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 <a.out.h>
  15 #include <minix/com.h>
  16 #include <minix/endpoint.h>
  17 #include "proc.h"
  18 #include "debug.h"
  19 #include "clock.h"
  20
  21 /* Prototype declarations for PRIVATE functions. */
  22 FORWARD _PROTOTYPE( void announce, (void));
  23
  24 /*===========================================================================*
  25  *                              main                                         *
  26  *===========================================================================*/
  27 PUBLIC void main()
  28 {
  29 /* Start the ball rolling. */
  30   struct boot_image *ip;        /* boot image pointer */
  31   register struct proc *rp;     /* process pointer */
  32   register struct priv *sp;     /* privilege structure pointer */
  33   register int i, j;
  34   int hdrindex;                 /* index to array of a.out headers */
  35   phys_clicks text_base;
  36   vir_clicks text_clicks, data_clicks, st_clicks;
  37   reg_t ktsb;                   /* kernel task stack base */
  38   struct exec e_hdr;            /* for a copy of an a.out header */
  39
  40    /* Global value to test segment sanity. */
  41    magictest = MAGICTEST;
  42
  43   /* Clear the process table. Anounce each slot as empty and set up mappings
  44    * for proc_addr() and proc_nr() macros. Do the same for the table with
  45    * privilege structures for the system processes.
  46    */
  47   for (rp = BEG_PROC_ADDR, i = -NR_TASKS; rp < END_PROC_ADDR; ++rp, ++i) {
  48         rp->p_rts_flags = RTS_SLOT_FREE;                /* initialize free slot */
  49 #if DEBUG_SCHED_CHECK
  50         rp->p_magic = PMAGIC;
  51 #endif
  52         rp->p_nr = i;                           /* proc number from ptr */
  53         rp->p_endpoint = _ENDPOINT(0, rp->p_nr); /* generation no. 0 */
  54   }
  55   for (sp = BEG_PRIV_ADDR, i = 0; sp < END_PRIV_ADDR; ++sp, ++i) {
  56         sp->s_proc_nr = NONE;                   /* initialize as free */
  57         sp->s_id = (proc_nr_t) i;               /* priv structure index */
  58         ppriv_addr[i] = sp;                     /* priv ptr from number */
  59   }
  60
  61   /* Set up proc table entries for processes in boot image.  The stacks of the
  62    * kernel tasks are initialized to an array in data space.  The stacks
  63    * of the servers have been added to the data segment by the monitor, so
  64    * the stack pointer is set to the end of the data segment.  All the
  65    * processes are in low memory on the 8086.  On the 386 only the kernel
  66    * is in low memory, the rest is loaded in extended memory.
  67    */
  68
  69   /* Task stacks. */
  70   ktsb = (reg_t) t_stack;
  71
  72   for (i=0; i < NR_BOOT_PROCS; ++i) {
  73         int schedulable_proc;
  74         proc_nr_t proc_nr;
  75         int ipc_to_m, kcalls;
  76
  77         ip = &image[i];                         /* process' attributes */
  78         rp = proc_addr(ip->proc_nr);            /* get process pointer */
  79         ip->endpoint = rp->p_endpoint;          /* ipc endpoint */
  80         rp->p_max_priority = ip->priority;      /* max scheduling priority */
  81         rp->p_priority = ip->priority;          /* current priority */
  82         rp->p_quantum_size = ip->quantum;       /* quantum size in ticks */
  83         rp->p_ticks_left = ip->quantum;         /* current credit */
  84         strncpy(rp->p_name, ip->proc_name, P_NAME_LEN); /* set process name */
  85
  86         /* See if this process is immediately schedulable.
  87          * In that case, set its privileges now and allow it to run.
  88          * Only kernel tasks and the root system process get to run immediately.
  89          * All the other system processes are inhibited from running by the
  90          * RTS_NO_PRIV flag. They can only be scheduled once the root system
  91          * process has set their privileges.
