1 /* $OpenBSD: mcount.c,v 1.16 2022/01/11 09:21:34 jsg Exp $ */
2 /*-
3 * Copyright (c) 1983, 1992, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 * may be used to endorse or promote products derived from this software
16 * without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/types.h>
32 #include <sys/gmon.h>
33
34 /*
35 * mcount is called on entry to each function compiled with the profiling
36 * switch set. _mcount(), which is declared in a machine-dependent way
37 * with _MCOUNT_DECL, does the actual work and is either inlined into a
38 * C routine or called by an assembly stub. In any case, this magic is
39 * taken care of by the MCOUNT definition in <machine/profile.h>.
40 *
41 * _mcount updates data structures that represent traversals of the
42 * program's call graph edges. frompc and selfpc are the return
43 * address and function address that represents the given call graph edge.
44 */
45 _MCOUNT_DECL(u_long frompc, u_long selfpc) __used;
46 /* _mcount; may be static, inline, etc */
_MCOUNT_DECL(u_long frompc,u_long selfpc)47 _MCOUNT_DECL(u_long frompc, u_long selfpc)
48 {
49 u_short *frompcindex;
50 struct tostruct *top, *prevtop;
51 struct gmonparam *p;
52 long toindex;
53 #ifdef _KERNEL
54 int s;
55
56 /*
57 * Do not profile execution if memory for the current CPU
58 * descriptor and profiling buffers has not yet been allocated
59 * or if the CPU we are running on has not yet set its trap
60 * handler.
61 */
62 if (gmoninit == 0)
63 return;
64
65 if ((p = curcpu()->ci_gmon) == NULL)
66 return;
67 #else
68 p = &_gmonparam;
69 #endif
70 /*
71 * check that we are profiling
72 * and that we aren't recursively invoked.
73 */
74 if (p->state != GMON_PROF_ON)
75 return;
76 #ifdef _KERNEL
77 MCOUNT_ENTER;
78 #else
79 p->state = GMON_PROF_BUSY;
80 #endif
81 /*
82 * check that frompcindex is a reasonable pc value.
83 * for example: signal catchers get called from the stack,
84 * not from text space. too bad.
85 */
86 frompc -= p->lowpc;
87 if (frompc > p->textsize)
88 goto done;
89
90 #if (HASHFRACTION & (HASHFRACTION - 1)) == 0
91 if (p->hashfraction == HASHFRACTION)
92 frompcindex =
93 &p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))];
94 else
95 #endif
96 frompcindex =
97 &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))];
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 done:
168 #ifdef _KERNEL
169 MCOUNT_EXIT;
170 #else
171 p->state = GMON_PROF_ON;
172 #endif
173 return;
174 overflow:
175 p->state = GMON_PROF_ERROR;
176 #ifdef _KERNEL
177 MCOUNT_EXIT;
178 #endif
179 return;
180 }
181
182 /*
183 * Actual definition of mcount function. Defined in <machine/profile.h>,
184 * which is included by <sys/gmon.h>.
185 */
186 MCOUNT
187