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1// SPDX-License-Identifier: GPL-2.0
2#include <linux/set_memory.h>
3#include <linux/ptdump.h>
4#include <linux/seq_file.h>
5#include <linux/debugfs.h>
6#include <linux/sort.h>
7#include <linux/mm.h>
8#include <linux/kfence.h>
9#include <linux/kasan.h>
10#include <asm/kasan.h>
11#include <asm/abs_lowcore.h>
12#include <asm/nospec-branch.h>
13#include <asm/sections.h>
14#include <asm/maccess.h>
15
16static unsigned long max_addr;
17
18struct addr_marker {
19 int is_start;
20 unsigned long start_address;
21 unsigned long size;
22 const char *name;
23};
24
25static struct addr_marker *markers;
26static unsigned int markers_cnt;
27
28struct pg_state {
29 struct ptdump_state ptdump;
30 struct seq_file *seq;
31 int level;
32 unsigned int current_prot;
33 bool check_wx;
34 unsigned long wx_pages;
35 unsigned long start_address;
36 const struct addr_marker *marker;
37};
38
39#define pt_dump_seq_printf(m, fmt, args...) \
40({ \
41 struct seq_file *__m = (m); \
42 \
43 if (__m) \
44 seq_printf(__m, fmt, ##args); \
45})
46
47#define pt_dump_seq_puts(m, fmt) \
48({ \
49 struct seq_file *__m = (m); \
50 \
51 if (__m) \
52 seq_printf(__m, fmt); \
53})
54
55static void print_prot(struct seq_file *m, unsigned int pr, int level)
56{
57 static const char * const level_name[] =
58 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
59
60 pt_dump_seq_printf(m, "%s ", level_name[level]);
61 if (pr & _PAGE_INVALID) {
62 pt_dump_seq_printf(m, "I\n");
63 return;
64 }
65 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
66 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
67}
68
69static void note_prot_wx(struct pg_state *st, unsigned long addr)
70{
71 if (!st->check_wx)
72 return;
73 if (st->current_prot & _PAGE_INVALID)
74 return;
75 if (st->current_prot & _PAGE_PROTECT)
76 return;
77 if (st->current_prot & _PAGE_NOEXEC)
78 return;
79 /*
80 * The first lowcore page is W+X if spectre mitigations are using
81 * trampolines or the BEAR enhancements facility is not installed,
82 * in which case we have two lpswe instructions in lowcore that need
83 * to be executable.
84 */
85 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
86 return;
87 WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX),
88 "s390/mm: Found insecure W+X mapping at address %pS\n",
89 (void *)st->start_address);
90 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
91}
92
93static void note_page_update_state(struct pg_state *st, unsigned long addr, unsigned int prot, int level)
94{
95 struct seq_file *m = st->seq;
96
97 while (addr >= st->marker[1].start_address) {
98 st->marker++;
99 pt_dump_seq_printf(m, "---[ %s %s ]---\n", st->marker->name,
100 st->marker->is_start ? "Start" : "End");
101 }
102 st->start_address = addr;
103 st->current_prot = prot;
104 st->level = level;
105}
106
107static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
108{
109 int width = sizeof(unsigned long) * 2;
110 static const char units[] = "KMGTPE";
111 const char *unit = units;
112 unsigned long delta;
113 struct pg_state *st;
114 struct seq_file *m;
115 unsigned int prot;
116
117 st = container_of(pt_st, struct pg_state, ptdump);
118 m = st->seq;
119 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
120 if (level == 4 && (val & _PAGE_INVALID))
121 prot = _PAGE_INVALID;
122 /* For pmd_none() & friends val gets passed as zero. */
123 if (level != 4 && !val)
124 prot = _PAGE_INVALID;
125 /* Final flush from generic code. */
126 if (level == -1)
127 addr = max_addr;
128 if (st->level == -1) {
129 pt_dump_seq_puts(m, "---[ Kernel Virtual Address Space ]---\n");
130 note_page_update_state(st, addr, prot, level);
131 } else if (prot != st->current_prot || level != st->level ||
132 addr >= st->marker[1].start_address) {
133 note_prot_wx(st, addr);
134 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
135 width, st->start_address,
136 width, addr);
