FreeBSD/Linux Kernel Cross Reference
sys/kern/subr_prof.c
1 /* $NetBSD: subr_prof.c,v 1.43 2007/12/20 23:03:10 dsl Exp $ */
2
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 8.4 (Berkeley) 2/14/95
32 */
33
34 #include <sys/cdefs.h>
35 __KERNEL_RCSID(0, "$NetBSD: subr_prof.c,v 1.43 2007/12/20 23:03:10 dsl Exp $");
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/kernel.h>
40 #include <sys/proc.h>
41 #include <sys/user.h>
42 #include <sys/mount.h>
43 #include <sys/syscallargs.h>
44 #include <sys/sysctl.h>
45
46 #include <sys/cpu.h>
47
48 #ifdef GPROF
49 #include <sys/malloc.h>
50 #include <sys/gmon.h>
51
52 MALLOC_DEFINE(M_GPROF, "gprof", "kernel profiling buffer");
53
54 /*
55 * Froms is actually a bunch of unsigned shorts indexing tos
56 */
57 struct gmonparam _gmonparam = { .state = GMON_PROF_OFF };
58
59 /* Actual start of the kernel text segment. */
60 extern char kernel_text[];
61
62 extern char etext[];
63
64
65 void
66 kmstartup(void)
67 {
68 char *cp;
69 struct gmonparam *p = &_gmonparam;
70 /*
71 * Round lowpc and highpc to multiples of the density we're using
72 * so the rest of the scaling (here and in gprof) stays in ints.
73 */
74 p->lowpc = rounddown(((u_long)kernel_text),
75 HISTFRACTION * sizeof(HISTCOUNTER));
76 p->highpc = roundup((u_long)etext,
77 HISTFRACTION * sizeof(HISTCOUNTER));
78 p->textsize = p->highpc - p->lowpc;
79 printf("Profiling kernel, textsize=%ld [%lx..%lx]\n",
80 p->textsize, p->lowpc, p->highpc);
81 p->kcountsize = p->textsize / HISTFRACTION;
82 p->hashfraction = HASHFRACTION;
83 p->fromssize = p->textsize / HASHFRACTION;
84 p->tolimit = p->textsize * ARCDENSITY / 100;
85 if (p->tolimit < MINARCS)
86 p->tolimit = MINARCS;
87 else if (p->tolimit > MAXARCS)
88 p->tolimit = MAXARCS;
89 p->tossize = p->tolimit * sizeof(struct tostruct);
90 cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
91 M_GPROF, M_NOWAIT | M_ZERO);
92 if (cp == 0) {
93 printf("No memory for profiling.\n");
94 return;
95 }
96 p->tos = (struct tostruct *)cp;
97 cp += p->tossize;
98 p->kcount = (u_short *)cp;
99 cp += p->kcountsize;
100 p->froms = (u_short *)cp;
101 }
102
103 /*
104 * Return kernel profiling information.
105 */
106 /*
107 * sysctl helper routine for kern.profiling subtree. enables/disables
108 * kernel profiling and gives out copies of the profiling data.
