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 * 3. 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 * @(#)mcount.c 8.1 (Berkeley) 6/4/93 30 * $FreeBSD: src/lib/libc/gmon/mcount.c,v 1.20 2004/10/16 06:32:43 obrien Exp $ 31 * $DragonFly: src/lib/libc/gmon/mcount.c,v 1.5 2005/11/13 01:18:20 swildner Exp $ 32 */ 33 34 #include <sys/param.h> 35 #include <sys/gmon.h> 36 #ifdef _KERNEL 37 #include <sys/systm.h> 38 #include <vm/vm.h> 39 #include <vm/vm_param.h> 40 #include <vm/pmap.h> 41 void bintr(void); 42 void btrap(void); 43 void eintr(void); 44 void user(void); 45 #endif 46 47 /* 48 * mcount is called on entry to each function compiled with the profiling 49 * switch set. _mcount(), which is declared in a machine-dependent way 50 * with _MCOUNT_DECL, does the actual work and is either inlined into a 51 * C routine or called by an assembly stub. In any case, this magic is 52 * taken care of by the MCOUNT definition in <machine/profile.h>. 53 * 54 * _mcount updates data structures that represent traversals of the 55 * program's call graph edges. frompc and selfpc are the return 56 * address and function address that represents the given call graph edge. 57 * 58 * Note: the original BSD code used the same variable (frompcindex) for 59 * both frompcindex and frompc. Any reasonable, modern compiler will 60 * perform this optimization. 61 */ 62 /* _mcount; may be static, inline, etc */ 63 _MCOUNT_DECL(uintfptr_t frompc, uintfptr_t selfpc) 64 { 65 #ifdef GUPROF 66 u_int delta; 67 #endif 68 fptrdiff_t frompci; 69 u_short *frompcindex; 70 struct tostruct *top, *prevtop; 71 struct gmonparam *p; 72 long toindex; 73 #ifdef _KERNEL 74 MCOUNT_DECL(s) 75 #endif 76 77 p = &_gmonparam; 78 #ifndef GUPROF /* XXX */ 79 /* 80 * check that we are profiling 81 * and that we aren't recursively invoked. 82 */ 83 if (p->state != GMON_PROF_ON) 84 return; 85 #endif 86 #ifdef _KERNEL 87 MCOUNT_ENTER(s); 88 #else 89 p->state = GMON_PROF_BUSY; /* XXX */ 90 #endif 91 frompci = frompc - p->lowpc; 92 93 #ifdef _KERNEL 94 /* 95 * When we are called from an exception handler, frompci may be 96 * for a user address. Convert such frompci's to the index of 97 * user() to merge all user counts. 98 */ 99 if (frompci >= p->textsize) { 100 if (frompci + p->lowpc 101 >= (uintfptr_t)(VM_MAXUSER_ADDRESS + UPAGES * PAGE_SIZE)) 102 goto done; 103 frompci = (uintfptr_t)user - p->lowpc; 104 if (frompci >= p->textsize) 105 goto done; 106 } 107 #endif 108 109 #ifdef GUPROF 110 if (p->state != GMON_PROF_HIRES) 111 goto skip_guprof_stuff; 112 /* 113 * Look at the clock and add the count of clock cycles since the 114 * clock was last looked at to a counter for frompc. This 115 * solidifies the count for the function containing frompc and 116 * effectively starts another clock for the current function. 117 * The count for the new clock will be solidified when another 118 * function call is made or the function returns. 119 * 120 * We use the usual sampling counters since they can be located 121 * efficiently. 4-byte counters are usually necessary. 122 * 123 * There are many complications for subtracting the profiling 124 * overheads from the counts for normal functions and adding 125 * them to the counts for mcount(), mexitcount() and cputime(). 126 * We attempt to handle fractional cycles, but the overheads 127 * are usually underestimated because they are calibrated for 128 * a simpler than usual setup. 129 */ 130 delta = cputime() - p->mcount_overhead; 131 p->cputime_overhead_resid += p->cputime_overhead_frac; 132 p->mcount_overhead_resid += p->mcount_overhead_frac; 133 if ((int)delta < 0) 134 *p->mcount_count += delta + p->mcount_overhead 135 - p->cputime_overhead; 136 else if (delta != 0) { 137 if (p->cputime_overhead_resid >= CALIB_SCALE) { 138 p->cputime_overhead_resid -= CALIB_SCALE; 139 ++*p->cputime_count; 140 --delta; 141 } 142 if (delta != 0) { 143 if (p->mcount_overhead_resid >= CALIB_SCALE) { 144 p->mcount_overhead_resid -= CALIB_SCALE; 145 ++*p->mcount_count; 146 --delta; 147 } 148 KCOUNT(p, frompci) += delta; 149 } 150 *p->mcount_count += p->mcount_overhead_sub; 151 } 152 *p->cputime_count += p->cputime_overhead; 