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                 unsigned long mem_total, sav_total;
  37                 unsigned int mem_unit, bitcount;
  38
  39                 /* If the sum of all the available memory (i.e. ram + swap)
  40                  * is less than can be stored in a 32 bit unsigned long then
  41                  * we can be binary compatible with 2.2.x kernels.  If not,
  42                  * well, in that case 2.2.x was broken anyways...
  43                  *
  44                  *  -Erik Andersen <andersee@debian.org> */
  45
  46                 mem_total = val.totalram + val.totalswap;
  47                 if (mem_total < val.totalram || mem_total < val.totalswap)
  48                         goto out;
  49                 bitcount = 0;
  50                 mem_unit = val.mem_unit;
  51                 while (mem_unit > 1) {
  52                         bitcount++;
  53                         mem_unit >>= 1;
  54                         sav_total = mem_total;
  55                         mem_total <<= 1;
  56                         if (mem_total < sav_total)
  57                                 goto out;
  58                 }
  59
  60                 /* If mem_total did not overflow, multiply all memory values by
  61                  * val.mem_unit and set it to 1.  This leaves things compatible
  62                  * with 2.2.x, and also retains compatibility with earlier 2.4.x
  63                  * kernels...  */
  64
  65                 val.mem_unit = 1;
  66                 val.totalram <<= bitcount;
  67                 val.freeram <<= bitcount;
  68                 val.sharedram <<= bitcount;
  69                 val.bufferram <<= bitcount;
  70                 val.totalswap <<= bitcount;
  71                 val.freeswap <<= bitcount;
  72                 val.totalhigh <<= bitcount;
  73                 val.freehigh <<= bitcount;
  74         }
  75 out:
  76         if (copy_to_user(info, &val, sizeof(struct sysinfo)))
  77                 return -EFAULT;
  78         return 0;
  79 }