root/init/main.c

/* */

DEFINITIONS

1. _syscall0
2. time_init
3. get_options
4. checksetup
5. calibrate_delay
6. parse_options
7. copro_timeout
8. start_kernel
9. printf
10. init

   1 /*
   2  *  linux/init/main.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 #include <stdarg.h>
   8 
   9 #include <asm/system.h>
  10 #include <asm/io.h>
  11 
  12 #include <linux/mktime.h>
  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 #include <linux/string.h>
  21 #include <linux/timer.h>
  22 #include <linux/fs.h>
  23 #include <linux/ctype.h>
  24 #include <linux/delay.h>
  25 #include <linux/utsname.h>
  26 
  27 extern unsigned long * prof_buffer;
  28 extern unsigned long prof_len;
  29 extern char edata, end;
  30 extern char *linux_banner;
  31 extern "C" void lcall7(void);
  32 struct desc_struct default_ldt;
  33 
  34 /*
  35  * we need this inline - forking from kernel space will result
  36  * in NO COPY ON WRITE (!!!), until an execve is executed. This
  37  * is no problem, but for the stack. This is handled by not letting
  38  * main() use the stack at all after fork(). Thus, no function
  39  * calls - which means inline code for fork too, as otherwise we
  40  * would use the stack upon exit from 'fork()'.
  41  *
  42  * Actually only pause and fork are needed inline, so that there
  43  * won't be any messing with the stack from main(), but we define
  44  * some others too.
  45  */
  46 static inline _syscall0(int,idle)
     /*  */
  47 static inline _syscall0(int,fork)
  48 static inline _syscall0(int,pause)
  49 static inline _syscall1(int,setup,void *,BIOS)
  50 static inline _syscall0(int,sync)
  51 static inline _syscall0(pid_t,setsid)
  52 static inline _syscall3(int,write,int,fd,const char *,buf,off_t,count)
  53 static inline _syscall1(int,dup,int,fd)
  54 static inline _syscall3(int,execve,const char *,file,char **,argv,char **,envp)
  55 static inline _syscall3(int,open,const char *,file,int,flag,int,mode)
  56 static inline _syscall1(int,close,int,fd)
  57 static inline _syscall1(int,exit,int,exitcode)
  58 static inline _syscall3(pid_t,waitpid,pid_t,pid,int *,wait_stat,int,options)
  59 
  60 static inline pid_t wait(int * wait_stat)
  61 {
  62         return waitpid(-1,wait_stat,0);
  63 }
  64 
  65 static char printbuf[1024];
  66 
  67 extern char empty_zero_page[PAGE_SIZE];
  68 extern int vsprintf(char *,const char *,va_list);
  69 extern void init(void);
  70 extern void init_IRQ(void);
  71 extern long blk_dev_init(long,long);
  72 extern long chr_dev_init(long,long);
  73 extern void floppy_init(void);
  74 extern void sock_init(void);
  75 extern long rd_init(long mem_start, int length);
  76 extern long kernel_mktime(struct mktime * time);
  77 extern unsigned long simple_strtoul(const char *,char **,unsigned int);
  78 
  79 extern void hd_setup(char *str, int *ints);
  80 extern void bmouse_setup(char *str, int *ints);
  81 extern void eth_setup(char *str, int *ints);
  82 
  83 #ifdef CONFIG_SYSVIPC
  84 extern void ipc_init(void);
  85 #endif
  86 #ifdef CONFIG_SCSI
  87 extern unsigned long scsi_dev_init(unsigned long, unsigned long);
  88 #endif
  89 
  90 /*
  91  * This is set up by the setup-routine at boot-time
  92  */
  93 #define PARAM   empty_zero_page
  94 #define EXT_MEM_K (*(unsigned short *) (PARAM+2))
  95 #define DRIVE_INFO (*(struct drive_info_struct *) (PARAM+0x80))
  96 #define SCREEN_INFO (*(struct screen_info *) (PARAM+0))
  97 #define MOUNT_ROOT_RDONLY (*(unsigned short *) (PARAM+0x1F2))
  98 #define RAMDISK_SIZE (*(unsigned short *) (PARAM+0x1F8))
  99 #define ORIG_ROOT_DEV (*(unsigned short *) (PARAM+0x1FC))
 100 #define AUX_DEVICE_INFO (*(unsigned char *) (PARAM+0x1FF))
 101 
 102 /*
 103  * Boot command-line arguments
 104  */
 105 #define MAX_INIT_ARGS 8
 106 #define MAX_INIT_ENVS 8
 107 #define COMMAND_LINE ((char *) (PARAM+2048))
 108 
 109 /*
 110  * Yeah, yeah, it's ugly, but I cannot find how to do this correctly
 111  * and this seems to work. I anybody has more info on the real-time
 112  * clock I'd be interested. Most of this was trial and error, and some
 113  * bios-listing reading. Urghh.
