fs/proc/page.c

   1 #include <linux/bootmem.h>
   2 #include <linux/compiler.h>
   3 #include <linux/fs.h>
   4 #include <linux/init.h>
   5 #include <linux/ksm.h>
   6 #include <linux/mm.h>
   7 #include <linux/mmzone.h>
   8 #include <linux/proc_fs.h>
   9 #include <linux/seq_file.h>
  10 #include <linux/hugetlb.h>
  11 #include <linux/kernel-page-flags.h>
  12 #include <asm/uaccess.h>
  13 #include "internal.h"
  14
  15 #define KPMSIZE sizeof(u64)
  16 #define KPMMASK (KPMSIZE - 1)
  17
  18 /* /proc/kpagecount - an array exposing page counts
  19  *
  20  * Each entry is a u64 representing the corresponding
  21  * physical page count.
  22  */
  23 static ssize_t kpagecount_read(struct file *file, char __user *buf,
  24                              size_t count, loff_t *ppos)
  25 {
  26         u64 __user *out = (u64 __user *)buf;
  27         struct page *ppage;
  28         unsigned long src = *ppos;
  29         unsigned long pfn;
  30         ssize_t ret = 0;
  31         u64 pcount;
  32
  33         pfn = src / KPMSIZE;
  34         count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
  35         if (src & KPMMASK || count & KPMMASK)
  36                 return -EINVAL;
  37
  38         while (count > 0) {
  39                 if (pfn_valid(pfn))
  40                         ppage = pfn_to_page(pfn);
  41                 else
  42                         ppage = NULL;
  43                 if (!ppage || PageSlab(ppage))
  44                         pcount = 0;
  45                 else
  46                         pcount = page_mapcount(ppage);
  47
  48                 if (put_user(pcount, out)) {
  49                         ret = -EFAULT;
  50                         break;
  51                 }
  52
  53                 pfn++;
  54                 out++;
  55                 count -= KPMSIZE;
  56         }
  57
  58         *ppos += (char __user *)out - buf;
  59         if (!ret)
  60                 ret = (char __user *)out - buf;
  61         return ret;
  62 }
  63
  64 static const struct file_operations proc_kpagecount_operations = {
  65         .llseek = mem_lseek,
  66         .read = kpagecount_read,
  67 };
  68
  69 /* /proc/kpageflags - an array exposing page flags
  70  *
  71  * Each entry is a u64 representing the corresponding
  72  * physical page flags.
  73  */
  74
  75 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
  76 {
  77         return ((kflags >> kbit) & 1) << ubit;
  78 }
  79
  80 u64 stable_page_flags(struct page *page)
  81 {
  82         u64 k;
  83         u64 u;
  84
  85         /*
  86          * pseudo flag: KPF_NOPAGE
  87          * it differentiates a memory hole from a page with no flags
  88          */
  89         if (!page)
  90                 return 1 << KPF_NOPAGE;
  91
  92         k = page->flags;
  93         u = 0;
  94
  95         /*
  96          * pseudo flags for the well known (anonymous) memory mapped pages
  97          *
  98          * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
  99          * simple test in page_mapped() is not enough.
 100          */
 101         if (!PageSlab(page) && page_mapped(page))
 102                 u |= 1 << KPF_MMAP;
 103         if (PageAnon(page))
 104                 u |= 1 << KPF_ANON;
 105         if (PageKsm(page))
 106                 u |= 1 << KPF_KSM;
 107
 108         /*
 109          * compound pages: export both head/tail info
 110          * they together define a compound page's start/end pos and order
 111          */
 112         if (PageHead(page))
 113                 u |= 1 << KPF_COMPOUND_HEAD;
 114         if (PageTail(page))
 115                 u |= 1 << KPF_COMPOUND_TAIL;
 116         if (PageHuge(page))
 117                 u |= 1 << KPF_HUGE;
 118         /*
 119          * PageTransCompound can be true for non-huge compound pages (slab
 120          * pages or pages allocated by drivers with __GFP_COMP) because it
 121          * just checks PG_head/PG_tail, so we need to check PageLRU/PageAnon
 122          * to make sure a given page is a thp, not a non-huge compound page.
