowcore, lowcore + sizeof(struct lowcore), "Lowcore");
334 rc |= add_marker(start: __identity_base, end: __identity_base + ident_map_size, name: "Identity Mapping");
335 rc |= add_marker((unsigned long)__samode31, (unsigned long)__eamode31, "Amode31 Area");
336 rc |= add_marker(MODULES_VADDR, MODULES_END, name: "Modules Area");
337 rc |= add_marker(start: __abs_lowcore, end: __abs_lowcore + ABS_LOWCORE_MAP_SIZE, name: "Lowcore Area");
338 rc |= add_marker(start: __memcpy_real_area, end: __memcpy_real_area + MEMCPY_REAL_SIZE, name: "Real Memory Copy Area");
339 rc |= add_marker(start: (unsigned long)vmemmap, end: (unsigned long)vmemmap + vmemmap_size, name: "vmemmap Area");
340 rc |= add_marker(VMALLOC_START, VMALLOC_END, name: "vmalloc Area");
341#ifdef CONFIG_KFENCE
342 rc |= add_marker(start: kfence_start, end: kfence_start + KFENCE_POOL_SIZE, name: "KFence Pool");
343#endif
344#ifdef CONFIG_KMSAN
345 rc |= add_marker(KMSAN_VMALLOC_SHADOW_START, KMSAN_VMALLOC_SHADOW_END, "Kmsan vmalloc Shadow");
346 rc |= add_marker(KMSAN_VMALLOC_ORIGIN_START, KMSAN_VMALLOC_ORIGIN_END, "Kmsan vmalloc Origins");
347 rc |= add_marker(KMSAN_MODULES_SHADOW_START, KMSAN_MODULES_SHADOW_END, "Kmsan Modules Shadow");
348 rc |= add_marker(KMSAN_MODULES_ORIGIN_START, KMSAN_MODULES_ORIGIN_END, "Kmsan Modules Origins");
349#endif
350#ifdef CONFIG_KASAN
351 rc |= add_marker(KASAN_SHADOW_START, KASAN_SHADOW_END, name: "Kasan Shadow");
352#endif
353 if (rc)
354 goto error;
355 sort(base: &markers[1], num: markers_cnt - 1, size: sizeof(*markers), cmp_func: ptdump_cmp, NULL);
356#ifdef CONFIG_PTDUMP_DEBUGFS
357 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
358#endif /* CONFIG_PTDUMP_DEBUGFS */
359 return 0;
360error:
361 kvfree(addr: markers);
362 return -ENOMEM;
363}
364device_initcall(pt_dump_init);
365

source code of linux/arch/s390/mm/dump_pagetables.c