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 <asm/uaccess.h>
  12 #include "internal.h"
  13
  14 #define KPMSIZE sizeof(u64)
  15 #define KPMMASK (KPMSIZE - 1)
  16
  17 /* /proc/kpagecount - an array exposing page counts
  18  *
  19  * Each entry is a u64 representing the corresponding
  20  * physical page count.
  21  */
  22 static ssize_t kpagecount_read(struct file *file, char __user *buf,
  23                              size_t count, loff_t *ppos)
  24 {
  25         u64 __user *out = (u64 __user *)buf;
  26         struct page *ppage;
  27         unsigned long src = *ppos;
  28         unsigned long pfn;
  29         ssize_t ret = 0;
  30         u64 pcount;
  31
  32         pfn = src / KPMSIZE;
  33         count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
  34         if (src & KPMMASK || count & KPMMASK)
  35                 return -EINVAL;
  36
  37         while (count > 0) {
  38                 if (pfn_valid(pfn))
  39                         ppage = pfn_to_page(pfn);
  40                 else
  41                         ppage = NULL;
  42                 if (!ppage)
  43                         pcount = 0;
  44                 else
  45                         pcount = page_mapcount(ppage);
  46
  47                 if (put_user(pcount, out)) {
  48                         ret = -EFAULT;
  49                         break;
  50                 }
  51
  52                 pfn++;
  53                 out++;
  54                 count -= KPMSIZE;
  55         }
  56
  57         *ppos += (char __user *)out - buf;
  58         if (!ret)
  59                 ret = (char __user *)out - buf;
  60         return ret;
  61 }
  62
  63 static const struct file_operations proc_kpagecount_operations = {
  64         .llseek = mem_lseek,
  65         .read = kpagecount_read,
  66 };
  67
  68 /* /proc/kpageflags - an array exposing page flags
  69  *
  70  * Each entry is a u64 representing the corresponding
  71  * physical page flags.
  72  */
  73
  74 /* These macros are used to decouple internal flags from exported ones */
  75
  76 #define KPF_LOCKED              0
  77 #define KPF_ERROR               1
  78 #define KPF_REFERENCED          2
  79 #define KPF_UPTODATE            3
  80 #define KPF_DIRTY               4
  81 #define KPF_LRU                 5
  82 #define KPF_ACTIVE              6
  83 #define KPF_SLAB                7
  84 #define KPF_WRITEBACK           8
  85 #define KPF_RECLAIM             9
  86 #define KPF_BUDDY               10
  87
  88 /* 11-20: new additions in 2.6.31 */
  89 #define KPF_MMAP                11
  90 #define KPF_ANON                12
  91 #define KPF_SWAPCACHE           13
  92 #define KPF_SWAPBACKED          14
  93 #define KPF_COMPOUND_HEAD       15
  94 #define KPF_COMPOUND_TAIL       16
  95 #define KPF_HUGE                17
  96 #define KPF_UNEVICTABLE         18
  97 #define KPF_HWPOISON            19
  98 #define KPF_NOPAGE              20
  99
 100 #define KPF_KSM                 21
 101
 102 /* kernel hacking assistances
 103  * WARNING: subject to change, never rely on them!
 104  */
 105 #define KPF_RESERVED            32
 106 #define KPF_MLOCKED             33
 107 #define KPF_MAPPEDTODISK        34
 108 #define KPF_PRIVATE             35
 109 #define KPF_PRIVATE_2           36
 110 #define KPF_OWNER_PRIVATE       37
 111 #define KPF_ARCH                38
 112 #define KPF_UNCACHED            39
 113
 114 static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
 115 {
 116         return ((kflags >> kbit) & 1) << ubit;
 117 }
 118
 119 static u64 get_uflags(struct page *page)
 120 {
 121         u64 k;
 122         u64 u;
 123
 124         /*
 125          * pseudo flag: KPF_NOPAGE
 126          * it differentiates a memory hole from a page with no flags
 127          */
 128         if (!page)
 129                 return 1 << KPF_NOPAGE;
 130
 131         k = page->flags;
 132         u = 0;
 133
 134         /*
 135          * pseudo flags for the well known (anonymous) memory mapped pages
 136          *
 137          * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
 138          * simple test in page_mapped() is not enough.
 139          */
 140         if (!PageSlab(page) && page_mapped(page))
 141                 u |= 1 << KPF_MMAP;
 142         if (PageAnon(page))
 143                 u |= 1 << KPF_ANON;
 144         if (PageKsm(page))
 145                 u |= 1 << KPF_KSM;
 146
 147         /*
 148          * compound pages: export both head/tail info
 149          * they together define a compound page's start/end pos and order
 150          */
 151         if (PageHead(page))
 152                 u |= 1 << KPF_COMPOUND_HEAD;
 153         if (PageTail(page))
 154                 u |= 1 << KPF_COMPOUND_TAIL;
 155         if (PageHuge(page))
 156                 u |= 1 << KPF_HUGE;
 157
 158         u |= kpf_copy_bit(k, KPF_LOCKED,        PG_locked);
 159
 160         /*
 161          * Caveats on high order pages:
 162          * PG_buddy will only be set on the head page; SLUB/SLQB do the same
 163          * for PG_slab; SLOB won't set PG_slab at all on compound pages.
 164          */
 165         u |= kpf_copy_bit(k, KPF_SLAB,          PG_slab);
 166         u |= kpf_copy_bit(k, KPF_BUDDY,         PG_buddy);
 167
 168         u |= kpf_copy_bit(k, KPF_ERROR,         PG_error);
 169         u |= kpf_copy_bit(k, KPF_DIRTY,         PG_dirty);
 170         u |= kpf_copy_bit(k, KPF_UPTODATE,      PG_uptodate);
 171         u |= kpf_copy_bit(k, KPF_WRITEBACK,     PG_writeback);
 172
 173         u |= kpf_copy_bit(k, KPF_LRU,           PG_lru);
 174         u |= kpf_copy_bit(k, KPF_REFERENCED,    PG_referenced);
 175         u |= kpf_copy_bit(k, KPF_ACTIVE,        PG_active);
 176         u |= kpf_copy_bit(k, KPF_RECLAIM,       PG_reclaim);
 177
 178         u |= kpf_copy_bit(k, KPF_SWAPCACHE,     PG_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_IA64_UNCACHED_ALLOCATOR
 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(get_uflags(ppage), out)) {
 223                         ret = -EFAULT;
 224                         break;
 225                 }
 226
 227                 pfn++;
 228                 out++;
 229                 count -= KPMSIZE;
 230         }
 231
 232         *ppos += (char __user *)out - buf;
 233         if (!ret)
 234                 ret = (char __user *)out - buf;
 235         return ret;
 236 }
 237
 238 static const struct file_operations proc_kpageflags_operations = {
 239         .llseek = mem_lseek,
 240         .read = kpageflags_read,
 241 };
 242
 243 static int __init proc_page_init(void)
 244 {
 245         proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
 246         proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
 247         return 0;
 248 }
 249 module_init(proc_page_init);