/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * Copyright (c) 2011, Joyent, Inc. All rights reserved.
 */

#include <sys/errno.h>
#include <sys/stat.h>
#include <sys/modctl.h>
#include <sys/conf.h>
#include <sys/systm.h>
#include <sys/ddi.h>
#include <sys/sunddi.h>
#include <sys/cpuvar.h>
#include <sys/kmem.h>
#include <sys/strsubr.h>
#include <sys/dtrace.h>
#include <sys/cyclic.h>
#include <sys/atomic.h>

static dev_info_t *profile_devi;
static dtrace_provider_id_t profile_id;

/*
 * Regardless of platform, the stack frames look like this in the case of the
 * profile provider:
 *
 *      profile_fire
 *      cyclic_expire
 *      cyclic_fire
 *      [ cbe ]
 *      [ interrupt code ]
 *
 * On x86, there are five frames from the generic interrupt code; further, the
 * interrupted instruction appears as its own stack frame, giving us a total of
 * 10.
 *
 * On SPARC, the picture is further complicated because the compiler
 * optimizes away tail-calls -- so the following frames are optimized away:
 *
 *      profile_fire
 *      cyclic_expire
 *
 * This gives three frames.  However, on DEBUG kernels, the cyclic_expire
 * frame cannot be tail-call eliminated, yielding four frames in this case.
 *
 * All of the above constraints lead to the mess below.  Yes, the profile
 * provider should ideally figure this out on-the-fly by hitting one of its own
 * probes and then walking its own stack trace.  This is complicated, however,
 * and the static definition doesn't seem to be overly brittle.  Still, we
 * allow for a manual override in case we get it completely wrong.
 */
#ifdef __x86
#define PROF_ARTIFICIAL_FRAMES  10
#else
#ifdef __sparc
#ifdef DEBUG
#define PROF_ARTIFICIAL_FRAMES  4
#else
#define PROF_ARTIFICIAL_FRAMES  3
#endif
#endif
#endif

#define PROF_NAMELEN            15

#define PROF_PROFILE            0
#define PROF_TICK               1
#define PROF_PREFIX_PROFILE     "profile-"
#define PROF_PREFIX_TICK        "tick-"

typedef struct profile_probe {
        char            prof_name[PROF_NAMELEN];
        dtrace_id_t     prof_id;
        int             prof_kind;
        hrtime_t        prof_interval;
        cyclic_id_t     prof_cyclic;
} profile_probe_t;

typedef struct profile_probe_percpu {
        hrtime_t        profc_expected;
        hrtime_t        profc_interval;
        profile_probe_t *profc_probe;
} profile_probe_percpu_t;

hrtime_t        profile_interval_min = NANOSEC / 5000;          /* 5000 hz */
int             profile_aframes = 0;                            /* override */

static int profile_rates[] = {
    97, 199, 499, 997, 1999,
    4001, 4999, 0, 0, 0,
    0, 0, 0, 0, 0,
    0, 0, 0, 0, 0
};

static int profile_ticks[] = {
    1, 10, 100, 500, 1000,
    5000, 0, 0, 0, 0,
    0, 0, 0, 0, 0
};

/*
 * profile_max defines the upper bound on the number of profile probes that
 * can exist (this is to prevent malicious or clumsy users from exhausing
 * system resources by creating a slew of profile probes). At mod load time,
 * this gets its value from PROFILE_MAX_DEFAULT or profile-max-probes if it's
 * present in the profile.conf file.
 */
#define PROFILE_MAX_DEFAULT     1000    /* default max. number of probes */
static uint32_t profile_max;            /* maximum number of profile probes */
static uint32_t profile_total;  /* current number of profile probes */

static void
profile_fire(void *arg)
{
        profile_probe_percpu_t *pcpu = arg;
        profile_probe_t *prof = pcpu->profc_probe;
        hrtime_t late;

        late = dtrace_gethrtime() - pcpu->profc_expected;
        pcpu->profc_expected += pcpu->profc_interval;

        dtrace_probe(prof->prof_id, CPU->cpu_profile_pc,
            CPU->cpu_profile_upc, late, 0, 0);
}

static void
profile_tick(void *arg)
{
        profile_probe_t *prof = arg;

        dtrace_probe(prof->prof_id, CPU->cpu_profile_pc,
            CPU->cpu_profile_upc, 0, 0, 0);
}

