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(_KERNEL) && defined(LIBC_SCCS) && !defined(lint)
31 static char sccsid[] = "@(#)mcount.c 8.1 (Berkeley) 6/4/93";
32 #endif
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <sys/param.h>
37 #include <sys/gmon.h>
38 #ifdef _KERNEL
39 #include <sys/systm.h>
40 #include <vm/vm.h>
41 #include <vm/vm_param.h>
42 #include <vm/pmap.h>
43 void bintr(void);
44 void btrap(void);
45 void eintr(void);
46 void user(void);
47 #endif
48 #include <machine/atomic.h>
49
50 /*
51 * mcount is called on entry to each function compiled with the profiling
52 * switch set. _mcount(), which is declared in a machine-dependent way
53 * with _MCOUNT_DECL, does the actual work and is either inlined into a
54 * C routine or called by an assembly stub. In any case, this magic is
55 * taken care of by the MCOUNT definition in <machine/profile.h>.
56 *
57 * _mcount updates data structures that represent traversals of the
58 * program's call graph edges. frompc and selfpc are the return
59 * address and function address that represents the given call graph edge.
60 *
61 * Note: the original BSD code used the same variable (frompcindex) for
62 * both frompcindex and frompc. Any reasonable, modern compiler will
63 * perform this optimization.
64 */
65 /* _mcount; may be static, inline, etc */
_MCOUNT_DECL(uintfptr_t frompc,uintfptr_t selfpc)66 _MCOUNT_DECL(uintfptr_t frompc, uintfptr_t selfpc)
67 {
68 #ifdef GUPROF
69 u_int delta;
70 #endif
71 fptrdiff_t frompci;
72 u_short *frompcindex;
73 struct tostruct *top, *prevtop;
74 struct gmonparam *p;
75 long toindex;
76 #ifdef _KERNEL
77 MCOUNT_DECL(s)
78 #endif
79
80 p = &_gmonparam;
81 #ifndef GUPROF /* XXX */
82 /*
83 * check that we are profiling
84 * and that we aren't recursively invoked.
85 */
86 if (p->state != GMON_PROF_ON)
87 return;
88 #endif
89 #ifdef _KERNEL
90 MCOUNT_ENTER(s);
91 #else
92 if (!atomic_cmpset_acq_int(&p->state, GMON_PROF_ON, GMON_PROF_BUSY))
93 return;
94 #endif
95 frompci = frompc - p->lowpc;
96
97 #ifdef _KERNEL
98 /*
99 * When we are called from an exception handler, frompci may be
100 * for a user address. Convert such frompci's to the index of
101 * user() to merge all user counts.
102 */
103 if (frompci >= p->textsize) {
104 if (frompci + p->lowpc
105 >= (uintfptr_t)(VM_MAXUSER_ADDRESS + UPAGES * PAGE_SIZE))
106 goto done;
107 frompci = (uintfptr_t)user - p->lowpc;
108 if (frompci >= p->textsize)
109 goto done;
110 }
111 #endif
112
113 #ifdef GUPROF
114 if (p->state != GMON_PROF_HIRES)
115 goto skip_guprof_stuff;
116 /*
117 * Look at the clock and add the count of clock cycles since the
118 * clock was last looked at to a counter for frompc. This
119 * solidifies the count for the function containing frompc and
120 * effectively starts another clock for the current function.
121 * The count for the new clock will be solidified when another
122 * function call is made or the function returns.
123 *
124 * We use the usual sampling counters since they can be located
125 * efficiently. 4-byte counters are usually necessary.
126 *
127 * There are many complications for subtracting the profiling
128 * overheads from the counts for normal functions and adding
129 * them to the counts for mcount(), mexitcount() and cputime().
130 * We attempt to handle fractional cycles, but the overheads
131 * are usually underestimated because they are calibrated for
132 * a simpler than usual setup.
133 */
134 delta = cputime() - p->mcount_overhead;
135 p->cputime_overhead_resid += p->cputime_overhead_frac;
136 p->mcount_overhead_resid += p->mcount_overhead_frac;
137 if ((int)delta < 0)
138 *p->mcount_count += delta + p->mcount_overhead
139 - p->cputime_overhead;
140 else if (delta != 0) {
141 if (p->cputime_overhead_resid >= CALIB_SCALE) {
142 p->cputime_overhead_resid -= CALIB_SCALE;
143 ++*p->cputime_count;
144 --delta;
145 }
146 if (delta != 0) {
147 if (p->mcount_overhead_resid >= CALIB_SCALE) {
148 p->mcount_overhead_resid -= CALIB_SCALE;
149 ++*p->mcount_count;
150 --delta;
151 }
152 KCOUNT(p, frompci) += delta;
153 }
154 *p->mcount_count += p->mcount_overhead_sub;
155 }
156 *p->cputime_count += p->cputime_overhead;
157 skip_guprof_stuff:
158 #endif /* GUPROF */
159
160 #ifdef _KERNEL
161 /*
162 * When we are called from an exception handler, frompc is faked
163 * to be for where the exception occurred. We've just solidified
164 * the count for there. Now convert frompci to the index of btrap()
165 * for trap handlers and bintr() for interrupt handlers to make
166 * exceptions appear in the call graph as calls from btrap() and
167 * bintr() instead of calls from all over.
