kernel/info.c

   1 /*
   2  * linux/kernel/info.c
   3  *
   4  * Copyright (C) 1992 Darren Senn
   5  */
   6
   7 /* This implements the sysinfo() system call */
   8
   9 #include <linux/mm.h>
  10 #include <linux/unistd.h>
  11 #include <linux/swap.h>
  12 #include <linux/smp_lock.h>
  13
  14 #include <asm/uaccess.h>
  15
  16 asmlinkage long sys_sysinfo(struct sysinfo *info)
  17 {
  18         struct sysinfo val;
  19
  20         memset((char *)&val, 0, sizeof(struct sysinfo));
  21
  22         cli();
  23         val.uptime = jiffies / HZ;
  24
  25         val.loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
  26         val.loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
  27         val.loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);
  28
  29         val.procs = nr_threads-1;
  30         sti();
  31
  32         si_meminfo(&val);
  33         si_swapinfo(&val);
  34
  35         {
  36                 /* If the sum of all the available memory (i.e. ram + swap +
  37                  * highmem) is less then can be stored in a 32 bit unsigned long
  38                  * then we can be binary compatible with 2.2.x kernels.  If not,
  39                  * well, who cares since in that case 2.2.x was broken anyways...
  40                  *
  41                  *  -Erik Andersen <andersee@debian.org> */
  42
  43                 unsigned long mem_total = val.totalram + val.totalswap;
  44                 if ( !(mem_total < val.totalram || mem_total < val.totalswap)) {
  45                         unsigned long mem_total2 = mem_total + val.totalhigh;
  46                         if (!(mem_total2 < mem_total || mem_total2 < val.totalhigh))
  47                         {
  48                                 /* If mem_total did not overflow.  Divide all memory values by
  49                                  * mem_unit and set mem_unit=1.  This leaves things compatible with
  50                                  * 2.2.x, and also retains compatibility with earlier 2.4.x
  51                                  * kernels...  */
  52
  53                                 int bitcount = 0;
  54                                 while (val.mem_unit > 1)
  55                                 {
  56                                         bitcount++;
  57                                         val.mem_unit >>= 1;
  58                                 }
  59                                 val.totalram <<= bitcount;
  60                                 val.freeram <<= bitcount;
  61                                 val.sharedram <<= bitcount;
  62                                 val.bufferram <<= bitcount;
  63                                 val.totalswap <<= bitcount;
  64                                 val.freeswap <<= bitcount;
  65                                 val.totalhigh <<= bitcount;
  66                                 val.freehigh <<= bitcount;
  67                         }
  68                 }
  69         }
  70
  71         if (copy_to_user(info, &val, sizeof(struct sysinfo)))
  72                 return -EFAULT;
  73         return 0;
  74 }