137 delta = (addr - st->start_address) >> 10;
138 while (!(delta & 0x3ff) && unit[1]) {
139 delta >>= 10;
140 unit++;
141 }
142 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
143 print_prot(m, st->current_prot, st->level);
144 note_page_update_state(st, addr, prot, level);
145 }
146}
147
148bool ptdump_check_wx(void)
149{
150 struct pg_state st = {
151 .ptdump = {
152 .note_page = note_page,
153 .range = (struct ptdump_range[]) {
154 {.start = 0, .end = max_addr},
155 {.start = 0, .end = 0},
156 }
157 },
158 .seq = NULL,
159 .level = -1,
160 .current_prot = 0,
161 .check_wx = true,
162 .wx_pages = 0,
163 .start_address = 0,
164 .marker = (struct addr_marker[]) {
165 { .start_address = 0, .name = NULL},
166 { .start_address = -1, .name = NULL},
167 },
168 };
169
170 if (!MACHINE_HAS_NX)
171 return true;
172 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
173 if (st.wx_pages) {
174 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
175
176 return false;
177 } else {
178 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
179 (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
180 "unexpected " : "");
181
182 return true;
183 }
184}
185
186#ifdef CONFIG_PTDUMP_DEBUGFS
187static int ptdump_show(struct seq_file *m, void *v)
188{
189 struct pg_state st = {
190 .ptdump = {
191 .note_page = note_page,
192 .range = (struct ptdump_range[]) {
193 {.start = 0, .end = max_addr},
194 {.start = 0, .end = 0},
195 }
196 },
197 .seq = m,
198 .level = -1,
199 .current_prot = 0,
200 .check_wx = false,
201 .wx_pages = 0,
202 .start_address = 0,
203 .marker = markers,
204 };
205
206 get_online_mems();
207 mutex_lock(&cpa_mutex);
208 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
209 mutex_unlock(&cpa_mutex);
210 put_online_mems();
211 return 0;
212}
213DEFINE_SHOW_ATTRIBUTE(ptdump);
214#endif /* CONFIG_PTDUMP_DEBUGFS */
215
216static int ptdump_cmp(const void *a, const void *b)
217{
218 const struct addr_marker *ama = a;
219 const struct addr_marker *amb = b;
220
221 if (ama->start_address > amb->start_address)
222 return 1;
223 if (ama->start_address < amb->start_address)
224 return -1;
225 /*
226 * If the start addresses of two markers are identical sort markers in an
227 * order that considers areas contained within other areas correctly.
228 */
229 if (ama->is_start && amb->is_start) {
230 if (ama->size > amb->size)
231 return -1;
232 if (ama->size < amb->size)
233 return 1;
234 return 0;
235 }
236 if (!ama->is_start && !amb->is_start) {
237 if (ama->size > amb->size)
238 return 1;
239 if (ama->size < amb->size)
240 return -1;
241 return 0;
242 }
243 if (ama->is_start)
244 return 1;
245 if (amb->is_start)
246 return -1;
247 return 0;
248}
249
250static int add_marker(unsigned long start, unsigned long end, const char *name)
251{
252 size_t oldsize, newsize;
253
254 oldsize = markers_cnt * sizeof(*markers);
255 newsize = oldsize + 2 * sizeof(*markers);
256 if (!oldsize)
257 markers = kvmalloc(newsize, GFP_KERNEL);
258 else
259 markers = kvrealloc(markers, newsize, GFP_KERNEL);
260 if (!markers)
261 goto error;
262 markers[markers_cnt].is_start = 1;
263 markers[markers_cnt].start_address = start;
264 markers[markers_cnt].size = end - start;
265 markers[markers_cnt].name = name;
266 markers_cnt++;
267 markers[markers_cnt].is_start = 0;
268 markers[markers_cnt].start_address = end;
269 markers[markers_cnt].size = end - start;
270 markers[markers_cnt].name = name;
271 markers_cnt++;
272 return 0;
273error:
274 markers_cnt = 0;
275 return -ENOMEM;
276}
277
278static int pt_dump_init(void)
279{
280#ifdef CONFIG_KFENCE
281 unsigned long kfence_start = (unsigned long)__kfence_pool;
282#endif
283 unsigned long lowcore = (unsigned long)get_lowcore();
284 int rc;
285
286 /*
287 * Figure out the maximum virtual address being accessible with the
288 * kernel ASCE. We need this to keep the page table walker functions
289 * from accessing non-existent entries.
