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 24 /* /proc/kpagecount - an array exposing page counts 25 * 26 * Each entry is a u64 representing the corresponding 27 * physical page count. 28 */ 29 static ssize_t kpagecount_read(struct file *file, char __user *buf, 30 size_t count, loff_t *ppos) 31 { 32 u64 __user *out = (u64 __user *)buf; 33 struct page *ppage; 34 unsigned long src = *ppos; 35 unsigned long pfn; 36 ssize_t ret = 0; 37 u64 pcount; 38 39 pfn = src / KPMSIZE; 40 count = min_t(size_t, count, (max_pfn * KPMSIZE) - src); 41 if (src & KPMMASK || count & KPMMASK) 42 return -EINVAL; 43 44 while (count > 0) { 45 if (pfn_valid(pfn)) 46 ppage = pfn_to_page(pfn); 47 else 48 ppage = NULL; 49 if (!ppage || PageSlab(ppage) || page_has_type(ppage)) 50 pcount = 0; 51 else 52 pcount = page_mapcount(ppage); 53 54 if (put_user(pcount, out)) { 55 ret = -EFAULT; 56 break; 57 } 58 59 pfn++; 60 out++; 61 count -= KPMSIZE; 62 63 cond_resched(); 64 } 65 66 *ppos += (char __user *)out - buf; 67 if (!ret) 68 ret = (char __user *)out - buf; 69 return ret; 70 } 71 72 static const struct file_operations proc_kpagecount_operations = { 73 .llseek = mem_lseek, 74 .read = kpagecount_read, 75 }; 76 77 /* /proc/kpageflags - an array exposing page flags 78 * 79 * Each entry is a u64 representing the corresponding 80 * physical page flags. 81 */ 82 83 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit) 84 { 85 return ((kflags >> kbit) & 1) << ubit; 86 } 87 88 u64 stable_page_flags(struct page *page) 89 { 90 u64 k; 91 u64 u; 92 93 /* 94 * pseudo flag: KPF_NOPAGE 95 * it differentiates a memory hole from a page with no flags 96 */ 97 if (!page) 98 return 1 << KPF_NOPAGE; 99 100 k = page->flags; 101 u = 0; 102 103 /* 104 * pseudo flags for the well known (anonymous) memory mapped pages 105 * 106 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the 107 * simple test in page_mapped() is not enough. 108 */ 109 if (!PageSlab(page) && page_mapped(page)) 110 u |= 1 << KPF_MMAP; 111 if (PageAnon(page)) 112 u |= 1 << KPF_ANON; 113 if (PageKsm(page)) 114 u |= 1 << KPF_KSM; 115 116 /* 117 * compound pages: export both head/tail info 118 * they together define a compound page's start/end pos and order 119 */ 120 if (PageHead(page)) 121 u |= 1 << KPF_COMPOUND_HEAD; 122 if (PageTail(page)) 123 u |= 1 << KPF_COMPOUND_TAIL; 124 if (PageHuge(page)) 125 u |= 1 << KPF_HUGE; 126 /* 127 * PageTransCompound can be true for non-huge compound pages (slab 128 * pages or pages allocated by drivers with __GFP_COMP) because it 129 * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon 130 * to make sure a given page is a thp, not a non-huge compound page. 131 */ 132 else if (PageTransCompound(page)) { 133 struct page *head = compound_head(page); 134 135 if (PageLRU(head) || PageAnon(head)) 136 u |= 1 << KPF_THP; 137 else if (is_huge_zero_page(head)) { 138 u |= 1 << KPF_ZERO_PAGE; 139 u |= 1 << KPF_THP; 140 } 141 } else if (is_zero_pfn(page_to_pfn(page))) 142 u |= 1 << KPF_ZERO_PAGE; 143 144 145 /* 146 * Caveats on high order pages: page->_refcount will only be set 147 * -1 on the head page; SLUB/SLQB do the same for PG_slab; 148 * SLOB won't set PG_slab at all on compound pages. 