init/main.c

/* */
This source file includes following definitions.
_syscall0
sprintf
time_init
start_kernel
printf
init
   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <stdarg.h>
   8 #include <time.h>
   9 
  10 #include <asm/system.h>
  11 #include <asm/io.h>
  12 
  13 #include <linux/types.h>
  14 #include <linux/fcntl.h>
  15 #include <linux/config.h>
  16 #include <linux/sched.h>
  17 #include <linux/tty.h>
  18 #include <linux/head.h>
  19 #include <linux/unistd.h>
  20 
  21 /*
  22  * we need this inline - forking from kernel space will result
  23  * in NO COPY ON WRITE (!!!), until an execve is executed. This
  24  * is no problem, but for the stack. This is handled by not letting
  25  * main() use the stack at all after fork(). Thus, no function
  26  * calls - which means inline code for fork too, as otherwise we
  27  * would use the stack upon exit from 'fork()'.
  28  *
  29  * Actually only pause and fork are needed inline, so that there
  30  * won't be any messing with the stack from main(), but we define
  31  * some others too.
  32  */
  33 static inline _syscall0(int,fork)
     /*  */
  34 static inline _syscall0(int,pause)
  35 static inline _syscall1(int,setup,void *,BIOS)
  36 static inline _syscall0(int,sync)
  37 static inline _syscall0(pid_t,setsid)
  38 static inline _syscall3(int,write,int,fd,const char *,buf,off_t,count)
  39 static inline _syscall1(int,dup,int,fd)
  40 static inline _syscall3(int,execve,const char *,file,char **,argv,char **,envp)
  41 static inline _syscall3(int,open,const char *,file,int,flag,int,mode)
  42 static inline _syscall1(int,close,int,fd)
  43 static inline _syscall3(pid_t,waitpid,pid_t,pid,int *,wait_stat,int,options)
  44 
  45 static inline pid_t wait(int * wait_stat)
  46 {
  47         return waitpid(-1,wait_stat,0);
  48 }
  49 
  50 static char printbuf[1024];
  51 
  52 extern int vsprintf();
  53 extern void init(void);
  54 extern void init_IRQ(void);
  55 extern long blk_dev_init(long,long);
  56 extern long chr_dev_init(long,long);
  57 extern void hd_init(void);
  58 extern void floppy_init(void);
  59 extern void sock_init(void);
  60 extern long rd_init(long mem_start, int length);
  61 extern long kernel_mktime(struct tm * tm);
  62 
  63 #ifdef CONFIG_SCSI
  64 extern void scsi_dev_init(void);
  65 #endif
  66 
  67 static int sprintf(char * str, const char *fmt, ...)
     /*  */
  68 {
  69         va_list args;
  70         int i;
  71 
  72         va_start(args, fmt);
  73         i = vsprintf(str, fmt, args);
  74         va_end(args);
  75         return i;
  76 }
  77 
  78 /*
  79  * This is set up by the setup-routine at boot-time
  80  */
  81 #define EXT_MEM_K (*(unsigned short *)0x90002)
  82 #define DRIVE_INFO (*(struct drive_info *)0x90080)
  83 #define SCREEN_INFO (*(struct screen_info *)0x90000)
  84 #define ORIG_ROOT_DEV (*(unsigned short *)0x901FC)
  85 
  86 /*
  87  * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
  88  * and this seems to work. I anybody has more info on the real-time
  89  * clock I'd be interested. Most of this was trial and error, and some
  90  * bios-listing reading. Urghh.
