gmon/mcount.c

   1 /*-
   2  * Copyright (c) 1983, 1992, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #if !defined(lint) && !defined(KERNEL) && defined(LIBC_SCCS)
  35 static char sccsid[] = "@(#)mcount.c    8.1 (Berkeley) 6/4/93";
  36 #endif
  37
  38 #include <sys/param.h>
  39 #include <sys/gmon.h>
  40
  41 /* This file provides the machine-dependent definitions of the _MCOUNT_DECL
  42    and MCOUNT macros.  */
  43 #include "machine-gmon.h"
  44
  45 /*
  46  * mcount is called on entry to each function compiled with the profiling
  47  * switch set.  _mcount(), which is declared in a machine-dependent way
  48  * with _MCOUNT_DECL, does the actual work and is either inlined into a
  49  * C routine or called by an assembly stub.  In any case, this magic is
  50  * taken care of by the MCOUNT definition in <machine/profile.h>.
  51  *
  52  * _mcount updates data structures that represent traversals of the
  53  * program's call graph edges.  frompc and selfpc are the return
  54  * address and function address that represents the given call graph edge.
  55  *
  56  * Note: the original BSD code used the same variable (frompcindex) for
  57  * both frompcindex and frompc.  Any reasonable, modern compiler will
  58  * perform this optimization.
  59  */
  60 _MCOUNT_DECL(frompc, selfpc)    /* _mcount; may be static, inline, etc */
  61 {
  62         register u_short *frompcindex;
  63         register struct tostruct *top, *prevtop;
  64         register struct gmonparam *p;
  65         register long toindex;
  66 #ifdef KERNEL
  67         register int s;
  68 #endif
  69         int i;
  70
  71         p = &_gmonparam;
  72         /*
  73          * check that we are profiling
  74          * and that we aren't recursively invoked.
  75          */
  76         if (p->state != GMON_PROF_ON)
  77                 return;
  78 #ifdef KERNEL
  79         MCOUNT_ENTER;
  80 #else
  81         p->state = GMON_PROF_BUSY;
  82 #endif
  83         /*
  84          * check that frompcindex is a reasonable pc value.
  85          * for example: signal catchers get called from the stack,
  86          *              not from text space.  too bad.
  87          */
  88         frompc -= p->lowpc;
  89         if (frompc > p->textsize)
  90                 goto done;
  91
  92         /* avoid integer divide if possible: */
  93         if (p->log_hashfraction >= 0) {
  94             i = frompc >> p->log_hashfraction;
  95         } else {
  96             i = frompc / (p->hashfraction * sizeof(*p->froms));
  97         }
  98         frompcindex = &p->froms[i];
  99         toindex = *frompcindex;
 100         if (toindex == 0) {
 101                 /*
 102                  *      first time traversing this arc
 103                  */
 104                 toindex = ++p->tos[0].link;
 105                 if (toindex >= p->tolimit)
 106                         /* halt further profiling */
 107                         goto overflow;
 108
 109                 *frompcindex = toindex;
 110                 top = &p->tos[toindex];
 111                 top->selfpc = selfpc;
 112                 top->count = 1;
 113                 top->link = 0;
 114                 goto done;
 115         }
 116         top = &p->tos[toindex];
 117         if (top->selfpc == selfpc) {
 118                 /*
 119                  * arc at front of chain; usual case.
 120                  */
 121                 top->count++;
 122                 goto done;
 123         }
 124         /*
 125          * have to go looking down chain for it.
 126          * top points to what we are looking at,
 127          * prevtop points to previous top.
 128          * we know it is not at the head of the chain.
 129          */
 130         for (; /* goto done */; ) {
 131                 if (top->link == 0) {
 132                         /*
 133                          * top is end of the chain and none of the chain
 134                          * had top->selfpc == selfpc.
 135                          * so we allocate a new tostruct
 136                          * and link it to the head of the chain.
 137                          */
 138                         toindex = ++p->tos[0].link;
 139                         if (toindex >= p->tolimit)
 140                                 goto overflow;
 141
 142                         top = &p->tos[toindex];
 143                         top->selfpc = selfpc;
 144                         top->count = 1;
 145                         top->link = *frompcindex;
 146                         *frompcindex = toindex;
 147                         goto done;
 148                 }
 149                 /*
 150                  * otherwise, check the next arc on the chain.
 151                  */
 152                 prevtop = top;
 153                 top = &p->tos[top->link];
 154                 if (top->selfpc == selfpc) {
 155                         /*
 156                          * there it is.
 157                          * increment its count
 158                          * move it to the head of the chain.
 159                          */
 160                         top->count++;
 161                         toindex = prevtop->link;
 162                         prevtop->link = top->link;
 163                         top->link = *frompcindex;
 164                         *frompcindex = toindex;
 165                         goto done;
 166                 }
 167
 168         }
 169 done:
 170 #ifdef KERNEL
 171         MCOUNT_EXIT;
 172 #else
 173         p->state = GMON_PROF_ON;
 174 #endif
 175         return;
 176 overflow:
 177         p->state = GMON_PROF_ERROR;
 178 #ifdef KERNEL
 179         MCOUNT_EXIT;
 180 #endif
 181         return;
 182 }
 183
 184 /*
 185  * Actual definition of mcount function.  Defined in <machine/profile.h>,
 186  * which is included by <sys/gmon.h>.
 187  */
 188 MCOUNT