8269 dtrace stddev aggregation is normalized incorrectly

[unleashed.git] / usr / src / lib / libdtrace / common / dt_consume.c

/*
 * 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) 2013, Joyent, Inc. All rights reserved.
 * Copyright (c) 2012 by Delphix. All rights reserved.
 */

#include <stdlib.h>
#include <strings.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <assert.h>
#include <ctype.h>
#include <alloca.h>
#include <dt_impl.h>
#include <dt_pq.h>

#define DT_MASK_LO 0x00000000FFFFFFFFULL

/*
 * We declare this here because (1) we need it and (2) we want to avoid a
 * dependency on libm in libdtrace.
 */
static long double
dt_fabsl(long double x)
{
        if (x < 0)
                return (-x);

        return (x);
}

static int
dt_ndigits(long long val)
{
        int rval = 1;
        long long cmp = 10;

        if (val < 0) {
                val = val == INT64_MIN ? INT64_MAX : -val;
                rval++;
        }

        while (val > cmp && cmp > 0) {
                rval++;
                cmp *= 10;
        }

        return (rval < 4 ? 4 : rval);
}

/*
 * 128-bit arithmetic functions needed to support the stddev() aggregating
 * action.
 */
static int
dt_gt_128(uint64_t *a, uint64_t *b)
{
        return (a[1] > b[1] || (a[1] == b[1] && a[0] > b[0]));
}

static int
dt_ge_128(uint64_t *a, uint64_t *b)
{
        return (a[1] > b[1] || (a[1] == b[1] && a[0] >= b[0]));
}

static int
dt_le_128(uint64_t *a, uint64_t *b)
{
        return (a[1] < b[1] || (a[1] == b[1] && a[0] <= b[0]));
}

/*
 * Shift the 128-bit value in a by b. If b is positive, shift left.
 * If b is negative, shift right.
 */
static void
dt_shift_128(uint64_t *a, int b)
{
        uint64_t mask;

        if (b == 0)
                return;

        if (b < 0) {
                b = -b;
                if (b >= 64) {
                        a[0] = a[1] >> (b - 64);
                        a[1] = 0;
                } else {
                        a[0] >>= b;
                        mask = 1LL << (64 - b);
                        mask -= 1;
                        a[0] |= ((a[1] & mask) << (64 - b));
                        a[1] >>= b;
                }
        } else {
                if (b >= 64) {
                        a[1] = a[0] << (b - 64);
                        a[0] = 0;
                } else {
                        a[1] <<= b;
                        mask = a[0] >> (64 - b);
                        a[1] |= mask;
                        a[0] <<= b;
                }
        }
}

static int
dt_nbits_128(uint64_t *a)
{
        int nbits = 0;
        uint64_t tmp[2];
        uint64_t zero[2] = { 0, 0 };

        tmp[0] = a[0];
        tmp[1] = a[1];

        dt_shift_128(tmp, -1);
        while (dt_gt_128(tmp, zero)) {
                dt_shift_128(tmp, -1);
                nbits++;
        }

        return (nbits);
}

static void
dt_subtract_128(uint64_t *minuend, uint64_t *subtrahend, uint64_t *difference)
{
        uint64_t result[2];

        result[0] = minuend[0] - subtrahend[0];
        result[1] = minuend[1] - subtrahend[1] -
            (minuend[0] < subtrahend[0] ? 1 : 0);

        difference[0] = result[0];
        difference[1] = result[1];
}

static void
dt_add_128(uint64_t *addend1, uint64_t *addend2, uint64_t *sum)
{
        uint64_t result[2];

        result[0] = addend1[0] + addend2[0];
        result[1] = addend1[1] + addend2[1] +
            (result[0] < addend1[0] || result[0] < addend2[0] ? 1 : 0);

        sum[0] = result[0];
        sum[1] = result[1];
}

/*
 * The basic idea is to break the 2 64-bit values into 4 32-bit values,
 * use native multiplication on those, and then re-combine into the
 * resulting 128-bit value.
 *
 * (hi1 << 32 + lo1) * (hi2 << 32 + lo2) =
 *     hi1 * hi2 << 64 +
 *     hi1 * lo2 << 32 +
 *     hi2 * lo1 << 32 +
 *     lo1 * lo2
 */
static void
dt_multiply_128(uint64_t factor1, uint64_t factor2, uint64_t *product)
{
        uint64_t hi1, hi2, lo1, lo2;
        uint64_t tmp[2];

        hi1 = factor1 >> 32;
        hi2 = factor2 >> 32;

        lo1 = factor1 & DT_MASK_LO;
        lo2 = factor2 & DT_MASK_LO;

        product[0] = lo1 * lo2;
        product[1] = hi1 * hi2;

        tmp[0] = hi1 * lo2;
        tmp[1] = 0;
        dt_shift_128(tmp, 32);
        dt_add_128(product, tmp, product);

        tmp[0] = hi2 * lo1;
        tmp[1] = 0;
        dt_shift_128(tmp, 32);
        dt_add_128(product, tmp, product);
}

/*
 * This is long-hand division.
 *
 * We initialize subtrahend by shifting divisor left as far as possible. We
 * loop, comparing subtrahend to dividend:  if subtrahend is smaller, we
 * subtract and set the appropriate bit in the result.  We then shift
 * subtrahend right by one bit for the next comparison.
 */
static void
dt_divide_128(uint64_t *dividend, uint64_t divisor, uint64_t *quotient)
{
        uint64_t result[2] = { 0, 0 };
        uint64_t remainder[2];
        uint64_t subtrahend[2];
        uint64_t divisor_128[2];
        uint64_t mask[2] = { 1, 0 };
        int log = 0;

        assert(divisor != 0);

        divisor_128[0] = divisor;
        divisor_128[1] = 0;

        remainder[0] = dividend[0];
        remainder[1] = dividend[1];

        subtrahend[0] = divisor;
        subtrahend[1] = 0;

        while (divisor > 0) {
                log++;
                divisor >>= 1;
        }

        dt_shift_128(subtrahend, 128 - log);
        dt_shift_128(mask, 128 - log);

        while (dt_ge_128(remainder, divisor_128)) {
                if (dt_ge_128(remainder, subtrahend)) {
                        dt_subtract_128(remainder, subtrahend, remainder);
                        result[0] |= mask[0];
                        result[1] |= mask[1];
                }

                dt_shift_128(subtrahend, -1);
                dt_shift_128(mask, -1);
        }

        quotient[0] = result[0];
        quotient[1] = result[1];
}

/*
 * This is the long-hand method of calculating a square root.
 * The algorithm is as follows:
 *
 * 1. Group the digits by 2 from the right.
 * 2. Over the leftmost group, find the largest single-digit number
 *    whose square is less than that group.
 * 3. Subtract the result of the previous step (2 or 4, depending) and
 *    bring down the next two-digit group.
 * 4. For the result R we have so far, find the largest single-digit number
 *    x such that 2 * R * 10 * x + x^2 is less than the result from step 3.
 *    (Note that this is doubling R and performing a decimal left-shift by 1
 *    and searching for the appropriate decimal to fill the one's place.)
 *    The value x is the next digit in the square root.
 * Repeat steps 3 and 4 until the desired precision is reached.  (We're
 * dealing with integers, so the above is sufficient.)
 *
 * In decimal, the square root of 582,734 would be calculated as so:
 *
 *     __7__6__3
 *    | 58 27 34
 *     -49       (7^2 == 49 => 7 is the first digit in the square root)
 *      --
 *       9 27    (Subtract and bring down the next group.)
 * 146   8 76    (2 * 7 * 10 * 6 + 6^2 == 876 => 6 is the next digit in
 *      -----     the square root)
 *         51 34 (Subtract and bring down the next group.)
 * 1523    45 69 (2 * 76 * 10 * 3 + 3^2 == 4569 => 3 is the next digit in
 *         -----  the square root)
 *          5 65 (remainder)
 *
 * The above algorithm applies similarly in binary, but note that the
 * only possible non-zero value for x in step 4 is 1, so step 4 becomes a
 * simple decision: is 2 * R * 2 * 1 + 1^2 (aka R << 2 + 1) less than the
 * preceding difference?
 *
 * In binary, the square root of 11011011 would be calculated as so:
 *
 *     __1__1__1__0
 *    | 11 01 10 11
 *      01          (0 << 2 + 1 == 1 < 11 => this bit is 1)
 *      --
 *      10 01 10 11
 * 101   1 01       (1 << 2 + 1 == 101 < 1001 => next bit is 1)
 *      -----
 *       1 00 10 11
 * 1101    11 01    (11 << 2 + 1 == 1101 < 10010 => next bit is 1)
 *       -------
 *          1 01 11
 * 11101    1 11 01 (111 << 2 + 1 == 11101 > 10111 => last bit is 0)
 *
 */
static uint64_t
dt_sqrt_128(uint64_t *square)
{
        uint64_t result[2] = { 0, 0 };
        uint64_t diff[2] = { 0, 0 };
        uint64_t one[2] = { 1, 0 };
        uint64_t next_pair[2];
        uint64_t next_try[2];
        uint64_t bit_pairs, pair_shift;
        int i;

