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 /*
  42  * mcount is called on entry to each function compiled with the profiling
  43  * switch set.  _mcount(), which is declared in a machine-dependent way
  44  * with _MCOUNT_DECL, does the actual work and is either inlined into a
  45  * C routine or called by an assembly stub.  In any case, this magic is
  46  * taken care of by the MCOUNT definition in <machine/profile.h>.
  47  *
  48  * _mcount updates data structures that represent traversals of the
  49  * program's call graph edges.  frompc and selfpc are the return
  50  * address and function address that represents the given call graph edge.
  51  *
  52  * Note: the original BSD code used the same variable (frompcindex) for
  53  * both frompcindex and frompc.  Any reasonable, modern compiler will
  54  * perform this optimization.
  55  */
  56 _MCOUNT_DECL(frompc, selfpc)    /* _mcount; may be static, inline, etc */
  57         register u_long frompc, selfpc;
  58 {
  59         register u_short *frompcindex;
  60         register struct tostruct *top, *prevtop;
  61         register struct gmonparam *p;
  62         register long toindex;
  63 #ifdef KERNEL
  64         register int s;
  65 #endif
  66
  67         p = &_gmonparam;
  68         /*
  69          * check that we are profiling
  70          * and that we aren't recursively invoked.
  71          */
  72         if (p->state != GMON_PROF_ON)
  73                 return;
  74 #ifdef KERNEL
  75         MCOUNT_ENTER;
  76 #else
  77         p->state = GMON_PROF_BUSY;
  78 #endif
  79         /*
  80          * check that frompcindex is a reasonable pc value.
  81          * for example: signal catchers get called from the stack,
  82          *              not from text space.  too bad.
  83          */
  84         frompc -= p->lowpc;
  85         if (frompc > p->textsize)
  86                 goto done;
  87
  88         frompcindex = &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))];
  89         toindex = *frompcindex;
  90         if (toindex == 0) {
  91                 /*
  92                  *      first time traversing this arc
  93                  */
  94                 toindex = ++p->tos[0].link;
  95                 if (toindex >= p->tolimit)
  96                         /* halt further profiling */
  97                         goto overflow;
  98
  99                 *frompcindex = toindex;
 100                 top = &p->tos[toindex];
 101                 top->selfpc = selfpc;
 102                 top->count = 1;
 103                 top->link = 0;
 104                 goto done;
 105         }
 106         top = &p->tos[toindex];
 107         if (top->selfpc == selfpc) {
 108                 /*
 109                  * arc at front of chain; usual case.
 110                  */
 111                 top->count++;
 112                 goto done;
 113         }
 114         /*
 115          * have to go looking down chain for it.
 116          * top points to what we are looking at,
 117          * prevtop points to previous top.
 118          * we know it is not at the head of the chain.
 119          */
 120         for (; /* goto done */; ) {
 121                 if (top->link == 0) {
 122                         /*
 123                          * top is end of the chain and none of the chain
 124                          * had top->selfpc == selfpc.
 125                          * so we allocate a new tostruct
 126                          * and link it to the head of the chain.
 127                          */
 128                         toindex = ++p->tos[0].link;
 129                         if (toindex >= p->tolimit)
 130                                 goto overflow;
 131
 132                         top = &p->tos[toindex];
 133                         top->selfpc = selfpc;
 134                         top->count = 1;
 135                         top->link = *frompcindex;
 136                         *frompcindex = toindex;
 137                         goto done;
 138                 }
 139                 /*
 140                  * otherwise, check the next arc on the chain.
 141                  */
 142                 prevtop = top;
 143                 top = &p->tos[top->link];
 144                 if (top->selfpc == selfpc) {
 145                         /*
 146                          * there it is.
 147                          * increment its count
 148                          * move it to the head of the chain.
 149                          */
 150                         top->count++;
 151                         toindex = prevtop->link;
 152                         prevtop->link = top->link;
 153                         top->link = *frompcindex;
 154                         *frompcindex = toindex;
 155                         goto done;
 156                 }
 157
 158         }
 159 done:
 160 #ifdef KERNEL
 161         MCOUNT_EXIT;
 162 #else
 163         p->state = GMON_PROF_ON;
 164 #endif
 165         return;
 166 overflow:
 167         p->state = GMON_PROF_ERROR;
 168 #ifdef KERNEL
 169         MCOUNT_EXIT;
 170 #endif
 171         return;
 172 }
 173
 174 /*
 175  * Actual definition of mcount function.  Defined in <machine/profile.h>,
 176  * which is included by <sys/gmon.h>.
 177  */
 178 MCOUNT