 114  */
 115 
 116 #define CMOS_READ(addr) ({ \
 117 outb_p(addr,0x70); \
 118 inb_p(0x71); \
 119 })
 120 
 121 #define BCD_TO_BIN(val) ((val)=((val)&15) + ((val)>>4)*10)
 122 
 123 static void time_init(void)
     /*  */
 124 {
 125         struct mktime time;
 126         int i;
 127 
 128         for (i = 0 ; i < 1000000 ; i++)
 129                 if (!(CMOS_READ(10) & 0x80))
 130                         break;
 131         do {
 132                 time.sec = CMOS_READ(0);
 133                 time.min = CMOS_READ(2);
 134                 time.hour = CMOS_READ(4);
 135                 time.day = CMOS_READ(7);
 136                 time.mon = CMOS_READ(8);
 137                 time.year = CMOS_READ(9);
 138         } while (time.sec != CMOS_READ(0));
 139         BCD_TO_BIN(time.sec);
 140         BCD_TO_BIN(time.min);
 141         BCD_TO_BIN(time.hour);
 142         BCD_TO_BIN(time.day);
 143         BCD_TO_BIN(time.mon);
 144         BCD_TO_BIN(time.year);
 145         time.mon--;
 146         startup_time = kernel_mktime(&time);
 147 }
 148 
 149 static unsigned long memory_start = 0;  /* After mem_init, stores the */
 150                                         /* amount of free user memory */
 151 static unsigned long memory_end = 0;
 152 static unsigned long low_memory_start = 0;
 153 
 154 static char * argv_init[MAX_INIT_ARGS+2] = { "init", NULL, };
 155 static char * envp_init[MAX_INIT_ENVS+2] = { "HOME=/", "TERM=console", NULL, };
 156 
 157 static char * argv_rc[] = { "/bin/sh", NULL };
 158 static char * envp_rc[] = { "HOME=/", "TERM=console", NULL };
 159 
 160 static char * argv[] = { "-/bin/sh",NULL };
 161 static char * envp[] = { "HOME=/usr/root", "TERM=console", NULL };
 162 
 163 struct drive_info_struct { char dummy[32]; } drive_info;
 164 struct screen_info screen_info;
 165 
 166 unsigned char aux_device_present;
 167 int ramdisk_size;
 168 int root_mountflags = 0;
 169 
 170 static char fpu_error = 0;
 171 
 172 static char command_line[80] = { 0, };
 173 
 174 char *get_options(char *str, int *ints) 
     /*  */
 175 {
 176         char *cur = str;
 177         int i=1;
 178 
 179         while (cur && isdigit(*cur) && i <= 10) {
 180                 ints[i++] = simple_strtoul(cur,NULL,0);
 181                 if ((cur = strchr(cur,',')) != NULL)
 182                         cur++;
 183         }
 184         ints[0] = i-1;
 185         return(cur);
 186 }
 187 
 188 struct {
 189         char *str;
 190         void (*setup_func)(char *, int *);
 191 } bootsetups[] = {
 192 #ifdef CONFIG_INET
 193         { "ether=", eth_setup },
 194 #endif
 195 #ifdef CONFIG_BLK_DEV_HD
 196         { "hd=", hd_setup },
 197 #endif
 198 #ifdef CONFIG_BUSMOUSE
 199         { "bmouse=", bmouse_setup },
 200 #endif
 201         { 0, 0 }
 202 };
 203 
 204 int checksetup(char *line)
     /*  */
 205 {
 206         int i = 0;
 207         int ints[11];
 208 
 209         while (bootsetups[i].str) {
 210                 int n = strlen(bootsetups[i].str);
 211                 if (!strncmp(line,bootsetups[i].str,n)) {
 212                         bootsetups[i].setup_func(get_options(line+n,ints), ints);
 213                         return(0);
 214                 }
 215                 i++;
 216         }
 217         return(1);
 218 }
 219 
 220 unsigned long loops_per_sec = 1;
 221 
 222 static void calibrate_delay(void)
     /*  */
 223 {
 224         int ticks;
 225 
 226         printk("Calibrating delay loop.. ");
 227         while (loops_per_sec <<= 1) {
 228                 ticks = jiffies;
