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/kfence.h>
8#include <linux/kasan.h>
9#include <asm/kasan.h>
10#include <asm/abs_lowcore.h>
11#include <asm/nospec-branch.h>
12#include <asm/sections.h>
13#include <asm/maccess.h>
14
15static unsigned long max_addr;
16
17struct addr_marker {
18 unsigned long start_address;
19 const char *name;
20};
21
22enum address_markers_idx {
23 IDENTITY_BEFORE_NR = 0,
24 IDENTITY_BEFORE_END_NR,
25 AMODE31_START_NR,
26 AMODE31_END_NR,
27 KERNEL_START_NR,
28 KERNEL_END_NR,
29#ifdef CONFIG_KFENCE
30 KFENCE_START_NR,
31 KFENCE_END_NR,
32#endif
33 IDENTITY_AFTER_NR,
34 IDENTITY_AFTER_END_NR,
35 VMEMMAP_NR,
36 VMEMMAP_END_NR,
37 VMALLOC_NR,
38 VMALLOC_END_NR,
39 MODULES_NR,
40 MODULES_END_NR,
41 ABS_LOWCORE_NR,
42 ABS_LOWCORE_END_NR,
43 MEMCPY_REAL_NR,
44 MEMCPY_REAL_END_NR,
45#ifdef CONFIG_KASAN
46 KASAN_SHADOW_START_NR,
47 KASAN_SHADOW_END_NR,
48#endif
49};
50
51static struct addr_marker address_markers[] = {
52 [IDENTITY_BEFORE_NR] = {.start_address: 0, .name: "Identity Mapping Start"},
53 [IDENTITY_BEFORE_END_NR] = {.start_address: (unsigned long)_stext, .name: "Identity Mapping End"},
54 [AMODE31_START_NR] = {.start_address: 0, .name: "Amode31 Area Start"},
55 [AMODE31_END_NR] = {.start_address: 0, .name: "Amode31 Area End"},
56 [KERNEL_START_NR] = {.start_address: (unsigned long)_stext, .name: "Kernel Image Start"},
57 [KERNEL_END_NR] = {.start_address: (unsigned long)_end, .name: "Kernel Image End"},
58#ifdef CONFIG_KFENCE
59 [KFENCE_START_NR] = {.start_address: 0, .name: "KFence Pool Start"},
60 [KFENCE_END_NR] = {.start_address: 0, .name: "KFence Pool End"},
61#endif
62 [IDENTITY_AFTER_NR] = {.start_address: (unsigned long)_end, .name: "Identity Mapping Start"},
63 [IDENTITY_AFTER_END_NR] = {.start_address: 0, .name: "Identity Mapping End"},
64 [VMEMMAP_NR] = {.start_address: 0, .name: "vmemmap Area Start"},
65 [VMEMMAP_END_NR] = {.start_address: 0, .name: "vmemmap Area End"},
66 [VMALLOC_NR] = {.start_address: 0, .name: "vmalloc Area Start"},
67 [VMALLOC_END_NR] = {.start_address: 0, .name: "vmalloc Area End"},
68 [MODULES_NR] = {.start_address: 0, .name: "Modules Area Start"},
69 [MODULES_END_NR] = {.start_address: 0, .name: "Modules Area End"},
70 [ABS_LOWCORE_NR] = {.start_address: 0, .name: "Lowcore Area Start"},
71 [ABS_LOWCORE_END_NR] = {.start_address: 0, .name: "Lowcore Area End"},
72 [MEMCPY_REAL_NR] = {.start_address: 0, .name: "Real Memory Copy Area Start"},
73 [MEMCPY_REAL_END_NR] = {.start_address: 0, .name: "Real Memory Copy Area End"},
74#ifdef CONFIG_KASAN
75 [KASAN_SHADOW_START_NR] = {KASAN_SHADOW_START, "Kasan Shadow Start"},
76 [KASAN_SHADOW_END_NR] = {KASAN_SHADOW_END, "Kasan Shadow End"},
77#endif
78 { -1, NULL }
79};
80
81struct pg_state {
82 struct ptdump_state ptdump;
83 struct seq_file *seq;
84 int level;
85 unsigned int current_prot;
86 bool check_wx;
87 unsigned long wx_pages;
88 unsigned long start_address;
89 const struct addr_marker *marker;
90};
91
92#define pt_dump_seq_printf(m, fmt, args...) \
93({ \
94 struct seq_file *__m = (m); \
95 \
96 if (__m) \
97 seq_printf(__m, fmt, ##args); \
98})
99
100#define pt_dump_seq_puts(m, fmt) \
101({ \
102 struct seq_file *__m = (m); \
103 \
104 if (__m) \
105 seq_printf(__m, fmt); \
106})
107
108static void print_prot(struct seq_file *m, unsigned int pr, int level)
109{
110 static const char * const level_name[] =
111 { "ASCE", "PGD", "PUD", "PMD", "PTE" };
112