  91  */
  92 
  93 #define CMOS_READ(addr) ({ \
  94 outb_p(0x80|addr,0x70); \
  95 inb_p(0x71); \
  96 })
  97 
  98 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
  99 
 100 static void time_init(void)
     /*  */
 101 {
 102         struct tm time;
 103 
 104         do {
 105                 time.tm_sec = CMOS_READ(0);
 106                 time.tm_min = CMOS_READ(2);
 107                 time.tm_hour = CMOS_READ(4);
 108                 time.tm_mday = CMOS_READ(7);
 109                 time.tm_mon = CMOS_READ(8);
 110                 time.tm_year = CMOS_READ(9);
 111         } while (time.tm_sec != CMOS_READ(0));
 112         BCD_TO_BIN(time.tm_sec);
 113         BCD_TO_BIN(time.tm_min);
 114         BCD_TO_BIN(time.tm_hour);
 115         BCD_TO_BIN(time.tm_mday);
 116         BCD_TO_BIN(time.tm_mon);
 117         BCD_TO_BIN(time.tm_year);
 118         time.tm_mon--;
 119         startup_time = kernel_mktime(&time);
 120 }
 121 
 122 static unsigned long memory_start = 0;
 123 static unsigned long memory_end = 0;
 124 
 125 static char term[32];
 126 
 127 static char * argv_init[] = { "/bin/init", NULL };
 128 static char * envp_init[] = { "HOME=/", NULL, NULL };
 129 
 130 static char * argv_rc[] = { "/bin/sh", NULL };
 131 static char * envp_rc[] = { "HOME=/", NULL ,NULL };
 132 
 133 static char * argv[] = { "-/bin/sh",NULL };
 134 static char * envp[] = { "HOME=/usr/root", NULL, NULL };
 135 
 136 struct drive_info { char dummy[32]; } drive_info;
 137 struct screen_info screen_info;
 138 
 139 void start_kernel(void)
     /*  */
 140 {
 141 /*
 142  * Interrupts are still disabled. Do necessary setups, then
 143  * enable them
 144  */
 145         ROOT_DEV = ORIG_ROOT_DEV;
 146         drive_info = DRIVE_INFO;
 147         screen_info = SCREEN_INFO;
 148         sprintf(term, "TERM=con%dx%d", ORIG_VIDEO_COLS, ORIG_VIDEO_LINES);
 149         envp[1] = term; 
 150         envp_rc[1] = term;
 151         envp_init[1] = term;
 152         memory_end = (1<<20) + (EXT_MEM_K<<10);
 153         memory_end &= 0xfffff000;
 154         if (memory_end > 16*1024*1024)
 155                 memory_end = 16*1024*1024;
 156         memory_start = 1024*1024;
 157         trap_init();
 158         init_IRQ();
 159         sched_init();
 160         memory_start = chr_dev_init(memory_start,memory_end);
 161         memory_start = blk_dev_init(memory_start,memory_end);
 162         memory_start = mem_init(memory_start,memory_end);
 163         buffer_init();
 164         time_init();
 165         printk("Linux version " UTS_RELEASE " " __DATE__ " " __TIME__ "\n");
 166         hd_init();
 167         floppy_init();
 168         sock_init();
 169         sti();
 170 #ifdef CONFIG_SCSI
 171         scsi_dev_init();
 172 #endif
 173         move_to_user_mode();
 174         if (!fork()) {          /* we count on this going ok */
 175                 init();
 176         }
 177 /*
 178  * task[0] is meant to be used as an "idle" task: it may not sleep, but
 179  * it might do some general things like count free pages or it could be
 180  * used to implement a reasonable LRU algorithm for the paging routines:
 181  * anything that can be useful, but shouldn't take time from the real
 182  * processes.
 183  *
 184  * Right now task[0] just does a infinite loop in user mode.
 185  */
 186         for(;;)
 187                 /* nothing */ ;
 188 }
 189 
 190 static int printf(const char *fmt, ...)
     /*  */
 191 {
 192         va_list args;
 193         int i;
 194 
 195         va_start(args, fmt);
 196         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 197         va_end(args);
 198         return i;
 199 }
 200 
 201 void init(void)
     /*  */
 202 {
 203         int pid,i;
 204 
 205         setup((void *) &drive_info);
 206         (void) open("/dev/tty1",O_RDWR,0);
 207         (void) dup(0);
 208         (void) dup(0);
 209         printf("%d buffers = %d bytes buffer space\n\r",nr_buffers,
 210                 nr_buffers*BLOCK_SIZE);
 211         printf("Free mem: %d bytes\n\r",memory_end-memory_start);
 212 
 213         execve("/etc/init",argv_init,envp_init);
 214         execve("/bin/init",argv_init,envp_init);
 215         /* if this fails, fall through to original stuff */
 216 
 217         if (!(pid=fork())) {
 218                 close(0);
 219                 if (open("/etc/rc",O_RDONLY,0))
 220                         _exit(1);
 221                 execve("/bin/sh",argv_rc,envp_rc);
 222                 _exit(2);
 223         }
 224         if (pid>0)
 225                 while (pid != wait(&i))
 226                         /* nothing */;
 227         while (1) {
 228                 if ((pid=fork())<0) {
 229                         printf("Fork failed in init\r\n");
 230                         continue;
 231                 }
 232                 if (!pid) {
 233                         close(0);close(1);close(2);
 234                         setsid();
 235                         (void) open("/dev/tty1",O_RDWR,0);
 236                         (void) dup(0);
 237                         (void) dup(0);
 238                         _exit(execve("/bin/sh",argv,envp));
 239                 }
 240                 while (1)
 241                         if (pid == wait(&i))
 242                                 break;
 243                 printf("\n\rchild %d died with code %04x\n\r",pid,i);
 244                 sync();
 245         }
 246         _exit(0);       /* NOTE! _exit, not exit() */
 247 }
/* */
root/init/main.c

DEFINITIONS
