1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright 2014 Sony Mobile Communications Inc.
4 *
5 * Selftest for runtime system size
6 *
7 * Prints the amount of RAM that the currently running system is using.
8 *
9 * This program tries to be as small as possible itself, to
10 * avoid perturbing the system memory utilization with its
11 * own execution. It also attempts to have as few dependencies
12 * on kernel features as possible.
13 *
14 * It should be statically linked, with startup libs avoided. It uses
15 * no library calls except the syscall() function for the following 3
16 * 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 * The test may crash if any of the above syscalls fails because in some
24 * libc implementations (e.g. the GNU C Library) errno is saved in
25 * thread-local storage, which does not get initialized due to avoiding
26 * startup libs.
27 */
28
29 #include <sys/sysinfo.h>
30 #include <unistd.h>
31 #include <sys/syscall.h>
32
33 #define STDOUT_FILENO 1
34
print(const char * s)35 static int print(const char *s)
36 {
37 size_t len = 0;
38
39 while (s[len] != '\0')
40 len++;
41
42 return syscall(SYS_write, STDOUT_FILENO, s, len);
43 }
44
num_to_str(unsigned long num,char * buf,int len)45 static inline char *num_to_str(unsigned long num, char *buf, int len)
46 {
47 unsigned int digit;
48
49 /* put digits in buffer from back to front */
50 buf += len - 1;
51 *buf = 0;
52 do {
53 digit = num % 10;
54 *(--buf) = digit + '0';
55 num /= 10;
56 } while (num > 0);
57
58 return buf;
59 }
60
print_num(unsigned long num)61 static int print_num(unsigned long num)
62 {
63 char num_buf[30];
64
65 return print(num_to_str(num, num_buf, sizeof(num_buf)));
66 }
67
print_k_value(const char * s,unsigned long num,unsigned long units)68 static int print_k_value(const char *s, unsigned long num, unsigned long units)
69 {
70 unsigned long long temp;
71 int ccode;
72
73 print(s);
74
75 temp = num;
76 temp = (temp * units)/1024;
77 num = temp;
78 ccode = print_num(num);
79 print("\n");
80 return ccode;
81 }
82
83 /* this program has no main(), as startup libraries are not used */
_start(void)84 void _start(void)
85 {
86 int ccode;
87 struct sysinfo info;
88 unsigned long used;
89 static const char *test_name = " get runtime memory use\n";
90
91 print("TAP version 13\n");
92 print("# Testing system size.\n");
93
94 ccode = syscall(SYS_sysinfo, &info);
95 if (ccode < 0) {
96 print("not ok 1");
97 print(test_name);
98 print(" ---\n reason: \"could not get sysinfo\"\n ...\n");
99 syscall(SYS_exit, ccode);
100 }
101 print("ok 1");
102 print(test_name);
103
104 /* ignore cache complexities for now */
105 used = info.totalram - info.freeram - info.bufferram;
106 print("# System runtime memory report (units in Kilobytes):\n");
107 print(" ---\n");
108 print_k_value(" Total: ", info.totalram, info.mem_unit);
109 print_k_value(" Free: ", info.freeram, info.mem_unit);
110 print_k_value(" Buffer: ", info.bufferram, info.mem_unit);
111 print_k_value(" In use: ", used, info.mem_unit);
112 print(" ...\n");
113 print("1..1\n");
114
115 syscall(SYS_exit, 0);
116 }
117