290 */
291 max_addr = (get_lowcore()->kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
292 max_addr = 1UL << (max_addr * 11 + 31);
293 /* start + end markers - must be added first */
294 rc = add_marker(0, -1UL, NULL);
295 rc |= add_marker((unsigned long)_stext, (unsigned long)_end, "Kernel Image");
296 rc |= add_marker(lowcore, lowcore + sizeof(struct lowcore), "Lowcore");
297 rc |= add_marker(__identity_base, __identity_base + ident_map_size, "Identity Mapping");
298 rc |= add_marker((unsigned long)__samode31, (unsigned long)__eamode31, "Amode31 Area");
299 rc |= add_marker(MODULES_VADDR, MODULES_END, "Modules Area");
300 rc |= add_marker(__abs_lowcore, __abs_lowcore + ABS_LOWCORE_MAP_SIZE, "Lowcore Area");
301 rc |= add_marker(__memcpy_real_area, __memcpy_real_area + MEMCPY_REAL_SIZE, "Real Memory Copy Area");
302 rc |= add_marker((unsigned long)vmemmap, (unsigned long)vmemmap + vmemmap_size, "vmemmap Area");
303 rc |= add_marker(VMALLOC_START, VMALLOC_END, "vmalloc Area");
304#ifdef CONFIG_KFENCE
305 rc |= add_marker(kfence_start, kfence_start + KFENCE_POOL_SIZE, "KFence Pool");
306#endif
307#ifdef CONFIG_KMSAN
308 rc |= add_marker(KMSAN_VMALLOC_SHADOW_START, KMSAN_VMALLOC_SHADOW_END, "Kmsan vmalloc Shadow");
309 rc |= add_marker(KMSAN_VMALLOC_ORIGIN_START, KMSAN_VMALLOC_ORIGIN_END, "Kmsan vmalloc Origins");
310 rc |= add_marker(KMSAN_MODULES_SHADOW_START, KMSAN_MODULES_SHADOW_END, "Kmsan Modules Shadow");
311 rc |= add_marker(KMSAN_MODULES_ORIGIN_START, KMSAN_MODULES_ORIGIN_END, "Kmsan Modules Origins");
312#endif
313#ifdef CONFIG_KASAN
314 rc |= add_marker(KASAN_SHADOW_START, KASAN_SHADOW_END, "Kasan Shadow");
315#endif
316 if (rc)
317 goto error;
318 sort(&markers[1], markers_cnt - 1, sizeof(*markers), ptdump_cmp, NULL);
319#ifdef CONFIG_PTDUMP_DEBUGFS
320 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
321#endif /* CONFIG_PTDUMP_DEBUGFS */
322 return 0;
323error:
324 kvfree(markers);
325 return -ENOMEM;
326}
327device_initcall(pt_dump_init);
1// SPDX-License-Identifier: GPL-2.0
2#include <linux/set_memory.h>
3#include <linux/ptdump.h>
4#include <linux/seq_file.h>
5#include <linux/debugfs.h>
6#include <linux/mm.h>
7#include <linux/kasan.h>
8#include <asm/ptdump.h>
9#include <asm/kasan.h>
10#include <asm/sections.h>
11
12static unsigned long max_addr;
13
14struct addr_marker {
15 unsigned long start_address;
16 const char *name;
17};
18
19enum address_markers_idx {
20 IDENTITY_BEFORE_NR = 0,
21 IDENTITY_BEFORE_END_NR,
22 KERNEL_START_NR,
23 KERNEL_END_NR,
24 IDENTITY_AFTER_NR,
25 IDENTITY_AFTER_END_NR,
26#ifdef CONFIG_KASAN
27 KASAN_SHADOW_START_NR,
28 KASAN_SHADOW_END_NR,
29#endif
30 VMEMMAP_NR,
31 VMEMMAP_END_NR,
32 VMALLOC_NR,
33 VMALLOC_END_NR,
34 MODULES_NR,
35 MODULES_END_NR,
36};
37
38static struct addr_marker address_markers[] = {
39 [IDENTITY_BEFORE_NR] = {0, "Identity Mapping Start"},
40 [IDENTITY_BEFORE_END_NR] = {(unsigned long)_stext, "Identity Mapping End"},
41 [KERNEL_START_NR] = {(unsigned long)_stext, "Kernel Image Start"},
42 [KERNEL_END_NR] = {(unsigned long)_end, "Kernel Image End"},
43 [IDENTITY_AFTER_NR] = {(unsigned long)_end, "Identity Mapping Start"},
44 [IDENTITY_AFTER_END_NR] = {0, "Identity Mapping End"},
45#ifdef CONFIG_KASAN