        bit_pairs = dt_nbits_128(square) / 2;
        pair_shift = bit_pairs * 2;

        for (i = 0; i <= bit_pairs; i++) {
                /*
                 * Bring down the next pair of bits.
                 */
                next_pair[0] = square[0];
                next_pair[1] = square[1];
                dt_shift_128(next_pair, -pair_shift);
                next_pair[0] &= 0x3;
                next_pair[1] = 0;

                dt_shift_128(diff, 2);
                dt_add_128(diff, next_pair, diff);

                /*
                 * next_try = R << 2 + 1
                 */
                next_try[0] = result[0];
                next_try[1] = result[1];
                dt_shift_128(next_try, 2);
                dt_add_128(next_try, one, next_try);

                if (dt_le_128(next_try, diff)) {
                        dt_subtract_128(diff, next_try, diff);
                        dt_shift_128(result, 1);
                        dt_add_128(result, one, result);
                } else {
                        dt_shift_128(result, 1);
                }

                pair_shift -= 2;
        }

        assert(result[1] == 0);

        return (result[0]);
}

uint64_t
dt_stddev(uint64_t *data, uint64_t normal)
{
        uint64_t avg_of_squares[2];
        uint64_t square_of_avg[2];
        int64_t norm_avg;
        uint64_t diff[2];

        /*
         * The standard approximation for standard deviation is
         * sqrt(average(x**2) - average(x)**2), i.e. the square root
         * of the average of the squares minus the square of the average.
         * When normalizing, we should divide the sum of x**2 by normal**2.
         */
        dt_divide_128(data + 2, normal, avg_of_squares);
        dt_divide_128(avg_of_squares, normal, avg_of_squares);
        dt_divide_128(avg_of_squares, data[0], avg_of_squares);

        norm_avg = (int64_t)data[1] / (int64_t)normal / (int64_t)data[0];

        if (norm_avg < 0)
                norm_avg = -norm_avg;

        dt_multiply_128((uint64_t)norm_avg, (uint64_t)norm_avg, square_of_avg);

        dt_subtract_128(avg_of_squares, square_of_avg, diff);

        return (dt_sqrt_128(diff));
}

static int
dt_flowindent(dtrace_hdl_t *dtp, dtrace_probedata_t *data, dtrace_epid_t last,
    dtrace_bufdesc_t *buf, size_t offs)
{
        dtrace_probedesc_t *pd = data->dtpda_pdesc, *npd;
        dtrace_eprobedesc_t *epd = data->dtpda_edesc, *nepd;
        char *p = pd->dtpd_provider, *n = pd->dtpd_name, *sub;
        dtrace_flowkind_t flow = DTRACEFLOW_NONE;
        const char *str = NULL;
        static const char *e_str[2] = { " -> ", " => " };
        static const char *r_str[2] = { " <- ", " <= " };
        static const char *ent = "entry", *ret = "return";
        static int entlen = 0, retlen = 0;
        dtrace_epid_t next, id = epd->dtepd_epid;
        int rval;

        if (entlen == 0) {
                assert(retlen == 0);
                entlen = strlen(ent);
                retlen = strlen(ret);
        }

        /*
         * If the name of the probe is "entry" or ends with "-entry", we
         * treat it as an entry; if it is "return" or ends with "-return",
         * we treat it as a return.  (This allows application-provided probes
         * like "method-entry" or "function-entry" to participate in flow
         * indentation -- without accidentally misinterpreting popular probe
         * names like "carpentry", "gentry" or "Coventry".)
         */
        if ((sub = strstr(n, ent)) != NULL && sub[entlen] == '\0' &&
            (sub == n || sub[-1] == '-')) {
                flow = DTRACEFLOW_ENTRY;
                str = e_str[strcmp(p, "syscall") == 0];
        } else if ((sub = strstr(n, ret)) != NULL && sub[retlen] == '\0' &&
            (sub == n || sub[-1] == '-')) {
                flow = DTRACEFLOW_RETURN;
                str = r_str[strcmp(p, "syscall") == 0];
        }

        /*
         * If we're going to indent this, we need to check the ID of our last
         * call.  If we're looking at the same probe ID but a different EPID,
         * we _don't_ want to indent.  (Yes, there are some minor holes in
         * this scheme -- it's a heuristic.)
         */
        if (flow == DTRACEFLOW_ENTRY) {
                if ((last != DTRACE_EPIDNONE && id != last &&
                    pd->dtpd_id == dtp->dt_pdesc[last]->dtpd_id))
                        flow = DTRACEFLOW_NONE;
        }

        /*
         * If we're going to unindent this, it's more difficult to see if
         * we don't actually want to unindent it -- we need to look at the
         * _next_ EPID.
         */
        if (flow == DTRACEFLOW_RETURN) {
                offs += epd->dtepd_size;

                do {
                        if (offs >= buf->dtbd_size)
                                goto out;

                        next = *(uint32_t *)((uintptr_t)buf->dtbd_data + offs);

                        if (next == DTRACE_EPIDNONE)
                                offs += sizeof (id);
                } while (next == DTRACE_EPIDNONE);

                if ((rval = dt_epid_lookup(dtp, next, &nepd, &npd)) != 0)
                        return (rval);

                if (next != id && npd->dtpd_id == pd->dtpd_id)
                        flow = DTRACEFLOW_NONE;
        }

out:
        if (flow == DTRACEFLOW_ENTRY || flow == DTRACEFLOW_RETURN) {
                data->dtpda_prefix = str;
        } else {
                data->dtpda_prefix = "| ";
        }

        if (flow == DTRACEFLOW_RETURN && data->dtpda_indent > 0)
                data->dtpda_indent -= 2;

        data->dtpda_flow = flow;

        return (0);
}

static int
dt_nullprobe()
{
        return (DTRACE_CONSUME_THIS);
}

static int
dt_nullrec()
{
        return (DTRACE_CONSUME_NEXT);
}

static void
dt_quantize_total(dtrace_hdl_t *dtp, int64_t datum, long double *total)
{
        long double val = dt_fabsl((long double)datum);

        if (dtp->dt_options[DTRACEOPT_AGGZOOM] == DTRACEOPT_UNSET) {
                *total += val;
                return;
        }

        /*
         * If we're zooming in on an aggregation, we want the height of the
         * highest value to be approximately 95% of total bar height -- so we
         * adjust up by the reciprocal of DTRACE_AGGZOOM_MAX when comparing to
         * our highest value.
         */
        val *= 1 / DTRACE_AGGZOOM_MAX;

        if (*total < val)
                *total = val;
}

static int
dt_print_quanthdr(dtrace_hdl_t *dtp, FILE *fp, int width)
{
        return (dt_printf(dtp, fp, "\n%*s %41s %-9s\n",
            width ? width : 16, width ? "key" : "value",
            "------------- Distribution -------------", "count"));
}

static int
dt_print_quanthdr_packed(dtrace_hdl_t *dtp, FILE *fp, int width,
    const dtrace_aggdata_t *aggdata, dtrace_actkind_t action)
{
        int min = aggdata->dtada_minbin, max = aggdata->dtada_maxbin;
        int minwidth, maxwidth, i;

        assert(action == DTRACEAGG_QUANTIZE || action == DTRACEAGG_LQUANTIZE);

        if (action == DTRACEAGG_QUANTIZE) {
                if (min != 0 && min != DTRACE_QUANTIZE_ZEROBUCKET)
                        min--;

                if (max < DTRACE_QUANTIZE_NBUCKETS - 1)
                        max++;

                minwidth = dt_ndigits(DTRACE_QUANTIZE_BUCKETVAL(min));
                maxwidth = dt_ndigits(DTRACE_QUANTIZE_BUCKETVAL(max));
        } else {
                maxwidth = 8;
                minwidth = maxwidth - 1;
                max++;
        }

        if (dt_printf(dtp, fp, "\n%*s %*s .",
            width, width > 0 ? "key" : "", minwidth, "min") < 0)
                return (-1);

        for (i = min; i <= max; i++) {
                if (dt_printf(dtp, fp, "-") < 0)
                        return (-1);
        }

        return (dt_printf(dtp, fp, ". %*s | count\n", -maxwidth, "max"));
}

/*
 * We use a subset of the Unicode Block Elements (U+2588 through U+258F,
 * inclusive) to represent aggregations via UTF-8 -- which are expressed via
 * 3-byte UTF-8 sequences.
 */
#define DTRACE_AGGUTF8_FULL     0x2588
#define DTRACE_AGGUTF8_BASE     0x258f
#define DTRACE_AGGUTF8_LEVELS   8

