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. Neither the name of the University nor the names of its contributors 14 * may be used to endorse or promote products derived from this software 15 * without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27 * SUCH DAMAGE. 28 */ 29 30 #if !defined(lint) && !defined(_KERNEL) && defined(LIBC_SCCS) 31 static char rcsid[] = "$OpenBSD: mcount.c,v 1.9 2005/03/23 19:32:09 otto Exp $"; 32 #endif 33 34 #include <sys/param.h> 35 #include <sys/gmon.h> 36 37 /* 38 * mcount is called on entry to each function compiled with the profiling 39 * switch set. _mcount(), which is declared in a machine-dependent way 40 * with _MCOUNT_DECL, does the actual work and is either inlined into a 41 * C routine or called by an assembly stub. In any case, this magic is 42 * taken care of by the MCOUNT definition in <machine/profile.h>. 43 * 44 * _mcount updates data structures that represent traversals of the 45 * program's call graph edges. frompc and selfpc are the return 46 * address and function address that represents the given call graph edge. 47 * 48 * Note: the original BSD code used the same variable (frompcindex) for 49 * both frompcindex and frompc. Any reasonable, modern compiler will 50 * perform this optimization. 51 */ 52 _MCOUNT_DECL(u_long frompc, u_long selfpc); 53 /* _mcount; may be static, inline, etc */ 54 _MCOUNT_DECL(u_long frompc, u_long selfpc) 55 { 56 u_short *frompcindex; 57 struct tostruct *top, *prevtop; 58 struct gmonparam *p; 59 long toindex; 60 #ifdef _KERNEL 61 int s; 62 #endif 63 64 p = &_gmonparam; 65 /* 66 * check that we are profiling 67 * and that we aren't recursively invoked. 68 */ 69 if (p->state != GMON_PROF_ON) 70 return; 71 #ifdef _KERNEL 72 MCOUNT_ENTER; 73 #else 74 p->state = GMON_PROF_BUSY; 75 #endif 76 /* 77 * check that frompcindex is a reasonable pc value. 78 * for example: signal catchers get called from the stack, 79 * not from text space. too bad. 80 */ 81 frompc -= p->lowpc; 82 if (frompc > p->textsize) 83 goto done; 84 85 #if (HASHFRACTION & (HASHFRACTION - 1)) == 0 86 if (p->hashfraction == HASHFRACTION) 87 frompcindex = 88 &p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))]; 89 else 90 #endif 91 frompcindex = 92 &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))]; 93 toindex = *frompcindex; 94 if (toindex == 0) { 95 /* 96 * first time traversing this arc 97 */ 98 toindex = ++p->tos[0].link; 99 if (toindex >= p->tolimit) 100 /* halt further profiling */ 101 goto overflow; 102 103 *frompcindex = toindex; 104 top = &p->tos[toindex]; 105 top->selfpc = selfpc; 106 top->count = 1; 107 top->link = 0; 108 goto done; 109 } 110 top = &p->tos[toindex]; 111 if (top->selfpc == selfpc) { 112 /* 113 * arc at front of chain; usual case. 114 */ 115 top->count++; 116 goto done; 117 } 118 /* 119 * have to go looking down chain for it. 120 * top points to what we are looking at, 121 * prevtop points to previous top. 122 * we know it is not at the head of the chain. 123 */ 124 for (; /* goto done */; ) { 125 if (top->link == 0) { 126 /* 127 * top is end of the chain and none of the chain 128 * had top->selfpc == selfpc. 129 * so we allocate a new tostruct 130 * and link it to the head of the chain. 131 */ 132 toindex = ++p->tos[0].link; 133 if (toindex >= p->tolimit) 134 goto overflow; 135 136 top = &p->tos[toindex]; 137 top->selfpc = selfpc; 138 top->count = 1; 139 top->link = *frompcindex; 140 *frompcindex = toindex; 141 goto done; 142 } 143 /* 144 * otherwise, check the next arc on the chain. 145 */ 146 prevtop = top; 147 top = &p->tos[top->link]; 148 if (top->selfpc == selfpc) { 149 /* 150 * there it is. 151 * increment its count 152 * move it to the head of the chain. 153 */ 154 top->count++; 155 toindex = prevtop->link; 156 prevtop->link = top->link; 157 top->link = *frompcindex; 158 *frompcindex = toindex; 159 goto done; 160 } 161 } 162 done: 163 #ifdef _KERNEL 164 MCOUNT_EXIT; 165 #else 166 p->state = GMON_PROF_ON; 167 #endif 168 return; 169 overflow: 170 p->state = GMON_PROF_ERROR; 171 #ifdef _KERNEL 172 MCOUNT_EXIT; 173 #endif 174 return; 175 } 176 177 #ifndef lint 178 /* 179 * Actual definition of mcount function. Defined in <machine/profile.h>, 180 * which is included by <sys/gmon.h>. 181 */ 182 MCOUNT 183 #endif 184