1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/memblock.h>
3 #include <linux/compiler.h>
4 #include <linux/fs.h>
5 #include <linux/init.h>
6 #include <linux/ksm.h>
7 #include <linux/mm.h>
8 #include <linux/mmzone.h>
9 #include <linux/huge_mm.h>
10 #include <linux/proc_fs.h>
11 #include <linux/seq_file.h>
12 #include <linux/hugetlb.h>
13 #include <linux/memremap.h>
14 #include <linux/memcontrol.h>
15 #include <linux/mmu_notifier.h>
16 #include <linux/page_idle.h>
17 #include <linux/kernel-page-flags.h>
18 #include <linux/uaccess.h>
19 #include "internal.h"
20
21 #define KPMSIZE sizeof(u64)
22 #define KPMMASK (KPMSIZE - 1)
23 #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
24
25 static inline unsigned long get_max_dump_pfn(void)
26 {
27 #ifdef CONFIG_SPARSEMEM
28 /*
29 * The memmap of early sections is completely populated and marked
30 * online even if max_pfn does not fall on a section boundary -
31 * pfn_to_online_page() will succeed on all pages. Allow inspecting
32 * these memmaps.
33 */
34 return round_up(max_pfn, PAGES_PER_SECTION);
35 #else
36 return max_pfn;
37 #endif
38 }
39
40 /* /proc/kpagecount - an array exposing page mapcounts
41 *
42 * Each entry is a u64 representing the corresponding
43 * physical page mapcount.
44 */
45 static ssize_t kpagecount_read(struct file *file, char __user *buf,
46 size_t count, loff_t *ppos)
47 {
48 const unsigned long max_dump_pfn = get_max_dump_pfn();
49 u64 __user *out = (u64 __user *)buf;
50 unsigned long src = *ppos;
51 unsigned long pfn;
52 ssize_t ret = 0;
53
54 pfn = src / KPMSIZE;
55 if (src & KPMMASK || count & KPMMASK)
56 return -EINVAL;
57 if (src >= max_dump_pfn * KPMSIZE)
58 return 0;
59 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
60
61 while (count > 0) {
62 struct page *page;
63 u64 mapcount = 0;
64
65 /*
66 * TODO: ZONE_DEVICE support requires to identify
67 * memmaps that were actually initialized.
68 */
69 page = pfn_to_online_page(pfn);
70 if (page)
71 mapcount = folio_precise_page_mapcount(page_folio(page),
72 page);
73
74 if (put_user(mapcount, out)) {
75 ret = -EFAULT;
76 break;
77 }
78
79 pfn++;
80 out++;
81 count -= KPMSIZE;
82
83 cond_resched();
84 }
85
86 *ppos += (char __user *)out - buf;
87 if (!ret)
88 ret = (char __user *)out - buf;
89 return ret;
90 }
91
92 static const struct proc_ops kpagecount_proc_ops = {
93 .proc_flags = PROC_ENTRY_PERMANENT,
94 .proc_lseek = mem_lseek,
95 .proc_read = kpagecount_read,
96 };
97
98 /* /proc/kpageflags - an array exposing page flags
99 *
100 * Each entry is a u64 representing the corresponding
101 * physical page flags.
102 */
103
104 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
105 {
106 return ((kflags >> kbit) & 1) << ubit;
107 }
108
109 u64 stable_page_flags(const struct page *page)
110 {
111 const struct folio *folio;
112 unsigned long k;
113 unsigned long mapping;
114 bool is_anon;
115 u64 u = 0;
116
117 /*
118 * pseudo flag: KPF_NOPAGE
119 * it differentiates a memory hole from a page with no flags
120 */
121 if (!page)
122 return 1 << KPF_NOPAGE;
123 folio = page_folio(page);
124
125 k = folio->flags;
126 mapping = (unsigned long)folio->mapping;
127 is_anon = mapping & PAGE_MAPPING_ANON;
128
129 /*
130 * pseudo flags for the well known (anonymous) memory mapped pages
131 */
132 if (page_mapped(page))
133 u |= 1 << KPF_MMAP;
134 if (is_anon) {
135 u |= 1 << KPF_ANON;
136 if (mapping & PAGE_MAPPING_KSM)
137 u |= 1 << KPF_KSM;
138 }
139
140 /*
141 * compound pages: export both head/tail info
142 * they together define a compound page's start/end pos and order
143 */
144 if (page == &folio->page)
145 u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
146 else
147 u |= 1 << KPF_COMPOUND_TAIL;
148 if (folio_test_hugetlb(folio))
149 u |= 1 << KPF_HUGE;
150 else if (folio_test_large(folio) &&
151 folio_test_large_rmappable(folio)) {
152 /* Note: we indicate any THPs here, not just PMD-sized ones */
153 u |= 1 << KPF_THP;
154 } else if (is_huge_zero_folio(folio)) {
155 u |= 1 << KPF_ZERO_PAGE;
156 u |= 1 << KPF_THP;
157 } else if (is_zero_folio(folio)) {
158 u |= 1 << KPF_ZERO_PAGE;
159 }
160
161 /*
162 * Caveats on high order pages: PG_buddy and PG_slab will only be set
163 * on the head page.