#define DTRACE_AGGUTF8_BYTE0(val)       (0xe0 | ((val) >> 12))
#define DTRACE_AGGUTF8_BYTE1(val)       (0x80 | (((val) >> 6) & 0x3f))
#define DTRACE_AGGUTF8_BYTE2(val)       (0x80 | ((val) & 0x3f))

static int
dt_print_quantline_utf8(dtrace_hdl_t *dtp, FILE *fp, int64_t val,
    uint64_t normal, long double total)
{
        uint_t len = 40, i, whole, partial;
        long double f = (dt_fabsl((long double)val) * len) / total;
        const char *spaces = "                                        ";

        whole = (uint_t)f;
        partial = (uint_t)((f - (long double)(uint_t)f) *
            (long double)DTRACE_AGGUTF8_LEVELS);

        if (dt_printf(dtp, fp, "|") < 0)
                return (-1);

        for (i = 0; i < whole; i++) {
                if (dt_printf(dtp, fp, "%c%c%c",
                    DTRACE_AGGUTF8_BYTE0(DTRACE_AGGUTF8_FULL),
                    DTRACE_AGGUTF8_BYTE1(DTRACE_AGGUTF8_FULL),
                    DTRACE_AGGUTF8_BYTE2(DTRACE_AGGUTF8_FULL)) < 0)
                        return (-1);
        }

        if (partial != 0) {
                partial = DTRACE_AGGUTF8_BASE - (partial - 1);

                if (dt_printf(dtp, fp, "%c%c%c",
                    DTRACE_AGGUTF8_BYTE0(partial),
                    DTRACE_AGGUTF8_BYTE1(partial),
                    DTRACE_AGGUTF8_BYTE2(partial)) < 0)
                        return (-1);

                i++;
        }

        return (dt_printf(dtp, fp, "%s %-9lld\n", spaces + i,
            (long long)val / normal));
}

static int
dt_print_quantline(dtrace_hdl_t *dtp, FILE *fp, int64_t val,
    uint64_t normal, long double total, char positives, char negatives)
{
        long double f;
        uint_t depth, len = 40;

        const char *ats = "@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@";
        const char *spaces = "                                        ";

        assert(strlen(ats) == len && strlen(spaces) == len);
        assert(!(total == 0 && (positives || negatives)));
        assert(!(val < 0 && !negatives));
        assert(!(val > 0 && !positives));
        assert(!(val != 0 && total == 0));

        if (!negatives) {
                if (positives) {
                        if (dtp->dt_encoding == DT_ENCODING_UTF8) {
                                return (dt_print_quantline_utf8(dtp, fp, val,
                                    normal, total));
                        }

                        f = (dt_fabsl((long double)val) * len) / total;
                        depth = (uint_t)(f + 0.5);
                } else {
                        depth = 0;
                }

                return (dt_printf(dtp, fp, "|%s%s %-9lld\n", ats + len - depth,
                    spaces + depth, (long long)val / normal));
        }

        if (!positives) {
                f = (dt_fabsl((long double)val) * len) / total;
                depth = (uint_t)(f + 0.5);

                return (dt_printf(dtp, fp, "%s%s| %-9lld\n", spaces + depth,
                    ats + len - depth, (long long)val / normal));
        }

        /*
         * If we're here, we have both positive and negative bucket values.
         * To express this graphically, we're going to generate both positive
         * and negative bars separated by a centerline.  These bars are half
         * the size of normal quantize()/lquantize() bars, so we divide the
         * length in half before calculating the bar length.
         */
        len /= 2;
        ats = &ats[len];
        spaces = &spaces[len];

        f = (dt_fabsl((long double)val) * len) / total;
        depth = (uint_t)(f + 0.5);

        if (val <= 0) {
                return (dt_printf(dtp, fp, "%s%s|%*s %-9lld\n", spaces + depth,
                    ats + len - depth, len, "", (long long)val / normal));
        } else {
                return (dt_printf(dtp, fp, "%20s|%s%s %-9lld\n", "",
                    ats + len - depth, spaces + depth,
                    (long long)val / normal));
        }
}

/*
 * As with UTF-8 printing of aggregations, we use a subset of the Unicode
 * Block Elements (U+2581 through U+2588, inclusive) to represent our packed
 * aggregation.
 */
#define DTRACE_AGGPACK_BASE     0x2581
#define DTRACE_AGGPACK_LEVELS   8

static int
dt_print_packed(dtrace_hdl_t *dtp, FILE *fp,
    long double datum, long double total)
{
        static boolean_t utf8_checked = B_FALSE;
        static boolean_t utf8;
        char *ascii = "__xxxxXX";
        char *neg = "vvvvVV";
        unsigned int len;
        long double val;

        if (!utf8_checked) {
                char *term;

                /*
                 * We want to determine if we can reasonably emit UTF-8 for our
                 * packed aggregation.  To do this, we will check for terminals
                 * that are known to be primitive to emit UTF-8 on these.
                 */
                utf8_checked = B_TRUE;

                if (dtp->dt_encoding == DT_ENCODING_ASCII) {
                        utf8 = B_FALSE;
                } else if (dtp->dt_encoding == DT_ENCODING_UTF8) {
                        utf8 = B_TRUE;
                } else if ((term = getenv("TERM")) != NULL &&
                    (strcmp(term, "sun") == 0 ||
                    strcmp(term, "sun-color") == 0) ||
                    strcmp(term, "dumb") == 0) {
                        utf8 = B_FALSE;
                } else {
                        utf8 = B_TRUE;
                }
        }

        if (datum == 0)
                return (dt_printf(dtp, fp, " "));

        if (datum < 0) {
                len = strlen(neg);
                val = dt_fabsl(datum * (len - 1)) / total;
                return (dt_printf(dtp, fp, "%c", neg[(uint_t)(val + 0.5)]));
        }

        if (utf8) {
                int block = DTRACE_AGGPACK_BASE + (unsigned int)(((datum *
                    (DTRACE_AGGPACK_LEVELS - 1)) / total) + 0.5);

                return (dt_printf(dtp, fp, "%c%c%c",
                    DTRACE_AGGUTF8_BYTE0(block),
                    DTRACE_AGGUTF8_BYTE1(block),
                    DTRACE_AGGUTF8_BYTE2(block)));
        }

        len = strlen(ascii);
        val = (datum * (len - 1)) / total;
        return (dt_printf(dtp, fp, "%c", ascii[(uint_t)(val + 0.5)]));
}

int
dt_print_quantize(dtrace_hdl_t *dtp, FILE *fp, const void *addr,
    size_t size, uint64_t normal)
{
        const int64_t *data = addr;
        int i, first_bin = 0, last_bin = DTRACE_QUANTIZE_NBUCKETS - 1;
        long double total = 0;
        char positives = 0, negatives = 0;

        if (size != DTRACE_QUANTIZE_NBUCKETS * sizeof (uint64_t))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        while (first_bin < DTRACE_QUANTIZE_NBUCKETS - 1 && data[first_bin] == 0)
                first_bin++;

        if (first_bin == DTRACE_QUANTIZE_NBUCKETS - 1) {
                /*
                 * There isn't any data.  This is possible if the aggregation
                 * has been clear()'d or if negative increment values have been
                 * used.  Regardless, we'll print the buckets around 0.
                 */
                first_bin = DTRACE_QUANTIZE_ZEROBUCKET - 1;
                last_bin = DTRACE_QUANTIZE_ZEROBUCKET + 1;
        } else {
                if (first_bin > 0)
                        first_bin--;