46 [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
47 [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
48#endif
49 [VMEMMAP_NR] = {0, "vmemmap Area Start"},
50 [VMEMMAP_END_NR] = {0, "vmemmap Area End"},
51 [VMALLOC_NR] = {0, "vmalloc Area Start"},
52 [VMALLOC_END_NR] = {0, "vmalloc Area End"},
53 [MODULES_NR] = {0, "Modules Area Start"},
54 [MODULES_END_NR] = {0, "Modules Area End"},
55 { -1, NULL }
56};
57
58struct pg_state {
59 struct ptdump_state ptdump;
60 struct seq_file *seq;
61 int level;
62 unsigned int current_prot;
63 bool check_wx;
64 unsigned long wx_pages;
65 unsigned long start_address;
66 const struct addr_marker *marker;
67};
68
69#define pt_dump_seq_printf(m, fmt, args...) \
70({ \
71 struct seq_file *__m = (m); \
72 \
73 if (__m) \
74 seq_printf(__m, fmt, ##args); \
75})
76
77#define pt_dump_seq_puts(m, fmt) \
78({ \
79 struct seq_file *__m = (m); \
80 \
81 if (__m) \
82 seq_printf(__m, fmt); \
83})
84
85static void print_prot(struct seq_file *m, unsigned int pr, int level)
86{
87 static const char * const level_name[] =
88 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
89
90 pt_dump_seq_printf(m, "%s ", level_name[level]);
91 if (pr & _PAGE_INVALID) {
92 pt_dump_seq_printf(m, "I\n");
93 return;
94 }
95 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
96 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
97}
98
99static void note_prot_wx(struct pg_state *st, unsigned long addr)
100{
101#ifdef CONFIG_DEBUG_WX
102 if (!st->check_wx)
103 return;
104 if (st->current_prot & _PAGE_INVALID)
105 return;
106 if (st->current_prot & _PAGE_PROTECT)
107 return;
108 if (st->current_prot & _PAGE_NOEXEC)
109 return;
110 /* The first lowcore page is currently still W+X. */
111 if (addr == PAGE_SIZE)
112 return;
113 WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n",
114 (void *)st->start_address);
115 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
116#endif /* CONFIG_DEBUG_WX */
117}
118
119static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
120{
121 int width = sizeof(unsigned long) * 2;
122 static const char units[] = "KMGTPE";
123 const char *unit = units;
124 unsigned long delta;
125 struct pg_state *st;
126 struct seq_file *m;
127 unsigned int prot;
128
129 st = container_of(pt_st, struct pg_state, ptdump);
130 m = st->seq;
131 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
132 if (level == 4 && (val & _PAGE_INVALID))
133 prot = _PAGE_INVALID;
134 /* For pmd_none() & friends val gets passed as zero. */
135 if (level != 4 && !val)
136 prot = _PAGE_INVALID;
137 /* Final flush from generic code. */
138 if (level == -1)
139 addr = max_addr;
140 if (st->level == -1) {
141 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
142 st->start_address = addr;
143 st->current_prot = prot;
144 st->level = level;
145 } else if (prot != st->current_prot || level != st->level ||
146 addr >= st->marker[1].start_address) {
147 note_prot_wx(st, addr);
148 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
149 width, st->start_address,
150 width, addr);
151 delta = (addr - st->start_address) >> 10;
152 while (!(delta & 0x3ff) && unit[1]) {
153 delta >>= 10;
154 unit++;
155 }
156 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
157 print_prot(m, st->current_prot, st->level);
