kernel/main.c

   1 /* This file contains the main program of MINIX as well as its shutdown code.
   2  * The routine main() initializes the system and starts the ball rolling by
   3  * setting up the process table, interrupt vectors, and scheduling each task
   4  * to run to initialize itself.
   5  * The routine shutdown() does the opposite and brings down MINIX.
   6  *
   7  * The entries into this file are:
   8  *   main:              MINIX main program
   9  *   prepare_shutdown:  prepare to take MINIX down
  10  */
  11 #include "kernel.h"
  12 #include <string.h>
  13 #include <unistd.h>
  14 #include <assert.h>
  15 #include <a.out.h>
  16 #include <minix/com.h>
  17 #include <minix/endpoint.h>
  18 #include <minix/u64.h>
  19 #include "proc.h"
  20 #include "debug.h"
  21 #include "clock.h"
  22
  23 /* Prototype declarations for PRIVATE functions. */
  24 FORWARD _PROTOTYPE( void announce, (void));
  25
  26 /*===========================================================================*
  27  *                              main                                         *
  28  *===========================================================================*/
  29 PUBLIC void main(void)
  30 {
  31 /* Start the ball rolling. */
  32   struct boot_image *ip;        /* boot image pointer */
  33   register struct proc *rp;     /* process pointer */
  34   register struct priv *sp;     /* privilege structure pointer */
  35   register int i, j;
  36   int hdrindex;                 /* index to array of a.out headers */
  37   phys_clicks text_base;
  38   vir_clicks text_clicks, data_clicks, st_clicks;
  39   reg_t ktsb;                   /* kernel task stack base */
  40   struct exec e_hdr;            /* for a copy of an a.out header */
  41
  42    /* Global value to test segment sanity. */
  43    magictest = MAGICTEST;
  44
  45    DEBUGEXTRA(("main()\n"));
  46
  47   /* Clear the process table. Anounce each slot as empty and set up mappings
  48    * for proc_addr() and proc_nr() macros. Do the same for the table with
  49    * privilege structures for the system processes.
  50    */
  51   for (rp = BEG_PROC_ADDR, i = -NR_TASKS; rp < END_PROC_ADDR; ++rp, ++i) {
  52         rp->p_rts_flags = RTS_SLOT_FREE;                /* initialize free slot */
  53         rp->p_magic = PMAGIC;
  54         rp->p_nr = i;                           /* proc number from ptr */
  55         rp->p_endpoint = _ENDPOINT(0, rp->p_nr); /* generation no. 0 */
  56   }
  57   for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
  58         sp->s_proc_nr = NONE;                   /* initialize as free */
  59         sp->s_id = (sys_id_t) i;                /* priv structure index */
  60         ppriv_addr[i] = sp;                     /* priv ptr from number */
  61   }
  62
  63   /* Set up proc table entries for processes in boot image.  The stacks of the
  64    * kernel tasks are initialized to an array in data space.  The stacks
  65    * of the servers have been added to the data segment by the monitor, so
  66    * the stack pointer is set to the end of the data segment.  All the
  67    * processes are in low memory on the 8086.  On the 386 only the kernel
  68    * is in low memory, the rest is loaded in extended memory.
  69    */
  70
  71   /* Task stacks. */
  72   ktsb = (reg_t) t_stack;
  73
  74   for (i=0; i < NR_BOOT_PROCS; ++i) {
  75         int schedulable_proc;
  76         proc_nr_t proc_nr;
  77         int ipc_to_m, kcalls;
  78
  79         ip = &image[i];                         /* process' attributes */
  80         DEBUGEXTRA(("initializing %s... ", ip->proc_name));
  81         rp = proc_addr(ip->proc_nr);            /* get process pointer */
  82         ip->endpoint = rp->p_endpoint;          /* ipc endpoint */
  83         rp->p_scheduler = NULL;                 /* no user space scheduler */
  84         rp->p_priority = ip->priority;          /* current priority */
  85         rp->p_quantum_size_ms = ip->quantum;    /* quantum size */
  86         make_zero64(rp->p_cpu_time_left);
  87         strncpy(rp->p_name, ip->proc_name, P_NAME_LEN); /* set process name */
  88
  89         /* See if this process is immediately schedulable.
  90          * In that case, set its privileges now and allow it to run.
  91          * Only kernel tasks and the root system process get to run immediately.
  92          * All the other system processes are inhibited from running by the
  93          * RTS_NO_PRIV flag. They can only be scheduled once the root system
  94          * process has set their privileges.