                while (last_bin > 0 && data[last_bin] == 0)
                        last_bin--;

                if (last_bin < DTRACE_QUANTIZE_NBUCKETS - 1)
                        last_bin++;
        }

        for (i = first_bin; i <= last_bin; i++) {
                positives |= (data[i] > 0);
                negatives |= (data[i] < 0);
                dt_quantize_total(dtp, data[i], &total);
        }

        if (dt_print_quanthdr(dtp, fp, 0) < 0)
                return (-1);

        for (i = first_bin; i <= last_bin; i++) {
                if (dt_printf(dtp, fp, "%16lld ",
                    (long long)DTRACE_QUANTIZE_BUCKETVAL(i)) < 0)
                        return (-1);

                if (dt_print_quantline(dtp, fp, data[i], normal, total,
                    positives, negatives) < 0)
                        return (-1);
        }

        return (0);
}

int
dt_print_quantize_packed(dtrace_hdl_t *dtp, FILE *fp, const void *addr,
    size_t size, const dtrace_aggdata_t *aggdata)
{
        const int64_t *data = addr;
        long double total = 0, count = 0;
        int min = aggdata->dtada_minbin, max = aggdata->dtada_maxbin, i;
        int64_t minval, maxval;

        if (size != DTRACE_QUANTIZE_NBUCKETS * sizeof (uint64_t))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        if (min != 0 && min != DTRACE_QUANTIZE_ZEROBUCKET)
                min--;

        if (max < DTRACE_QUANTIZE_NBUCKETS - 1)
                max++;

        minval = DTRACE_QUANTIZE_BUCKETVAL(min);
        maxval = DTRACE_QUANTIZE_BUCKETVAL(max);

        if (dt_printf(dtp, fp, " %*lld :", dt_ndigits(minval),
            (long long)minval) < 0)
                return (-1);

        for (i = min; i <= max; i++) {
                dt_quantize_total(dtp, data[i], &total);
                count += data[i];
        }

        for (i = min; i <= max; i++) {
                if (dt_print_packed(dtp, fp, data[i], total) < 0)
                        return (-1);
        }

        if (dt_printf(dtp, fp, ": %*lld | %lld\n",
            -dt_ndigits(maxval), (long long)maxval, (long long)count) < 0)
                return (-1);

        return (0);
}

int
dt_print_lquantize(dtrace_hdl_t *dtp, FILE *fp, const void *addr,
    size_t size, uint64_t normal)
{
        const int64_t *data = addr;
        int i, first_bin, last_bin, base;
        uint64_t arg;
        long double total = 0;
        uint16_t step, levels;
        char positives = 0, negatives = 0;

        if (size < sizeof (uint64_t))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        arg = *data++;
        size -= sizeof (uint64_t);

        base = DTRACE_LQUANTIZE_BASE(arg);
        step = DTRACE_LQUANTIZE_STEP(arg);
        levels = DTRACE_LQUANTIZE_LEVELS(arg);

        first_bin = 0;
        last_bin = levels + 1;

        if (size != sizeof (uint64_t) * (levels + 2))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        while (first_bin <= levels + 1 && data[first_bin] == 0)
                first_bin++;

        if (first_bin > levels + 1) {
                first_bin = 0;
                last_bin = 2;
        } else {
                if (first_bin > 0)
                        first_bin--;

                while (last_bin > 0 && data[last_bin] == 0)
                        last_bin--;

                if (last_bin < levels + 1)
                        last_bin++;
        }

        for (i = first_bin; i <= last_bin; i++) {
                positives |= (data[i] > 0);
                negatives |= (data[i] < 0);
                dt_quantize_total(dtp, data[i], &total);
        }

        if (dt_printf(dtp, fp, "\n%16s %41s %-9s\n", "value",
            "------------- Distribution -------------", "count") < 0)
                return (-1);

        for (i = first_bin; i <= last_bin; i++) {
                char c[32];
                int err;

                if (i == 0) {
                        (void) snprintf(c, sizeof (c), "< %d", base);
                        err = dt_printf(dtp, fp, "%16s ", c);
                } else if (i == levels + 1) {
                        (void) snprintf(c, sizeof (c), ">= %d",
                            base + (levels * step));
                        err = dt_printf(dtp, fp, "%16s ", c);
                } else {
                        err = dt_printf(dtp, fp, "%16d ",
                            base + (i - 1) * step);
                }

                if (err < 0 || dt_print_quantline(dtp, fp, data[i], normal,
                    total, positives, negatives) < 0)
                        return (-1);
        }

        return (0);
}

/*ARGSUSED*/
int
dt_print_lquantize_packed(dtrace_hdl_t *dtp, FILE *fp, const void *addr,
    size_t size, const dtrace_aggdata_t *aggdata)
{
        const int64_t *data = addr;
        long double total = 0, count = 0;
        int min, max, base, err;
        uint64_t arg;
        uint16_t step, levels;
        char c[32];
        unsigned int i;

        if (size < sizeof (uint64_t))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        arg = *data++;
        size -= sizeof (uint64_t);

        base = DTRACE_LQUANTIZE_BASE(arg);
        step = DTRACE_LQUANTIZE_STEP(arg);
        levels = DTRACE_LQUANTIZE_LEVELS(arg);

        if (size != sizeof (uint64_t) * (levels + 2))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        min = 0;
        max = levels + 1;

        if (min == 0) {
                (void) snprintf(c, sizeof (c), "< %d", base);
                err = dt_printf(dtp, fp, "%8s :", c);
        } else {
                err = dt_printf(dtp, fp, "%8d :", base + (min - 1) * step);
        }

        if (err < 0)
                return (-1);

        for (i = min; i <= max; i++) {
                dt_quantize_total(dtp, data[i], &total);
                count += data[i];
        }

        for (i = min; i <= max; i++) {
                if (dt_print_packed(dtp, fp, data[i], total) < 0)
                        return (-1);
        }

        (void) snprintf(c, sizeof (c), ">= %d", base + (levels * step));
        return (dt_printf(dtp, fp, ": %-8s | %lld\n", c, (long long)count));
}

int
dt_print_llquantize(dtrace_hdl_t *dtp, FILE *fp, const void *addr,
    size_t size, uint64_t normal)
{
        int i, first_bin, last_bin, bin = 1, order, levels;
        uint16_t factor, low, high, nsteps;
        const int64_t *data = addr;
        int64_t value = 1, next, step;
        char positives = 0, negatives = 0;
        long double total = 0;
        uint64_t arg;
        char c[32];

        if (size < sizeof (uint64_t))
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        arg = *data++;
        size -= sizeof (uint64_t);

        factor = DTRACE_LLQUANTIZE_FACTOR(arg);
        low = DTRACE_LLQUANTIZE_LOW(arg);
        high = DTRACE_LLQUANTIZE_HIGH(arg);
        nsteps = DTRACE_LLQUANTIZE_NSTEP(arg);

        /*
         * We don't expect to be handed invalid llquantize() parameters here,
         * but sanity check them (to a degree) nonetheless.
         */
        if (size > INT32_MAX || factor < 2 || low >= high ||
            nsteps == 0 || factor > nsteps)
                return (dt_set_errno(dtp, EDT_DMISMATCH));

        levels = (int)size / sizeof (uint64_t);

        first_bin = 0;
        last_bin = levels - 1;

        while (first_bin < levels && data[first_bin] == 0)
                first_bin++;

        if (first_bin == levels) {
                first_bin = 0;
                last_bin = 1;
        } else {
                if (first_bin > 0)
                        first_bin--;

                while (last_bin > 0 && data[last_bin] == 0)
                        last_bin--;

                if (last_bin < levels - 1)
                        last_bin++;
        }

        for (i = first_bin; i <= last_bin; i++) {
                positives |= (data[i] > 0);
                negatives |= (data[i] < 0);
                dt_quantize_total(dtp, data[i], &total);
        }

        if (dt_printf(dtp, fp, "\n%16s %41s %-9s\n", "value",
            "------------- Distribution -------------", "count") < 0)
                return (-1);

        for (order = 0; order < low; order++)
                value *= factor;

        next = value * factor;
        step = next > nsteps ? next / nsteps : 1;

        if (first_bin == 0) {
                (void) snprintf(c, sizeof (c), "< %lld", value);

                if (dt_printf(dtp, fp, "%16s ", c) < 0)
                        return (-1);

                if (dt_print_quantline(dtp, fp, data[0], normal,
                    total, positives, negatives) < 0)
                        return (-1);
        }

        while (order <= high) {
                if (bin >= first_bin && bin <= last_bin) {
                        if (dt_printf(dtp, fp, "%16lld ", (long long)value) < 0)
                                return (-1);

