/* $OpenBSD: mcount.c,v 1.11 2010/05/09 15:56:08 kettenis Exp $ */ /*- * Copyright (c) 1983, 1992, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include <sys/param.h> #include <sys/gmon.h> /* * mcount is called on entry to each function compiled with the profiling * switch set. _mcount(), which is declared in a machine-dependent way * with _MCOUNT_DECL, does the actual work and is either inlined into a * C routine or called by an assembly stub. In any case, this magic is * taken care of by the MCOUNT definition in <machine/profile.h>. * * _mcount updates data structures that represent traversals of the * program's call graph edges. frompc and selfpc are the return * address and function address that represents the given call graph edge. * * Note: the original BSD code used the same variable (frompcindex) for * both frompcindex and frompc. Any reasonable, modern compiler will * perform this optimization. */ _MCOUNT_DECL(u_long frompc, u_long selfpc) __used; /* _mcount; may be static, inline, etc */ _MCOUNT_DECL(u_long frompc, u_long selfpc) { u_short *frompcindex; struct tostruct *top, *prevtop; struct gmonparam *p; long toindex; #ifdef _KERNEL int s; #endif p = &_gmonparam; /* * check that we are profiling * and that we aren't recursively invoked. */ if (p->state != GMON_PROF_ON) return; #ifdef _KERNEL MCOUNT_ENTER; #else p->state = GMON_PROF_BUSY; #endif /* * check that frompcindex is a reasonable pc value. * for example: signal catchers get called from the stack, * not from text space. too bad. */ frompc -= p->lowpc; if (frompc > p->textsize) goto done; #if (HASHFRACTION & (HASHFRACTION - 1)) == 0 if (p->hashfraction == HASHFRACTION) frompcindex = &p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))]; else #endif frompcindex = &p->froms[frompc / (p->hashfraction * sizeof(*p->froms))]; toindex = *frompcindex; if (toindex == 0) { /* * first time traversing this arc */ toindex = ++p->tos[0].link; if (toindex >= p->tolimit) /* halt further profiling */ goto overflow; *frompcindex = toindex; top = &p->tos[toindex]; top->selfpc = selfpc; top->count = 1; top->link = 0; goto done; } top = &p->tos[toindex]; if (top->selfpc == selfpc) { /* * arc at front of chain; usual case. */ top->count++; goto done; } /* * have to go looking down chain for it. * top points to what we are looking at, * prevtop points to previous top. * we know it is not at the head of the chain. */ for (; /* goto done */; ) { if (top->link == 0) { /* * top is end of the chain and none of the chain * had top->selfpc == selfpc. * so we allocate a new tostruct * and link it to the head of the chain. */ toindex = ++p->tos[0].link; if (toindex >= p->tolimit) goto overflow; top = &p->tos[toindex]; top->selfpc = selfpc; top->count = 1; top->link = *frompcindex; *frompcindex = toindex; goto done; } /* * otherwise, check the next arc on the chain. */ prevtop = top; top = &p->tos[top->link]; if (top->selfpc == selfpc) { /* * there it is. * increment its count * move it to the head of the chain. */ top->count++; toindex = prevtop->link; prevtop->link = top->link; top->link = *frompcindex; *frompcindex = toindex; goto done; } } done: #ifdef _KERNEL MCOUNT_EXIT; #else p->state = GMON_PROF_ON; #endif return; overflow: p->state = GMON_PROF_ERROR; #ifdef _KERNEL MCOUNT_EXIT; #endif return; } #ifndef lint /* * Actual definition of mcount function. Defined in <machine/profile.h>, * which is included by <sys/gmon.h>. */ MCOUNT #endif