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/mm.h>
   6 #include <linux/mmzone.h>
   7 #include <linux/proc_fs.h>
   8 #include <linux/seq_file.h>
   9 #include <linux/hugetlb.h>
  10 #include <asm/uaccess.h>
  11 #include "internal.h"
  12
  13 #define KPMSIZE sizeof(u64)
  14 #define KPMMASK (KPMSIZE - 1)
  15
  16 /* /proc/kpagecount - an array exposing page counts
  17  *
  18  * Each entry is a u64 representing the corresponding
  19  * physical page count.
  20  */
  21 static ssize_t kpagecount_read(struct file *file, char __user *buf,
  22                              size_t count, loff_t *ppos)
  23 {
  24         u64 __user *out = (u64 __user *)buf;
  25         struct page *ppage;
  26         unsigned long src = *ppos;
  27         unsigned long pfn;
  28         ssize_t ret = 0;
  29         u64 pcount;
  30
  31         pfn = src / KPMSIZE;
  32         count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
  33         if (src & KPMMASK || count & KPMMASK)
  34                 return -EINVAL;
  35
  36         while (count > 0) {
  37                 if (pfn_valid(pfn))
  38                         ppage = pfn_to_page(pfn);
  39                 else
  40                         ppage = NULL;
  41                 if (!ppage)
  42                         pcount = 0;
  43                 else
  44                         pcount = page_mapcount(ppage);
  45
  46                 if (put_user(pcount, out)) {
  47                         ret = -EFAULT;
  48                         break;
  49                 }
  50
  51                 pfn++;
  52                 out++;
  53                 count -= KPMSIZE;
  54         }
  55
  56         *ppos += (char __user *)out - buf;
  57         if (!ret)
  58                 ret = (char __user *)out - buf;
  59         return ret;
  60 }
  61
  62 static const struct file_operations proc_kpagecount_operations = {
  63         .llseek = mem_lseek,
  64         .read = kpagecount_read,
  65 };
  66
  67 /* /proc/kpageflags - an array exposing page flags
  68  *
  69  * Each entry is a u64 representing the corresponding
  70  * physical page flags.
  71  */
  72
  73 /* These macros are used to decouple internal flags from exported ones */
  74
  75 #define KPF_LOCKED              0
  76 #define KPF_ERROR               1
  77 #define KPF_REFERENCED          2
  78 #define KPF_UPTODATE            3
  79 #define KPF_DIRTY               4
  80 #define KPF_LRU                 5
  81 #define KPF_ACTIVE              6
  82 #define KPF_SLAB                7
  83 #define KPF_WRITEBACK           8
  84 #define KPF_RECLAIM             9
  85 #define KPF_BUDDY               10
  86
  87 /* 11-20: new additions in 2.6.31 */
  88 #define KPF_MMAP                11
  89 #define KPF_ANON                12
  90 #define KPF_SWAPCACHE           13
  91 #define KPF_SWAPBACKED          14
  92 #define KPF_COMPOUND_HEAD       15
  93 #define KPF_COMPOUND_TAIL       16
  94 #define KPF_HUGE                17
  95 #define KPF_UNEVICTABLE         18
  96 #define KPF_NOPAGE              20
  97
  98 /* kernel hacking assistances
  99  * WARNING: subject to change, never rely on them!
 100  */
 101 #define KPF_RESERVED            32
 102 #define KPF_MLOCKED             33
 103 #define KPF_MAPPEDTODISK        34
 104 #define KPF_PRIVATE             35
 105 #define KPF_PRIVATE_2           36
 106 #define KPF_OWNER_PRIVATE       37
 107 #define KPF_ARCH                38
 108 #define KPF_UNCACHED            39
 109
 110 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
 111 {
 112         return ((kflags >> kbit) & 1) << ubit;
 113 }
 114
 115 static u64 get_uflags(struct page *page)
 116 {
 117         u64 k;
 118         u64 u;
 119
 120         /*
 121          * pseudo flag: KPF_NOPAGE
 122          * it differentiates a memory hole from a page with no flags
 123          */
 124         if (!page)
 125                 return 1 << KPF_NOPAGE;
 126
 127         k = page->flags;
 128         u = 0;
 129
 130         /*
 131          * pseudo flags for the well known (anonymous) memory mapped pages
 132          *
 133          * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
 134          * simple test in page_mapped() is not enough.
