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 || 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_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(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 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the 129 * simple test in page_mapped() is not enough. 130 */ 131 if (!PageSlab(page) && page_mapped(page)) 132 u |= 1 << KPF_MMAP; 133 if (PageAnon(page)) 134 u |= 1 << KPF_ANON; 135 if (PageKsm(page)) 136 u |= 1 << KPF_KSM; 137 138 /* 139 * compound pages: export both head/tail info 140 * they together define a compound page's start/end pos and order 141 */ 142 if (PageHead(page)) 143 u |= 1 << KPF_COMPOUND_HEAD; 144 if (PageTail(page)) 145 u |= 1 << KPF_COMPOUND_TAIL; 146 if (PageHuge(page)) 147 u |= 1 << KPF_HUGE; 148 /* 149 * PageTransCompound can be true for non-huge compound pages (slab 150 * pages or pages allocated by drivers with __GFP_COMP) because it 151 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon 152 * to make sure a given page is a thp, not a non-huge compound page. 153 */ 154 else if (PageTransCompound(page)) { 155 struct page *head = compound_head(page); 156 157 if (PageLRU(head) || PageAnon(head)) 158 u |= 1 << KPF_THP; 159 else if (is_huge_zero_page(head)) { 160 u |= 1 << KPF_ZERO_PAGE; 161 u |= 1 << KPF_THP; 162 } 163 } else if (is_zero_pfn(page_to_pfn(page))) 164 u |= 1 << KPF_ZERO_PAGE; 165 166 167 /* 168 * Caveats on high order pages: page->_refcount will only be set 169 * -1 on the head page; SLUB/SLQB do the same for PG_slab; 170 * SLOB won't set PG_slab at all on compound pages. 171 */ 172 if (PageBuddy(page)) 173 u |= 1 << KPF_BUDDY; 174 else if (page_count(page) == 0 && is_free_buddy_page(page)) 175 u |= 1 << KPF_BUDDY; 176 177 if (PageOffline(page)) 178 u |= 1 << KPF_OFFLINE; 179 if (PageTable(page)) 180 u |= 1 << KPF_PGTABLE; 181 182 if (page_is_idle(page)) 183 u |= 1 << KPF_IDLE; 184 185 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); 186 187 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab); 188 if (PageTail(page) && PageSlab(compound_head(page))) 189 u |= 1 << KPF_SLAB; 190 191 u |= kpf_copy_bit(k, KPF_ERROR, PG_error); 192 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty); 193 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate); 194 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback); 195 196 u |= kpf_copy_bit(k, KPF_LRU, PG_lru); 197 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced); 198 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active); 199 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim); 200 201 if (PageSwapCache(page)) 202 u |= 1 << KPF_SWAPCACHE; 203 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked); 204 205 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable); 206 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked); 207 208 #ifdef CONFIG_MEMORY_FAILURE 209 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison); 210 #endif 211 212 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 213 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached); 214 #endif 215 216 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); 217 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk); 218 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); 219 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); 220 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); 221 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); 222 #ifdef CONFIG_64BIT 223 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); 224 #endif 225 226 return u; 227 }; 228 229 static ssize_t kpageflags_read(struct file *file, char __user *buf, 230 size_t count, loff_t *ppos) 231 { 232 const unsigned long max_dump_pfn = get_max_dump_pfn(); 233 u64 __user *out = (u64 __user *)buf; 234 struct page *ppage; 235 unsigned long src = *ppos; 236 unsigned long pfn; 237 ssize_t ret = 0; 238 239 pfn = src / KPMSIZE; 240 if (src & KPMMASK || count & KPMMASK) 241 return -EINVAL; 242 if (src >= max_dump_pfn * KPMSIZE) 243 return 0; 244 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 245 246 while (count > 0) { 247 /* 248 * TODO: ZONE_DEVICE support requires to identify 249 * memmaps that were actually initialized. 250 */ 251 ppage = pfn_to_online_page(pfn); 252 253 if (put_user(stable_page_flags(ppage), out)) { 254 ret = -EFAULT; 255 break; 256 } 257 258 pfn++; 259 out++; 260 count -= KPMSIZE; 261 262 cond_resched(); 263 } 264 265 *ppos += (char __user *)out - buf; 266 if (!ret) 267 ret = (char __user *)out - buf; 268 return ret; 269 } 270 271 static const struct proc_ops kpageflags_proc_ops = { 272 .proc_flags = PROC_ENTRY_PERMANENT, 273 .proc_lseek = mem_lseek, 274 .proc_read = kpageflags_read, 275 }; 276 277 #ifdef CONFIG_MEMCG 278 static ssize_t kpagecgroup_read(struct file *file, char __user *buf, 279 size_t count, loff_t *ppos) 280 { 281 const unsigned long max_dump_pfn = get_max_dump_pfn(); 282 u64 __user *out = (u64 __user *)buf; 283 struct page *ppage; 284 unsigned long src = *ppos; 285 unsigned long pfn; 286 ssize_t ret = 0; 287 u64 ino; 288 289 pfn = src / KPMSIZE; 290 if (src & KPMMASK || count & KPMMASK) 291 return -EINVAL; 292 if (src >= max_dump_pfn * KPMSIZE) 293 return 0; 294 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 295 296 while (count > 0) { 297 /* 298 * TODO: ZONE_DEVICE support requires to identify 299 * memmaps that were actually initialized. 300 */ 301 ppage = pfn_to_online_page(pfn); 302 303 if (ppage) 304 ino = page_cgroup_ino(ppage); 305 else 306 ino = 0; 307 308 if (put_user(ino, out)) { 309 ret = -EFAULT; 310 break; 311 } 312 313 pfn++; 314 out++; 315 count -= KPMSIZE; 316 317 cond_resched(); 318 } 319 320 *ppos += (char __user *)out - buf; 321 if (!ret) 322 ret = (char __user *)out - buf; 323 return ret; 324 } 325 326 static const struct proc_ops kpagecgroup_proc_ops = { 327 .proc_flags = PROC_ENTRY_PERMANENT, 328 .proc_lseek = mem_lseek, 329 .proc_read = kpagecgroup_read, 330 }; 331 #endif /* CONFIG_MEMCG */ 332 333 static int __init proc_page_init(void) 334 { 335 proc_create("kpagecount", S_IRUSR, NULL, &kpagecount_proc_ops); 336 proc_create("kpageflags", S_IRUSR, NULL, &kpageflags_proc_ops); 337 #ifdef CONFIG_MEMCG 338 proc_create("kpagecgroup", S_IRUSR, NULL, &kpagecgroup_proc_ops); 339 #endif 340 return 0; 341 } 342 fs_initcall(proc_page_init); 343