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                 /*
  46                  * TODO: ZONE_DEVICE support requires to identify
  47                  * memmaps that were actually initialized.
  48                  */
  49                 ppage = pfn_to_online_page(pfn);
  50
  51                 if (!ppage || PageSlab(ppage))
  52                         pcount = 0;
  53                 else
  54                         pcount = page_mapcount(ppage);
  55
  56                 if (put_user(pcount, out)) {
  57                         ret = -EFAULT;
  58                         break;
  59                 }
  60
  61                 pfn++;
  62                 out++;
  63                 count -= KPMSIZE;
  64
  65                 cond_resched();
  66         }
  67
  68         *ppos += (char __user *)out - buf;
  69         if (!ret)
  70                 ret = (char __user *)out - buf;
  71         return ret;
  72 }
  73
  74 static const struct file_operations proc_kpagecount_operations = {
  75         .llseek = mem_lseek,
  76         .read = kpagecount_read,
  77 };
  78
  79 /* /proc/kpageflags - an array exposing page flags
  80  *
  81  * Each entry is a u64 representing the corresponding
  82  * physical page flags.
  83  */
  84
  85 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
  86 {
  87         return ((kflags >> kbit) & 1) << ubit;
  88 }
  89
  90 u64 stable_page_flags(struct page *page)
  91 {
  92         u64 k;
  93         u64 u;
  94
  95         /*
  96          * pseudo flag: KPF_NOPAGE
  97          * it differentiates a memory hole from a page with no flags
  98          */
  99         if (!page)
 100                 return 1 << KPF_NOPAGE;
 101
 102         k = page->flags;
 103         u = 0;
 104
 105         /*
 106          * pseudo flags for the well known (anonymous) memory mapped pages
 107          *
 108          * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
 109          * simple test in page_mapped() is not enough.
 110          */
 111         if (!PageSlab(page) && page_mapped(page))
 112                 u |= 1 << KPF_MMAP;
 113         if (PageAnon(page))
 114                 u |= 1 << KPF_ANON;
 115         if (PageKsm(page))
 116                 u |= 1 << KPF_KSM;
 117
 118         /*
 119          * compound pages: export both head/tail info
 120          * they together define a compound page's start/end pos and order
 121          */
 122         if (PageHead(page))
 123                 u |= 1 << KPF_COMPOUND_HEAD;
 124         if (PageTail(page))
 125                 u |= 1 << KPF_COMPOUND_TAIL;
 126         if (PageHuge(page))
 127                 u |= 1 << KPF_HUGE;
 128         /*
 129          * PageTransCompound can be true for non-huge compound pages (slab
 130          * pages or pages allocated by drivers with __GFP_COMP) because it
 131          * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
 132          * to make sure a given page is a thp, not a non-huge compound page.
 133          */
 134         else if (PageTransCompound(page)) {
 135                 struct page *head = compound_head(page);
 136
 137                 if (PageLRU(head) || PageAnon(head))
 138                         u |= 1 << KPF_THP;
 139                 else if (is_huge_zero_page(head)) {
 140                         u |= 1 << KPF_ZERO_PAGE;
 141                         u |= 1 << KPF_THP;
 142                 }
 143         } else if (is_zero_pfn(page_to_pfn(page)))
 144                 u |= 1 << KPF_ZERO_PAGE;
 145
 146
 147         /*
 148          * Caveats on high order pages: page->_refcount will only be set
 149          * -1 on the head page; SLUB/SLQB do the same for PG_slab;
 150          * SLOB won't set PG_slab at all on compound pages.
 151          */
 152         if (PageBuddy(page))
 153                 u |= 1 << KPF_BUDDY;
 154         else if (page_count(page) == 0 && is_free_buddy_page(page))
 155                 u |= 1 << KPF_BUDDY;
 156
 157         if (PageBalloon(page))
 158                 u |= 1 << KPF_BALLOON;
 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                 /*
 220                  * TODO: ZONE_DEVICE support requires to identify
 221                  * memmaps that were actually initialized.
 222                  */
 223                 ppage = pfn_to_online_page(pfn);
 224
 225                 if (put_user(stable_page_flags(ppage), out)) {
 226                         ret = -EFAULT;
 227                         break;
 228                 }
 229
 230                 pfn++;
 231                 out++;
 232                 count -= KPMSIZE;
 233
 234                 cond_resched();
 235         }
 236
 237         *ppos += (char __user *)out - buf;
 238         if (!ret)
 239                 ret = (char __user *)out - buf;
 240         return ret;
 241 }
 242
 243 static const struct file_operations proc_kpageflags_operations = {
 244         .llseek = mem_lseek,
 245         .read = kpageflags_read,
 246 };
 247
 248 #ifdef CONFIG_MEMCG
 249 static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
 250                                 size_t count, loff_t *ppos)
 251 {
 252         u64 __user *out = (u64 __user *)buf;
 253         struct page *ppage;
 254         unsigned long src = *ppos;
 255         unsigned long pfn;
 256         ssize_t ret = 0;
 257         u64 ino;
 258
 259         pfn = src / KPMSIZE;
 260         count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
 261         if (src & KPMMASK || count & KPMMASK)
 262                 return -EINVAL;
 263
 264         while (count > 0) {
 265                 /*
 266                  * TODO: ZONE_DEVICE support requires to identify
 267                  * memmaps that were actually initialized.
 268                  */
 269                 ppage = pfn_to_online_page(pfn);
 270
 271                 if (ppage)
 272                         ino = page_cgroup_ino(ppage);
 273                 else
 274                         ino = 0;
 275
 276                 if (put_user(ino, out)) {
 277                         ret = -EFAULT;
 278                         break;
 279                 }
 280
 281                 pfn++;
 282                 out++;
 283                 count -= KPMSIZE;
 284
 285                 cond_resched();
 286         }
 287
 288         *ppos += (char __user *)out - buf;
 289         if (!ret)
 290                 ret = (char __user *)out - buf;
 291         return ret;
 292 }
 293
 294 static const struct file_operations proc_kpagecgroup_operations = {
 295         .llseek = mem_lseek,
 296         .read = kpagecgroup_read,
 297 };
 298 #endif /* CONFIG_MEMCG */
 299
 300 static int __init proc_page_init(void)
 301 {
 302         proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 303         proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 304 #ifdef CONFIG_MEMCG
 305         proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);
 306 #endif
 307         return 0;
 308 }
 309 fs_initcall(proc_page_init);