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Diffstat (limited to 'sys/libkern/mcount.c')
| -rw-r--r-- | sys/libkern/mcount.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/sys/libkern/mcount.c b/sys/libkern/mcount.c new file mode 100644 index 0000000..569f80b --- /dev/null +++ b/sys/libkern/mcount.c @@ -0,0 +1,308 @@ +/*- + * 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. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. 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. + * + * $FreeBSD$ + */ + +#include <sys/param.h> +#include <sys/gmon.h> +#ifdef _KERNEL +#ifndef GUPROF +#include <sys/systm.h> +#endif +#include <vm/vm.h> +#include <vm/vm_param.h> +#include <vm/pmap.h> +void bintr(void); +void btrap(void); +void eintr(void); +void user(void); +#endif + +/* + * 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(frompc, selfpc) /* _mcount; may be static, inline, etc */ + register uintfptr_t frompc, selfpc; +{ +#ifdef GUPROF + int delta; +#endif + register fptrdiff_t frompci; + register u_short *frompcindex; + register struct tostruct *top, *prevtop; + register struct gmonparam *p; + register long toindex; +#ifdef _KERNEL + MCOUNT_DECL(s) +#endif + + p = &_gmonparam; +#ifndef GUPROF /* XXX */ + /* + * check that we are profiling + * and that we aren't recursively invoked. + */ + if (p->state != GMON_PROF_ON) + return; +#endif +#ifdef _KERNEL + MCOUNT_ENTER(s); +#else + p->state = GMON_PROF_BUSY; +#endif + frompci = frompc - p->lowpc; + +#ifdef _KERNEL + /* + * When we are called from an exception handler, frompci may be + * for a user address. Convert such frompci's to the index of + * user() to merge all user counts. + */ + if (frompci >= p->textsize) { + if (frompci + p->lowpc + >= (uintfptr_t)(VM_MAXUSER_ADDRESS)) + goto done; + frompci = (uintfptr_t)user - p->lowpc; + if (frompci >= p->textsize) + goto done; + } +#endif + +#ifdef GUPROF + if (p->state == GMON_PROF_HIRES) { + /* + * Count the time since cputime() was previously called + * against `frompc'. Compensate for overheads. + * + * cputime() sets its prev_count variable to the count when + * it is called. This in effect starts a counter for + * the next period of execution (normally from now until + * the next call to mcount() or mexitcount()). We set + * cputime_bias to compensate for our own overhead. + * + * We use the usual sampling counters since they can be + * located efficiently. 4-byte counters are usually + * necessary. gprof will add up the scattered counts + * just like it does for statistical profiling. All + * counts are signed so that underflow in the subtractions + * doesn't matter much (negative counts are normally + * compensated for by larger counts elsewhere). Underflow + * shouldn't occur, but may be caused by slightly wrong + * calibrations or from not clearing cputime_bias. + */ + delta = cputime() - cputime_bias - p->mcount_pre_overhead; + cputime_bias = p->mcount_post_overhead; + KCOUNT(p, frompci) += delta; + *p->cputime_count += p->cputime_overhead; + *p->mcount_count += p->mcount_overhead; + } +#endif /* GUPROF */ + +#ifdef _KERNEL + /* + * When we are called from an exception handler, frompc is faked + * to be for where the exception occurred. We've just solidified + * the count for there. Now convert frompci to the index of btrap() + * for trap handlers and bintr() for interrupt handlers to make + * exceptions appear in the call graph as calls from btrap() and + * bintr() instead of calls from all over. + */ + if ((uintfptr_t)selfpc >= (uintfptr_t)btrap + && (uintfptr_t)selfpc < (uintfptr_t)eintr) { + if ((uintfptr_t)selfpc >= (uintfptr_t)bintr) + frompci = (uintfptr_t)bintr - p->lowpc; + else + frompci = (uintfptr_t)btrap - p->lowpc; + } +#endif + + /* + * check that frompc is a reasonable pc value. + * for example: signal catchers get called from the stack, + * not from text space. too bad. + */ + if (frompci >= p->textsize) + goto done; + + frompcindex = &p->froms[frompci / (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(s); +#else + p->state = GMON_PROF_ON; +#endif + return; +overflow: + p->state = GMON_PROF_ERROR; +#ifdef _KERNEL + MCOUNT_EXIT(s); +#endif + return; +} + +/* + * Actual definition of mcount function. Defined in <machine/profile.h>, + * which is included by <sys/gmon.h>. + */ +MCOUNT + +#ifdef GUPROF +void +mexitcount(selfpc) + uintfptr_t selfpc; +{ + struct gmonparam *p; + uintfptr_t selfpcdiff; + + p = &_gmonparam; + selfpcdiff = selfpc - (uintfptr_t)p->lowpc; + if (selfpcdiff < p->textsize) { + int delta; + + /* + * Count the time since cputime() was previously called + * against `selfpc'. Compensate for overheads. + */ + delta = cputime() - cputime_bias - p->mexitcount_pre_overhead; + cputime_bias = p->mexitcount_post_overhead; + KCOUNT(p, selfpcdiff) += delta; + *p->cputime_count += p->cputime_overhead; + *p->mexitcount_count += p->mexitcount_overhead; + } +} + +void +empty_loop() +{ + int i; + + for (i = 0; i < CALIB_SCALE; i++) + ; +} + +void +nullfunc() +{ +} + +void +nullfunc_loop() +{ + int i; + + for (i = 0; i < CALIB_SCALE; i++) + nullfunc(); +} +#endif /* GUPROF */ |