113 pt_dump_seq_printf(m, "%s ", level_name[level]);
114 if (pr & _PAGE_INVALID) {
115 pt_dump_seq_printf(m, "I\n");
116 return;
117 }
118 pt_dump_seq_puts(m, (pr & _PAGE_PROTECT) ? "RO " : "RW ");
119 pt_dump_seq_puts(m, (pr & _PAGE_NOEXEC) ? "NX\n" : "X\n");
120}
121
122static void note_prot_wx(struct pg_state *st, unsigned long addr)
123{
124 if (!st->check_wx)
125 return;
126 if (st->current_prot & _PAGE_INVALID)
127 return;
128 if (st->current_prot & _PAGE_PROTECT)
129 return;
130 if (st->current_prot & _PAGE_NOEXEC)
131 return;
132 /*
133 * The first lowcore page is W+X if spectre mitigations are using
134 * trampolines or the BEAR enhancements facility is not installed,
135 * in which case we have two lpswe instructions in lowcore that need
136 * to be executable.
137 */
138 if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)))
139 return;
140 WARN_ONCE(IS_ENABLED(CONFIG_DEBUG_WX),
141 "s390/mm: Found insecure W+X mapping at address %pS\n",
142 (void *)st->start_address);
143 st->wx_pages += (addr - st->start_address) / PAGE_SIZE;
144}
145
146static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, u64 val)
147{
148 int width = sizeof(unsigned long) * 2;
149 static const char units[] = "KMGTPE";
150 const char *unit = units;
151 unsigned long delta;
152 struct pg_state *st;
153 struct seq_file *m;
154 unsigned int prot;
155
156 st = container_of(pt_st, struct pg_state, ptdump);
157 m = st->seq;
158 prot = val & (_PAGE_PROTECT | _PAGE_NOEXEC);
159 if (level == 4 && (val & _PAGE_INVALID))
160 prot = _PAGE_INVALID;
161 /* For pmd_none() & friends val gets passed as zero. */
162 if (level != 4 && !val)
163 prot = _PAGE_INVALID;
164 /* Final flush from generic code. */
165 if (level == -1)
166 addr = max_addr;
167 if (st->level == -1) {
168 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
169 st->start_address = addr;
170 st->current_prot = prot;
171 st->level = level;
172 } else if (prot != st->current_prot || level != st->level ||
173 addr >= st->marker[1].start_address) {
174 note_prot_wx(st, addr);
175 pt_dump_seq_printf(m, "0x%0*lx-0x%0*lx ",
176 width, st->start_address,
177 width, addr);
178 delta = (addr - st->start_address) >> 10;
179 while (!(delta & 0x3ff) && unit[1]) {
180 delta >>= 10;
181 unit++;
182 }
183 pt_dump_seq_printf(m, "%9lu%c ", delta, *unit);
184 print_prot(m, pr: st->current_prot, level: st->level);
185 while (addr >= st->marker[1].start_address) {
186 st->marker++;
187 pt_dump_seq_printf(m, "---[ %s ]---\n", st->marker->name);
188 }
189 st->start_address = addr;
190 st->current_prot = prot;
191 st->level = level;
192 }
193}
194
195bool ptdump_check_wx(void)
196{
197 struct pg_state st = {
198 .ptdump = {
199 .note_page = note_page,
200 .range = (struct ptdump_range[]) {
201 {.start = 0, .end = max_addr},
202 {.start = 0, .end = 0},
203 }
204 },
205 .seq = NULL,
206 .level = -1,
207 .current_prot = 0,
208 .check_wx = true,
209 .wx_pages = 0,
210 .start_address = 0,
211 .marker = (struct addr_marker[]) {
212 { .start_address = 0, .name = NULL},
213 { .start_address = -1, .name = NULL},
214 },
215 };
216
217 if (!MACHINE_HAS_NX)
218 return true;
219 ptdump_walk_pgd(st: &st.ptdump, mm: &init_mm, NULL);
220 if (st.wx_pages) {
221 pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages);
222
223 return false;
224 } else {
225 pr_info("Checked W+X mappings: passed, no %sW+X pages found\n",
226 (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ?
