1 // SPDX-License-Identifier: GPL-2.0 2 #include <linux/bootmem.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)) 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; 157 158 if (page_is_idle(page)) 159 u |= 1 << KPF_IDLE; 160 161 u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked); 162 163 u |= kpf_copy_bit(k, KPF_SLAB, PG_slab); 164 if (PageTail(page) && PageSlab(compound_head(page))) 165 u |= 1 << KPF_SLAB; 166 167 u |= kpf_copy_bit(k, KPF_ERROR, PG_error); 168 u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty); 169 u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate); 170 u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback); 171 172 u |= kpf_copy_bit(k, KPF_LRU, PG_lru); 173 u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced); 174 u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active); 175 u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim); 176 177 if (PageSwapCache(page)) 178 u |= 1 << KPF_SWAPCACHE; 179 u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked); 180 181 u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable); 182 u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked); 183 184 #ifdef CONFIG_MEMORY_FAILURE 185 u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison); 186 #endif 187 188 #ifdef CONFIG_ARCH_USES_PG_UNCACHED 189 u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached); 190 #endif 191 192 u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved); 193 u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk); 194 u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private); 195 u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2); 196 u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1); 197 u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1); 198 199 return u; 200 }; 201 202 static ssize_t kpageflags_read(struct file *file, char __user *buf, 203 size_t count, loff_t *ppos) 204 { 205 u64 __user *out = (u64 __user *)buf; 206 struct page *ppage; 207 unsigned long src = *ppos; 208 unsigned long pfn; 209 ssize_t ret = 0; 210 211 pfn = src / KPMSIZE; 212 count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src); 213 if (src & KPMMASK || count & KPMMASK) 214 return -EINVAL; 215 216 while (count > 0) { 217 if (pfn_valid(pfn)) 218 ppage = pfn_to_page(pfn); 219 else 220 ppage = NULL; 221 222 if (put_user(stable_page_flags(ppage), out)) { 223 ret = -EFAULT; 224 break; 225 } 226 227 pfn++; 228 out++; 229 count -= KPMSIZE; 230 231 cond_resched(); 232 } 233 234 *ppos += (char __user *)out - buf; 235 if (!ret) 236 ret = (char __user *)out - buf; 237 return ret; 238 } 239 240 static const struct file_operations proc_kpageflags_operations = { 241 .llseek = mem_lseek, 242 .read = kpageflags_read, 243 }; 244 245 #ifdef CONFIG_MEMCG 246 static ssize_t kpagecgroup_read(struct file *file, char __user *buf, 247 size_t count, loff_t *ppos) 248 { 249 u64 __user *out = (u64 __user *)buf; 250 struct page *ppage; 251 unsigned long src = *ppos; 252 unsigned long pfn; 253 ssize_t ret = 0; 254 u64 ino; 255 256 pfn = src / KPMSIZE; 257 count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src); 258 if (src & KPMMASK || count & KPMMASK) 259 return -EINVAL; 260 261 while (count > 0) { 262 if (pfn_valid(pfn)) 263 ppage = pfn_to_page(pfn); 264 else 265 ppage = NULL; 266 267 if (ppage) 268 ino = page_cgroup_ino(ppage); 269 else 270 ino = 0; 271 272 if (put_user(ino, out)) { 273 ret = -EFAULT; 274 break; 275 } 276 277 pfn++; 278 out++; 279 count -= KPMSIZE; 280 281 cond_resched(); 282 } 283 284 *ppos += (char __user *)out - buf; 285 if (!ret) 286 ret = (char __user *)out - buf; 287 return ret; 288 } 289 290 static const struct file_operations proc_kpagecgroup_operations = { 291 .llseek = mem_lseek, 292 .read = kpagecgroup_read, 293 }; 294 #endif /* CONFIG_MEMCG */ 295 296 static int __init proc_page_init(void) 297 { 298 proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations); 299 proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations); 300 #ifdef CONFIG_MEMCG 301 proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations); 302 #endif 303 return 0; 304 } 305 fs_initcall(proc_page_init); 306