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 enum kpage_operation {
26 KPAGE_FLAGS,
27 KPAGE_COUNT,
28 KPAGE_CGROUP,
29 };
30
get_max_dump_pfn(void)31 static inline unsigned long get_max_dump_pfn(void)
32 {
33 #ifdef CONFIG_SPARSEMEM
34 /*
35 * The memmap of early sections is completely populated and marked
36 * online even if max_pfn does not fall on a section boundary -
37 * pfn_to_online_page() will succeed on all pages. Allow inspecting
38 * these memmaps.
39 */
40 return round_up(max_pfn, PAGES_PER_SECTION);
41 #else
42 return max_pfn;
43 #endif
44 }
45
kpage_read(struct file * file,char __user * buf,size_t count,loff_t * ppos,enum kpage_operation op)46 static ssize_t kpage_read(struct file *file, char __user *buf,
47 size_t count, loff_t *ppos,
48 enum kpage_operation op)
49 {
50 const unsigned long max_dump_pfn = get_max_dump_pfn();
51 u64 __user *out = (u64 __user *)buf;
52 struct page *page;
53 unsigned long src = *ppos;
54 unsigned long pfn;
55 ssize_t ret = 0;
56 u64 info;
57
58 pfn = src / KPMSIZE;
59 if (src & KPMMASK || count & KPMMASK)
60 return -EINVAL;
61 if (src >= max_dump_pfn * KPMSIZE)
62 return 0;
63 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src);
64
65 while (count > 0) {
66 /*
67 * TODO: ZONE_DEVICE support requires to identify
68 * memmaps that were actually initialized.
69 */
70 page = pfn_to_online_page(pfn);
71
72 if (page) {
73 switch (op) {
74 case KPAGE_FLAGS:
75 info = stable_page_flags(page);
76 break;
77 case KPAGE_COUNT:
78 if (IS_ENABLED(CONFIG_PAGE_MAPCOUNT))
79 info = folio_precise_page_mapcount(page_folio(page), page);
80 else
81 info = folio_average_page_mapcount(page_folio(page));
82 break;
83 case KPAGE_CGROUP:
84 info = page_cgroup_ino(page);
85 break;
86 default:
87 info = 0;
88 break;
89 }
90 } else
91 info = 0;
92
93 if (put_user(info, out)) {
94 ret = -EFAULT;
95 break;
96 }
97
98 pfn++;
99 out++;
100 count -= KPMSIZE;
101
102 cond_resched();
103 }
104
105 *ppos += (char __user *)out - buf;
106 if (!ret)
107 ret = (char __user *)out - buf;
108 return ret;
109 }
110
111 /* /proc/kpagecount - an array exposing page mapcounts
112 *
113 * Each entry is a u64 representing the corresponding
114 * physical page mapcount.
115 */
kpagecount_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)116 static ssize_t kpagecount_read(struct file *file, char __user *buf,
117 size_t count, loff_t *ppos)
118 {
119 return kpage_read(file, buf, count, ppos, KPAGE_COUNT);
120 }
121
122 static const struct proc_ops kpagecount_proc_ops = {
123 .proc_flags = PROC_ENTRY_PERMANENT,
124 .proc_lseek = mem_lseek,
125 .proc_read = kpagecount_read,
126 };
127
128
kpf_copy_bit(u64 kflags,int ubit,int kbit)129 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
130 {
131 return ((kflags >> kbit) & 1) << ubit;
132 }
133
stable_page_flags(const struct page * page)134 u64 stable_page_flags(const struct page *page)
135 {
136 const struct folio *folio;
137 unsigned long k;
138 unsigned long mapping;
139 bool is_anon;
140 u64 u = 0;
141
142 /*
143 * pseudo flag: KPF_NOPAGE
144 * it differentiates a memory hole from a page with no flags
145 */
146 if (!page)
147 return 1 << KPF_NOPAGE;
148 folio = page_folio(page);
149
150 k = folio->flags;
151 mapping = (unsigned long)folio->mapping;
152 is_anon = mapping & PAGE_MAPPING_ANON;
153
154 /*
155 * pseudo flags for the well known (anonymous) memory mapped pages
156 */
157 if (page_mapped(page))
158 u |= 1 << KPF_MMAP;
159 if (is_anon) {
160 u |= 1 << KPF_ANON;
161 if (mapping & PAGE_MAPPING_KSM)
162 u |= 1 << KPF_KSM;
163 }
164
165 /*
166 * compound pages: export both head/tail info
167 * they together define a compound page's start/end pos and order
168 */
169 if (page == &folio->page)
170 u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head);
171 else
172 u |= 1 << KPF_COMPOUND_TAIL;
173 if (folio_test_hugetlb(folio))
174 u |= 1 << KPF_HUGE;
175 else if (folio_test_large(folio) &&
176 folio_test_large_rmappable(folio)) {
177 /* Note: we indicate any THPs here, not just PMD-sized ones */
178 u |= 1 << KPF_THP;
179 } else if (is_huge_zero_folio(folio)) {
180 u |= 1 << KPF_ZERO_PAGE;
181 u |= 1 << KPF_THP;
182 } else if (is_zero_folio(folio)) {
183 u |= 1 << KPF_ZERO_PAGE;
184 }
185
186 /*
187 * Caveats on high order pages: PG_buddy and PG_slab will only be set
188 * on the head page.