227 "unexpected " : "");
228
229 return true;
230 }
231}
232
233#ifdef CONFIG_PTDUMP_DEBUGFS
234static int ptdump_show(struct seq_file *m, void *v)
235{
236 struct pg_state st = {
237 .ptdump = {
238 .note_page = note_page,
239 .range = (struct ptdump_range[]) {
240 {.start = 0, .end = max_addr},
241 {.start = 0, .end = 0},
242 }
243 },
244 .seq = m,
245 .level = -1,
246 .current_prot = 0,
247 .check_wx = false,
248 .wx_pages = 0,
249 .start_address = 0,
250 .marker = address_markers,
251 };
252
253 get_online_mems();
254 mutex_lock(&cpa_mutex);
255 ptdump_walk_pgd(st: &st.ptdump, mm: &init_mm, NULL);
256 mutex_unlock(lock: &cpa_mutex);
257 put_online_mems();
258 return 0;
259}
260DEFINE_SHOW_ATTRIBUTE(ptdump);
261#endif /* CONFIG_PTDUMP_DEBUGFS */
262
263/*
264 * Heapsort from lib/sort.c is not a stable sorting algorithm, do a simple
265 * insertion sort to preserve the original order of markers with the same
266 * start address.
267 */
268static void sort_address_markers(void)
269{
270 struct addr_marker tmp;
271 int i, j;
272
273 for (i = 1; i < ARRAY_SIZE(address_markers) - 1; i++) {
274 tmp = address_markers[i];
275 for (j = i - 1; j >= 0 && address_markers[j].start_address > tmp.start_address; j--)
276 address_markers[j + 1] = address_markers[j];
277 address_markers[j + 1] = tmp;
278 }
279}
280
281static int pt_dump_init(void)
282{
283#ifdef CONFIG_KFENCE
284 unsigned long kfence_start = (unsigned long)__kfence_pool;
285#endif
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 = (S390_lowcore.kernel_asce.val & _REGION_ENTRY_TYPE_MASK) >> 2;
292 max_addr = 1UL << (max_addr * 11 + 31);
293 address_markers[IDENTITY_AFTER_END_NR].start_address = ident_map_size;
294 address_markers[AMODE31_START_NR].start_address = (unsigned long)__samode31;
295 address_markers[AMODE31_END_NR].start_address = (unsigned long)__eamode31;
296 address_markers[MODULES_NR].start_address = MODULES_VADDR;
297 address_markers[MODULES_END_NR].start_address = MODULES_END;
298 address_markers[ABS_LOWCORE_NR].start_address = __abs_lowcore;
299 address_markers[ABS_LOWCORE_END_NR].start_address = __abs_lowcore + ABS_LOWCORE_MAP_SIZE;
300 address_markers[MEMCPY_REAL_NR].start_address = __memcpy_real_area;
301 address_markers[MEMCPY_REAL_END_NR].start_address = __memcpy_real_area + MEMCPY_REAL_SIZE;
302 address_markers[VMEMMAP_NR].start_address = (unsigned long) vmemmap;
303 address_markers[VMEMMAP_END_NR].start_address = (unsigned long)vmemmap + vmemmap_size;
304 address_markers[VMALLOC_NR].start_address = VMALLOC_START;
305 address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
306#ifdef CONFIG_KFENCE
307 address_markers[KFENCE_START_NR].start_address = kfence_start;
308 address_markers[KFENCE_END_NR].start_address = kfence_start + KFENCE_POOL_SIZE;
309#endif
310 sort_address_markers();
311#ifdef CONFIG_PTDUMP_DEBUGFS
312 debugfs_create_file(name: "kernel_page_tables", mode: 0400, NULL, NULL, fops: &ptdump_fops);
313#endif /* CONFIG_PTDUMP_DEBUGFS */
314 return 0;
315}
316device_initcall(pt_dump_init);
317

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