tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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.
15 * It uses no library calls, and only the following 3 syscalls:
16 * sysinfo(), write(), and _exit()
17 *
18 * For output, it avoids printf (which in some C libraries
19 * has large external dependencies) by implementing it's own
20 * number output and print routines, and using __builtin_strlen()
21 */
22
23#include <sys/sysinfo.h>
24#include <unistd.h>
25
26#define STDOUT_FILENO 1
27
28static int print(const char *s)
29{
30 return write(STDOUT_FILENO, s, __builtin_strlen(s));
31}
32
33static inline char *num_to_str(unsigned long num, char *buf, int len)
34{
35 unsigned int digit;
36
37 /* put digits in buffer from back to front */
38 buf += len - 1;
39 *buf = 0;
40 do {
41 digit = num % 10;
42 *(--buf) = digit + '0';
43 num /= 10;
44 } while (num > 0);
45
46 return buf;
47}
48
49static int print_num(unsigned long num)
50{
51 char num_buf[30];
52
53 return print(num_to_str(num, num_buf, sizeof(num_buf)));
54}
55
56static int print_k_value(const char *s, unsigned long num, unsigned long units)
57{
58 unsigned long long temp;
59 int ccode;
60
61 print(s);
62
63 temp = num;
64 temp = (temp * units)/1024;
65 num = temp;
66 ccode = print_num(num);
67 print("\n");
68 return ccode;
69}
70
71/* this program has no main(), as startup libraries are not used */
72void _start(void)
73{
74 int ccode;
75 struct sysinfo info;
76 unsigned long used;
77 static const char *test_name = " get runtime memory use\n";
78
79 print("TAP version 13\n");
80 print("# Testing system size.\n");
81
82 ccode = sysinfo(&info);
83 if (ccode < 0) {
84 print("not ok 1");
85 print(test_name);
86 print(" ---\n reason: \"could not get sysinfo\"\n ...\n");
87 _exit(ccode);
88 }
89 print("ok 1");
90 print(test_name);
91
92 /* ignore cache complexities for now */
93 used = info.totalram - info.freeram - info.bufferram;
94 print("# System runtime memory report (units in Kilobytes):\n");
95 print(" ---\n");
96 print_k_value(" Total: ", info.totalram, info.mem_unit);
97 print_k_value(" Free: ", info.freeram, info.mem_unit);
98 print_k_value(" Buffer: ", info.bufferram, info.mem_unit);
99 print_k_value(" In use: ", used, info.mem_unit);
100 print(" ...\n");
101 print("1..1\n");
102
103 _exit(0);
104}