1 /* $OpenBSD: mcount.c,v 1.8 2004/08/07 00:38:32 deraadt Exp $ */
2 /* $NetBSD: mcount.c,v 1.3.6.1 1996/06/12 04:23:01 cgd Exp $ */
3
4 /*-
5 * Copyright (c) 1983, 1992, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #if !defined(lint) && !defined(_KERNEL) && defined(LIBC_SCCS)
34 #if 0
35 static char sccsid[] = "@(#)mcount.c 8.1 (Berkeley) 6/4/93";
36 #else
37 static char rcsid[] = "$OpenBSD: mcount.c,v 1.8 2004/08/07 00:38:32 deraadt Exp $";
38 #endif
39 #endif
40
41 #include <sys/param.h>
42 #include <sys/gmon.h>
43
44 /*
45 * mcount is called on entry to each function compiled with the profiling
46 * switch set. _mcount(), which is declared in a machine-dependent way
47 * with _MCOUNT_DECL, does the actual work and is either inlined into a
48 * C routine or called by an assembly stub. In any case, this magic is
49 * taken care of by the MCOUNT definition in <machine/profile.h>.
50 *
51 * _mcount updates data structures that represent traversals of the
52 * program's call graph edges. frompc and selfpc are the return
53 * address and function address that represents the given call graph edge.
54 *
55 * Note: the original BSD code used the same variable (frompcindex) for
56 * both frompcindex and frompc. Any reasonable, modern compiler will
57 * perform this optimization.
58 *
59 * XXX - the unused attribute is there because some archs define _mcount
60 * as static and gcc doesn't check for function calls in assembler
61 * stubs.
62 */
63 _MCOUNT_DECL(u_long frompc, u_long selfpc) __attribute__((unused));
64 _MCOUNT_DECL(u_long frompc, u_long selfpc) /* _mcount; may be static, inline, etc */
65 {
66 u_short *frompcindex;
67 struct tostruct *top, *prevtop;
68 struct gmonparam *p;
69 long toindex;
70 #ifdef _KERNEL
71 int s;
72 #endif
73
74 p = &_gmonparam;
75 /*
76 * check that we are profiling
77 * and that we aren't recursively invoked.
78 */
79 if (p->state != GMON_PROF_ON)
80 return;
81 #ifdef _KERNEL
82 MCOUNT_ENTER;
83 #else
84 p->state = GMON_PROF_BUSY;
85 #endif
86 /*
87 * check that frompcindex is a reasonable pc value.
88 * for example: signal catchers get called from the stack,
89 * not from text space. too bad.
90 */
91 frompc -= p->lowpc;
92 if (frompc > p->textsize)
93 goto done;
94
95 #if (HASHFRACTION & (HASHFRACTION - 1)) == 0
96 if (p->hashfraction == HASHFRACTION)
97 frompcindex =
98 &p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))];
99 else
100 #endif
101 frompcindex =
102 &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))];
103 toindex = *frompcindex;
104 if (toindex == 0) {
105 /*
106 * first time traversing this arc
107 */
108 toindex = ++p->tos[0].link;
109 if (toindex >= p->tolimit)
110 /* halt further profiling */
111 goto overflow;
112
113 *frompcindex = toindex;
114 top = &p->tos[toindex];
115 top->selfpc = selfpc;
116 top->count = 1;
117 top->link = 0;
118 goto done;
119 }
120 top = &p->tos[toindex];
121 if (top->selfpc == selfpc) {
122 /*
123 * arc at front of chain; usual case.
124 */
125 top->count++;
126 goto done;
127 }
128 /*
129 * have to go looking down chain for it.
130 * top points to what we are looking at,
131 * prevtop points to previous top.
132 * we know it is not at the head of the chain.
133 */
134 for (; /* goto done */; ) {
135 if (top->link == 0) {
136 /*
137 * top is end of the chain and none of the chain
138 * had top->selfpc == selfpc.
139 * so we allocate a new tostruct
140 * and link it to the head of the chain.
141 */
142 toindex = ++p->tos[0].link;
143 if (toindex >= p->tolimit)
144 goto overflow;
145
146 top = &p->tos[toindex];
147 top->selfpc = selfpc;
148 top->count = 1;
149 top->link = *frompcindex;
150 *frompcindex = toindex;
151 goto done;
152 }
153 /*
154 * otherwise, check the next arc on the chain.
155 */
156 prevtop = top;
157 top = &p->tos[top->link];
158 if (top->selfpc == selfpc) {
159 /*
160 * there it is.
161 * increment its count
162 * move it to the head of the chain.
163 */
164 top->count++;
165 toindex = prevtop->link;
166 prevtop->link = top->link;
167 top->link = *frompcindex;
168 *frompcindex = toindex;
169 goto done;
170 }
171
172 }
173 done:
174 #ifdef _KERNEL
175 MCOUNT_EXIT;
176 #else
177 p->state = GMON_PROF_ON;
178 #endif
179 return;
180 overflow:
181 p->state = GMON_PROF_ERROR;
182 #ifdef _KERNEL
183 MCOUNT_EXIT;
184 #endif
185 return;
186 }
187
188 /*
189 * Actual definition of mcount function. Defined in <machine/profile.h>,
190 * which is included by <sys/gmon.h>.
191 */
192 MCOUNT