static void
profile_create(hrtime_t interval, const char *name, int kind)
{
        profile_probe_t *prof;
        int nr_frames = PROF_ARTIFICIAL_FRAMES + dtrace_mach_aframes();

        if (profile_aframes)
                nr_frames = profile_aframes;

        if (interval < profile_interval_min)
                return;

        if (dtrace_probe_lookup(profile_id, NULL, NULL, name) != 0)
                return;

        atomic_inc_32(&profile_total);
        if (profile_total > profile_max) {
                atomic_dec_32(&profile_total);
                return;
        }

        prof = kmem_zalloc(sizeof (profile_probe_t), KM_SLEEP);
        (void) strcpy(prof->prof_name, name);
        prof->prof_interval = interval;
        prof->prof_cyclic = CYCLIC_NONE;
        prof->prof_kind = kind;
        prof->prof_id = dtrace_probe_create(profile_id,
            NULL, NULL, name, nr_frames, prof);
}

/*ARGSUSED*/
static void
profile_provide(void *arg, const dtrace_probedesc_t *desc)
{
        int i, j, rate, kind;
        hrtime_t val = 0, mult = 1, len;
        const char *name, *suffix = NULL;

        const struct {
                char *prefix;
                int kind;
        } types[] = {
                { PROF_PREFIX_PROFILE, PROF_PROFILE },
                { PROF_PREFIX_TICK, PROF_TICK },
                { NULL, 0 }
        };

        const struct {
                char *name;
                hrtime_t mult;
        } suffixes[] = {
                { "ns",         NANOSEC / NANOSEC },
                { "nsec",       NANOSEC / NANOSEC },
                { "us",         NANOSEC / MICROSEC },
                { "usec",       NANOSEC / MICROSEC },
                { "ms",         NANOSEC / MILLISEC },
                { "msec",       NANOSEC / MILLISEC },
                { "s",          NANOSEC / SEC },
                { "sec",        NANOSEC / SEC },
                { "m",          NANOSEC * (hrtime_t)60 },
                { "min",        NANOSEC * (hrtime_t)60 },
                { "h",          NANOSEC * (hrtime_t)(60 * 60) },
                { "hour",       NANOSEC * (hrtime_t)(60 * 60) },
                { "d",          NANOSEC * (hrtime_t)(24 * 60 * 60) },
                { "day",        NANOSEC * (hrtime_t)(24 * 60 * 60) },
                { "hz",         0 },
                { NULL }
        };

        if (desc == NULL) {
                char n[PROF_NAMELEN];

                /*
                 * If no description was provided, provide all of our probes.
                 */
                for (i = 0; i < sizeof (profile_rates) / sizeof (int); i++) {
                        if ((rate = profile_rates[i]) == 0)
                                continue;

                        (void) snprintf(n, PROF_NAMELEN, "%s%d",
                            PROF_PREFIX_PROFILE, rate);
                        profile_create(NANOSEC / rate, n, PROF_PROFILE);
                }

                for (i = 0; i < sizeof (profile_ticks) / sizeof (int); i++) {
                        if ((rate = profile_ticks[i]) == 0)
                                continue;

                        (void) snprintf(n, PROF_NAMELEN, "%s%d",
                            PROF_PREFIX_TICK, rate);
                        profile_create(NANOSEC / rate, n, PROF_TICK);
                }

                return;
        }

        name = desc->dtpd_name;

        for (i = 0; types[i].prefix != NULL; i++) {
                len = strlen(types[i].prefix);

                if (strncmp(name, types[i].prefix, len) != 0)
                        continue;
                break;
        }

        if (types[i].prefix == NULL)
                return;

        kind = types[i].kind;
        j = strlen(name) - len;

        /*
         * We need to start before any time suffix.
         */
        for (j = strlen(name); j >= len; j--) {
                if (name[j] >= '0' && name[j] <= '9')
                        break;
                suffix = &name[j];
        }

        ASSERT(suffix != NULL);

        /*
         * Now determine the numerical value present in the probe name.
         */
        for (; j >= len; j--) {
                if (name[j] < '0' || name[j] > '9')
                        return;

                val += (name[j] - '0') * mult;
                mult *= (hrtime_t)10;
        }

        if (val == 0)
                return;

