1 /*
2  * Copyright 2014 Sony Mobile Communications Inc.
3  *
4  * Licensed under the terms of the GNU GPL License version 2
5  *
6  * Selftest for runtime system size
7  *
8  * Prints the amount of RAM that the currently running system is using.
9  *
10  * This program tries to be as small as possible itself, to
11  * avoid perturbing the system memory utilization with its
12  * own execution.  It also attempts to have as few dependencies
13  * on kernel features as possible.
14  *
15  * It should be statically linked, with startup libs avoided.
16  * It uses no library calls, and only the following 3 syscalls:
17  *   sysinfo(), write(), and _exit()
18  *
19  * For output, it avoids printf (which in some C libraries
20  * has large external dependencies) by  implementing it's own
21  * number output and print routines, and using __builtin_strlen()
22  */
23 
24 #include <sys/sysinfo.h>
25 #include <unistd.h>
26 
27 #define STDOUT_FILENO 1
28 
29 static int print(const char *s)
30 {
31 	return write(STDOUT_FILENO, s, __builtin_strlen(s));
32 }
33 
34 static inline char *num_to_str(unsigned long num, char *buf, int len)
35 {
36 	unsigned int digit;
37 
38 	/* put digits in buffer from back to front */
39 	buf += len - 1;
40 	*buf = 0;
41 	do {
42 		digit = num % 10;
43 		*(--buf) = digit + '0';
44 		num /= 10;
45 	} while (num > 0);
46 
47 	return buf;
48 }
49 
50 static int print_num(unsigned long num)
51 {
52 	char num_buf[30];
53 
54 	return print(num_to_str(num, num_buf, sizeof(num_buf)));
55 }
56 
57 static int print_k_value(const char *s, unsigned long num, unsigned long units)
58 {
59 	unsigned long long temp;
60 	int ccode;
61 
62 	print(s);
63 
64 	temp = num;
65 	temp = (temp * units)/1024;
66 	num = temp;
67 	ccode = print_num(num);
68 	print("\n");
69 	return ccode;
70 }
71 
72 /* this program has no main(), as startup libraries are not used */
73 void _start(void)
74 {
75 	int ccode;
76 	struct sysinfo info;
77 	unsigned long used;
78 
79 	print("Testing system size.\n");
80 	print("1..1\n");
81 
82 	ccode = sysinfo(&info);
83 	if (ccode < 0) {
84 		print("not ok 1 get runtime memory use\n");
85 		print("# could not get sysinfo\n");
86 		_exit(ccode);
87 	}
88 	/* ignore cache complexities for now */
89 	used = info.totalram - info.freeram - info.bufferram;
90 	print_k_value("ok 1 get runtime memory use # size = ", used,
91 		info.mem_unit);
92 
93 	print("# System runtime memory report (units in Kilobytes):\n");
94 	print_k_value("#   Total:  ", info.totalram, info.mem_unit);
95 	print_k_value("#   Free:   ", info.freeram, info.mem_unit);
96 	print_k_value("#   Buffer: ", info.bufferram, info.mem_unit);
97 	print_k_value("#   In use: ", used, info.mem_unit);
98 
99 	_exit(0);
100 }
101