 229                 __delay(loops_per_sec);
 230                 ticks = jiffies - ticks;
 231                 if (ticks >= HZ) {
 232                         __asm__("mull %1 ; divl %2"
 233                                 :"=a" (loops_per_sec)
 234                                 :"d" (HZ),
 235                                  "r" (ticks),
 236                                  "0" (loops_per_sec)
 237                                 :"dx");
 238                         printk("ok - %d.%02d BogoMips (tm)\n",
 239                                 loops_per_sec/500000,
 240                                 (loops_per_sec/5000) % 100);
 241                         return;
 242                 }
 243         }
 244         printk("failed\n");
 245 }
 246         
 247 
 248 /*
 249  * This is a simple kernel command line parsing function: it parses
 250  * the command line, and fills in the arguments/environment to init
 251  * as appropriate. Any cmd-line option is taken to be an environment
 252  * variable if it contains the character '='.
 253  *
 254  *
 255  * This routine also checks for options meant for the kernel - currently
 256  * only the "root=XXXX" option is recognized. These options are not given
 257  * to init - they are for internal kernel use only.
 258  */
 259 static void parse_options(char *line)
     /*  */
 260 {
 261         char *next;
 262         char *devnames[] = { "hda", "hdb", "sda", "sdb", "sdc", "sdd", "sde", "fd", NULL };
 263         int devnums[]    = { 0x300, 0x340, 0x800, 0x810, 0x820, 0x830, 0x840, 0x200, 0};
 264         int args, envs;
 265 
 266         if (!*line)
 267                 return;
 268         args = 0;
 269         envs = 1;       /* TERM is set to 'console' by default */
 270         next = line;
 271         while ((line = next) != NULL) {
 272                 if ((next = strchr(line,' ')) != NULL)
 273                         *next++ = 0;
 274                 /*
 275                  * check for kernel options first..
 276                  */
 277                 if (!strncmp(line,"root=",5)) {
 278                         int n;
 279                         line += 5;
 280                         if (strncmp(line,"/dev/",5)) {
 281                                 ROOT_DEV = simple_strtoul(line,NULL,16);
 282                                 continue;
 283                         }
 284                         line += 5;
 285                         for (n = 0 ; devnames[n] ; n++) {
 286                                 int len = strlen(devnames[n]);
 287                                 if (!strncmp(line,devnames[n],len)) {
 288                                         ROOT_DEV = devnums[n]+simple_strtoul(line+len,NULL,16);
 289                                         break;
 290                                 }
 291                         }
 292                 } else if (!strcmp(line,"ro"))
 293                         root_mountflags |= MS_RDONLY;
 294                 else if (!strcmp(line,"rw"))
 295                         root_mountflags &= ~MS_RDONLY;
 296                 else if (!strcmp(line,"no387")) {
 297                         hard_math = 0;
 298                         __asm__("movl %%cr0,%%eax\n\t"
 299                                 "orl $0xE,%%eax\n\t"
 300                                 "movl %%eax,%%cr0\n\t" : : : "ax");
 301                 } else
 302                         checksetup(line);
 303                 /*
 304                  * Then check if it's an environment variable or
 305                  * an option.