164 */
165 if (PageBuddy(page))
166 u |= 1 << KPF_BUDDY;
167 else if (page_count(page) == 0 && is_free_buddy_page(page))
168 u |= 1 << KPF_BUDDY;
169
170 if (PageOffline(page))
171 u |= 1 << KPF_OFFLINE;
172 if (PageTable(page))
173 u |= 1 << KPF_PGTABLE;
174 if (folio_test_slab(folio))
175 u |= 1 << KPF_SLAB;
176
177 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
178 u |= kpf_copy_bit(k, KPF_IDLE, PG_idle);
179 #else
180 if (folio_test_idle(folio))
181 u |= 1 << KPF_IDLE;
182 #endif
183
184 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
185 u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
186 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
187 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
188 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
189
190 u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
191 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
192 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
193 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
194
195 #define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache))
196 if ((k & SWAPCACHE) == SWAPCACHE)
197 u |= 1 << KPF_SWAPCACHE;
198 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
199
200 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
201 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
202
203 #ifdef CONFIG_MEMORY_FAILURE
204 if (u & (1 << KPF_HUGE))
205 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
206 else
207 u |= kpf_copy_bit(page->flags, KPF_HWPOISON, PG_hwpoison);
208 #endif
209
210 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
211 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached);
212 #endif
213
214 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
215 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk);
216 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
217 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
218 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
219 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
220 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
221 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
222 u |= kpf_copy_bit(k, KPF_ARCH_3, PG_arch_3);
223 #endif
224
225 return u;
226 };
227
228 static ssize_t kpageflags_read(struct file *file, char __user *buf,
229 size_t count, loff_t *ppos)
230 {
231 const unsigned long max_dump_pfn = get_max_dump_pfn();
232 u64 __user *out = (u64 __user *)buf;
233 unsigned long src = *ppos;
234 unsigned long pfn;
235 ssize_t ret = 0;
236
237 pfn = src / KPMSIZE;
238 if (src & KPMMASK || count & KPMMASK)
239 return -EINVAL;
240 if (src >= max_dump_pfn * KPMSIZE)
241 return 0;
242 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
243
244 while (count > 0) {
245 /*
246 * TODO: ZONE_DEVICE support requires to identify
247 * memmaps that were actually initialized.
248 */
249 struct page *page = pfn_to_online_page(pfn);
250
251 if (put_user(stable_page_flags(page), out)) {
252 ret = -EFAULT;
253 break;
254 }
255
256 pfn++;
257 out++;
258 count -= KPMSIZE;
259
260 cond_resched();
261 }
262
263 *ppos += (char __user *)out - buf;
264 if (!ret)
265 ret = (char __user *)out - buf;
266 return ret;
267 }
268
269 static const struct proc_ops kpageflags_proc_ops = {
270 .proc_flags = PROC_ENTRY_PERMANENT,
271 .proc_lseek = mem_lseek,
272 .proc_read = kpageflags_read,
273 };
274
275 #ifdef CONFIG_MEMCG
276 static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
277 size_t count, loff_t *ppos)
278 {
279 const unsigned long max_dump_pfn = get_max_dump_pfn();
280 u64 __user *out = (u64 __user *)buf;
281 struct page *ppage;
282 unsigned long src = *ppos;
283 unsigned long pfn;
284 ssize_t ret = 0;
285 u64 ino;
286
287 pfn = src / KPMSIZE;
288 if (src & KPMMASK || count & KPMMASK)
289 return -EINVAL;
290 if (src >= max_dump_pfn * KPMSIZE)
291 return 0;
292 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
293
294 while (count > 0) {
295 /*
296 * TODO: ZONE_DEVICE support requires to identify
297 * memmaps that were actually initialized.
298 */
299 ppage = pfn_to_online_page(pfn);
300
301 if (ppage)
302 ino = page_cgroup_ino(ppage);
303 else
304 ino = 0;
305
306 if (put_user(ino, out)) {
307 ret = -EFAULT;
308 break;
309 }
310
311 pfn++;
312 out++;
313 count -= KPMSIZE;
314
315 cond_resched();
316 }
317
318 *ppos += (char __user *)out - buf;
319 if (!ret)
320 ret = (char __user *)out - buf;
321 return ret;
322 }
323
324 static const struct proc_ops kpagecgroup_proc_ops = {
325 .proc_flags = PROC_ENTRY_PERMANENT,
326 .proc_lseek = mem_lseek,
327 .proc_read = kpagecgroup_read,
328 };
329 #endif /* CONFIG_MEMCG */
330
331 static int __init proc_page_init(void)
332 {
333 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops);
334 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops);
335 #ifdef CONFIG_MEMCG
336 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops);
337 #endif
338 return 0;
339 }
340 fs_initcall(proc_page_init);
341
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