1: /*
   2:  * Copyright (c) 1986 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  *
   6:  *	@(#)vm_proc.c	1.2 (2.11BSD GTE) 12/24/92
   7:  */
   8: 
   9: #include "param.h"
  10: #include "user.h"
  11: #include "proc.h"
  12: #include "text.h"
  13: #include "map.h"
  14: #include "kernel.h"
  15: 
  16: /*
  17:  * Change the size of the data+stack regions of the process.
  18:  * If the size is shrinking, it's easy -- just release the extra core.
  19:  * If it's growing, and there is core, just allocate it and copy the
  20:  * image, taking care to reset registers to account for the fact that
  21:  * the system's stack has moved.  If there is no core, arrange for the
  22:  * process to be swapped out after adjusting the size requirement -- when
  23:  * it comes in, enough core will be allocated.  After the expansion, the
  24:  * caller will take care of copying the user's stack towards or away from
  25:  * the data area.  The data and stack segments are separated from each
  26:  * other.  The second argument to expand specifies which to change.  The
  27:  * stack segment will not have to be copied again after expansion.
  28:  */
  29: expand(newsize,segment)
  30:     int newsize, segment;
  31: {
  32:     register struct proc *p;
  33:     register int i, n;
  34:     int a1, a2;
  35: 
  36:     p = u.u_procp;
  37:     if (segment == S_DATA) {
  38:         n = p->p_dsize;
  39:         p->p_dsize = newsize;
  40:         a1 = p->p_daddr;
  41:         if(n >= newsize) {
  42:             n -= newsize;
  43:             mfree(coremap, n, a1+newsize);
  44:             return;
  45:         }
  46:     } else {
  47:         n = p->p_ssize;
  48:         p->p_ssize = newsize;
  49:         a1 = p->p_saddr;
  50:         if(n >= newsize) {
  51:             n -= newsize;
  52:             p->p_saddr += n;
  53:             mfree(coremap, n, a1);
  54:             /*
  55: 			 *  Since the base of stack is different,
  56: 			 *  segmentation registers must be repointed.
  57: 			 */
  58:             sureg();
  59:             return;
  60:         }
  61:     }
  62:     if (setjmp(&u.u_ssave)) {
  63:         /*
  64: 		 * If we had to swap, the stack needs moving up.
  65: 		 */
  66:         if (segment == S_STACK) {
  67:             a1 = p->p_saddr;
  68:             i = newsize - n;
  69:             a2 = a1 + i;
  70:             /*
  71: 			 * i is the amount of growth.  Copy i clicks
  72: 			 * at a time, from the top; do the remainder
  73: 			 * (n % i) separately.
  74: 			 */
  75:             while (n >= i) {
  76:                 n -= i;
  77:                 copy(a1+n, a2+n, i);
  78:             }
  79:             copy(a1, a2, n);
  80:         }
  81:         sureg();
  82:         return;
  83:     }
  84:     if (u.u_fpsaved == 0) {
  85:         savfp(&u.u_fps);
  86:         u.u_fpsaved = 1;
  87:     }
  88:     a2 = malloc(coremap, newsize);
  89:     if (a2 == NULL) {
  90:         if (segment == S_DATA)
  91:             swapout(p, X_FREECORE, n, X_OLDSIZE);
  92:         else
  93:             swapout(p, X_FREECORE, X_OLDSIZE, n);
  94:         p->p_flag |= SSWAP;
  95:         swtch();
  96:         /* NOTREACHED */
  97:     }
  98:     if (segment == S_STACK) {
  99:         p->p_saddr = a2;
 100:         /*
 101: 		 * Make the copy put the stack at the top of the new area.
 102: 		 */
 103:         a2 += newsize - n;
 104:     } else
 105:         p->p_daddr = a2;
 106:     copy(a1, a2, n);
 107:     mfree(coremap, n, a1);
 108:     sureg();
 109: }

Defined functions

Last modified: 1992-12-27
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