File: /usr/src/linux/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     }
80