        /*
         * Look-up the suffix to determine the multiplier.
         */
        for (i = 0, mult = 0; suffixes[i].name != NULL; i++) {
                if (strcasecmp(suffixes[i].name, suffix) == 0) {
                        mult = suffixes[i].mult;
                        break;
                }
        }

        if (suffixes[i].name == NULL && *suffix != '\0')
                return;

        if (mult == 0) {
                /*
                 * The default is frequency-per-second.
                 */
                val = NANOSEC / val;
        } else {
                val *= mult;
        }

        profile_create(val, name, kind);
}

/*ARGSUSED*/
static void
profile_destroy(void *arg, dtrace_id_t id, void *parg)
{
        profile_probe_t *prof = parg;

        ASSERT(prof->prof_cyclic == CYCLIC_NONE);
        kmem_free(prof, sizeof (profile_probe_t));

        ASSERT(profile_total >= 1);
        atomic_dec_32(&profile_total);
}

/*ARGSUSED*/
static void
profile_online(void *arg, cpu_t *cpu, cyc_handler_t *hdlr, cyc_time_t *when)
{
        profile_probe_t *prof = arg;
        profile_probe_percpu_t *pcpu;

        pcpu = kmem_zalloc(sizeof (profile_probe_percpu_t), KM_SLEEP);
        pcpu->profc_probe = prof;

        hdlr->cyh_func = profile_fire;
        hdlr->cyh_arg = pcpu;
        hdlr->cyh_level = CY_HIGH_LEVEL;

        when->cyt_interval = prof->prof_interval;
        when->cyt_when = dtrace_gethrtime() + when->cyt_interval;

        pcpu->profc_expected = when->cyt_when;
        pcpu->profc_interval = when->cyt_interval;
}

/*ARGSUSED*/
static void
profile_offline(void *arg, cpu_t *cpu, void *oarg)
{
        profile_probe_percpu_t *pcpu = oarg;

        ASSERT(pcpu->profc_probe == arg);
        kmem_free(pcpu, sizeof (profile_probe_percpu_t));
}

/*ARGSUSED*/
static int
profile_enable(void *arg, dtrace_id_t id, void *parg)
{
        profile_probe_t *prof = parg;
        cyc_omni_handler_t omni;
        cyc_handler_t hdlr;
        cyc_time_t when;

        ASSERT(prof->prof_interval != 0);
        ASSERT(MUTEX_HELD(&cpu_lock));

        if (prof->prof_kind == PROF_TICK) {
                hdlr.cyh_func = profile_tick;
                hdlr.cyh_arg = prof;
                hdlr.cyh_level = CY_HIGH_LEVEL;

                when.cyt_interval = prof->prof_interval;
                when.cyt_when = dtrace_gethrtime() + when.cyt_interval;
        } else {
                ASSERT(prof->prof_kind == PROF_PROFILE);
                omni.cyo_online = profile_online;
                omni.cyo_offline = profile_offline;
                omni.cyo_arg = prof;
        }

        if (prof->prof_kind == PROF_TICK) {
                prof->prof_cyclic = cyclic_add(&hdlr, &when);
        } else {
                prof->prof_cyclic = cyclic_add_omni(&omni);
        }
        return (0);
}

/*ARGSUSED*/
static void
profile_disable(void *arg, dtrace_id_t id, void *parg)
{
        profile_probe_t *prof = parg;

        ASSERT(prof->prof_cyclic != CYCLIC_NONE);
        ASSERT(MUTEX_HELD(&cpu_lock));

        cyclic_remove(prof->prof_cyclic);
        prof->prof_cyclic = CYCLIC_NONE;
}

/*ARGSUSED*/
static int
profile_mode(void *arg, dtrace_id_t id, void *parg)
{
        profile_probe_t *prof = parg;
        int mode;

        if (CPU->cpu_profile_pc != 0) {
                mode = DTRACE_MODE_KERNEL;
        } else {
                mode = DTRACE_MODE_USER;
        }

        if (prof->prof_kind == PROF_TICK) {
                mode |= DTRACE_MODE_NOPRIV_RESTRICT;
        } else {
                ASSERT(prof->prof_kind == PROF_PROFILE);
                mode |= DTRACE_MODE_NOPRIV_DROP;
        }