  95          */
  96         proc_nr = proc_nr(rp);
  97         schedulable_proc = (iskerneln(proc_nr) || isrootsysn(proc_nr));
  98         if(schedulable_proc) {
  99             /* Assign privilege structure. Force a static privilege id. */
 100             (void) get_priv(rp, static_priv_id(proc_nr));
 101
 102             /* Priviliges for kernel tasks. */
 103             if(iskerneln(proc_nr)) {
 104                 /* Privilege flags. */
 105                 priv(rp)->s_flags = (proc_nr == IDLE ? IDL_F : TSK_F);
 106                 /* Allowed traps. */
 107                 priv(rp)->s_trap_mask = (proc_nr == CLOCK
 108                     || proc_nr == SYSTEM  ? CSK_T : TSK_T);
 109                 ipc_to_m = TSK_M;                  /* allowed targets */
 110                 kcalls = TSK_KC;                   /* allowed kernel calls */
 111             }
 112             /* Priviliges for the root system process. */
 113             else if(isrootsysn(proc_nr)) {
 114                 priv(rp)->s_flags= RSYS_F;         /* privilege flags */
 115                 priv(rp)->s_trap_mask= RSYS_T;     /* allowed traps */
 116                 ipc_to_m = RSYS_M;                 /* allowed targets */
 117                 kcalls = RSYS_KC;                  /* allowed kernel calls */
 118                 priv(rp)->s_sig_mgr = RSYS_SM;     /* signal manager */
 119             }
 120             /* Priviliges for ordinary process. */
 121             else {
 122                 NOT_REACHABLE;
 123             }
 124
 125             /* Fill in target mask. */
 126             for (j=0; j < NR_SYS_PROCS; j++) {
 127                 if (ipc_to_m & (1 << j))
 128                     set_sendto_bit(rp, j);
 129                 else
 130                     unset_sendto_bit(rp, j);
 131             }
 132
 133             /* Fill in kernel call mask. */
 134             for(j = 0; j < SYS_CALL_MASK_SIZE; j++) {
 135                 priv(rp)->s_k_call_mask[j] = (kcalls == NO_C ? 0 : (~0));
 136             }
 137         }
 138         else {
 139             /* Don't let the process run for now. */
 140             RTS_SET(rp, RTS_NO_PRIV);
 141         }
 142
 143         if (iskerneln(proc_nr)) {               /* part of the kernel? */
 144                 if (ip->stksize > 0) {          /* HARDWARE stack size is 0 */
 145                         rp->p_priv->s_stack_guard = (reg_t *) ktsb;
 146                         *rp->p_priv->s_stack_guard = STACK_GUARD;
 147                 }
 148                 ktsb += ip->stksize;    /* point to high end of stack */
 149                 rp->p_reg.sp = ktsb;    /* this task's initial stack ptr */
 150                 hdrindex = 0;           /* all use the first a.out header */
 151         } else {
 152                 hdrindex = 1 + i-NR_TASKS;      /* system/user processes */
 153         }
 154
 155         /* Architecture-specific way to find out aout header of this
 156          * boot process.
 157          */
 158         arch_get_aout_headers(hdrindex, &e_hdr);
 159
 160         /* Convert addresses to clicks and build process memory map */
 161         text_base = e_hdr.a_syms >> CLICK_SHIFT;
 162         text_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_text) >> CLICK_SHIFT);
 163         data_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_data
 164                 + e_hdr.a_bss) >> CLICK_SHIFT);
 165         st_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_total) >> CLICK_SHIFT);
 166         if (!(e_hdr.a_flags & A_SEP))
 167         {
 168                 data_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_text +
 169                         e_hdr.a_data + e_hdr.a_bss) >> CLICK_SHIFT);
 170                 text_clicks = 0;           /* common I&D */
 171         }
 172         rp->p_memmap[T].mem_phys = text_base;
 173         rp->p_memmap[T].mem_len  = text_clicks;
 174         rp->p_memmap[D].mem_phys = text_base + text_clicks;
 175         rp->p_memmap[D].mem_len  = data_clicks;
 176         rp->p_memmap[S].mem_phys = text_base + text_clicks + st_clicks;
 177         rp->p_memmap[S].mem_vir  = st_clicks;
 178         rp->p_memmap[S].mem_len  = 0;
 179
 180         /* Set initial register values.  The processor status word for tasks
 181          * is different from that of other processes because tasks can
 182          * access I/O; this is not allowed to less-privileged processes
 183          */
 184         rp->p_reg.pc = 0; /* we cannot start anything else */
 185         rp->p_reg.psw = (iskerneln(proc_nr)) ? INIT_TASK_PSW : INIT_PSW;
 186
 187         /* Initialize the server stack pointer. Take it down one word
 188          * to give crtso.s something to use as "argc".