  92          */
  93         proc_nr = proc_nr(rp);
  94         schedulable_proc = (iskerneln(proc_nr) || isrootsysn(proc_nr));
  95         if(schedulable_proc) {
  96             /* Assign privilege structure. Force a static privilege id. */
  97             (void) get_priv(rp, static_priv_id(proc_nr));
  98
  99             /* Priviliges for kernel tasks. */
 100             if(iskerneln(proc_nr)) {
 101                 /* Privilege flags. */
 102                 priv(rp)->s_flags = (proc_nr == IDLE ? IDL_F : TSK_F);
 103                 /* Allowed traps. */
 104                 priv(rp)->s_trap_mask = (proc_nr == CLOCK
 105                     || proc_nr == SYSTEM  ? CSK_T : TSK_T);
 106                 ipc_to_m = TSK_M;                  /* allowed targets */
 107                 kcalls = TSK_KC;                   /* allowed kernel calls */
 108             }
 109             /* Priviliges for the root system process. */
 110             else if(isrootsysn(proc_nr)) {
 111                 priv(rp)->s_flags= RSYS_F;         /* privilege flags */
 112                 priv(rp)->s_trap_mask= RSYS_T;     /* allowed traps */
 113                 ipc_to_m = RSYS_M;                 /* allowed targets */
 114                 kcalls = RSYS_KC;                  /* allowed kernel calls */
 115             }
 116             /* Priviliges for ordinary process. */
 117             else {
 118                 NOT_REACHABLE;
 119             }
 120
 121             /* Fill in target mask. */
 122             for (j=0; j < NR_SYS_PROCS; j++) {
 123                 if (ipc_to_m & (1 << j))
 124                     set_sendto_bit(rp, j);
 125                 else
 126                     unset_sendto_bit(rp, j);
 127             }
 128
 129             /* Fill in kernel call mask. */
 130             for(j = 0; j < SYS_CALL_MASK_SIZE; j++) {
 131                 priv(rp)->s_k_call_mask[j] = (kcalls == NO_C ? 0 : (~0));
 132             }
 133         }
 134         else {
 135             /* Don't let the process run for now. */
 136             RTS_SET(rp, RTS_NO_PRIV);
 137         }
 138
 139         if (iskerneln(proc_nr)) {               /* part of the kernel? */
 140                 if (ip->stksize > 0) {          /* HARDWARE stack size is 0 */
 141                         rp->p_priv->s_stack_guard = (reg_t *) ktsb;
 142                         *rp->p_priv->s_stack_guard = STACK_GUARD;
 143                 }
 144                 ktsb += ip->stksize;    /* point to high end of stack */
 145                 rp->p_reg.sp = ktsb;    /* this task's initial stack ptr */
 146                 hdrindex = 0;           /* all use the first a.out header */
 147         } else {
 148                 hdrindex = 1 + i-NR_TASKS;      /* system/user processes */
 149         }
 150
 151         /* Architecture-specific way to find out aout header of this
 152          * boot process.
 153          */
 154         arch_get_aout_headers(hdrindex, &e_hdr);
 155
 156         /* Convert addresses to clicks and build process memory map */
 157         text_base = e_hdr.a_syms >> CLICK_SHIFT;
 158         text_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_text) >> CLICK_SHIFT);
 159         data_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_data
 160                 + e_hdr.a_bss) >> CLICK_SHIFT);
 161         st_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_total) >> CLICK_SHIFT);
 162         if (!(e_hdr.a_flags & A_SEP))
 163         {
 164                 data_clicks = (vir_clicks) (CLICK_CEIL(e_hdr.a_text +
 165                         e_hdr.a_data + e_hdr.a_bss) >> CLICK_SHIFT);
 166                 text_clicks = 0;           /* common I&D */
 167         }
 168         rp->p_memmap[T].mem_phys = text_base;
 169         rp->p_memmap[T].mem_len  = text_clicks;
 170         rp->p_memmap[D].mem_phys = text_base + text_clicks;
 171         rp->p_memmap[D].mem_len  = data_clicks;
 172         rp->p_memmap[S].mem_phys = text_base + text_clicks + st_clicks;
 173         rp->p_memmap[S].mem_vir  = st_clicks;
 174         rp->p_memmap[S].mem_len  = 0;
 175
 176         /* Set initial register values.  The processor status word for tasks
 177          * is different from that of other processes because tasks can
 178          * access I/O; this is not allowed to less-privileged processes
 179          */
 180         rp->p_reg.pc = (reg_t) ip->initial_pc;
 181         rp->p_reg.psw = (iskerneln(proc_nr)) ? INIT_TASK_PSW : INIT_PSW;
 182
 183         /* Initialize the server stack pointer. Take it down one word
 184          * to give crtso.s something to use as "argc".
 185          */
 186         if (isusern(proc_nr)) {         /* user-space process? */
 187                 rp->p_reg.sp = (rp->p_memmap[S].mem_vir +
 188                                 rp->p_memmap[S].mem_len) << CLICK_SHIFT;
 189                 rp->p_reg.sp -= sizeof(reg_t);
 190         }
 191
 192         /* scheduling functions depend on proc_ptr pointing somewhere. */
 193         if(!proc_ptr) proc_ptr = rp;
 194
 195         /* If this process has its own page table, VM will set the
 196          * PT up and manage it. VM will signal the kernel when it has
 197          * done this; until then, don't let it run.