                        if (dt_print_quantline(dtp, fp, data[bin],
                            normal, total, positives, negatives) < 0)
                                return (-1);
                }

                assert(value < next);
                bin++;

                if ((value += step) != next)
                        continue;

                next = value * factor;
                step = next > nsteps ? next / nsteps : 1;
                order++;
        }

        if (last_bin < bin)
                return (0);

        assert(last_bin == bin);
        (void) snprintf(c, sizeof (c), ">= %lld", value);

        if (dt_printf(dtp, fp, "%16s ", c) < 0)
                return (-1);

        return (dt_print_quantline(dtp, fp, data[bin], normal,
            total, positives, negatives));
}

/*ARGSUSED*/
static int
dt_print_average(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
    size_t size, uint64_t normal)
{
        /* LINTED - alignment */
        int64_t *data = (int64_t *)addr;

        return (dt_printf(dtp, fp, " %16lld", data[0] ?
            (long long)(data[1] / (int64_t)normal / data[0]) : 0));
}

/*ARGSUSED*/
static int
dt_print_stddev(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
    size_t size, uint64_t normal)
{
        /* LINTED - alignment */
        uint64_t *data = (uint64_t *)addr;

        return (dt_printf(dtp, fp, " %16llu", data[0] ?
            (unsigned long long) dt_stddev(data, normal) : 0));
}

/*ARGSUSED*/
static int
dt_print_bytes(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr,
    size_t nbytes, int width, int quiet, int forceraw)
{
        /*
         * If the byte stream is a series of printable characters, followed by
         * a terminating byte, we print it out as a string.  Otherwise, we
         * assume that it's something else and just print the bytes.
         */
        int i, j, margin = 5;
        char *c = (char *)addr;

        if (nbytes == 0)
                return (0);

        if (forceraw)
                goto raw;

        if (dtp->dt_options[DTRACEOPT_RAWBYTES] != DTRACEOPT_UNSET)
                goto raw;

        for (i = 0; i < nbytes; i++) {
                /*
                 * We define a "printable character" to be one for which
                 * isprint(3C) returns non-zero, isspace(3C) returns non-zero,
                 * or a character which is either backspace or the bell.
                 * Backspace and the bell are regrettably special because
                 * they fail the first two tests -- and yet they are entirely
                 * printable.  These are the only two control characters that
                 * have meaning for the terminal and for which isprint(3C) and
                 * isspace(3C) return 0.
                 */
                if (isprint(c[i]) || isspace(c[i]) ||
                    c[i] == '\b' || c[i] == '\a')
                        continue;

                if (c[i] == '\0' && i > 0) {
                        /*
                         * This looks like it might be a string.  Before we
                         * assume that it is indeed a string, check the
                         * remainder of the byte range; if it contains
                         * additional non-nul characters, we'll assume that
                         * it's a binary stream that just happens to look like
                         * a string, and we'll print out the individual bytes.
                         */
                        for (j = i + 1; j < nbytes; j++) {
                                if (c[j] != '\0')
                                        break;
                        }

                        if (j != nbytes)
                                break;

                        if (quiet) {
                                return (dt_printf(dtp, fp, "%s", c));
                        } else {
                                return (dt_printf(dtp, fp, " %s%*s",
                                    width < 0 ? " " : "", width, c));
                        }
                }

                break;
        }

        if (i == nbytes) {
                /*
                 * The byte range is all printable characters, but there is
                 * no trailing nul byte.  We'll assume that it's a string and
                 * print it as such.
                 */
                char *s = alloca(nbytes + 1);
                bcopy(c, s, nbytes);
                s[nbytes] = '\0';
                return (dt_printf(dtp, fp, "  %-*s", width, s));
        }

raw:
        if (dt_printf(dtp, fp, "\n%*s      ", margin, "") < 0)
                return (-1);

        for (i = 0; i < 16; i++)
                if (dt_printf(dtp, fp, "  %c", "0123456789abcdef"[i]) < 0)
                        return (-1);

        if (dt_printf(dtp, fp, "  0123456789abcdef\n") < 0)
                return (-1);


        for (i = 0; i < nbytes; i += 16) {
                if (dt_printf(dtp, fp, "%*s%5x:", margin, "", i) < 0)
                        return (-1);

                for (j = i; j < i + 16 && j < nbytes; j++) {
                        if (dt_printf(dtp, fp, " %02x", (uchar_t)c[j]) < 0)
                                return (-1);
                }

                while (j++ % 16) {
                        if (dt_printf(dtp, fp, "   ") < 0)
                                return (-1);
                }

                if (dt_printf(dtp, fp, "  ") < 0)
                        return (-1);

                for (j = i; j < i + 16 && j < nbytes; j++) {
                        if (dt_printf(dtp, fp, "%c",
                            c[j] < ' ' || c[j] > '~' ? '.' : c[j]) < 0)
                                return (-1);
                }

                if (dt_printf(dtp, fp, "\n") < 0)
                        return (-1);
        }

        return (0);
}

int
dt_print_stack(dtrace_hdl_t *dtp, FILE *fp, const char *format,
    caddr_t addr, int depth, int size)
{
        dtrace_syminfo_t dts;
        GElf_Sym sym;
        int i, indent;
        char c[PATH_MAX * 2];
        uint64_t pc;

        if (dt_printf(dtp, fp, "\n") < 0)
                return (-1);

        if (format == NULL)
                format = "%s";

        if (dtp->dt_options[DTRACEOPT_STACKINDENT] != DTRACEOPT_UNSET)
                indent = (int)dtp->dt_options[DTRACEOPT_STACKINDENT];
        else
                indent = _dtrace_stkindent;

        for (i = 0; i < depth; i++) {
                switch (size) {
                case sizeof (uint32_t):
                        /* LINTED - alignment */
                        pc = *((uint32_t *)addr);
                        break;

                case sizeof (uint64_t):
                        /* LINTED - alignment */
                        pc = *((uint64_t *)addr);
                        break;

                default:
                        return (dt_set_errno(dtp, EDT_BADSTACKPC));
                }

                if (pc == NULL)
                        break;

                addr += size;

                if (dt_printf(dtp, fp, "%*s", indent, "") < 0)
                        return (-1);

                if (dtrace_lookup_by_addr(dtp, pc, &sym, &dts) == 0) {
                        if (pc > sym.st_value) {
                                (void) snprintf(c, sizeof (c), "%s`%s+0x%llx",
                                    dts.dts_object, dts.dts_name,
                                    pc - sym.st_value);
                        } else {
                                (void) snprintf(c, sizeof (c), "%s`%s",
                                    dts.dts_object, dts.dts_name);
                        }
                } else {
                        /*
                         * We'll repeat the lookup, but this time we'll specify
                         * a NULL GElf_Sym -- indicating that we're only
                         * interested in the containing module.
                         */
                        if (dtrace_lookup_by_addr(dtp, pc, NULL, &dts) == 0) {
                                (void) snprintf(c, sizeof (c), "%s`0x%llx",
                                    dts.dts_object, pc);
                        } else {
                                (void) snprintf(c, sizeof (c), "0x%llx", pc);
                        }
                }

                if (dt_printf(dtp, fp, format, c) < 0)
                        return (-1);

                if (dt_printf(dtp, fp, "\n") < 0)
                        return (-1);
        }

        return (0);
}

int
dt_print_ustack(dtrace_hdl_t *dtp, FILE *fp, const char *format,
    caddr_t addr, uint64_t arg)
{
        /* LINTED - alignment */
        uint64_t *pc = (uint64_t *)addr;
        uint32_t depth = DTRACE_USTACK_NFRAMES(arg);
        uint32_t strsize = DTRACE_USTACK_STRSIZE(arg);
        const char *strbase = addr + (depth + 1) * sizeof (uint64_t);
        const char *str = strsize ? strbase : NULL;
        int err = 0;

        char name[PATH_MAX], objname[PATH_MAX], c[PATH_MAX * 2];
        struct ps_prochandle *P;
        GElf_Sym sym;
        int i, indent;
        pid_t pid;

        if (depth == 0)
                return (0);

        pid = (pid_t)*pc++;

        if (dt_printf(dtp, fp, "\n") < 0)
                return (-1);

        if (format == NULL)
                format = "%s";

        if (dtp->dt_options[DTRACEOPT_STACKINDENT] != DTRACEOPT_UNSET)
                indent = (int)dtp->dt_options[DTRACEOPT_STACKINDENT];
        else
                indent = _dtrace_stkindent;

