1 /* $OpenBSD: mcount.c,v 1.14 2022/01/11 09:21:34 jsg 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 #include <sys/param.h>
34 #include <sys/gmon.h>
35
36 /*
37 * mcount is called on entry to each function compiled with the profiling
38 * switch set. _mcount(), which is declared in a machine-dependent way
39 * with _MCOUNT_DECL, does the actual work and is either inlined into a
40 * C routine or called by an assembly stub. In any case, this magic is
41 * taken care of by the MCOUNT definition in <machine/profile.h>.
42 *
43 * _mcount updates data structures that represent traversals of the
44 * program's call graph edges. frompc and selfpc are the return
45 * address and function address that represents the given call graph edge.
46 */
47 _MCOUNT_DECL(u_long frompc, u_long selfpc) __used;
48 /* _mcount; may be static, inline, etc */
_MCOUNT_DECL(u_long frompc,u_long selfpc)49 _MCOUNT_DECL(u_long frompc, u_long selfpc)
50 {
51 u_short *frompcindex;
52 struct tostruct *top, *prevtop;
53 struct gmonparam *p;
54 long toindex;
55 #ifdef _KERNEL
56 int s;
57
58 /*
59 * Do not profile execution if memory for the current CPU
60 * descriptor and profiling buffers has not yet been allocated
61 * or if the CPU we are running on has not yet set its trap
62 * handler.
63 */
64 if (gmoninit == 0)
65 return;
66
67 if ((p = curcpu()->ci_gmon) == NULL)
68 return;
69 #else
70 p = &_gmonparam;
71 #endif
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 #if (HASHFRACTION & (HASHFRACTION - 1)) == 0
93 if (p->hashfraction == HASHFRACTION)
94 frompcindex =
95 &p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))];
96 else
97 #endif
98 frompcindex =
99 &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))];
100 toindex = *frompcindex;
101 if (toindex == 0) {
102 /*
103 * first time traversing this arc
104 */
105 toindex = ++p->tos[0].link;
106 if (toindex >= p->tolimit)
107 /* halt further profiling */
108 goto overflow;
109
110 *frompcindex = toindex;
111 top = &p->tos[toindex];
112 top->selfpc = selfpc;
113 top->count = 1;
114 top->link = 0;
115 goto done;
116 }
117 top = &p->tos[toindex];
118 if (top->selfpc == selfpc) {
119 /*
120 * arc at front of chain; usual case.
121 */
122 top->count++;
123 goto done;
124 }
125 /*
126 * have to go looking down chain for it.
127 * top points to what we are looking at,
128 * prevtop points to previous top.
129 * we know it is not at the head of the chain.
130 */
131 for (; /* goto done */; ) {
132 if (top->link == 0) {
133 /*
134 * top is end of the chain and none of the chain
135 * had top->selfpc == selfpc.
136 * so we allocate a new tostruct
137 * and link it to the head of the chain.
138 */
139 toindex = ++p->tos[0].link;
140 if (toindex >= p->tolimit)
141 goto overflow;
142
143 top = &p->tos[toindex];
144 top->selfpc = selfpc;
145 top->count = 1;
146 top->link = *frompcindex;
147 *frompcindex = toindex;
148 goto done;
149 }
150 /*
151 * otherwise, check the next arc on the chain.
152 */
153 prevtop = top;
154 top = &p->tos[top->link];
155 if (top->selfpc == selfpc) {
156 /*
157 * there it is.
158 * increment its count
159 * move it to the head of the chain.
160 */
161 top->count++;
162 toindex = prevtop->link;
163 prevtop->link = top->link;
164 top->link = *frompcindex;
165 *frompcindex = toindex;
166 goto done;
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
189