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)
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_flags = PROC_ENTRY_PERMANENT,
95 .proc_lseek = mem_lseek,
96 .proc_read = kpagecount_read,
97 };
98
99 /* /proc/kpageflags - an array exposing page flags
100 *
101 * Each entry is a u64 representing the corresponding
102 * physical page flags.
103 */
104
kpf_copy_bit(u64 kflags,int ubit,int kbit)105 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
106 {
107 return ((kflags >> kbit) & 1) << ubit;
108 }
109
stable_page_flags(struct page * page)110 u64 stable_page_flags(struct page *page)
111 {
112 u64 k;
113 u64 u;
114
115 /*
116 * pseudo flag: KPF_NOPAGE
117 * it differentiates a memory hole from a page with no flags
118 */
119 if (!page)
120 return 1 << KPF_NOPAGE;
121
122 k = page->flags;
123 u = 0;
124
125 /*
126 * pseudo flags for the well known (anonymous) memory mapped pages
127 */
128 if (page_mapped(page))
129 u |= 1 << KPF_MMAP;
130 if (PageAnon(page))
131 u |= 1 << KPF_ANON;
132 if (PageKsm(page))
133 u |= 1 << KPF_KSM;
134
135 /*
136 * compound pages: export both head/tail info
137 * they together define a compound page's start/end pos and order
138 */
139 if (PageHead(page))
140 u |= 1 << KPF_COMPOUND_HEAD;
141 if (PageTail(page))
142 u |= 1 << KPF_COMPOUND_TAIL;
143 if (PageHuge(page))
144 u |= 1 << KPF_HUGE;
145 /*
146 * PageTransCompound can be true for non-huge compound pages (slab
147 * pages or pages allocated by drivers with __GFP_COMP) because it
148 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
149 * to make sure a given page is a thp, not a non-huge compound page.
150 */
151 else if (PageTransCompound(page)) {
152 struct page *head = compound_head(page);
153
154 if (PageLRU(head) || PageAnon(head))
155 u |= 1 << KPF_THP;
156 else if (is_huge_zero_page(head)) {
157 u |= 1 << KPF_ZERO_PAGE;
158 u |= 1 << KPF_THP;
159 }
160 } else if (is_zero_pfn(page_to_pfn(page)))
161 u |= 1 << KPF_ZERO_PAGE;
162
163
164 /*
165 * Caveats on high order pages: PG_buddy and PG_slab will only be set
166 * on the head page.
167 */
168 if (PageBuddy(page))
169 u |= 1 << KPF_BUDDY;
170 else if (page_count(page) == 0 && is_free_buddy_page(page))
171 u |= 1 << KPF_BUDDY;
172
173 if (PageOffline(page))
174 u |= 1 << KPF_OFFLINE;
175 if (PageTable(page))
176 u |= 1 << KPF_PGTABLE;
177
178 if (page_is_idle(page))
179 u |= 1 << KPF_IDLE;
180
181 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
182
183 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
184 if (PageTail(page) && PageSlab(page))
185 u |= 1 << KPF_SLAB;
186
187 u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
188 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
189 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
190 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
191
192 u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
193 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
194 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
195 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
196
197 if (PageSwapCache(page))
198 u |= 1 << KPF_SWAPCACHE;
199 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
200
201 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
202 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
203
204 #ifdef CONFIG_MEMORY_FAILURE
205 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
206 #endif
207
208 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
209 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached);
210 #endif
211
212 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
213 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk);
214 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
215 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
216 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
217 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
218 #ifdef CONFIG_ARCH_USES_PG_ARCH_X
219 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
220 u |= kpf_copy_bit(k, KPF_ARCH_3, PG_arch_3);
221 #endif
222
223 return u;
224 };
225
kpageflags_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)226 static ssize_t kpageflags_read(struct file *file, char __user *buf,
227 size_t count, loff_t *ppos)
228 {
229 const unsigned long max_dump_pfn = get_max_dump_pfn();
230 u64 __user *out = (u64 __user *)buf;
231 struct page *ppage;
232 unsigned long src = *ppos;
233 unsigned long pfn;
234 ssize_t ret = 0;
235
236 pfn = src / KPMSIZE;
237 if (src & KPMMASK || count & KPMMASK)
238 return -EINVAL;
239 if (src >= max_dump_pfn * KPMSIZE)
240 return 0;
241 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
242
243 while (count > 0) {
244 /*
245 * TODO: ZONE_DEVICE support requires to identify
246 * memmaps that were actually initialized.
247 */
248 ppage = pfn_to_online_page(pfn);
249
250 if (put_user(stable_page_flags(ppage), out)) {
251 ret = -EFAULT;
252 break;
253 }
254
255 pfn++;
256 out++;
257 count -= KPMSIZE;
258
259 cond_resched();
260 }
261
262 *ppos += (char __user *)out - buf;
263 if (!ret)
264 ret = (char __user *)out - buf;
265 return ret;
266 }
267
268 static const struct proc_ops kpageflags_proc_ops = {
269 .proc_flags = PROC_ENTRY_PERMANENT,
270 .proc_lseek = mem_lseek,
271 .proc_read = kpageflags_read,
272 };
273
274 #ifdef CONFIG_MEMCG
kpagecgroup_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)275 static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
276 size_t count, loff_t *ppos)
277 {
278 const unsigned long max_dump_pfn = get_max_dump_pfn();
279 u64 __user *out = (u64 __user *)buf;
280 struct page *ppage;
281 unsigned long src = *ppos;
282 unsigned long pfn;
283 ssize_t ret = 0;
284 u64 ino;
285
286 pfn = src / KPMSIZE;
287 if (src & KPMMASK || count & KPMMASK)
288 return -EINVAL;
289 if (src >= max_dump_pfn * KPMSIZE)
290 return 0;
291 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
292
293 while (count > 0) {
294 /*
295 * TODO: ZONE_DEVICE support requires to identify
296 * memmaps that were actually initialized.
297 */
298 ppage = pfn_to_online_page(pfn);
299
300 if (ppage)
301 ino = page_cgroup_ino(ppage);
302 else
303 ino = 0;
304
305 if (put_user(ino, out)) {
306 ret = -EFAULT;
307 break;
308 }
309
310 pfn++;
311 out++;
312 count -= KPMSIZE;
313
314 cond_resched();
315 }
316
317 *ppos += (char __user *)out - buf;
318 if (!ret)
319 ret = (char __user *)out - buf;
320 return ret;
321 }
322
323 static const struct proc_ops kpagecgroup_proc_ops = {
324 .proc_flags = PROC_ENTRY_PERMANENT,
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