        /*
         * Ultimately, we need to add an entry point in the library vector for
         * determining <symbol, offset> from <pid, address>.  For now, if
         * this is a vector open, we just print the raw address or string.
         */
        if (dtp->dt_vector == NULL)
                P = dt_proc_grab(dtp, pid, PGRAB_RDONLY | PGRAB_FORCE, 0);
        else
                P = NULL;

        if (P != NULL)
                dt_proc_lock(dtp, P); /* lock handle while we perform lookups */

        for (i = 0; i < depth && pc[i] != NULL; i++) {
                const prmap_t *map;

                if ((err = dt_printf(dtp, fp, "%*s", indent, "")) < 0)
                        break;

                if (P != NULL && Plookup_by_addr(P, pc[i],
                    name, sizeof (name), &sym) == 0) {
                        (void) Pobjname(P, pc[i], objname, sizeof (objname));

                        if (pc[i] > sym.st_value) {
                                (void) snprintf(c, sizeof (c),
                                    "%s`%s+0x%llx", dt_basename(objname), name,
                                    (u_longlong_t)(pc[i] - sym.st_value));
                        } else {
                                (void) snprintf(c, sizeof (c),
                                    "%s`%s", dt_basename(objname), name);
                        }
                } else if (str != NULL && str[0] != '\0' && str[0] != '@' &&
                    (P == NULL || (map = Paddr_to_map(P, pc[i])) == NULL ||
                    map->pr_mflags & MA_WRITE)) {
                        /*
                         * If the current string pointer in the string table
                         * does not point to an empty string _and_ the program
                         * counter falls in a writable region, we'll use the
                         * string from the string table instead of the raw
                         * address.  This last condition is necessary because
                         * some (broken) ustack helpers will return a string
                         * even for a program counter that they can't
                         * identify.  If we have a string for a program
                         * counter that falls in a segment that isn't
                         * writable, we assume that we have fallen into this
                         * case and we refuse to use the string.  Finally,
                         * note that if we could not grab the process (e.g.,
                         * because it exited), the information from the helper
                         * is better than nothing.
                         */
                        (void) snprintf(c, sizeof (c), "%s", str);
                } else {
                        if (P != NULL && Pobjname(P, pc[i], objname,
                            sizeof (objname)) != NULL) {
                                (void) snprintf(c, sizeof (c), "%s`0x%llx",
                                    dt_basename(objname), (u_longlong_t)pc[i]);
                        } else {
                                (void) snprintf(c, sizeof (c), "0x%llx",
                                    (u_longlong_t)pc[i]);
                        }
                }

                if ((err = dt_printf(dtp, fp, format, c)) < 0)
                        break;

                if ((err = dt_printf(dtp, fp, "\n")) < 0)
                        break;

                if (str != NULL && str[0] == '@') {
                        /*
                         * If the first character of the string is an "at" sign,
                         * then the string is inferred to be an annotation --
                         * and it is printed out beneath the frame and offset
                         * with brackets.
                         */
                        if ((err = dt_printf(dtp, fp, "%*s", indent, "")) < 0)
                                break;

                        (void) snprintf(c, sizeof (c), "  [ %s ]", &str[1]);

                        if ((err = dt_printf(dtp, fp, format, c)) < 0)
                                break;

                        if ((err = dt_printf(dtp, fp, "\n")) < 0)
                                break;
                }

                if (str != NULL) {
                        str += strlen(str) + 1;
                        if (str - strbase >= strsize)
                                str = NULL;
                }
        }

        if (P != NULL) {
                dt_proc_unlock(dtp, P);
                dt_proc_release(dtp, P);
        }

        return (err);
}

static int
dt_print_usym(dtrace_hdl_t *dtp, FILE *fp, caddr_t addr, dtrace_actkind_t act)
{
        /* LINTED - alignment */
        uint64_t pid = ((uint64_t *)addr)[0];
        /* LINTED - alignment */
        uint64_t pc = ((uint64_t *)addr)[1];
        const char *format = "  %-50s";
        char *s;
        int n, len = 256;

        if (act == DTRACEACT_USYM && dtp->dt_vector == NULL) {
                struct ps_prochandle *P;

                if ((P = dt_proc_grab(dtp, pid,
                    PGRAB_RDONLY | PGRAB_FORCE, 0)) != NULL) {
                        GElf_Sym sym;

                        dt_proc_lock(dtp, P);

                        if (Plookup_by_addr(P, pc, NULL, 0, &sym) == 0)
                                pc = sym.st_value;

                        dt_proc_unlock(dtp, P);
                        dt_proc_release(dtp, P);
                }
        }

        do {
                n = len;
                s = alloca(n);
        } while ((len = dtrace_uaddr2str(dtp, pid, pc, s, n)) > n);

        return (dt_printf(dtp, fp, format, s));
}

int
dt_print_umod(dtrace_hdl_t *dtp, FILE *fp, const char *format, caddr_t addr)
{
        /* LINTED - alignment */
        uint64_t pid = ((uint64_t *)addr)[0];
        /* LINTED - alignment */
        uint64_t pc = ((uint64_t *)addr)[1];
        int err = 0;

        char objname[PATH_MAX], c[PATH_MAX * 2];
        struct ps_prochandle *P;

        if (format == NULL)
                format = "  %-50s";

        /*
         * See the comment in dt_print_ustack() for the rationale for
         * printing raw addresses in the vectored case.
         */
        if (dtp->dt_vector == NULL)
                P = dt_proc_grab(dtp, pid, PGRAB_RDONLY | PGRAB_FORCE, 0);
        else
                P = NULL;

        if (P != NULL)
                dt_proc_lock(dtp, P); /* lock handle while we perform lookups */

        if (P != NULL && Pobjname(P, pc, objname, sizeof (objname)) != NULL) {
                (void) snprintf(c, sizeof (c), "%s", dt_basename(objname));
        } else {
                (void) snprintf(c, sizeof (c), "0x%llx", (u_longlong_t)pc);
        }

        err = dt_printf(dtp, fp, format, c);

        if (P != NULL) {
                dt_proc_unlock(dtp, P);
                dt_proc_release(dtp, P);
        }

        return (err);
}

static int
dt_print_sym(dtrace_hdl_t *dtp, FILE *fp, const char *format, caddr_t addr)
{
        /* LINTED - alignment */
        uint64_t pc = *((uint64_t *)addr);
        dtrace_syminfo_t dts;
        GElf_Sym sym;
        char c[PATH_MAX * 2];

        if (format == NULL)
                format = "  %-50s";

        if (dtrace_lookup_by_addr(dtp, pc, &sym, &dts) == 0) {
                (void) snprintf(c, sizeof (c), "%s`%s",
                    dts.dts_object, dts.dts_name);
        } else {
                /*
                 * We'll repeat the lookup, but this time we'll specify a
                 * NULL GElf_Sym -- indicating that we're only interested in
                 * the containing module.
                 */
                if (dtrace_lookup_by_addr(dtp, pc, NULL, &dts) == 0) {
                        (void) snprintf(c, sizeof (c), "%s`0x%llx",
                            dts.dts_object, (u_longlong_t)pc);
                } else {
                        (void) snprintf(c, sizeof (c), "0x%llx",
                            (u_longlong_t)pc);
                }
        }

        if (dt_printf(dtp, fp, format, c) < 0)
                return (-1);

        return (0);
}

int
dt_print_mod(dtrace_hdl_t *dtp, FILE *fp, const char *format, caddr_t addr)
{
        /* LINTED - alignment */
        uint64_t pc = *((uint64_t *)addr);
        dtrace_syminfo_t dts;
        char c[PATH_MAX * 2];

        if (format == NULL)
                format = "  %-50s";

        if (dtrace_lookup_by_addr(dtp, pc, NULL, &dts) == 0) {
                (void) snprintf(c, sizeof (c), "%s", dts.dts_object);
        } else {
                (void) snprintf(c, sizeof (c), "0x%llx", (u_longlong_t)pc);
        }

        if (dt_printf(dtp, fp, format, c) < 0)
                return (-1);

        return (0);
}

typedef struct dt_normal {
        dtrace_aggvarid_t dtnd_id;
        uint64_t dtnd_normal;
} dt_normal_t;

static int
dt_normalize_agg(const dtrace_aggdata_t *aggdata, void *arg)
{
        dt_normal_t *normal = arg;
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        dtrace_aggvarid_t id = normal->dtnd_id;

        if (agg->dtagd_nrecs == 0)
                return (DTRACE_AGGWALK_NEXT);

        if (agg->dtagd_varid != id)
                return (DTRACE_AGGWALK_NEXT);

