usr/src/sys/kern/subr_prof.c

/*-
 * Copyright (c) 1982, 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * %sccs.include.redist.c%
 *
 *      @(#)subr_prof.c 8.3 (Berkeley) %G%
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <machine/cpu.h>

#ifdef GPROF
#include <sys/malloc.h>
#include <sys/gmon.h>

/*
 * Froms is actually a bunch of unsigned shorts indexing tos
 */
struct gmonparam _gmonparam = { GMON_PROF_OFF };

extern char etext[];

kmstartup()
{
        char *cp;
        struct gmonparam *p = &_gmonparam;
        /*
         * Round lowpc and highpc to multiples of the density we're using
         * so the rest of the scaling (here and in gprof) stays in ints.
         */
        p->lowpc = ROUNDDOWN(KERNBASE, HISTFRACTION * sizeof(HISTCOUNTER));
        p->highpc = ROUNDUP((u_long)etext, HISTFRACTION * sizeof(HISTCOUNTER));
        p->textsize = p->highpc - p->lowpc;
        printf("Profiling kernel, textsize=%d [%x..%x]\n",
               p->textsize, p->lowpc, p->highpc);
        p->kcountsize = p->textsize / HISTFRACTION;
        p->hashfraction = HASHFRACTION;
        p->fromssize = p->textsize / HASHFRACTION;
        p->tolimit = p->textsize * ARCDENSITY / 100;
        if (p->tolimit < MINARCS)
                p->tolimit = MINARCS;
        else if (p->tolimit > MAXARCS)
                p->tolimit = MAXARCS;
        p->tossize = p->tolimit * sizeof(struct tostruct);
        cp = (char *)malloc(p->kcountsize + p->fromssize + p->tossize,
            M_GPROF, M_NOWAIT);
        if (cp == 0) {
                printf("No memory for profiling.\n");
                return;
        }
        bzero(cp, p->kcountsize + p->tossize + p->fromssize);
        p->tos = (struct tostruct *)cp;
        cp += p->tossize;
        p->kcount = (u_short *)cp;
        cp += p->kcountsize;
        p->froms = (u_short *)cp;
}

/*
 * Return kernel profiling information.
 */
sysctl_doprof(name, namelen, oldp, oldlenp, newp, newlen, p)
        int *name;
        u_int namelen;
        void *oldp;
        size_t *oldlenp;
        void *newp;
        size_t newlen;
{
        struct gmonparam *gp = &_gmonparam;
        int error;

        /* all sysctl names at this level are terminal */
        if (namelen != 1)
                return (ENOTDIR);               /* overloaded */

        switch (name[0]) {
        case GPROF_STATE:
                error = sysctl_int(oldp, oldlenp, newp, newlen, &gp->state);
                if (error)
                        return (error);
                if (gp->state == GMON_PROF_OFF)
                        stopprofclock(&proc0);
                else
                        startprofclock(&proc0);
                return (0);
        case GPROF_COUNT:
                return (sysctl_struct(oldp, oldlenp, newp, newlen,
                    gp->kcount, gp->kcountsize));
        case GPROF_FROMS:
                return (sysctl_struct(oldp, oldlenp, newp, newlen,
                    gp->froms, gp->fromssize));
        case GPROF_TOS:
                return (sysctl_struct(oldp, oldlenp, newp, newlen,
                    gp->tos, gp->tossize));
        case GPROF_GMONPARAM:
                return (sysctl_rdstruct(oldp, oldlenp, newp, gp, sizeof *gp));
        default:
                return (EOPNOTSUPP);
        }
        /* NOTREACHED */
}
#endif /* GPROF */

/*
 * Profiling system call.
 *
 * The scale factor is a fixed point number with 16 bits of fraction, so that
 * 1.0 is represented as 0x10000.  A scale factor of 0 turns off profiling.
 */
struct profil_args {
        caddr_t samples;
        u_int   size;
        u_int   offset;
        u_int   scale;
};
/* ARGSUSED */
profil(p, uap, retval)
        struct proc *p;
        register struct profil_args *uap;
        int *retval;
{
        register struct uprof *upp;
        int s;

        if (uap->scale > (1 << 16))
                return (EINVAL);
        if (uap->scale == 0) {
                stopprofclock(p);
                return (0);
        }
        upp = &p->p_stats->p_prof;

        /* Block profile interrupts while changing state. */
        s = splstatclock();
        upp->pr_off = uap->offset;
        upp->pr_scale = uap->scale;
        upp->pr_base = uap->samples;
        upp->pr_size = uap->size;
        startprofclock(p);
        splx(s);

        return (0);
}

/*
 * Scale is a fixed-point number with the binary point 16 bits
 * into the value, and is <= 1.0.  pc is at most 32 bits, so the
 * intermediate result is at most 48 bits.
 */
#define PC_TO_INDEX(pc, prof) \
        ((int)(((u_quad_t)((pc) - (prof)->pr_off) * \
            (u_quad_t)((prof)->pr_scale)) >> 16) & ~1)

/*
 * Collect user-level profiling statistics; called on a profiling tick,
 * when a process is running in user-mode.  This routine may be called
 * from an interrupt context.  We try to update the user profiling buffers
 * cheaply with fuswintr() and suswintr().  If that fails, we revert to
 * an AST that will vector us to trap() with a context in which copyin
 * and copyout will work.  Trap will then call addupc_task().
 *
 * Note that we may (rarely) not get around to the AST soon enough, and
 * lose profile ticks when the next tick overwrites this one, but in this
 * case the system is overloaded and the profile is probably already
 * inaccurate.
 */
void
addupc_intr(p, pc, ticks)
        register struct proc *p;
        register u_long pc;
        u_int ticks;
{
        register struct uprof *prof;
        register caddr_t addr;
        register u_int i;
        register int v;

        if (ticks == 0)
                return;
        prof = &p->p_stats->p_prof;
        if (pc < prof->pr_off ||
            (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
                return;                 /* out of range; ignore */

        addr = prof->pr_base + i;
        if ((v = fuswintr(addr)) == -1 || suswintr(addr, v + ticks) == -1) {
                prof->pr_addr = pc;
                prof->pr_ticks = ticks;
                need_proftick(p);
        }
}

/*
 * Much like before, but we can afford to take faults here.  If the
 * update fails, we simply turn off profiling.
 */
void
addupc_task(p, pc, ticks)
        register struct proc *p;
        register u_long pc;
        u_int ticks;
{
        register struct uprof *prof;
        register caddr_t addr;
        register u_int i;
        u_short v;

        /* Testing P_PROFIL may be unnecessary, but is certainly safe. */
        if ((p->p_flag & P_PROFIL) == 0 || ticks == 0)
                return;

        prof = &p->p_stats->p_prof;
        if (pc < prof->pr_off ||
            (i = PC_TO_INDEX(pc, prof)) >= prof->pr_size)
                return;

        addr = prof->pr_base + i;
        if (copyin(addr, (caddr_t)&v, sizeof(v)) == 0) {
                v += ticks;
                if (copyout((caddr_t)&v, addr, sizeof(v)) == 0)
                        return;
        }
        stopprofclock(p);
}