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 | #include <not-cancel.h> |
45 | #include <unistd.h> |
46 | #define ERR(s) __write_nocancel (STDERR_FILENO, s, sizeof (s) - 1) |
47 | |
48 | /* |
49 | * mcount is called on entry to each function compiled with the profiling |
50 | * switch set. _mcount(), which is declared in a machine-dependent way |
51 | * with _MCOUNT_DECL, does the actual work and is either inlined into a |
52 | * C routine or called by an assembly stub. In any case, this magic is |
53 | * taken care of by the MCOUNT definition in <machine/profile.h>. |
54 | * |
55 | * _mcount updates data structures that represent traversals of the |
56 | * program's call graph edges. frompc and selfpc are the return |
57 | * address and function address that represents the given call graph edge. |
58 | * |
59 | * Note: the original BSD code used the same variable (frompcindex) for |
60 | * both frompcindex and frompc. Any reasonable, modern compiler will |
61 | * perform this optimization. |
62 | */ |
63 | _MCOUNT_DECL(frompc, selfpc) /* _mcount; may be static, inline, etc */ |
64 | { |
65 | ARCINDEX *frompcindex; |
66 | struct tostruct *top, *prevtop; |
67 | struct gmonparam *p; |
68 | ARCINDEX toindex; |
69 | int i; |
70 | |
71 | p = &_gmonparam; |
72 | /* |
73 | * check that we are profiling |
74 | * and that we aren't recursively invoked. |
75 | */ |
76 | if (atomic_compare_and_exchange_bool_acq (&p->state, GMON_PROF_BUSY, |
77 | GMON_PROF_ON)) |
78 | return; |
79 | |
80 | /* |
81 | * check that frompcindex is a reasonable pc value. |
82 | * for example: signal catchers get called from the stack, |
83 | * not from text space. too bad. |
84 | */ |
85 | frompc -= p->lowpc; |
86 | if (frompc > p->textsize) |
87 | goto done; |
88 | |
89 | /* The following test used to be |
90 | if (p->log_hashfraction >= 0) |
91 | But we can simplify this if we assume the profiling data |
92 | is always initialized by the functions in gmon.c. But |
93 | then it is possible to avoid a runtime check and use the |
94 | smae `if' as in gmon.c. So keep these tests in sync. */ |
95 | if ((HASHFRACTION & (HASHFRACTION - 1)) == 0) { |
96 | /* avoid integer divide if possible: */ |
97 | i = frompc >> p->log_hashfraction; |
98 | } else { |
99 | i = frompc / (p->hashfraction * sizeof(*p->froms)); |
100 | } |
101 | frompcindex = &p->froms[i]; |
102 | toindex = *frompcindex; |
103 | if (toindex == 0) { |
104 | /* |
105 | * first time traversing this arc |
106 | */ |
107 | toindex = ++p->tos[0].link; |
108 | if (toindex >= p->tolimit) |
109 | /* halt further profiling */ |
110 | goto overflow; |
111 | |
112 | *frompcindex = toindex; |
113 | top = &p->tos[toindex]; |
114 | top->selfpc = selfpc; |
115 | top->count = 1; |
116 | top->link = 0; |
117 | goto done; |
118 | } |
119 | top = &p->tos[toindex]; |
120 | if (top->selfpc == selfpc) { |
121 | /* |
122 | * arc at front of chain; usual case. |
123 | */ |
124 | top->count++; |
125 | goto done; |
126 | } |
127 | /* |
128 | * have to go looking down chain for it. |
129 | * top points to what we are looking at, |
130 | * prevtop points to previous top. |
131 | * we know it is not at the head of the chain. |
132 | */ |
133 | for (; /* goto done */; ) { |
134 | if (top->link == 0) { |
135 | /* |
136 | * top is end of the chain and none of the chain |
137 | * had top->selfpc == selfpc. |
138 | * so we allocate a new tostruct |
139 | * and link it to the head of the chain. |
140 | */ |
141 | toindex = ++p->tos[0].link; |
142 | if (toindex >= p->tolimit) |
143 | goto overflow; |
144 | |
145 | top = &p->tos[toindex]; |
146 | top->selfpc = selfpc; |
147 | top->count = 1; |
148 | top->link = *frompcindex; |
149 | *frompcindex = toindex; |
150 | goto done; |
151 | } |
152 | /* |
153 | * otherwise, check the next arc on the chain. |
154 | */ |
155 | prevtop = top; |
156 | top = &p->tos[top->link]; |
157 | if (top->selfpc == selfpc) { |
158 | /* |
159 | * there it is. |
160 | * increment its count |
161 | * move it to the head of the chain. |
162 | */ |
163 | top->count++; |
164 | toindex = prevtop->link; |
165 | prevtop->link = top->link; |
166 | top->link = *frompcindex; |
167 | *frompcindex = toindex; |
168 | goto done; |
169 | } |
170 | |
171 | } |
172 | done: |
173 | p->state = GMON_PROF_ON; |
174 | return; |
175 | overflow: |
176 | p->state = GMON_PROF_ERROR; |
177 | ERR("mcount: call graph buffer size limit exceeded, gmon.out will not be generated\n" ); |
178 | return; |
179 | } |
180 | |
181 | /* |
182 | * Actual definition of mcount function. Defined in <machine/profile.h>, |
183 | * which is included by <sys/gmon.h>. |
184 | */ |
185 | MCOUNT |
186 | |