        ((dtrace_aggdata_t *)aggdata)->dtada_normal = normal->dtnd_normal;
        return (DTRACE_AGGWALK_NORMALIZE);
}

static int
dt_normalize(dtrace_hdl_t *dtp, caddr_t base, dtrace_recdesc_t *rec)
{
        dt_normal_t normal;
        caddr_t addr;

        /*
         * We (should) have two records:  the aggregation ID followed by the
         * normalization value.
         */
        addr = base + rec->dtrd_offset;

        if (rec->dtrd_size != sizeof (dtrace_aggvarid_t))
                return (dt_set_errno(dtp, EDT_BADNORMAL));

        /* LINTED - alignment */
        normal.dtnd_id = *((dtrace_aggvarid_t *)addr);
        rec++;

        if (rec->dtrd_action != DTRACEACT_LIBACT)
                return (dt_set_errno(dtp, EDT_BADNORMAL));

        if (rec->dtrd_arg != DT_ACT_NORMALIZE)
                return (dt_set_errno(dtp, EDT_BADNORMAL));

        addr = base + rec->dtrd_offset;

        switch (rec->dtrd_size) {
        case sizeof (uint64_t):
                /* LINTED - alignment */
                normal.dtnd_normal = *((uint64_t *)addr);
                break;
        case sizeof (uint32_t):
                /* LINTED - alignment */
                normal.dtnd_normal = *((uint32_t *)addr);
                break;
        case sizeof (uint16_t):
                /* LINTED - alignment */
                normal.dtnd_normal = *((uint16_t *)addr);
                break;
        case sizeof (uint8_t):
                normal.dtnd_normal = *((uint8_t *)addr);
                break;
        default:
                return (dt_set_errno(dtp, EDT_BADNORMAL));
        }

        (void) dtrace_aggregate_walk(dtp, dt_normalize_agg, &normal);

        return (0);
}

static int
dt_denormalize_agg(const dtrace_aggdata_t *aggdata, void *arg)
{
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        dtrace_aggvarid_t id = *((dtrace_aggvarid_t *)arg);

        if (agg->dtagd_nrecs == 0)
                return (DTRACE_AGGWALK_NEXT);

        if (agg->dtagd_varid != id)
                return (DTRACE_AGGWALK_NEXT);

        return (DTRACE_AGGWALK_DENORMALIZE);
}

static int
dt_clear_agg(const dtrace_aggdata_t *aggdata, void *arg)
{
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        dtrace_aggvarid_t id = *((dtrace_aggvarid_t *)arg);

        if (agg->dtagd_nrecs == 0)
                return (DTRACE_AGGWALK_NEXT);

        if (agg->dtagd_varid != id)
                return (DTRACE_AGGWALK_NEXT);

        return (DTRACE_AGGWALK_CLEAR);
}

typedef struct dt_trunc {
        dtrace_aggvarid_t dttd_id;
        uint64_t dttd_remaining;
} dt_trunc_t;

static int
dt_trunc_agg(const dtrace_aggdata_t *aggdata, void *arg)
{
        dt_trunc_t *trunc = arg;
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        dtrace_aggvarid_t id = trunc->dttd_id;

        if (agg->dtagd_nrecs == 0)
                return (DTRACE_AGGWALK_NEXT);

        if (agg->dtagd_varid != id)
                return (DTRACE_AGGWALK_NEXT);

        if (trunc->dttd_remaining == 0)
                return (DTRACE_AGGWALK_REMOVE);

        trunc->dttd_remaining--;
        return (DTRACE_AGGWALK_NEXT);
}

static int
dt_trunc(dtrace_hdl_t *dtp, caddr_t base, dtrace_recdesc_t *rec)
{
        dt_trunc_t trunc;
        caddr_t addr;
        int64_t remaining;
        int (*func)(dtrace_hdl_t *, dtrace_aggregate_f *, void *);

        /*
         * We (should) have two records:  the aggregation ID followed by the
         * number of aggregation entries after which the aggregation is to be
         * truncated.
         */
        addr = base + rec->dtrd_offset;

        if (rec->dtrd_size != sizeof (dtrace_aggvarid_t))
                return (dt_set_errno(dtp, EDT_BADTRUNC));

        /* LINTED - alignment */
        trunc.dttd_id = *((dtrace_aggvarid_t *)addr);
        rec++;

        if (rec->dtrd_action != DTRACEACT_LIBACT)
                return (dt_set_errno(dtp, EDT_BADTRUNC));

        if (rec->dtrd_arg != DT_ACT_TRUNC)
                return (dt_set_errno(dtp, EDT_BADTRUNC));

        addr = base + rec->dtrd_offset;

        switch (rec->dtrd_size) {
        case sizeof (uint64_t):
                /* LINTED - alignment */
                remaining = *((int64_t *)addr);
                break;
        case sizeof (uint32_t):
                /* LINTED - alignment */
                remaining = *((int32_t *)addr);
                break;
        case sizeof (uint16_t):
                /* LINTED - alignment */
                remaining = *((int16_t *)addr);
                break;
        case sizeof (uint8_t):
                remaining = *((int8_t *)addr);
                break;
        default:
                return (dt_set_errno(dtp, EDT_BADNORMAL));
        }

        if (remaining < 0) {
                func = dtrace_aggregate_walk_valsorted;
                remaining = -remaining;
        } else {
                func = dtrace_aggregate_walk_valrevsorted;
        }

        assert(remaining >= 0);
        trunc.dttd_remaining = remaining;

        (void) func(dtp, dt_trunc_agg, &trunc);

        return (0);
}

static int
dt_print_datum(dtrace_hdl_t *dtp, FILE *fp, dtrace_recdesc_t *rec,
    caddr_t addr, size_t size, const dtrace_aggdata_t *aggdata,
    uint64_t normal, dt_print_aggdata_t *pd)
{
        int err, width;
        dtrace_actkind_t act = rec->dtrd_action;
        boolean_t packed = pd->dtpa_agghist || pd->dtpa_aggpack;
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;

        static struct {
                size_t size;
                int width;
                int packedwidth;
        } *fmt, fmttab[] = {
                { sizeof (uint8_t),     3,      3 },
                { sizeof (uint16_t),    5,      5 },
                { sizeof (uint32_t),    8,      8 },
                { sizeof (uint64_t),    16,     16 },
                { 0,                    -50,    16 }
        };

        if (packed && pd->dtpa_agghisthdr != agg->dtagd_varid) {
                dtrace_recdesc_t *r;

                width = 0;

                /*
                 * To print our quantization header for either an agghist or
                 * aggpack aggregation, we need to iterate through all of our
                 * of our records to determine their width.
                 */
                for (r = rec; !DTRACEACT_ISAGG(r->dtrd_action); r++) {
                        for (fmt = fmttab; fmt->size &&
                            fmt->size != r->dtrd_size; fmt++)
                                continue;