        return (mode);
}

static dtrace_pattr_t profile_attr = {
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_UNSTABLE, DTRACE_STABILITY_UNSTABLE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_PRIVATE, DTRACE_STABILITY_PRIVATE, DTRACE_CLASS_UNKNOWN },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
{ DTRACE_STABILITY_EVOLVING, DTRACE_STABILITY_EVOLVING, DTRACE_CLASS_COMMON },
};

static dtrace_pops_t profile_pops = {
        profile_provide,
        NULL,
        profile_enable,
        profile_disable,
        NULL,
        NULL,
        NULL,
        NULL,
        profile_mode,
        profile_destroy
};

static int
profile_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
        switch (cmd) {
        case DDI_ATTACH:
                break;
        case DDI_RESUME:
                return (DDI_SUCCESS);
        default:
                return (DDI_FAILURE);
        }

        if (ddi_create_minor_node(devi, "profile", S_IFCHR, 0,
            DDI_PSEUDO, 0) == DDI_FAILURE ||
            dtrace_register("profile", &profile_attr,
            DTRACE_PRIV_KERNEL | DTRACE_PRIV_USER, NULL,
            &profile_pops, NULL, &profile_id) != 0) {
                ddi_remove_minor_node(devi, NULL);
                return (DDI_FAILURE);
        }

        profile_max = ddi_getprop(DDI_DEV_T_ANY, devi, DDI_PROP_DONTPASS,
            "profile-max-probes", PROFILE_MAX_DEFAULT);

        ddi_report_dev(devi);
        profile_devi = devi;
        return (DDI_SUCCESS);
}

static int
profile_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
{
        switch (cmd) {
        case DDI_DETACH:
                break;
        case DDI_SUSPEND:
                return (DDI_SUCCESS);
        default:
                return (DDI_FAILURE);
        }

        if (dtrace_unregister(profile_id) != 0)
                return (DDI_FAILURE);

        ddi_remove_minor_node(devi, NULL);
        return (DDI_SUCCESS);
}

/*ARGSUSED*/
static int
profile_info(dev_info_t *dip, ddi_info_cmd_t infocmd, void *arg, void **result)
{
        int error;

        switch (infocmd) {
        case DDI_INFO_DEVT2DEVINFO:
                *result = (void *)profile_devi;
                error = DDI_SUCCESS;
                break;
        case DDI_INFO_DEVT2INSTANCE:
                *result = (void *)0;
                error = DDI_SUCCESS;
                break;
        default:
                error = DDI_FAILURE;
        }
        return (error);
}

/*ARGSUSED*/
static int
profile_open(dev_t *devp, int flag, int otyp, cred_t *cred_p)
{
        return (0);
}

static struct cb_ops profile_cb_ops = {
        profile_open,           /* open */
        nodev,                  /* close */
        nulldev,                /* strategy */
        nulldev,                /* print */
        nodev,                  /* dump */
        nodev,                  /* read */
        nodev,                  /* write */
        nodev,                  /* ioctl */
        nodev,                  /* devmap */
        nodev,                  /* mmap */
        nodev,                  /* segmap */
        nochpoll,               /* poll */
        ddi_prop_op,            /* cb_prop_op */
        0,                      /* streamtab  */
        D_NEW | D_MP            /* Driver compatibility flag */
};

static struct dev_ops profile_ops = {
        DEVO_REV,               /* devo_rev, */
        0,                      /* refcnt  */
        profile_info,           /* get_dev_info */
        nulldev,                /* identify */
        nulldev,                /* probe */
        profile_attach,         /* attach */
        profile_detach,         /* detach */
        nodev,                  /* reset */
        &profile_cb_ops,        /* driver operations */
        NULL,                   /* bus operations */
        nodev,                  /* dev power */
        ddi_quiesce_not_needed,         /* quiesce */
};

/*
 * Module linkage information for the kernel.
 */
static struct modldrv modldrv = {
        &mod_driverops,         /* module type (this is a pseudo driver) */
        "Profile Interrupt Tracing",    /* name of module */
        &profile_ops,           /* driver ops */
};

static struct modlinkage modlinkage = {
        MODREV_1,
        (void *)&modldrv,
        NULL
};

int
_init(void)
{
        return (mod_install(&modlinkage));
}

int
_info(struct modinfo *modinfop)
{
        return (mod_info(&modlinkage, modinfop));
}

int
_fini(void)
{
        return (mod_remove(&modlinkage));
}