 189          */
 190         if (isusern(proc_nr)) {         /* user-space process? */
 191                 rp->p_reg.sp = (rp->p_memmap[S].mem_vir +
 192                                 rp->p_memmap[S].mem_len) << CLICK_SHIFT;
 193                 rp->p_reg.sp -= sizeof(reg_t);
 194         }
 195
 196         /* scheduling functions depend on proc_ptr pointing somewhere. */
 197         if(!proc_ptr) proc_ptr = rp;
 198
 199         /* If this process has its own page table, VM will set the
 200          * PT up and manage it. VM will signal the kernel when it has
 201          * done this; until then, don't let it run.
 202          */
 203         if(ip->flags & PROC_FULLVM)
 204                 RTS_SET(rp, RTS_VMINHIBIT);
 205
 206         /* None of the kernel tasks run */
 207         if (rp->p_nr < 0) RTS_SET(rp, RTS_PROC_STOP);
 208         RTS_UNSET(rp, RTS_SLOT_FREE); /* remove RTS_SLOT_FREE and schedule */
 209         alloc_segments(rp);
 210         DEBUGEXTRA(("done\n"));
 211   }
 212
 213   /* Architecture-dependent initialization. */
 214   DEBUGEXTRA(("arch_init()... "));
 215   arch_init();
 216   DEBUGEXTRA(("done\n"));
 217
 218   /* System and processes initialization */
 219   DEBUGEXTRA(("system_init()... "));
 220   system_init();
 221   DEBUGEXTRA(("done\n"));
 222
 223 #if SPROFILE
 224   sprofiling = 0;      /* we're not profiling until instructed to */
 225 #endif /* SPROFILE */
 226   cprof_procs_no = 0;  /* init nr of hash table slots used */
 227
 228   vm_running = 0;
 229   krandom.random_sources = RANDOM_SOURCES;
 230   krandom.random_elements = RANDOM_ELEMENTS;
 231
 232   /* MINIX is now ready. All boot image processes are on the ready queue.
 233    * Return to the assembly code to start running the current process.
 234    */
 235   bill_ptr = proc_addr(IDLE);   /* it has to point somewhere */
 236   announce();                           /* print MINIX startup banner */
 237
 238   /*
 239    * enable timer interrupts and clock task on the boot CPU
 240    */
 241
 242   if (boot_cpu_init_timer(system_hz)) {
 243           panic( "FATAL : failed to initialize timer interrupts; "
 244                 "cannot continue without any clock source!");
 245   }
 246
 247 /* Warnings for sanity checks that take time. These warnings are printed
 248  * so it's a clear warning no full release should be done with them
 249  * enabled.
 250  */
 251 #if DEBUG_PROC_CHECK
 252   FIXME("PROC check enabled");
 253 #endif
 254
 255   DEBUGEXTRA(("cycles_accounting_init()... "));
 256   cycles_accounting_init();
 257   DEBUGEXTRA(("done\n"));
 258
 259   assert(runqueues_ok());
 260
 261   switch_to_user();
 262   NOT_REACHABLE;
 263 }
 264
 265 /*===========================================================================*
 266  *                              announce                                     *
 267  *===========================================================================*/
 268 PRIVATE void announce(void)
 269 {
 270   /* Display the MINIX startup banner. */
 271   printf("\nMINIX %s.%s. "
 272 #ifdef _SVN_REVISION
 273         "(" _SVN_REVISION ")\n"
 274 #endif
 275       "Copyright 2010, Vrije Universiteit, Amsterdam, The Netherlands\n",
 276       OS_RELEASE, OS_VERSION);
 277   printf("MINIX is open source software, see http://www.minix3.org\n");
 278 }
 279
 280 /*===========================================================================*
 281  *                              prepare_shutdown                             *
 282  *===========================================================================*/
 283 PUBLIC void prepare_shutdown(const int how)
 284 {
 285 /* This function prepares to shutdown MINIX. */
 286   static timer_t shutdown_timer;
 287
 288   /* Continue after 1 second, to give processes a chance to get scheduled to
 289    * do shutdown work.  Set a watchog timer to call shutdown(). The timer
 290    * argument passes the shutdown status.
 291    */
 292   printf("MINIX will now be shut down ...\n");
 293   tmr_arg(&shutdown_timer)->ta_int = how;
 294   set_timer(&shutdown_timer, get_uptime() + system_hz, minix_shutdown);
 295 }
 296
 297 /*===========================================================================*
 298  *                              shutdown                                     *
 299  *===========================================================================*/
 300 PUBLIC void minix_shutdown(timer_t *tp)
 301 {
 302 /* This function is called from prepare_shutdown or stop_sequence to bring
 303  * down MINIX. How to shutdown is in the argument: RBT_HALT (return to the
 304  * monitor), RBT_MONITOR (execute given code), RBT_RESET (hard reset).
 305  */
 306   arch_stop_local_timer();
 307   intr_init(INTS_ORIG, 0);
 308   arch_shutdown(tp ? tmr_arg(tp)->ta_int : RBT_PANIC);
 309 }
 310