109 */
110 static int
111 sysctl_kern_profiling(SYSCTLFN_ARGS)
112 {
113 struct gmonparam *gp = &_gmonparam;
114 int error;
115 struct sysctlnode node;
116
117 node = *rnode;
118
119 switch (node.sysctl_num) {
120 case GPROF_STATE:
121 node.sysctl_data = &gp->state;
122 break;
123 case GPROF_COUNT:
124 node.sysctl_data = gp->kcount;
125 node.sysctl_size = gp->kcountsize;
126 break;
127 case GPROF_FROMS:
128 node.sysctl_data = gp->froms;
129 node.sysctl_size = gp->fromssize;
130 break;
131 case GPROF_TOS:
132 node.sysctl_data = gp->tos;
133 node.sysctl_size = gp->tossize;
134 break;
135 case GPROF_GMONPARAM:
136 node.sysctl_data = gp;
137 node.sysctl_size = sizeof(*gp);
138 break;
139 default:
140 return (EOPNOTSUPP);
141 }
142
143 error = sysctl_lookup(SYSCTLFN_CALL(&node));
144 if (error || newp == NULL)
145 return (error);
146
147 if (node.sysctl_num == GPROF_STATE) {
148 mutex_spin_enter(&proc0.p_stmutex);
149 if (gp->state == GMON_PROF_OFF)
150 stopprofclock(&proc0);
151 else
152 startprofclock(&proc0);
153 mutex_spin_exit(&proc0.p_stmutex);
154 }
155
156 return (0);
157 }
158
159 SYSCTL_SETUP(sysctl_kern_gprof_setup, "sysctl kern.profiling subtree setup")
160 {
161
162 sysctl_createv(clog, 0, NULL, NULL,
163 CTLFLAG_PERMANENT,
164 CTLTYPE_NODE, "kern", NULL,
165 NULL, 0, NULL, 0,
166 CTL_KERN, CTL_EOL);
167 sysctl_createv(clog, 0, NULL, NULL,
168 CTLFLAG_PERMANENT,
169 CTLTYPE_NODE, "profiling",
170 SYSCTL_DESCR("Profiling information (available)"),
171 NULL, 0, NULL, 0,
172 CTL_KERN, KERN_PROF, CTL_EOL);
173
174 sysctl_createv(clog, 0, NULL, NULL,
175 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
176 CTLTYPE_INT, "state",
177 SYSCTL_DESCR("Profiling state"),
178 sysctl_kern_profiling, 0, NULL, 0,
179 CTL_KERN, KERN_PROF, GPROF_STATE, CTL_EOL);
180 sysctl_createv(clog, 0, NULL, NULL,
181 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
182 CTLTYPE_STRUCT, "count",
183 SYSCTL_DESCR("Array of statistical program counters"),
184 sysctl_kern_profiling, 0, NULL, 0,
185 CTL_KERN, KERN_PROF, GPROF_COUNT, CTL_EOL);
186 sysctl_createv(clog, 0, NULL, NULL,
187 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
188 CTLTYPE_STRUCT, "froms",
189 SYSCTL_DESCR("Array indexed by program counter of "
190 "call-from points"),
191 sysctl_kern_profiling, 0, NULL, 0,
192 CTL_KERN, KERN_PROF, GPROF_FROMS, CTL_EOL);
193 sysctl_createv(clog, 0, NULL, NULL,
194 CTLFLAG_PERMANENT|CTLFLAG_READWRITE,
195 CTLTYPE_STRUCT, "tos",
196 SYSCTL_DESCR("Array of structures describing "
197 "destination of calls and their counts"),
198 sysctl_kern_profiling, 0, NULL, 0,
199 CTL_KERN, KERN_PROF, GPROF_TOS, CTL_EOL);
200 sysctl_createv(clog, 0, NULL, NULL,
201 CTLFLAG_PERMANENT,
202 CTLTYPE_STRUCT, "gmonparam",
203 SYSCTL_DESCR("Structure giving the sizes of the above "
204 "arrays"),
205 sysctl_kern_profiling, 0, NULL, 0,
206 CTL_KERN, KERN_PROF, GPROF_GMONPARAM, CTL_EOL);
207 }
208 #endif /* GPROF */
209
210 /*
211 * Profiling system call.
212 *
213 * The scale factor is a fixed point number with 16 bits of fraction, so that
214 * 1.0 is represented as 0x10000. A scale factor of 0 turns off profiling.