189 */
190 if (PageBuddy(page))
191 u |= 1 << KPF_BUDDY;
192 else if (page_count(page) == 0 && is_free_buddy_page(page))
193 u |= 1 << KPF_BUDDY;
194
195 if (PageOffline(page))
196 u |= 1 << KPF_OFFLINE;
197 if (PageTable(page))
198 u |= 1 << KPF_PGTABLE;
199 if (folio_test_slab(folio))
200 u |= 1 << KPF_SLAB;
201
202 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
203 u |= kpf_copy_bit(k, KPF_IDLE, PG_idle);
204 #else
205 if (folio_test_idle(folio))
206 u |= 1 << KPF_IDLE;
207 #endif
208
209 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
210 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
211 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
212 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
213
214 u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
215 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
216 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
217 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
218
219 #define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache))
220 if ((k & SWAPCACHE) == SWAPCACHE)
221 u |= 1 << KPF_SWAPCACHE;
222 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
223
224 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
225 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
226
227 #ifdef CONFIG_MEMORY_FAILURE
228 if (u & (1 << KPF_HUGE))
229 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
230 else
231 u |= kpf_copy_bit(page->flags, KPF_HWPOISON, PG_hwpoison);
232 #endif
233
234 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
235 u |= kpf_copy_bit(k, KPF_OWNER_2, PG_owner_2);
236 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
237 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
238 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
239 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
240 #ifdef CONFIG_ARCH_USES_PG_ARCH_2
241 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2);
242 #endif
243 #ifdef CONFIG_ARCH_USES_PG_ARCH_3
244 u |= kpf_copy_bit(k, KPF_ARCH_3, PG_arch_3);
245 #endif
246
247 return u;
248 }
249
250 /* /proc/kpageflags - an array exposing page flags
251 *
252 * Each entry is a u64 representing the corresponding
253 * physical page flags.
254 */
kpageflags_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)255 static ssize_t kpageflags_read(struct file *file, char __user *buf,
256 size_t count, loff_t *ppos)
257 {
258 return kpage_read(file, buf, count, ppos, KPAGE_FLAGS);
259 }
260
261 static const struct proc_ops kpageflags_proc_ops = {
262 .proc_flags = PROC_ENTRY_PERMANENT,
263 .proc_lseek = mem_lseek,
264 .proc_read = kpageflags_read,
265 };
266
267 #ifdef CONFIG_MEMCG
kpagecgroup_read(struct file * file,char __user * buf,size_t count,loff_t * ppos)268 static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
269 size_t count, loff_t *ppos)
270 {
271 return kpage_read(file, buf, count, ppos, KPAGE_CGROUP);
272 }
273 static const struct proc_ops kpagecgroup_proc_ops = {
274 .proc_flags = PROC_ENTRY_PERMANENT,
275 .proc_lseek = mem_lseek,
276 .proc_read = kpagecgroup_read,
277 };
278 #endif /* CONFIG_MEMCG */
279
proc_page_init(void)280 static int __init proc_page_init(void)
281 {
282 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops);
283 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops);
284 #ifdef CONFIG_MEMCG
285 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops);
286 #endif
287 return 0;
288 }
289 fs_initcall(proc_page_init);
290