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_lseek = mem_lseek, 95 .proc_read = kpagecount_read, 96 }; 97 98 /* /proc/kpageflags - an array exposing page flags 99 * 100 * Each entry is a u64 representing the corresponding 101 * physical page flags. 102 */ 103 104 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit) 105 { 106 return ((kflags >> kbit) & 1) << ubit; 107 } 108 109 u64 stable_page_flags(struct page *page) 110 { 111 u64 k; 112 u64 u; 113 114 /* 115 * pseudo flag: KPF_NOPAGE 116 * it differentiates a memory hole from a page with no flags 117 */ 118 if (!page) 119 return 1 << KPF_NOPAGE; 120 121 k = page->flags; 122 u = 0; 123 124 /* 125 * pseudo flags for the well known (anonymous) memory mapped pages 126 * 127 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the 128 * simple test in page_mapped() is not enough. 129 */ 130 if (!PageSlab(page) && page_mapped(page)) 131 u |= 1 << KPF_MMAP; 132 if (PageAnon(page)) 133 u |= 1 << KPF_ANON; 134 if (PageKsm(page)) 135 u |= 1 << KPF_KSM; 136 137 /* 138 * compound pages: export both head/tail info 139 * they together define a compound page's start/end pos and order 140 */ 141 if (PageHead(page)) 142 u |= 1 << KPF_COMPOUND_HEAD; 143 if (PageTail(page)) 144 u |= 1 << KPF_COMPOUND_TAIL; 145 if (PageHuge(page)) 146 u |= 1 << KPF_HUGE; 147 /* 148 * PageTransCompound can be true for non-huge compound pages (slab 149 * pages or pages allocated by drivers with __GFP_COMP) because it 150 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon 151 * to make sure a given page is a thp, not a non-huge compound page. 152 */ 153 else if (PageTransCompound(page)) { 154 struct page *head = compound_head(page); 155 156 if (PageLRU(head) || PageAnon(head)) 157 u |= 1 << KPF_THP; 158 else if (is_huge_zero_page(head)) { 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 /* 167 * Caveats on high order pages: page->_refcount will only be set 168 * -1 on the head page; SLUB/SLQB do the same for PG_slab; 169 * SLOB won't set PG_slab at all on compound pages. 170 */ 171 if (PageBuddy(page)) 172 u |= 1 << KPF_BUDDY; 173 else if (page_count(page) == 0 && is_free_buddy_page(page)) 174 u |= 1 << KPF_BUDDY; 175 176 if (PageOffline(page)) 177 u |= 1 << KPF_OFFLINE; 178 if (PageTable(page)) 179 u |= 1 << KPF_PGTABLE; 180 181 if (page_is_idle(page)) 182 u |= 1 << KPF_IDLE; 183 184 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); 185 186 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab); 187 if (PageTail(page) && PageSlab(compound_head(page))) 188 u |= 1 << KPF_SLAB; 189 190 u |= kpf_copy_bit(k, KPF_ERROR, PG_error); 191 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty); 192 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate); 193 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback); 194 195 u |= kpf_copy_bit(k, KPF_LRU, PG_lru); 196 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced); 197 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active); 198 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim); 199 200 if (PageSwapCache(page)) 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 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison); 209 #endif 210 211 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 212 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached); 213 #endif 214 215 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); 216 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk); 217 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); 218 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); 219 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); 220 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); 221 #ifdef CONFIG_64BIT 222 u |= kpf_copy_bit(k, KPF_ARCH_2, PG_arch_2); 223 #endif 224 225 return u; 226 }; 227 228 static ssize_t kpageflags_read(struct file *file, char __user *buf, 229 size_t count, loff_t *ppos) 230 { 231 const unsigned long max_dump_pfn = get_max_dump_pfn(); 232 u64 __user *out = (u64 __user *)buf; 233 struct page *ppage; 234 unsigned long src = *ppos; 235 unsigned long pfn; 236 ssize_t ret = 0; 237 238 pfn = src / KPMSIZE; 239 if (src & KPMMASK || count & KPMMASK) 240 return -EINVAL; 241 if (src >= max_dump_pfn * KPMSIZE) 242 return 0; 243 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 244 245 while (count > 0) { 246 /* 247 * TODO: ZONE_DEVICE support requires to identify 248 * memmaps that were actually initialized. 249 */ 250 ppage = pfn_to_online_page(pfn); 251 252 if (put_user(stable_page_flags(ppage), out)) { 253 ret = -EFAULT; 254 break; 255 } 256 257 pfn++; 258 out++; 259 count -= KPMSIZE; 260 261 cond_resched(); 262 } 263 264 *ppos += (char __user *)out - buf; 265 if (!ret) 266 ret = (char __user *)out - buf; 267 return ret; 268 } 269 270 static const struct proc_ops kpageflags_proc_ops = { 271 .proc_lseek = mem_lseek, 272 .proc_read = kpageflags_read, 273 }; 274 275 #ifdef CONFIG_MEMCG 276 static ssize_t kpagecgroup_read(struct file *file, char __user *buf, 277 size_t count, loff_t *ppos) 278 { 279 const unsigned long max_dump_pfn = get_max_dump_pfn(); 280 u64 __user *out = (u64 __user *)buf; 281 struct page *ppage; 282 unsigned long src = *ppos; 283 unsigned long pfn; 284 ssize_t ret = 0; 285 u64 ino; 286 287 pfn = src / KPMSIZE; 288 if (src & KPMMASK || count & KPMMASK) 289 return -EINVAL; 290 if (src >= max_dump_pfn * KPMSIZE) 291 return 0; 292 count = min_t(unsigned long, count, (max_dump_pfn * KPMSIZE) - src); 293 294 while (count > 0) { 295 /* 296 * TODO: ZONE_DEVICE support requires to identify 297 * memmaps that were actually initialized. 298 */ 299 ppage = pfn_to_online_page(pfn); 300 301 if (ppage) 302 ino = page_cgroup_ino(ppage); 303 else 304 ino = 0; 305 306 if (put_user(ino, out)) { 307 ret = -EFAULT; 308 break; 309 } 310 311 pfn++; 312 out++; 313 count -= KPMSIZE; 314 315 cond_resched(); 316 } 317 318 *ppos += (char __user *)out - buf; 319 if (!ret) 320 ret = (char __user *)out - buf; 321 return ret; 322 } 323 324 static const struct proc_ops kpagecgroup_proc_ops = { 325 .proc_lseek = mem_lseek, 326 .proc_read = kpagecgroup_read, 327 }; 328 #endif /* CONFIG_MEMCG */ 329 330 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