 306                  */     
 307                 if (strchr(line,'=')) {
 308                         if (envs >= MAX_INIT_ENVS)
 309                                 break;
 310                         envp_init[++envs] = line;
 311                 } else {
 312                         if (args >= MAX_INIT_ARGS)
 313                                 break;
 314                         argv_init[++args] = line;
 315                 }
 316         }
 317         argv_init[args+1] = NULL;
 318         envp_init[envs+1] = NULL;
 319 }
 320 
 321 static void copro_timeout(void)
     /*  */
 322 {
 323         fpu_error = 1;
 324         timer_table[COPRO_TIMER].expires = jiffies+100;
 325         timer_active |= 1<<COPRO_TIMER;
 326         printk("387 failed: trying to reset\n");
 327         send_sig(SIGFPE, last_task_used_math, 1);
 328         outb_p(0,0xf1);
 329         outb_p(0,0xf0);
 330 }
 331 
 332 extern "C" void start_kernel(void)
     /*  */
 333 {
 334 /*
 335  * Interrupts are still disabled. Do necessary setups, then
 336  * enable them
 337  */
 338         set_call_gate(&default_ldt,lcall7);
 339         ROOT_DEV = ORIG_ROOT_DEV;
 340         drive_info = DRIVE_INFO;
 341         screen_info = SCREEN_INFO;
 342         aux_device_present = AUX_DEVICE_INFO;
 343         memory_end = (1<<20) + (EXT_MEM_K<<10);
 344         memory_end &= PAGE_MASK;
 345         ramdisk_size = RAMDISK_SIZE;
 346         strcpy(command_line,COMMAND_LINE);
 347 #ifdef CONFIG_MAX_16M
 348         if (memory_end > 16*1024*1024)
 349                 memory_end = 16*1024*1024;
 350 #endif
 351         if (MOUNT_ROOT_RDONLY)
 352                 root_mountflags |= MS_RDONLY;
 353         if ((unsigned long)&end >= (1024*1024)) {
 354                 memory_start = (unsigned long) &end;
 355                 low_memory_start = PAGE_SIZE;
 356         } else {
 357                 memory_start = 1024*1024;
 358                 low_memory_start = (unsigned long) &end;
 359         }
 360         low_memory_start = PAGE_ALIGN(low_memory_start);
 361         memory_start = paging_init(memory_start,memory_end);
 362         trap_init();
 363         init_IRQ();
 364         sched_init();
 365         parse_options(command_line);
 366 #ifdef CONFIG_PROFILE
 367         prof_buffer = (unsigned long *) memory_start;
 368         prof_len = (unsigned long) &end;
 369         prof_len >>= 2;
 370         memory_start += prof_len * sizeof(unsigned long);
 371 #endif
 372         memory_start = chr_dev_init(memory_start,memory_end);
 373         memory_start = blk_dev_init(memory_start,memory_end);
 374 #ifdef CONFIG_SCSI
 375         memory_start = scsi_dev_init(memory_start,memory_end);
 376 #endif
 377         memory_start = inode_init(memory_start,memory_end);
 378         memory_start = file_table_init(memory_start,memory_end);
 379         mem_init(low_memory_start,memory_start,memory_end);
 380         buffer_init();
 381         time_init();
 382         floppy_init();
 383         sock_init();
 384 #ifdef CONFIG_SYSVIPC
 385         ipc_init();
 386 #endif
 387         sti();
 388         calibrate_delay();
 389         /*
 390          * check if exception 16 works correctly.. This is truly evil
 391          * code: it disables the high 8 interrupts to make sure that
 392          * the irq13 doesn't happen. But as this will lead to a lockup
 393          * if no exception16 arrives, it depends on the fact that the
 394          * high 8 interrupts will be re-enabled by the next timer tick.