215 */
216 /* ARGSUSED */
217 int
218 sys_profil(struct lwp *l, const struct sys_profil_args *uap, register_t *retval)
219 {
220 /* {
221 syscallarg(char *) samples;
222 syscallarg(u_int) size;
223 syscallarg(u_int) offset;
224 syscallarg(u_int) scale;
225 } */
226 struct proc *p = l->l_proc;
227 struct uprof *upp;
228
229 if (SCARG(uap, scale) > (1 << 16))
230 return (EINVAL);
231 if (SCARG(uap, scale) == 0) {
232 mutex_spin_enter(&p->p_stmutex);
233 stopprofclock(p);
234 mutex_spin_exit(&p->p_stmutex);
235 return (0);
236 }
237 upp = &p->p_stats->p_prof;
238
239 /* Block profile interrupts while changing state. */
240 mutex_spin_enter(&p->p_stmutex);
241 upp->pr_off = SCARG(uap, offset);
242 upp->pr_scale = SCARG(uap, scale);
243 upp->pr_base = SCARG(uap, samples);
244 upp->pr_size = SCARG(uap, size);
245 startprofclock(p);
246 mutex_spin_exit(&p->p_stmutex);
247
248 return (0);
249 }
250
251 /*
252 * Scale is a fixed-point number with the binary point 16 bits
253 * into the value, and is <= 1.0. pc is at most 32 bits, so the
254 * intermediate result is at most 48 bits.
255 */
256 #define PC_TO_INDEX(pc, prof) \
257 ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
258 (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)
259
260 /*
261 * Collect user-level profiling statistics; called on a profiling tick,
262 * when a process is running in user-mode. This routine may be called
263 * from an interrupt context. We try to update the user profiling buffers
264 * cheaply with fuswintr() and suswintr(). If that fails, we revert to
265 * an AST that will vector us to trap() with a context in which copyin
266 * and copyout will work. Trap will then call addupc_task().
267 *
268 * Note that we may (rarely) not get around to the AST soon enough, and
269 * lose profile ticks when the next tick overwrites this one, but in this
270 * case the system is overloaded and the profile is probably already
271 * inaccurate.
272 */
273 void
274 addupc_intr(struct lwp *l, u_long pc)
275 {
276 struct uprof *prof;
277 struct proc *p;
278 void *addr;
279 u_int i;
280 int v;
281
282 p = l->l_proc;
283
284 KASSERT(mutex_owned(&p->p_stmutex));
285
286 prof = &p->p_stats->p_prof;
287 if (pc < prof->pr_off ||
288 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
289 return; /* out of range; ignore */
290
291 addr = prof->pr_base + i;
292 mutex_spin_exit(&p->p_stmutex);
293 if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + 1) == -1) {
294 /* XXXSMP */
295 prof->pr_addr = pc;
296 prof->pr_ticks++;
297 cpu_need_proftick(l);
298 }
299 mutex_spin_enter(&p->p_stmutex);
300 }
301
302 /*
303 * Much like before, but we can afford to take faults here. If the
304 * update fails, we simply turn off profiling.
305 */
306 void
307 addupc_task(struct lwp *l, u_long pc, u_int ticks)
308 {
309 struct uprof *prof;
310 struct proc *p;
311 void *addr;
312 int error;
313 u_int i;
314 u_short v;
315
316 p = l->l_proc;
317
318 if (ticks == 0)
319 return;
320
321 mutex_spin_enter(&p->p_stmutex);
322 prof = &p->p_stats->p_prof;
323
324 /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
325 if ((p->p_stflag & PST_PROFIL) == 0 || pc < prof->pr_off ||
326 (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size) {
327 mutex_spin_exit(&p->p_stmutex);
328 return;
329 }
330
331 addr = prof->pr_base + i;
332 mutex_spin_exit(&p->p_stmutex);
333 if ((error = copyin(addr, (void *)&v, sizeof(v))) == 0) {
334 v += ticks;
335 error = copyout((void *)&v, addr, sizeof(v));
336 }
337 if (error != 0) {
338 mutex_spin_enter(&p->p_stmutex);
339 stopprofclock(p);
340 mutex_spin_exit(&p->p_stmutex);
341 }
342 }
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