1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1983, 1992, 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 32 #include <sys/cdefs.h> 33 __FBSDID("$FreeBSD$"); 34 35 #include <sys/param.h> 36 #include <sys/gmon.h> 37 #ifdef _KERNEL 38 #ifndef GUPROF 39 #include <sys/systm.h> 40 #endif 41 #include <vm/vm.h> 42 #include <vm/vm_param.h> 43 #include <vm/pmap.h> 44 #endif 45 46 /* 47 * mcount is called on entry to each function compiled with the profiling 48 * switch set. _mcount(), which is declared in a machine-dependent way 49 * with _MCOUNT_DECL, does the actual work and is either inlined into a 50 * C routine or called by an assembly stub. In any case, this magic is 51 * taken care of by the MCOUNT definition in <machine/profile.h>. 52 * 53 * _mcount updates data structures that represent traversals of the 54 * program's call graph edges. frompc and selfpc are the return 55 * address and function address that represents the given call graph edge. 56 * 57 * Note: the original BSD code used the same variable (frompcindex) for 58 * both frompcindex and frompc. Any reasonable, modern compiler will 59 * perform this optimization. 60 */ 61 _MCOUNT_DECL(uintfptr_t frompc, uintfptr_t selfpc) /* _mcount; may be static, inline, etc */ 62 { 63 #ifdef GUPROF 64 int delta; 65 #endif 66 fptrdiff_t frompci; 67 u_short *frompcindex; 68 struct tostruct *top, *prevtop; 69 struct gmonparam *p; 70 long toindex; 71 #ifdef _KERNEL 72 MCOUNT_DECL(s) 73 #endif 74 75 p = &_gmonparam; 76 #ifndef GUPROF /* XXX */ 77 /* 78 * check that we are profiling 79 * and that we aren't recursively invoked. 80 */ 81 if (p->state != GMON_PROF_ON) 82 return; 83 #endif 84 #ifdef _KERNEL 85 MCOUNT_ENTER(s); 86 #else 87 p->state = GMON_PROF_BUSY; 88 #endif 89 90 #ifdef _KERNEL 91 /* 92 * When we are called from an exception handler, frompc may be 93 * a user address. Convert such frompc's to some representation 94 * in kernel address space. 95 */ 96 frompc = MCOUNT_FROMPC_USER(frompc); 97 #endif 98 99 frompci = frompc - p->lowpc; 100 if (frompci >= p->textsize) 101 goto done; 102 103 #ifdef GUPROF 104 if (p->state == GMON_PROF_HIRES) { 105 /* 106 * Count the time since cputime() was previously called 107 * against `frompc'. Compensate for overheads. 108 * 109 * cputime() sets its prev_count variable to the count when 110 * it is called. This in effect starts a counter for 111 * the next period of execution (normally from now until 112 * the next call to mcount() or mexitcount()). We set 113 * cputime_bias to compensate for our own overhead. 114 * 115 * We use the usual sampling counters since they can be 116 * located efficiently. 4-byte counters are usually 117 * necessary. gprof will add up the scattered counts 118 * just like it does for statistical profiling. All 119 * counts are signed so that underflow in the subtractions 120 * doesn't matter much (negative counts are normally 121 * compensated for by larger counts elsewhere). Underflow 122 * shouldn't occur, but may be caused by slightly wrong 123 * calibrations or from not clearing cputime_bias. 124 */ 125 delta = cputime() - cputime_bias - p->mcount_pre_overhead; 126 cputime_bias = p->mcount_post_overhead; 127 KCOUNT(p, frompci) += delta; 128 *p->cputime_count += p->cputime_overhead; 129 *p->mcount_count += p->mcount_overhead; 130 } 131 #endif /* GUPROF */ 132 133 #ifdef _KERNEL 134 /* 135 * When we are called from an exception handler, frompc is faked 136 * to be for where the exception occurred. We've just solidified 137 * the count for there. Now convert frompci to an index that 138 * represents the kind of exception so that interruptions appear 139 * in the call graph as calls from those index instead of calls 140 * from all over. 141 */ 142 frompc = MCOUNT_FROMPC_INTR(selfpc); 143 if ((frompc - p->lowpc) < p->textsize) 144 frompci = frompc - p->lowpc; 145 #endif 146 147 /* 148 * check that frompc is a reasonable pc value. 