 135          */
 136         if (!PageSlab(page) && page_mapped(page))
 137                 u |= 1 << KPF_MMAP;
 138         if (PageAnon(page))
 139                 u |= 1 << KPF_ANON;
 140
 141         /*
 142          * compound pages: export both head/tail info
 143          * they together define a compound page's start/end pos and order
 144          */
 145         if (PageHead(page))
 146                 u |= 1 << KPF_COMPOUND_HEAD;
 147         if (PageTail(page))
 148                 u |= 1 << KPF_COMPOUND_TAIL;
 149         if (PageHuge(page))
 150                 u |= 1 << KPF_HUGE;
 151
 152         u |= kpf_copy_bit(k, KPF_LOCKED,        PG_locked);
 153
 154         /*
 155          * Caveats on high order pages:
 156          * PG_buddy will only be set on the head page; SLUB/SLQB do the same
 157          * for PG_slab; SLOB won't set PG_slab at all on compound pages.
 158          */
 159         u |= kpf_copy_bit(k, KPF_SLAB,          PG_slab);
 160         u |= kpf_copy_bit(k, KPF_BUDDY,         PG_buddy);
 161
 162         u |= kpf_copy_bit(k, KPF_ERROR,         PG_error);
 163         u |= kpf_copy_bit(k, KPF_DIRTY,         PG_dirty);
 164         u |= kpf_copy_bit(k, KPF_UPTODATE,      PG_uptodate);
 165         u |= kpf_copy_bit(k, KPF_WRITEBACK,     PG_writeback);
 166
 167         u |= kpf_copy_bit(k, KPF_LRU,           PG_lru);
 168         u |= kpf_copy_bit(k, KPF_REFERENCED,    PG_referenced);
 169         u |= kpf_copy_bit(k, KPF_ACTIVE,        PG_active);
 170         u |= kpf_copy_bit(k, KPF_RECLAIM,       PG_reclaim);
 171
 172         u |= kpf_copy_bit(k, KPF_SWAPCACHE,     PG_swapcache);
 173         u |= kpf_copy_bit(k, KPF_SWAPBACKED,    PG_swapbacked);
 174
 175 #ifdef CONFIG_UNEVICTABLE_LRU
 176         u |= kpf_copy_bit(k, KPF_UNEVICTABLE,   PG_unevictable);
 177         u |= kpf_copy_bit(k, KPF_MLOCKED,       PG_mlocked);
 178 #endif
 179
 180 #ifdef CONFIG_IA64_UNCACHED_ALLOCATOR
 181         u |= kpf_copy_bit(k, KPF_UNCACHED,      PG_uncached);
 182 #endif
 183
 184         u |= kpf_copy_bit(k, KPF_RESERVED,      PG_reserved);
 185         u |= kpf_copy_bit(k, KPF_MAPPEDTODISK,  PG_mappedtodisk);
 186         u |= kpf_copy_bit(k, KPF_PRIVATE,       PG_private);
 187         u |= kpf_copy_bit(k, KPF_PRIVATE_2,     PG_private_2);
 188         u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
 189         u |= kpf_copy_bit(k, KPF_ARCH,          PG_arch_1);
 190
 191         return u;
 192 };
 193
 194 static ssize_t kpageflags_read(struct file *file, char __user *buf,
 195                              size_t count, loff_t *ppos)
 196 {
 197         u64 __user *out = (u64 __user *)buf;
 198         struct page *ppage;
 199         unsigned long src = *ppos;
 200         unsigned long pfn;
 201         ssize_t ret = 0;
 202
 203         pfn = src / KPMSIZE;
 204         count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
 205         if (src & KPMMASK || count & KPMMASK)
 206                 return -EINVAL;
 207
 208         while (count > 0) {
 209                 if (pfn_valid(pfn))
 210                         ppage = pfn_to_page(pfn);
 211                 else
 212                         ppage = NULL;
 213
 214                 if (put_user(get_uflags(ppage), out)) {
 215                         ret = -EFAULT;
 216                         break;
 217                 }
 218
 219                 pfn++;
 220                 out++;
 221                 count -= KPMSIZE;
 222         }
 223
 224         *ppos += (char __user *)out - buf;
 225         if (!ret)
 226                 ret = (char __user *)out - buf;
 227         return ret;
 228 }
 229
 230 static const struct file_operations proc_kpageflags_operations = {
 231         .llseek = mem_lseek,
 232         .read = kpageflags_read,
 233 };
 234
 235 static int __init proc_page_init(void)
 236 {
 237         proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 238         proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 239         return 0;
 240 }
 241 module_init(proc_page_init);