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 * 4. 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 sccsid[] = "@(#)mcount.c 8.1 (Berkeley) 6/4/93";
32 #endif
33
34 #include <unistd.h>
35 #include <sys/param.h>
36 #include <sys/gmon.h>
37
38 /* This file provides the machine-dependent definitions of the _MCOUNT_DECL
39 and MCOUNT macros. */
40 #include <machine-gmon.h>
41
42 #include <atomic.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 */
_MCOUNT_DECL(frompc,selfpc)59 _MCOUNT_DECL(frompc, selfpc) /* _mcount; may be static, inline, etc */
60 {
61 ARCINDEX *frompcindex;
62 struct tostruct *top, *prevtop;
63 struct gmonparam *p;
64 ARCINDEX toindex;
65 int i;
66
67 p = &_gmonparam;
68 /*
69 * check that we are profiling
70 * and that we aren't recursively invoked.
71 */
72 if (atomic_compare_and_exchange_bool_acq (&p->state, GMON_PROF_BUSY,
73 GMON_PROF_ON))
74 return;
75
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 /* The following test used to be
86 if (p->log_hashfraction >= 0)
87 But we can simplify this if we assume the profiling data
88 is always initialized by the functions in gmon.c. But
89 then it is possible to avoid a runtime check and use the
90 smae `if' as in gmon.c. So keep these tests in sync. */
91 if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) {
92 /* avoid integer divide if possible: */
93 i = frompc >> p->log_hashfraction;
94 } else {
95 i = frompc / (p->hashfraction * sizeof(*p->froms));
96 }
97 frompcindex = &p->froms[i];
98 toindex = *frompcindex;
99 if (toindex == 0) {
100 /*
101 * first time traversing this arc
102 */
103 toindex = ++p->tos[0].link;
104 if (toindex >= p->tolimit)
105 /* halt further profiling */
106 goto overflow;
107
108 *frompcindex = toindex;
109 top = &p->tos[toindex];
110 top->selfpc = selfpc;
111 top->count = 1;
112 top->link = 0;
113 goto done;
114 }
115 top = &p->tos[toindex];
116 if (top->selfpc == selfpc) {
117 /*
118 * arc at front of chain; usual case.
119 */
120 top->count++;
121 goto done;
122 }
123 /*
124 * have to go looking down chain for it.
125 * top points to what we are looking at,
126 * prevtop points to previous top.
127 * we know it is not at the head of the chain.
128 */
129 for (; /* goto done */; ) {
130 if (top->link == 0) {
131 /*
132 * top is end of the chain and none of the chain
133 * had top->selfpc == selfpc.
134 * so we allocate a new tostruct
135 * and link it to the head of the chain.
136 */
137 toindex = ++p->tos[0].link;
138 if (toindex >= p->tolimit)
139 goto overflow;
140
141 top = &p->tos[toindex];
142 top->selfpc = selfpc;
143 top->count = 1;
144 top->link = *frompcindex;
145 *frompcindex = toindex;
146 goto done;
147 }
148 /*
149 * otherwise, check the next arc on the chain.
150 */
151 prevtop = top;
152 top = &p->tos[top->link];
153 if (top->selfpc == selfpc) {
154 /*
155 * there it is.
156 * increment its count
157 * move it to the head of the chain.
158 */
159 top->count++;
160 toindex = prevtop->link;
161 prevtop->link = top->link;
162 top->link = *frompcindex;
163 *frompcindex = toindex;
164 goto done;
165 }
166
167 }
168 done:
169 p->state = GMON_PROF_ON;
170 return;
171 overflow:
172 p->state = GMON_PROF_ERROR;
173 return;
174 }
175
176 /*
177 * Actual definition of mcount function. Defined in <machine/profile.h>,
178 * which is included by <sys/gmon.h>.
179 */
180 MCOUNT
181