158 while (addr >= st->marker[1].start_address) {
159 st->marker++;
160 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
161 }
162 st->start_address = addr;
163 st->current_prot = prot;
164 st->level = level;
165 }
166}
167
168#ifdef CONFIG_DEBUG_WX
169void ptdump_check_wx(void)
170{
171 struct pg_state st = {
172 .ptdump = {
173 .note_page = note_page,
174 .range = (struct ptdump_range[]) {
175 {.start = 0, .end = max_addr},
176 {.start = 0, .end = 0},
177 }
178 },
179 .seq = NULL,
180 .level = -1,
181 .current_prot = 0,
182 .check_wx = true,
183 .wx_pages = 0,
184 .start_address = 0,
185 .marker = (struct addr_marker[]) {
186 { .start_address = 0, .name = NULL},
187 { .start_address = -1, .name = NULL},
188 },
189 };
190
191 if (!MACHINE_HAS_NX)
192 return;
193 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
194 if (st.wx_pages)
195 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
196 else
197 pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n");
198}
199#endif /* CONFIG_DEBUG_WX */
200
201#ifdef CONFIG_PTDUMP_DEBUGFS
202static int ptdump_show(struct seq_file *m, void *v)
203{
204 struct pg_state st = {
205 .ptdump = {
206 .note_page = note_page,
207 .range = (struct ptdump_range[]) {
208 {.start = 0, .end = max_addr},
209 {.start = 0, .end = 0},
210 }
211 },
212 .seq = m,
213 .level = -1,
214 .current_prot = 0,
215 .check_wx = false,
216 .wx_pages = 0,
217 .start_address = 0,
218 .marker = address_markers,
219 };
220
221 get_online_mems();
222 mutex_lock(&cpa_mutex);
223 ptdump_walk_pgd(&st.ptdump, &init_mm, NULL);
224 mutex_unlock(&cpa_mutex);
225 put_online_mems();
226 return 0;
227}
228DEFINE_SHOW_ATTRIBUTE(ptdump);
229#endif /* CONFIG_PTDUMP_DEBUGFS */
230
231/*
232 * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
233 * insertion sort to preserve the original order of markers with the same
234 * start address.
235 */
236static void sort_address_markers(void)
237{
238 struct addr_marker tmp;
239 int i, j;
240
241 for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
242 tmp = address_markers[i];
243 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
244 address_markers[j + 1] = address_markers[j];
245 address_markers[j + 1] = tmp;
246 }
247}
248
249static int pt_dump_init(void)
250{
251 /*
252 * Figure out the maximum virtual address being accessible with the
253 * kernel ASCE. We need this to keep the page table walker functions
254 * from accessing non-existent entries.
255 */
256 max_addr = (S390_lowcore.kernel_asce & _REGION_ENTRY_TYPE_MASK) >> 2;
257 max_addr = 1UL << (max_addr * 11 + 31);
258 address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
259 address_markers[MODULES_NR].start_address = MODULES_VADDR;
260 address_markers[MODULES_END_NR].start_address = MODULES_END;
261 address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
262 address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
263 address_markers[VMALLOC_NR].start_address = VMALLOC_START;
264 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
265 sort_address_markers();
266#ifdef CONFIG_PTDUMP_DEBUGFS
267 debugfs_create_file("kernel_page_tables", 0400, NULL, NULL, &ptdump_fops);
268#endif /* CONFIG_PTDUMP_DEBUGFS */
269 return 0;
270}
271device_initcall(pt_dump_init);