lib/libc/gmon/mcount.c

   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 */