 123          */
 124         else if (PageTransCompound(page) && (PageLRU(compound_head(page)) ||
 125                                              PageAnon(compound_head(page))))
 126                 u |= 1 << KPF_THP;
 127
 128         /*
 129          * Caveats on high order pages: page->_count will only be set
 130          * -1 on the head page; SLUB/SLQB do the same for PG_slab;
 131          * SLOB won't set PG_slab at all on compound pages.
 132          */
 133         if (PageBuddy(page))
 134                 u |= 1 << KPF_BUDDY;
 135
 136         u |= kpf_copy_bit(k, KPF_LOCKED,        PG_locked);
 137
 138         u |= kpf_copy_bit(k, KPF_SLAB,          PG_slab);
 139
 140         u |= kpf_copy_bit(k, KPF_ERROR,         PG_error);
 141         u |= kpf_copy_bit(k, KPF_DIRTY,         PG_dirty);
 142         u |= kpf_copy_bit(k, KPF_UPTODATE,      PG_uptodate);
 143         u |= kpf_copy_bit(k, KPF_WRITEBACK,     PG_writeback);
 144
 145         u |= kpf_copy_bit(k, KPF_LRU,           PG_lru);
 146         u |= kpf_copy_bit(k, KPF_REFERENCED,    PG_referenced);
 147         u |= kpf_copy_bit(k, KPF_ACTIVE,        PG_active);
 148         u |= kpf_copy_bit(k, KPF_RECLAIM,       PG_reclaim);
 149
 150         u |= kpf_copy_bit(k, KPF_SWAPCACHE,     PG_swapcache);
 151         u |= kpf_copy_bit(k, KPF_SWAPBACKED,    PG_swapbacked);
 152
 153         u |= kpf_copy_bit(k, KPF_UNEVICTABLE,   PG_unevictable);
 154         u |= kpf_copy_bit(k, KPF_MLOCKED,       PG_mlocked);
 155
 156 #ifdef CONFIG_MEMORY_FAILURE
 157         u |= kpf_copy_bit(k, KPF_HWPOISON,      PG_hwpoison);
 158 #endif
 159
 160 #ifdef CONFIG_ARCH_USES_PG_UNCACHED
 161         u |= kpf_copy_bit(k, KPF_UNCACHED,      PG_uncached);
 162 #endif
 163
 164         u |= kpf_copy_bit(k, KPF_RESERVED,      PG_reserved);
 165         u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,  PG_mappedtodisk);
 166         u |= kpf_copy_bit(k, KPF_PRIVATE,       PG_private);
 167         u |= kpf_copy_bit(k, KPF_PRIVATE_2,     PG_private_2);
 168         u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
 169         u |= kpf_copy_bit(k, KPF_ARCH,          PG_arch_1);
 170
 171         return u;
 172 };
 173
 174 static ssize_t kpageflags_read(struct file *file, char __user *buf,
 175                              size_t count, loff_t *ppos)
 176 {
 177         u64 __user *out = (u64 __user *)buf;
 178         struct page *ppage;
 179         unsigned long src = *ppos;
 180         unsigned long pfn;
 181         ssize_t ret = 0;
 182
 183         pfn = src / KPMSIZE;
 184         count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
 185         if (src & KPMMASK || count & KPMMASK)
 186                 return -EINVAL;
 187
 188         while (count > 0) {
 189                 if (pfn_valid(pfn))
 190                         ppage = pfn_to_page(pfn);
 191                 else
 192                         ppage = NULL;
 193
 194                 if (put_user(stable_page_flags(ppage), out)) {
 195                         ret = -EFAULT;
 196                         break;
 197                 }
 198
 199                 pfn++;
 200                 out++;
 201                 count -= KPMSIZE;
 202         }
 203
 204         *ppos += (char __user *)out - buf;
 205         if (!ret)
 206                 ret = (char __user *)out - buf;
 207         return ret;
 208 }
 209
 210 static const struct file_operations proc_kpageflags_operations = {
 211         .llseek = mem_lseek,
 212         .read = kpageflags_read,
 213 };
 214
 215 static int __init proc_page_init(void)
 216 {
 217         proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 218         proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 219         return 0;
 220 }
 221 fs_initcall(proc_page_init);