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 counts 41 * 42 * Each entry is a u64 representing the corresponding 43 * physical page count. 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 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 */ 104 105 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit) 106 { 107 return ((kflags >> kbit) & 1) << ubit; 108 } 109 110 u64 stable_page_flags(const struct page *page) 111 { 112 const struct folio *folio; 113 unsigned long k; 114 unsigned long mapping; 115 bool is_anon; 116 u64 u = 0; 117 118 /* 119 * pseudo flag: KPF_NOPAGE 120 * it differentiates a memory hole from a page with no flags 121 */ 122 if (!page) 123 return 1 << KPF_NOPAGE; 124 folio = page_folio(page); 125 126 k = folio->flags; 127 mapping = (unsigned long)folio->mapping; 128 is_anon = mapping & PAGE_MAPPING_ANON; 129 130 /* 131 * pseudo flags for the well known (anonymous) memory mapped pages 132 */ 133 if (page_mapped(page)) 134 u |= 1 << KPF_MMAP; 135 if (is_anon) { 136 u |= 1 << KPF_ANON; 137 if (mapping & PAGE_MAPPING_KSM) 138 u |= 1 << KPF_KSM; 139 } 140 141 /* 142 * compound pages: export both head/tail info 143 * they together define a compound page's start/end pos and order 144 */ 145 if (page == &folio->page) 146 u |= kpf_copy_bit(k, KPF_COMPOUND_HEAD, PG_head); 147 else 148 u |= 1 << KPF_COMPOUND_TAIL; 149 if (folio_test_hugetlb(folio)) 150 u |= 1 << KPF_HUGE; 151 /* 152 * We need to check PageLRU/PageAnon 153 * to make sure a given page is a thp, not a non-huge compound page. 154 */ 155 else if (folio_test_large(folio)) { 156 if ((k & (1 << PG_lru)) || is_anon) 157 u |= 1 << KPF_THP; 158 else if (is_huge_zero_folio(folio)) { 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 * Caveats on high order pages: PG_buddy and PG_slab will only be set 167 * on the head page. 168 */ 169 if (PageBuddy(page)) 170 u |= 1 << KPF_BUDDY; 171 else if (page_count(page) == 0 && is_free_buddy_page(page)) 172 u |= 1 << KPF_BUDDY; 173 174 if (PageOffline(page)) 175 u |= 1 << KPF_OFFLINE; 176 if (PageTable(page)) 177 u |= 1 << KPF_PGTABLE; 178 if (folio_test_slab(folio)) 179 u |= 1 << KPF_SLAB; 180 181 #if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT) 182 u |= kpf_copy_bit(k, KPF_IDLE, PG_idle); 183 #else 184 if (folio_test_idle(folio)) 185 u |= 1 << KPF_IDLE; 186 #endif 187 188 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); 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 #define SWAPCACHE ((1 << PG_swapbacked) | (1 << PG_swapcache)) 200 if ((k & SWAPCACHE) == SWAPCACHE) 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 if (u & (1 << KPF_HUGE)) 209 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison); 210 else 211 u |= kpf_copy_bit(page->flags, KPF_HWPOISON, PG_hwpoison); 212 #endif 213 214 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 215 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached); 216 #endif 217 218 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); 219 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk); 220 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); 221 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); 222 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); 223 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); 224 #ifdef CONFIG_ARCH_USES_PG_ARCH_X 225 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); 226 u |= kpf_copy_bit(k, KPF_ARCH_3, PG_arch_3); 227 #endif 228 229 return u; 230 }; 231 232 static ssize_t kpageflags_read(struct file *file, char __user *buf, 233 size_t count, loff_t *ppos) 234 { 235 const unsigned long max_dump_pfn = get_max_dump_pfn(); 236 u64 __user *out = (u64 __user *)buf; 237 unsigned long src = *ppos; 238 unsigned long pfn; 239 ssize_t ret = 0; 240 241 pfn = src / KPMSIZE; 242 if (src & KPMMASK || count & KPMMASK) 243 return -EINVAL; 244 if (src >= max_dump_pfn * KPMSIZE) 245 return 0; 246 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 247 248 while (count > 0) { 249 /* 250 * TODO: ZONE_DEVICE support requires to identify 251 * memmaps that were actually initialized. 252 */ 253 struct page *page = pfn_to_online_page(pfn); 254 255 if (put_user(stable_page_flags(page), out)) { 256 ret = -EFAULT; 257 break; 258 } 259 260 pfn++; 261 out++; 262 count -= KPMSIZE; 263 264 cond_resched(); 265 } 266 267 *ppos += (char __user *)out - buf; 268 if (!ret) 269 ret = (char __user *)out - buf; 270 return ret; 271 } 272 273 static const struct proc_ops kpageflags_proc_ops = { 274 .proc_flags = PROC_ENTRY_PERMANENT, 275 .proc_lseek = mem_lseek, 276 .proc_read = kpageflags_read, 277 }; 278 279 #ifdef CONFIG_MEMCG 280 static ssize_t kpagecgroup_read(struct file *file, char __user *buf, 281 size_t count, loff_t *ppos) 282 { 283 const unsigned long max_dump_pfn = get_max_dump_pfn(); 284 u64 __user *out = (u64 __user *)buf; 285 struct page *ppage; 286 unsigned long src = *ppos; 287 unsigned long pfn; 288 ssize_t ret = 0; 289 u64 ino; 290 291 pfn = src / KPMSIZE; 292 if (src & KPMMASK || count & KPMMASK) 293 return -EINVAL; 294 if (src >= max_dump_pfn * KPMSIZE) 295 return 0; 296 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 297 298 while (count > 0) { 299 /* 300 * TODO: ZONE_DEVICE support requires to identify 301 * memmaps that were actually initialized. 302 */ 303 ppage = pfn_to_online_page(pfn); 304 305 if (ppage) 306 ino = page_cgroup_ino(ppage); 307 else 308 ino = 0; 309 310 if (put_user(ino, out)) { 311 ret = -EFAULT; 312 break; 313 } 314 315 pfn++; 316 out++; 317 count -= KPMSIZE; 318 319 cond_resched(); 320 } 321 322 *ppos += (char __user *)out - buf; 323 if (!ret) 324 ret = (char __user *)out - buf; 325 return ret; 326 } 327 328 static const struct proc_ops kpagecgroup_proc_ops = { 329 .proc_flags = PROC_ENTRY_PERMANENT, 330 .proc_lseek = mem_lseek, 331 .proc_read = kpagecgroup_read, 332 }; 333 #endif /* CONFIG_MEMCG */ 334 335 static int __init proc_page_init(void) 336 { 337 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops); 338 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops); 339 #ifdef CONFIG_MEMCG 340 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops); 341 #endif 342 return 0; 343 } 344 fs_initcall(proc_page_init); 345