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
35static 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
45static 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
61static 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
68static 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 */
84void _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