tools/testing/selftests/size/get_size.c

   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
  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
  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
  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
  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 */
  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 }