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
get_max_dump_pfn(void)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 counts
41 *
42 * Each entry is a u64 representing the corresponding
43 * physical page count.
44 */
kpagecount_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)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 struct page *ppage;
51 unsigned long src = *ppos;
52 unsigned long pfn;
53 ssize_t ret = 0;
54 u64 pcount;
55
56 pfn = src / KPMSIZE;
57 if (src & KPMMASK || count & KPMMASK)
58 return -EINVAL;
59 if (src >= max_dump_pfn * KPMSIZE)
60 return 0;
61 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
62
63 while (count > 0) {
64 /*
65 * TODO: ZONE_DEVICE support requires to identify
66 * memmaps that were actually initialized.
67 */
68 ppage = pfn_to_online_page(pfn);
69
70 if (!ppage || PageSlab(ppage) || page_has_type(ppage))
71 pcount = 0;
72 else
73 pcount = page_mapcount(ppage);
74
75 if (put_user(pcount, out)) {
76 ret = -EFAULT;
77 break;
78 }
79
80 pfn++;
81 out++;
82 count -= KPMSIZE;
83
84 cond_resched();
85 }
86
87 *ppos += (char __user *)out - buf;
88 if (!ret)
89 ret = (char __user *)out - buf;
90 return ret;
91 }
92
93 static const struct proc_ops kpagecount_proc_ops = {
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
kpf_copy_bit(u64 kflags,int ubit,int kbit)104 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
105 {
106 return ((kflags >> kbit) & 1) << ubit;
107 }
108
stable_page_flags(struct page * page)109 u64 stable_page_flags(struct page *page)
110 {
111 u64 k;
112 u64 u;
113
114 /*
115 * pseudo flag: KPF_NOPAGE
116 * it differentiates a memory hole from a page with no flags
117 */
118 if (!page)
119 return 1 << KPF_NOPAGE;
120
121 k = page->flags;
122 u = 0;
123
124 /*
125 * pseudo flags for the well known (anonymous) memory mapped pages
126 *
127 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
128 * simple test in page_mapped() is not enough.
129 */
130 if (!PageSlab(page) && page_mapped(page))
131 u |= 1 << KPF_MMAP;
132 if (PageAnon(page))
133 u |= 1 << KPF_ANON;
134 if (PageKsm(page))
135 u |= 1 << KPF_KSM;
136
137 /*
138 * compound pages: export both head/tail info
139 * they together define a compound page's start/end pos and order
140 */
141 if (PageHead(page))
142 u |= 1 << KPF_COMPOUND_HEAD;
143 if (PageTail(page))
144 u |= 1 << KPF_COMPOUND_TAIL;
145 if (PageHuge(page))
146 u |= 1 << KPF_HUGE;
147 /*
148 * PageTransCompound can be true for non-huge compound pages (slab
149 * pages or pages allocated by drivers with __GFP_COMP) because it
150 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
151 * to make sure a given page is a thp, not a non-huge compound page.
152 */
153 else if (PageTransCompound(page)) {
154 struct page *head = compound_head(page);
155
156 if (PageLRU(head) || PageAnon(head))
157 u |= 1 << KPF_THP;
158 else if (is_huge_zero_page(head)) {
159 u |= 1 << KPF_ZERO_PAGE;
160 u |= 1 << KPF_THP;
161 }
162 } else if (is_zero_pfn(page_to_pfn(page)))
163 u |= 1 << KPF_ZERO_PAGE;
164
165
166 /*
167 * Caveats on high order pages: page->_refcount will only be set
168 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
169 * SLOB won't set PG_slab at all on compound pages.
170 */
171 if (PageBuddy(page))
172 u |= 1 << KPF_BUDDY;
173 else if (page_count(page) == 0 && is_free_buddy_page(page))
174 u |= 1 << KPF_BUDDY;
175
176 if (PageOffline(page))
177 u |= 1 << KPF_OFFLINE;
178 if (PageTable(page))
179 u |= 1 << KPF_PGTABLE;
180
181 if (page_is_idle(page))
182 u |= 1 << KPF_IDLE;
183
184 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
185
186 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
187 if (PageTail(page) && PageSlab(compound_head(page)))
188 u |= 1 << KPF_SLAB;
189
190 u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
191 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
192 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
193 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
194
195 u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
196 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
197 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
198 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
199
200 if (PageSwapCache(page))
201 u |= 1 << KPF_SWAPCACHE;
202 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
203
204 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
205 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
206
207 #ifdef CONFIG_MEMORY_FAILURE
208 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
209 #endif
210
211 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
212 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached);
213 #endif
214
215 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
216 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk);
217 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
218 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
219 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
220 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
221 #ifdef CONFIG_64BIT
222 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
223 #endif
224
225 return u;
226 };
227
kpageflags_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)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 struct page *ppage;
234 unsigned long src = *ppos;
235 unsigned long pfn;
236 ssize_t ret = 0;
237
238 pfn = src / KPMSIZE;
239 if (src & KPMMASK || count & KPMMASK)
240 return -EINVAL;
241 if (src >= max_dump_pfn * KPMSIZE)
242 return 0;
243 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
244
245 while (count > 0) {
246 /*
247 * TODO: ZONE_DEVICE support requires to identify
248 * memmaps that were actually initialized.
249 */
250 ppage = pfn_to_online_page(pfn);
251
252 if (put_user(stable_page_flags(ppage), out)) {
253 ret = -EFAULT;
254 break;
255 }
256
257 pfn++;
258 out++;
259 count -= KPMSIZE;
260
261 cond_resched();
262 }
263
264 *ppos += (char __user *)out - buf;
265 if (!ret)
266 ret = (char __user *)out - buf;
267 return ret;
268 }
269
270 static const struct proc_ops kpageflags_proc_ops = {
271 .proc_lseek = mem_lseek,
272 .proc_read = kpageflags_read,
273 };
274
275 #ifdef CONFIG_MEMCG
kpagecgroup_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)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_lseek = mem_lseek,
326 .proc_read = kpagecgroup_read,
327 };
328 #endif /* CONFIG_MEMCG */
329
proc_page_init(void)330 static int __init proc_page_init(void)
331 {
332 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops);
333 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops);
334 #ifdef CONFIG_MEMCG
335 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops);
336 #endif
337 return 0;
338 }
339 fs_initcall(proc_page_init);
340