153 skip_guprof_stuff: 154 #endif /* GUPROF */ 155 156 #ifdef _KERNEL 157 /* 158 * When we are called from an exception handler, frompc is faked 159 * to be for where the exception occurred. We've just solidified 160 * the count for there. Now convert frompci to the index of btrap() 161 * for trap handlers and bintr() for interrupt handlers to make 162 * exceptions appear in the call graph as calls from btrap() and 163 * bintr() instead of calls from all over. 164 */ 165 if ((uintfptr_t)selfpc >= (uintfptr_t)btrap 166 && (uintfptr_t)selfpc < (uintfptr_t)eintr) { 167 if ((uintfptr_t)selfpc >= (uintfptr_t)bintr) 168 frompci = (uintfptr_t)bintr - p->lowpc; 169 else 170 frompci = (uintfptr_t)btrap - p->lowpc; 171 } 172 #endif 173 174 /* 175 * check that frompc is a reasonable pc value. 176 * for example: signal catchers get called from the stack, 177 * not from text space. too bad. 178 */ 179 if (frompci >= p->textsize) 180 goto done; 181 182 frompcindex = &p->froms[frompci / (p->hashfraction * sizeof(*p->froms))]; 183 toindex = *frompcindex; 184 if (toindex == 0) { 185 /* 186 * first time traversing this arc 187 */ 188 toindex = ++p->tos[0].link; 189 if (toindex >= p->tolimit) 190 /* halt further profiling */ 191 goto overflow; 192 193 *frompcindex = toindex; 194 top = &p->tos[toindex]; 195 top->selfpc = selfpc; 196 top->count = 1; 197 top->link = 0; 198 goto done; 199 } 200 top = &p->tos[toindex]; 201 if (top->selfpc == selfpc) { 202 /* 203 * arc at front of chain; usual case. 204 */ 205 top->count++; 206 goto done; 207 } 208 /* 209 * have to go looking down chain for it. 210 * top points to what we are looking at, 211 * prevtop points to previous top. 212 * we know it is not at the head of the chain. 213 */ 214 for (; /* goto done */; ) { 215 if (top->link == 0) { 216 /* 217 * top is end of the chain and none of the chain 218 * had top->selfpc == selfpc. 219 * so we allocate a new tostruct 220 * and link it to the head of the chain. 221 */ 222 toindex = ++p->tos[0].link; 223 if (toindex >= p->tolimit) 224 goto overflow; 225 226 top = &p->tos[toindex]; 227 top->selfpc = selfpc; 228 top->count = 1; 229 top->link = *frompcindex; 230 *frompcindex = toindex; 231 goto done; 232 } 233 /* 234 * otherwise, check the next arc on the chain. 235 */ 236 prevtop = top; 237 top = &p->tos[top->link]; 238 if (top->selfpc == selfpc) { 239 /* 240 * there it is. 241 * increment its count 242 * move it to the head of the chain. 243 */ 244 top->count++; 245 toindex = prevtop->link; 246 prevtop->link = top->link; 247 top->link = *frompcindex; 248 *frompcindex = toindex; 249 goto done; 250 } 251 252 } 253 done: 254 #ifdef _KERNEL 255 MCOUNT_EXIT(s); 256 #else 257 p->state = GMON_PROF_ON; /* XXX */ 258 #endif 259 return; 260 overflow: 261 p->state = GMON_PROF_ERROR; /* XXX */ 262 #ifdef _KERNEL 263 MCOUNT_EXIT(s); 264 #endif 265 return; 266 } 267 268 /* 269 * Actual definition of mcount function. Defined in <machine/profile.h>, 270 * which is included by <sys/gmon.h>. 271 */ 272 MCOUNT 273 274 #ifdef GUPROF 275 void 276 mexitcount(uintfptr_t selfpc) 277 { 278 struct gmonparam *p; 279 uintfptr_t selfpcdiff; 280 281 p = &_gmonparam; 282 selfpcdiff = selfpc - (uintfptr_t)p->lowpc; 283 if (selfpcdiff < p->textsize) { 284 u_int delta; 285 286 /* 287 * Solidify the count for the current function. 288 */ 289 delta = cputime() - p->mexitcount_overhead; 290 p->cputime_overhead_resid += p->cputime_overhead_frac; 291 p->mexitcount_overhead_resid += p->mexitcount_overhead_frac; 292 if ((int)delta < 0) 293 *p->mexitcount_count += delta + p->mexitcount_overhead 294 - p->cputime_overhead; 295 else if (delta != 0) { 296 if (p->cputime_overhead_resid >= CALIB_SCALE) { 297 p->cputime_overhead_resid -= CALIB_SCALE; 298 ++*p->cputime_count; 299 --delta; 300 } 301 if (delta != 0) { 302 if (p->mexitcount_overhead_resid 303 >= CALIB_SCALE) { 304 p->mexitcount_overhead_resid 305 -= CALIB_SCALE; 306 ++*p->mexitcount_count; 307 --delta; 308 } 309 KCOUNT(p, selfpcdiff) += delta; 310 } 311 *p->mexitcount_count += p->mexitcount_overhead_sub; 312 } 313 *p->cputime_count += p->cputime_overhead; 314 } 315 } 316 #endif /* GUPROF */ 317