fs/proc/page.c

   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);