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/memcontrol.h>
14 #include <linux/mmu_notifier.h>
15 #include <linux/page_idle.h>
16 #include <linux/kernel-page-flags.h>
17 #include <linux/uaccess.h>
18 #include "internal.h"
19
20 #define KPMSIZE sizeof(u64)
21 #define KPMMASK (KPMSIZE - 1)
22 #define KPMBITS (KPMSIZE * BITS_PER_BYTE)
23
get_max_dump_pfn(void)24 static inline unsigned long get_max_dump_pfn(void)
25 {
26 #ifdef CONFIG_SPARSEMEM
27 /*
28 * The memmap of early sections is completely populated and marked
29 * online even if max_pfn does not fall on a section boundary -
30 * pfn_to_online_page() will succeed on all pages. Allow inspecting
31 * these memmaps.
32 */
33 return round_up(max_pfn, PAGES_PER_SECTION);
34 #else
35 return max_pfn;
36 #endif
37 }
38
39 /* /proc/kpagecount - an array exposing page counts
40 *
41 * Each entry is a u64 representing the corresponding
42 * physical page count.
43 */
kpagecount_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)44 static ssize_t kpagecount_read(struct file *file, char __user *buf,
45 size_t count, loff_t *ppos)
46 {
47 const unsigned long max_dump_pfn = get_max_dump_pfn();
48 u64 __user *out = (u64 __user *)buf;
49 struct page *ppage;
50 unsigned long src = *ppos;
51 unsigned long pfn;
52 ssize_t ret = 0;
53 u64 pcount;
54
55 pfn = src / KPMSIZE;
56 if (src & KPMMASK || count & KPMMASK)
57 return -EINVAL;
58 if (src >= max_dump_pfn * KPMSIZE)
59 return 0;
60 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
61
62 while (count > 0) {
63 /*
64 * TODO: ZONE_DEVICE support requires to identify
65 * memmaps that were actually initialized.
66 */
67 ppage = pfn_to_online_page(pfn);
68
69 if (!ppage || PageSlab(ppage) || page_has_type(ppage))
70 pcount = 0;
71 else
72 pcount = page_mapcount(ppage);
73
74 if (put_user(pcount, 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_lseek = mem_lseek,
94 .proc_read = kpagecount_read,
95 };
96
97 /* /proc/kpageflags - an array exposing page flags
98 *
99 * Each entry is a u64 representing the corresponding
100 * physical page flags.
101 */
102
kpf_copy_bit(u64 kflags,int ubit,int kbit)103 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
104 {
105 return ((kflags >> kbit) & 1) << ubit;
106 }
107
stable_page_flags(struct page * page)108 u64 stable_page_flags(struct page *page)
109 {
110 u64 k;
111 u64 u;
112
113 /*
114 * pseudo flag: KPF_NOPAGE
115 * it differentiates a memory hole from a page with no flags
116 */
117 if (!page)
118 return 1 << KPF_NOPAGE;
119
120 k = page->flags;
121 u = 0;
122
123 /*
124 * pseudo flags for the well known (anonymous) memory mapped pages
125 *
126 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
127 * simple test in page_mapped() is not enough.
128 */
129 if (!PageSlab(page) && page_mapped(page))
130 u |= 1 << KPF_MMAP;
131 if (PageAnon(page))
132 u |= 1 << KPF_ANON;
133 if (PageKsm(page))
134 u |= 1 << KPF_KSM;
135
136 /*
137 * compound pages: export both head/tail info
138 * they together define a compound page's start/end pos and order
139 */
140 if (PageHead(page))
141 u |= 1 << KPF_COMPOUND_HEAD;
142 if (PageTail(page))
143 u |= 1 << KPF_COMPOUND_TAIL;
144 if (PageHuge(page))
145 u |= 1 << KPF_HUGE;
146 /*
147 * PageTransCompound can be true for non-huge compound pages (slab
148 * pages or pages allocated by drivers with __GFP_COMP) because it
149 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
150 * to make sure a given page is a thp, not a non-huge compound page.
151 */
152 else if (PageTransCompound(page)) {
153 struct page *head = compound_head(page);
154
155 if (PageLRU(head) || PageAnon(head))
156 u |= 1 << KPF_THP;
157 else if (is_huge_zero_page(head)) {
158 u |= 1 << KPF_ZERO_PAGE;
159 u |= 1 << KPF_THP;
160 }
161 } else if (is_zero_pfn(page_to_pfn(page)))
162 u |= 1 << KPF_ZERO_PAGE;
163
164
165 /*
166 * Caveats on high order pages: page->_refcount will only be set
167 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
168 * SLOB won't set PG_slab at all on compound pages.
169 */
170 if (PageBuddy(page))
171 u |= 1 << KPF_BUDDY;
172 else if (page_count(page) == 0 && is_free_buddy_page(page))
173 u |= 1 << KPF_BUDDY;
174
175 if (PageOffline(page))
176 u |= 1 << KPF_OFFLINE;
177 if (PageTable(page))
178 u |= 1 << KPF_PGTABLE;
179
180 if (page_is_idle(page))
181 u |= 1 << KPF_IDLE;
182
183 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
184
185 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
186 if (PageTail(page) && PageSlab(compound_head(page)))
187 u |= 1 << KPF_SLAB;
188
189 u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
190 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
191 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
192 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
193
194 u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
195 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
196 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
197 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
198
199 if (PageSwapCache(page))
200 u |= 1 << KPF_SWAPCACHE;
201 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
202
203 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
204 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
205
206 #ifdef CONFIG_MEMORY_FAILURE
207 u |= kpf_copy_bit(k, 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_64BIT
221 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
222 #endif
223
224 return u;
225 };
226
kpageflags_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)227 static ssize_t kpageflags_read(struct file *file, char __user *buf,
228 size_t count, loff_t *ppos)
229 {
230 const unsigned long max_dump_pfn = get_max_dump_pfn();
231 u64 __user *out = (u64 __user *)buf;
232 struct page *ppage;
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 ppage = pfn_to_online_page(pfn);
250
251 if (put_user(stable_page_flags(ppage), 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_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_lseek = mem_lseek,
325 .proc_read = kpagecgroup_read,
326 };
327 #endif /* CONFIG_MEMCG */
328
proc_page_init(void)329 static int __init proc_page_init(void)
330 {
331 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops);
332 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops);
333 #ifdef CONFIG_MEMCG
334 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops);
335 #endif
336 return 0;
337 }
338 fs_initcall(proc_page_init);
339