FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_prof.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 * may be used to endorse or promote products derived from this software
17 * without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * @(#)subr_prof.c 8.3 (Berkeley) 9/23/93
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/sysproto.h>
40 #include <sys/kernel.h>
41 #include <sys/lock.h>
42 #include <sys/mutex.h>
43 #include <sys/proc.h>
44 #include <sys/resourcevar.h>
45 #include <sys/sysctl.h>
46
47 #include <machine/cpu.h>
48
49 /*
50 * Profiling system call.
51 *
52 * The scale factor is a fixed point number with 16 bits of fraction, so that
53 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
54 */
55 #ifndef _SYS_SYSPROTO_H_
56 struct profil_args {
57 caddr_t samples;
58 size_t size;
59 size_t offset;
60 u_int scale;
61 };
62 #endif
63 /* ARGSUSED */
64 int
65 sys_profil(struct thread *td, struct profil_args *uap)
66 {
67 struct uprof *upp;
68 struct proc *p;
69
70 if (uap->scale > (1 << 16))
71 return (EINVAL);
72
73 p = td->td_proc;
74 if (uap->scale == 0) {
75 PROC_LOCK(p);
76 stopprofclock(p);
77 PROC_UNLOCK(p);
78 return (0);
79 }
80 PROC_LOCK(p);
81 upp = &td->td_proc->p_stats->p_prof;
82 PROC_PROFLOCK(p);
83 upp->pr_off = uap->offset;
84 upp->pr_scale = uap->scale;
85 upp->pr_base = uap->samples;
86 upp->pr_size = uap->size;
87 PROC_PROFUNLOCK(p);
88 startprofclock(p);
89 PROC_UNLOCK(p);
90
91 return (0);
92 }
93
94 /*
95 * Scale is a fixed-point number with the binary point 16 bits
96 * into the value, and is <= 1.0. pc is at most 32 bits, so the
97 * intermediate result is at most 48 bits.
98 */
99 #define PC_TO_INDEX(pc, prof) \
100 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
101 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
102
103 /*
104 * Collect user-level profiling statistics; called on a profiling tick,
105 * when a process is running in user-mode. This routine may be called
106 * from an interrupt context. We perform the update with an AST
107 * that will vector us to trap() with a context in which copyin and
108 * copyout will work. Trap will then call addupc_task().
109 *
110 * Note that we may (rarely) not get around to the AST soon enough, and
111 * lose profile ticks when the next tick overwrites this one, but in this
112 * case the system is overloaded and the profile is probably already
113 * inaccurate.
114 */
115 void
116 addupc_intr(struct thread *td, uintfptr_t pc, u_int ticks)
117 {
118 struct uprof *prof;
119
120 if (ticks == 0)
121 return;
122 prof = &td->td_proc->p_stats->p_prof;
123 PROC_PROFLOCK(td->td_proc);
124 if (pc < prof->pr_off || PC_TO_INDEX(pc, prof) >= prof->pr_size) {
125 PROC_PROFUNLOCK(td->td_proc);
126 return; /* out of range; ignore */
127 }
128
129 PROC_PROFUNLOCK(td->td_proc);
130 td->td_profil_addr = pc;
131 td->td_profil_ticks = ticks;
132 td->td_pflags |= TDP_OWEUPC;
133 ast_sched(td, TDA_OWEUPC);
134 }
135
136 /*
137 * Actually update the profiling statistics. If the update fails, we
138 * simply turn off profiling.
139 */
140 void
141 addupc_task(struct thread *td, uintfptr_t pc, u_int ticks)
142 {
143 struct proc *p = td->td_proc;
144 struct uprof *prof;
145 caddr_t addr;
146 u_int i;
147 u_short v;
148 int stop = 0;
149
150 if (ticks == 0)
151 return;
152
153 PROC_LOCK(p);
154 if (!(p->p_flag & P_PROFIL)) {
155 PROC_UNLOCK(p);
156 return;
157 }
158 p->p_profthreads++;
159 prof = &p->p_stats->p_prof;
160 PROC_PROFLOCK(p);
161 if (pc < prof->pr_off ||
162 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
163 PROC_PROFUNLOCK(p);
164 goto out;
165 }
166
167 addr = prof->pr_base + i;
168 PROC_PROFUNLOCK(p);
169 PROC_UNLOCK(p);
170 if (copyin(addr, &v, sizeof(v)) == 0) {
171 v += ticks;
172 if (copyout(&v, addr, sizeof(v)) == 0) {
173 PROC_LOCK(p);
174 goto out;
175 }
176 }
177 stop = 1;
178 PROC_LOCK(p);
179
180 out:
181 if (--p->p_profthreads == 0) {
182 if (p->p_flag & P_STOPPROF) {
183 wakeup(&p->p_profthreads);
184 p->p_flag &= ~P_STOPPROF;
185 stop = 0;
186 }
187 }
188 if (stop)
189 stopprofclock(p);
190 PROC_UNLOCK(p);
191 }
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