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/* $OpenBSD: mcount.c,v 1.15 2015/01/16 16:48:51 deraadt Exp $ */ |
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/*- |
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* Copyright (c) 1983, 1992, 1993 |
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* The Regents of the University of California. All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* 3. Neither the name of the University nor the names of its contributors |
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* may be used to endorse or promote products derived from this software |
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* without specific prior written permission. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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*/ |
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#include <sys/types.h> |
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#include <sys/gmon.h> |
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/* |
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* mcount is called on entry to each function compiled with the profiling |
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* switch set. _mcount(), which is declared in a machine-dependent way |
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* with _MCOUNT_DECL, does the actual work and is either inlined into a |
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* C routine or called by an assembly stub. In any case, this magic is |
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* taken care of by the MCOUNT definition in <machine/profile.h>. |
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* |
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* _mcount updates data structures that represent traversals of the |
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* program's call graph edges. frompc and selfpc are the return |
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* address and function address that represents the given call graph edge. |
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*/ |
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_MCOUNT_DECL(u_long frompc, u_long selfpc) __used; |
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/* _mcount; may be static, inline, etc */ |
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_MCOUNT_DECL(u_long frompc, u_long selfpc) |
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{ |
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u_short *frompcindex; |
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struct tostruct *top, *prevtop; |
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struct gmonparam *p; |
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long toindex; |
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#ifdef _KERNEL |
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int s; |
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/* |
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* Do not profile execution if memory for the current CPU |
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* desciptor and profiling buffers has not yet been allocated |
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* or if the CPU we are running on has not yet set its trap |
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* handler. |
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*/ |
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if (gmoninit == 0) |
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return; |
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if ((p = curcpu()->ci_gmon) == NULL) |
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return; |
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#else |
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p = &_gmonparam; |
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#endif |
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/* |
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* check that we are profiling |
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* and that we aren't recursively invoked. |
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*/ |
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if (p->state != GMON_PROF_ON) |
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return; |
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#ifdef _KERNEL |
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MCOUNT_ENTER; |
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#else |
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p->state = GMON_PROF_BUSY; |
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#endif |
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/* |
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* check that frompcindex is a reasonable pc value. |
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* for example: signal catchers get called from the stack, |
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* not from text space. too bad. |
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*/ |
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frompc -= p->lowpc; |
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if (frompc > p->textsize) |
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goto done; |
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#if (HASHFRACTION & (HASHFRACTION - 1)) == 0 |
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if (p->hashfraction == HASHFRACTION) |
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frompcindex = |
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&p->froms[frompc / (HASHFRACTION * sizeof(*p->froms))]; |
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else |
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#endif |
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frompcindex = |
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&p->froms[frompc / (p->hashfraction * sizeof(*p->froms))]; |
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toindex = *frompcindex; |
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if (toindex == 0) { |
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/* |
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* first time traversing this arc |
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*/ |
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toindex = ++p->tos[0].link; |
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if (toindex >= p->tolimit) |
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/* halt further profiling */ |
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goto overflow; |
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*frompcindex = toindex; |
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top = &p->tos[toindex]; |
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top->selfpc = selfpc; |
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top->count = 1; |
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top->link = 0; |
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goto done; |
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} |
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top = &p->tos[toindex]; |
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if (top->selfpc == selfpc) { |
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/* |
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* arc at front of chain; usual case. |
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*/ |
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top->count++; |
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goto done; |
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} |
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/* |
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* have to go looking down chain for it. |
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* top points to what we are looking at, |
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* prevtop points to previous top. |
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* we know it is not at the head of the chain. |
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*/ |
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for (; /* goto done */; ) { |
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if (top->link == 0) { |
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/* |
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* top is end of the chain and none of the chain |
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* had top->selfpc == selfpc. |
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* so we allocate a new tostruct |
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* and link it to the head of the chain. |
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*/ |
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toindex = ++p->tos[0].link; |
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if (toindex >= p->tolimit) |
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goto overflow; |
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top = &p->tos[toindex]; |
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top->selfpc = selfpc; |
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top->count = 1; |
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top->link = *frompcindex; |
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*frompcindex = toindex; |
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goto done; |
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} |
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/* |
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* otherwise, check the next arc on the chain. |
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*/ |
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prevtop = top; |
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top = &p->tos[top->link]; |
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if (top->selfpc == selfpc) { |
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/* |
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* there it is. |
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* increment its count |
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* move it to the head of the chain. |
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*/ |
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top->count++; |
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toindex = prevtop->link; |
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prevtop->link = top->link; |
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top->link = *frompcindex; |
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*frompcindex = toindex; |
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goto done; |
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} |
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} |
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done: |
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#ifdef _KERNEL |
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MCOUNT_EXIT; |
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#else |
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p->state = GMON_PROF_ON; |
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#endif |
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return; |
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overflow: |
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p->state = GMON_PROF_ERROR; |
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#ifdef _KERNEL |
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MCOUNT_EXIT; |
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#endif |
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return; |
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} |
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/* |
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* Actual definition of mcount function. Defined in <machine/profile.h>, |
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* which is included by <sys/gmon.h>. |
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*/ |
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MCOUNT |