 395          * So the irq13 will happen eventually, but the exception 16
 396          * should get there first..
 397          */
 398         if (hard_math) {
 399                 unsigned short control_word;
 400 
 401                 printk("Checking 386/387 coupling... ");
 402                 timer_table[COPRO_TIMER].expires = jiffies+50;
 403                 timer_table[COPRO_TIMER].fn = copro_timeout;
 404                 timer_active |= 1<<COPRO_TIMER;
 405                 __asm__("clts ; fninit ; fnstcw %0 ; fwait":"=m" (*&control_word));
 406                 control_word &= 0xffc0;
 407                 __asm__("fldcw %0 ; fwait": :"m" (*&control_word));
 408                 outb_p(inb_p(0x21) | (1 << 2), 0x21);
 409                 __asm__("fldz ; fld1 ; fdiv %st,%st(1) ; fwait");
 410                 timer_active &= ~(1<<COPRO_TIMER);
 411                 if (!fpu_error)
 412                         printk("Ok, fpu using %s error reporting.\n",
 413                                 ignore_irq13?"exception 16":"irq13");
 414         }
 415 #ifndef CONFIG_MATH_EMULATION
 416         else {
 417                 printk("No coprocessor found and no math emulation present.\n");
 418                 printk("Giving up.\n");
 419                 for (;;) ;
 420         }
 421 #endif
 422         move_to_user_mode();
 423         if (!fork())            /* we count on this going ok */
 424                 init();
 425 /*
 426  * task[0] is meant to be used as an "idle" task: it may not sleep, but
 427  * it might do some general things like count free pages or it could be
 428  * used to implement a reasonable LRU algorithm for the paging routines:
 429  * anything that can be useful, but shouldn't take time from the real
 430  * processes.
 431  *
 432  * Right now task[0] just does a infinite idle loop.
 433  */
 434         for(;;)
 435                 idle();
 436 }
 437 
 438 static int printf(const char *fmt, ...)
     /*  */
 439 {
 440         va_list args;
 441         int i;
 442 
 443         va_start(args, fmt);
 444         write(1,printbuf,i=vsprintf(printbuf, fmt, args));
 445         va_end(args);
 446         return i;
 447 }
 448 
 449 void init(void)
     /*  */
 450 {
 451         int pid,i;
 452 
 453         setup((void *) &drive_info);
 454         (void) open("/dev/tty1",O_RDWR,0);
 455         (void) dup(0);
 456         (void) dup(0);
 457 
 458         system_utsname.machine[1] = '0' + x86;
 459         printf(linux_banner);
 460 
 461         execve("/etc/init",argv_init,envp_init);
 462         execve("/bin/init",argv_init,envp_init);
 463         execve("/sbin/init",argv_init,envp_init);
 464         /* if this fails, fall through to original stuff */
 465 
 466         if (!(pid=fork())) {
 467                 close(0);
 468                 if (open("/etc/rc",O_RDONLY,0))
 469                         exit(1);
 470                 execve("/bin/sh",argv_rc,envp_rc);
 471                 exit(2);
 472         }
 473         if (pid>0)
 474                 while (pid != wait(&i))
 475                         /* nothing */;
 476         while (1) {
 477                 if ((pid = fork()) < 0) {
 478                         printf("Fork failed in init\n\r");
 479                         continue;
 480                 }
 481                 if (!pid) {
 482                         close(0);close(1);close(2);
 483                         setsid();
 484                         (void) open("/dev/tty1",O_RDWR,0);
 485                         (void) dup(0);
 486                         (void) dup(0);
 487                         exit(execve("/bin/sh",argv,envp));
 488                 }
 489                 while (1)
 490                         if (pid == wait(&i))
 491                                 break;
 492                 printf("\n\rchild %d died with code %04x\n\r",pid,i);
 493                 sync();
 494         }
 495         exit(0);
 496 }

/* */