168 */
169 if ((uintfptr_t)selfpc >= (uintfptr_t)btrap
170 && (uintfptr_t)selfpc < (uintfptr_t)eintr) {
171 if ((uintfptr_t)selfpc >= (uintfptr_t)bintr)
172 frompci = (uintfptr_t)bintr - p->lowpc;
173 else
174 frompci = (uintfptr_t)btrap - p->lowpc;
175 }
176 #endif
177
178 /*
179 * check that frompc is a reasonable pc value.
180 * for example: signal catchers get called from the stack,
181 * not from text space. too bad.
182 */
183 if (frompci >= p->textsize)
184 goto done;
185
186 frompcindex = &p->froms[frompci / (p->hashfraction * sizeof(*p->froms))];
187 toindex = *frompcindex;
188 if (toindex == 0) {
189 /*
190 * first time traversing this arc
191 */
192 toindex = ++p->tos[0].link;
193 if (toindex >= p->tolimit)
194 /* halt further profiling */
195 goto overflow;
196
197 *frompcindex = toindex;
198 top = &p->tos[toindex];
199 top->selfpc = selfpc;
200 top->count = 1;
201 top->link = 0;
202 goto done;
203 }
204 top = &p->tos[toindex];
205 if (top->selfpc == selfpc) {
206 /*
207 * arc at front of chain; usual case.
208 */
209 top->count++;
210 goto done;
211 }
212 /*
213 * have to go looking down chain for it.
214 * top points to what we are looking at,
215 * prevtop points to previous top.
216 * we know it is not at the head of the chain.
217 */
218 for (; /* goto done */; ) {
219 if (top->link == 0) {
220 /*
221 * top is end of the chain and none of the chain
222 * had top->selfpc == selfpc.
223 * so we allocate a new tostruct
224 * and link it to the head of the chain.
225 */
226 toindex = ++p->tos[0].link;
227 if (toindex >= p->tolimit)
228 goto overflow;
229
230 top = &p->tos[toindex];
231 top->selfpc = selfpc;
232 top->count = 1;
233 top->link = *frompcindex;
234 *frompcindex = toindex;
235 goto done;
236 }
237 /*
238 * otherwise, check the next arc on the chain.
239 */
240 prevtop = top;
241 top = &p->tos[top->link];
242 if (top->selfpc == selfpc) {
243 /*
244 * there it is.
245 * increment its count
246 * move it to the head of the chain.
247 */
248 top->count++;
249 toindex = prevtop->link;
250 prevtop->link = top->link;
251 top->link = *frompcindex;
252 *frompcindex = toindex;
253 goto done;
254 }
255
256 }
257 done:
258 #ifdef _KERNEL
259 MCOUNT_EXIT(s);
260 #else
261 atomic_store_rel_int(&p->state, GMON_PROF_ON);
262 #endif
263 return;
264 overflow:
265 atomic_store_rel_int(&p->state, GMON_PROF_ERROR);
266 #ifdef _KERNEL
267 MCOUNT_EXIT(s);
268 #endif
269 return;
270 }
271
272 /*
273 * Actual definition of mcount function. Defined in <machine/profile.h>,
274 * which is included by <sys/gmon.h>.
275 */
276 MCOUNT
277
278 #ifdef GUPROF
279 void
mexitcount(selfpc)280 mexitcount(selfpc)
281 uintfptr_t selfpc;
282 {
283 struct gmonparam *p;
284 uintfptr_t selfpcdiff;
285
286 p = &_gmonparam;
287 selfpcdiff = selfpc - (uintfptr_t)p->lowpc;
288 if (selfpcdiff < p->textsize) {
289 u_int delta;
290
291 /*
292 * Solidify the count for the current function.
293 */
294 delta = cputime() - p->mexitcount_overhead;
295 p->cputime_overhead_resid += p->cputime_overhead_frac;
296 p->mexitcount_overhead_resid += p->mexitcount_overhead_frac;
297 if ((int)delta < 0)
298 *p->mexitcount_count += delta + p->mexitcount_overhead
299 - p->cputime_overhead;
300 else if (delta != 0) {
301 if (p->cputime_overhead_resid >= CALIB_SCALE) {
302 p->cputime_overhead_resid -= CALIB_SCALE;
303 ++*p->cputime_count;
304 --delta;
305 }
306 if (delta != 0) {
307 if (p->mexitcount_overhead_resid
308 >= CALIB_SCALE) {
309 p->mexitcount_overhead_resid
310 -= CALIB_SCALE;
311 ++*p->mexitcount_count;
312 --delta;
313 }
314 KCOUNT(p, selfpcdiff) += delta;
315 }
316 *p->mexitcount_count += p->mexitcount_overhead_sub;
317 }
318 *p->cputime_count += p->cputime_overhead;
319 }
320 }
321 #endif /* GUPROF */
322