149 * for example: signal catchers get called from the stack, 150 * not from text space. too bad. 151 */ 152 if (frompci >= p->textsize) 153 goto done; 154 155 frompcindex = &p->froms[frompci / (p->hashfraction * sizeof(*p->froms))]; 156 toindex = *frompcindex; 157 if (toindex == 0) { 158 /* 159 * first time traversing this arc 160 */ 161 toindex = ++p->tos[0].link; 162 if (toindex >= p->tolimit) 163 /* halt further profiling */ 164 goto overflow; 165 166 *frompcindex = toindex; 167 top = &p->tos[toindex]; 168 top->selfpc = selfpc; 169 top->count = 1; 170 top->link = 0; 171 goto done; 172 } 173 top = &p->tos[toindex]; 174 if (top->selfpc == selfpc) { 175 /* 176 * arc at front of chain; usual case. 177 */ 178 top->count++; 179 goto done; 180 } 181 /* 182 * have to go looking down chain for it. 183 * top points to what we are looking at, 184 * prevtop points to previous top. 185 * we know it is not at the head of the chain. 186 */ 187 for (; /* goto done */; ) { 188 if (top->link == 0) { 189 /* 190 * top is end of the chain and none of the chain 191 * had top->selfpc == selfpc. 192 * so we allocate a new tostruct 193 * and link it to the head of the chain. 194 */ 195 toindex = ++p->tos[0].link; 196 if (toindex >= p->tolimit) 197 goto overflow; 198 199 top = &p->tos[toindex]; 200 top->selfpc = selfpc; 201 top->count = 1; 202 top->link = *frompcindex; 203 *frompcindex = toindex; 204 goto done; 205 } 206 /* 207 * otherwise, check the next arc on the chain. 208 */ 209 prevtop = top; 210 top = &p->tos[top->link]; 211 if (top->selfpc == selfpc) { 212 /* 213 * there it is. 214 * increment its count 215 * move it to the head of the chain. 216 */ 217 top->count++; 218 toindex = prevtop->link; 219 prevtop->link = top->link; 220 top->link = *frompcindex; 221 *frompcindex = toindex; 222 goto done; 223 } 224 225 } 226 done: 227 #ifdef _KERNEL 228 MCOUNT_EXIT(s); 229 #else 230 p->state = GMON_PROF_ON; 231 #endif 232 return; 233 overflow: 234 p->state = GMON_PROF_ERROR; 235 #ifdef _KERNEL 236 MCOUNT_EXIT(s); 237 #endif 238 return; 239 } 240 241 /* 242 * Actual definition of mcount function. Defined in <machine/profile.h>, 243 * which is included by <sys/gmon.h>. 244 */ 245 MCOUNT 246 247 #ifdef GUPROF 248 void 249 mexitcount(uintfptr_t selfpc) 250 { 251 struct gmonparam *p; 252 uintfptr_t selfpcdiff; 253 254 p = &_gmonparam; 255 selfpcdiff = selfpc - (uintfptr_t)p->lowpc; 256 if (selfpcdiff < p->textsize) { 257 int delta; 258 259 /* 260 * Count the time since cputime() was previously called 261 * against `selfpc'. Compensate for overheads. 262 */ 263 delta = cputime() - cputime_bias - p->mexitcount_pre_overhead; 264 cputime_bias = p->mexitcount_post_overhead; 265 KCOUNT(p, selfpcdiff) += delta; 266 *p->cputime_count += p->cputime_overhead; 267 *p->mexitcount_count += p->mexitcount_overhead; 268 } 269 } 270 271 #ifndef __GNUCLIKE_ASM 272 #error "This file uses null asms to prevent timing loops being optimized away." 273 #endif 274 275 void 276 empty_loop() 277 { 278 int i; 279 280 for (i = 0; i < CALIB_SCALE; i++) 281 __asm __volatile(""); 282 } 283 284 void 285 nullfunc() 286 { 287 __asm __volatile(""); 288 } 289 290 void 291 nullfunc_loop() 292 { 293 int i; 294 295 for (i = 0; i < CALIB_SCALE; i++) 296 nullfunc(); 297 } 298 #endif /* GUPROF */ 299