149 */ 150 if (PageBuddy(page)) 151 u |= 1 << KPF_BUDDY; 152 else if (page_count(page) == 0 && is_free_buddy_page(page)) 153 u |= 1 << KPF_BUDDY; 154 155 if (PageBalloon(page)) 156 u |= 1 << KPF_BALLOON; 157 if (PageTable(page)) 158 u |= 1 << KPF_PGTABLE; 159 160 if (page_is_idle(page)) 161 u |= 1 << KPF_IDLE; 162 163 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); 164 165 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab); 166 if (PageTail(page) && PageSlab(compound_head(page))) 167 u |= 1 << KPF_SLAB; 168 169 u |= kpf_copy_bit(k, KPF_ERROR, PG_error); 170 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty); 171 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate); 172 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback); 173 174 u |= kpf_copy_bit(k, KPF_LRU, PG_lru); 175 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced); 176 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active); 177 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim); 178 179 if (PageSwapCache(page)) 180 u |= 1 << KPF_SWAPCACHE; 181 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked); 182 183 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable); 184 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked); 185 186 #ifdef CONFIG_MEMORY_FAILURE 187 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison); 188 #endif 189 190 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 191 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached); 192 #endif 193 194 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); 195 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk); 196 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); 197 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); 198 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); 199 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); 200 201 return u; 202 }; 203 204 static ssize_t kpageflags_read(struct file *file, char __user *buf, 205 size_t count, loff_t *ppos) 206 { 207 u64 __user *out = (u64 __user *)buf; 208 struct page *ppage; 209 unsigned long src = *ppos; 210 unsigned long pfn; 211 ssize_t ret = 0; 212 213 pfn = src / KPMSIZE; 214 count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src); 215 if (src & KPMMASK || count & KPMMASK) 216 return -EINVAL; 217 218 while (count > 0) { 219 if (pfn_valid(pfn)) 220 ppage = pfn_to_page(pfn); 221 else 222 ppage = NULL; 223 224 if (put_user(stable_page_flags(ppage), out)) { 225 ret = -EFAULT; 226 break; 227 } 228 229 pfn++; 230 out++; 231 count -= KPMSIZE; 232 233 cond_resched(); 234 } 235 236 *ppos += (char __user *)out - buf; 237 if (!ret) 238 ret = (char __user *)out - buf; 239 return ret; 240 } 241 242 static const struct file_operations proc_kpageflags_operations = { 243 .llseek = mem_lseek, 244 .read = kpageflags_read, 245 }; 246 247 #ifdef CONFIG_MEMCG 248 static ssize_t kpagecgroup_read(struct file *file, char __user *buf, 249 size_t count, loff_t *ppos) 250 { 251 u64 __user *out = (u64 __user *)buf; 252 struct page *ppage; 253 unsigned long src = *ppos; 254 unsigned long pfn; 255 ssize_t ret = 0; 256 u64 ino; 257 258 pfn = src / KPMSIZE; 259 count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src); 260 if (src & KPMMASK || count & KPMMASK) 261 return -EINVAL; 262 263 while (count > 0) { 264 if (pfn_valid(pfn)) 265 ppage = pfn_to_page(pfn); 266 else 267 ppage = NULL; 268 269 if (ppage) 270 ino = page_cgroup_ino(ppage); 271 else 272 ino = 0; 273 274 if (put_user(ino, out)) { 275 ret = -EFAULT; 276 break; 277 } 278 279 pfn++; 280 out++; 281 count -= KPMSIZE; 282 283 cond_resched(); 284 } 285 286 *ppos += (char __user *)out - buf; 287 if (!ret) 288 ret = (char __user *)out - buf; 289 return ret; 290 } 291 292 static const struct file_operations proc_kpagecgroup_operations = { 293 .llseek = mem_lseek, 294 .read = kpagecgroup_read, 295 }; 296 #endif /* CONFIG_MEMCG */ 297 298 static int __init proc_page_init(void) 299 { 300 proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations); 301 proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations); 302 #ifdef CONFIG_MEMCG 303 proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations); 304 #endif 305 return 0; 306 } 307 fs_initcall(proc_page_init); 308