 198          */
 199         if(ip->flags & PROC_FULLVM)
 200                 RTS_SET(rp, RTS_VMINHIBIT);
 201
 202         /* Set ready. The HARDWARE task is never ready. */
 203         if (rp->p_nr == HARDWARE) RTS_SET(rp, RTS_PROC_STOP);
 204         /* IDLE task is never put on a run queue as it is never ready to run */
 205         if (rp->p_nr == IDLE) RTS_SET(rp, RTS_PROC_STOP);
 206         RTS_UNSET(rp, RTS_SLOT_FREE); /* remove RTS_SLOT_FREE and schedule */
 207         alloc_segments(rp);
 208   }
 209
 210   /* Architecture-dependent initialization. */
 211   arch_init();
 212
 213 #if SPROFILE
 214   sprofiling = 0;      /* we're not profiling until instructed to */
 215 #endif /* SPROFILE */
 216   cprof_procs_no = 0;  /* init nr of hash table slots used */
 217
 218 #ifdef CONFIG_IDLE_TSC
 219   idle_tsc = cvu64(0);
 220 #endif
 221
 222   vm_running = 0;
 223   krandom.random_sources = RANDOM_SOURCES;
 224   krandom.random_elements = RANDOM_ELEMENTS;
 225
 226   /* MINIX is now ready. All boot image processes are on the ready queue.
 227    * Return to the assembly code to start running the current process.
 228    */
 229   bill_ptr = proc_addr(IDLE);   /* it has to point somewhere */
 230   announce();                           /* print MINIX startup banner */
 231
 232   /*
 233    * enable timer interrupts and clock task on the boot CPU
 234    */
 235   if (boot_cpu_init_timer(system_hz)) {
 236           minix_panic("FATAL : failed to initialize timer interrupts, "
 237                           "cannot continue without any clock source!",
 238                           NO_NUM);
 239   }
 240
 241 /* Warnings for sanity checks that take time. These warnings are printed
 242  * so it's a clear warning no full release should be done with them
 243  * enabled.
 244  */
 245 #if DEBUG_SCHED_CHECK
 246   FIXME("DEBUG_SCHED_CHECK enabled");
 247 #endif
 248 #if DEBUG_VMASSERT
 249   FIXME("DEBUG_VMASSERT enabled");
 250 #endif
 251 #if DEBUG_PROC_CHECK
 252   FIXME("PROC check enabled");
 253 #endif
 254
 255   restart();
 256   NOT_REACHABLE;
 257 }
 258
 259 /*===========================================================================*
 260  *                              announce                                     *
 261  *===========================================================================*/
 262 PRIVATE void announce(void)
 263 {
 264   /* Display the MINIX startup banner. */
 265   kprintf("\nMINIX %s.%s. "
 266 #ifdef _SVN_REVISION
 267         "(" _SVN_REVISION ")\n"
 268 #endif
 269       "Copyright 2010, Vrije Universiteit, Amsterdam, The Netherlands\n",
 270       OS_RELEASE, OS_VERSION);
 271   kprintf("MINIX is open source software, see http://www.minix3.org\n");
 272 }
 273
 274 /*===========================================================================*
 275  *                              prepare_shutdown                             *
 276  *===========================================================================*/
 277 PUBLIC void prepare_shutdown(how)
 278 int how;
 279 {
 280 /* This function prepares to shutdown MINIX. */
 281   static timer_t shutdown_timer;
 282
 283   /* Continue after 1 second, to give processes a chance to get scheduled to
 284    * do shutdown work.  Set a watchog timer to call shutdown(). The timer
 285    * argument passes the shutdown status.
 286    */
 287   kprintf("MINIX will now be shut down ...\n");
 288   tmr_arg(&shutdown_timer)->ta_int = how;
 289   set_timer(&shutdown_timer, get_uptime() + system_hz, minix_shutdown);
 290 }
 291
 292 /*===========================================================================*
 293  *                              shutdown                                     *
 294  *===========================================================================*/
 295 PUBLIC void minix_shutdown(tp)
 296 timer_t *tp;
 297 {
 298 /* This function is called from prepare_shutdown or stop_sequence to bring
 299  * down MINIX. How to shutdown is in the argument: RBT_HALT (return to the
 300  * monitor), RBT_MONITOR (execute given code), RBT_RESET (hard reset).
 301  */
 302   arch_stop_local_timer();
 303   intr_init(INTS_ORIG, 0);
 304   arch_shutdown(tp ? tmr_arg(tp)->ta_int : RBT_PANIC);
 305 }
 306