                        width += fmt->packedwidth + 1;
                }

                if (pd->dtpa_agghist) {
                        if (dt_print_quanthdr(dtp, fp, width) < 0)
                                return (-1);
                } else {
                        if (dt_print_quanthdr_packed(dtp, fp,
                            width, aggdata, r->dtrd_action) < 0)
                                return (-1);
                }

                pd->dtpa_agghisthdr = agg->dtagd_varid;
        }

        if (pd->dtpa_agghist && DTRACEACT_ISAGG(act)) {
                char positives = aggdata->dtada_flags & DTRACE_A_HASPOSITIVES;
                char negatives = aggdata->dtada_flags & DTRACE_A_HASNEGATIVES;
                int64_t val;

                assert(act == DTRACEAGG_SUM || act == DTRACEAGG_COUNT);
                val = (long long)*((uint64_t *)addr);

                if (dt_printf(dtp, fp, " ") < 0)
                        return (-1);

                return (dt_print_quantline(dtp, fp, val, normal,
                    aggdata->dtada_total, positives, negatives));
        }

        if (pd->dtpa_aggpack && DTRACEACT_ISAGG(act)) {
                switch (act) {
                case DTRACEAGG_QUANTIZE:
                        return (dt_print_quantize_packed(dtp,
                            fp, addr, size, aggdata));
                case DTRACEAGG_LQUANTIZE:
                        return (dt_print_lquantize_packed(dtp,
                            fp, addr, size, aggdata));
                default:
                        break;
                }
        }

        switch (act) {
        case DTRACEACT_STACK:
                return (dt_print_stack(dtp, fp, NULL, addr,
                    rec->dtrd_arg, rec->dtrd_size / rec->dtrd_arg));

        case DTRACEACT_USTACK:
        case DTRACEACT_JSTACK:
                return (dt_print_ustack(dtp, fp, NULL, addr, rec->dtrd_arg));

        case DTRACEACT_USYM:
        case DTRACEACT_UADDR:
                return (dt_print_usym(dtp, fp, addr, act));

        case DTRACEACT_UMOD:
                return (dt_print_umod(dtp, fp, NULL, addr));

        case DTRACEACT_SYM:
                return (dt_print_sym(dtp, fp, NULL, addr));

        case DTRACEACT_MOD:
                return (dt_print_mod(dtp, fp, NULL, addr));

        case DTRACEAGG_QUANTIZE:
                return (dt_print_quantize(dtp, fp, addr, size, normal));

        case DTRACEAGG_LQUANTIZE:
                return (dt_print_lquantize(dtp, fp, addr, size, normal));

        case DTRACEAGG_LLQUANTIZE:
                return (dt_print_llquantize(dtp, fp, addr, size, normal));

        case DTRACEAGG_AVG:
                return (dt_print_average(dtp, fp, addr, size, normal));

        case DTRACEAGG_STDDEV:
                return (dt_print_stddev(dtp, fp, addr, size, normal));

        default:
                break;
        }

        for (fmt = fmttab; fmt->size && fmt->size != size; fmt++)
                continue;

        width = packed ? fmt->packedwidth : fmt->width;

        switch (size) {
        case sizeof (uint64_t):
                err = dt_printf(dtp, fp, " %*lld", width,
                    /* LINTED - alignment */
                    (long long)*((uint64_t *)addr) / normal);
                break;
        case sizeof (uint32_t):
                /* LINTED - alignment */
                err = dt_printf(dtp, fp, " %*d", width, *((uint32_t *)addr) /
                    (uint32_t)normal);
                break;
        case sizeof (uint16_t):
                /* LINTED - alignment */
                err = dt_printf(dtp, fp, " %*d", width, *((uint16_t *)addr) /
                    (uint32_t)normal);
                break;
        case sizeof (uint8_t):
                err = dt_printf(dtp, fp, " %*d", width, *((uint8_t *)addr) /
                    (uint32_t)normal);
                break;
        default:
                err = dt_print_bytes(dtp, fp, addr, size, width, 0, 0);
                break;
        }

        return (err);
}

int
dt_print_aggs(const dtrace_aggdata_t **aggsdata, int naggvars, void *arg)
{
        int i, aggact = 0;
        dt_print_aggdata_t *pd = arg;
        const dtrace_aggdata_t *aggdata = aggsdata[0];
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        FILE *fp = pd->dtpa_fp;
        dtrace_hdl_t *dtp = pd->dtpa_dtp;
        dtrace_recdesc_t *rec;
        dtrace_actkind_t act;
        caddr_t addr;
        size_t size;

        pd->dtpa_agghist = (aggdata->dtada_flags & DTRACE_A_TOTAL);
        pd->dtpa_aggpack = (aggdata->dtada_flags & DTRACE_A_MINMAXBIN);

        /*
         * Iterate over each record description in the key, printing the traced
         * data, skipping the first datum (the tuple member created by the
         * compiler).
         */
        for (i = 1; i < agg->dtagd_nrecs; i++) {
                rec = &agg->dtagd_rec[i];
                act = rec->dtrd_action;
                addr = aggdata->dtada_data + rec->dtrd_offset;
                size = rec->dtrd_size;

                if (DTRACEACT_ISAGG(act)) {
                        aggact = i;
                        break;
                }

                if (dt_print_datum(dtp, fp, rec, addr,
                    size, aggdata, 1, pd) < 0)
                        return (-1);

                if (dt_buffered_flush(dtp, NULL, rec, aggdata,
                    DTRACE_BUFDATA_AGGKEY) < 0)
                        return (-1);
        }

        assert(aggact != 0);

        for (i = (naggvars == 1 ? 0 : 1); i < naggvars; i++) {
                uint64_t normal;

                aggdata = aggsdata[i];
                agg = aggdata->dtada_desc;
                rec = &agg->dtagd_rec[aggact];
                act = rec->dtrd_action;
                addr = aggdata->dtada_data + rec->dtrd_offset;
                size = rec->dtrd_size;

                assert(DTRACEACT_ISAGG(act));
                normal = aggdata->dtada_normal;

                if (dt_print_datum(dtp, fp, rec, addr,
                    size, aggdata, normal, pd) < 0)
                        return (-1);

                if (dt_buffered_flush(dtp, NULL, rec, aggdata,
                    DTRACE_BUFDATA_AGGVAL) < 0)
                        return (-1);

                if (!pd->dtpa_allunprint)
                        agg->dtagd_flags |= DTRACE_AGD_PRINTED;
        }

        if (!pd->dtpa_agghist && !pd->dtpa_aggpack) {
                if (dt_printf(dtp, fp, "\n") < 0)
                        return (-1);
        }

        if (dt_buffered_flush(dtp, NULL, NULL, aggdata,
            DTRACE_BUFDATA_AGGFORMAT | DTRACE_BUFDATA_AGGLAST) < 0)
                return (-1);

        return (0);
}

int
dt_print_agg(const dtrace_aggdata_t *aggdata, void *arg)
{
        dt_print_aggdata_t *pd = arg;
        dtrace_aggdesc_t *agg = aggdata->dtada_desc;
        dtrace_aggvarid_t aggvarid = pd->dtpa_id;

        if (pd->dtpa_allunprint) {
                if (agg->dtagd_flags & DTRACE_AGD_PRINTED)
                        return (0);
        } else {
                /*
                 * If we're not printing all unprinted aggregations, then the
                 * aggregation variable ID denotes a specific aggregation
                 * variable that we should print -- skip any other aggregations
                 * that we encounter.
                 */
                if (agg->dtagd_nrecs == 0)
                        return (0);

                if (aggvarid != agg->dtagd_varid)
                        return (0);
        }

        return (dt_print_aggs(&aggdata, 1, arg));
}

int
dt_setopt(dtrace_hdl_t *dtp, const dtrace_probedata_t *data,
    const char *option, const char *value)
{
        int len, rval;
        char *msg;
        const char *errstr;
        dtrace_setoptdata_t optdata;

        bzero(&optdata, sizeof (optdata));
        (void) dtrace_getopt(dtp, option, &optdata.dtsda_oldval);

        if (dtrace_setopt(dtp, option, value) == 0) {
                (void) dtrace_getopt(dtp, option, &optdata.dtsda_newval);
                optdata.dtsda_probe = data;
                optdata.dtsda_option = option;
                optdata.dtsda_handle = dtp;

                if ((rval = dt_handle_setopt(dtp, &optdata)) != 0)
                        return (rval);

                return (0);
        }

        errstr = dtrace_errmsg(dtp, dtrace_errno(dtp));
        len = strlen(option) + strlen(value) + strlen(errstr) + 80;
        msg = alloca(len);

        (void) snprintf(msg, len, "couldn't set option \"%s\" to \"%s\": %s\n",
            option, value, errstr);

        if ((rval = dt_handle_liberr(dtp, data, msg)) == 0)
                return (0);

        return (rval);
}

static int
dt_consume_cpu(dtrace_hdl_t *dtp, FILE *fp, int cpu,
    dtrace_bufdesc_t *buf, boolean_t just_one,
    dtrace_consume_probe_f *efunc, dtrace_consume_rec_f *rfunc, void *arg)
{
        dtrace_epid_t id;
        size_t offs;
        int flow = (dtp->dt_options[DTRACEOPT_FLOWINDENT] != DTRACEOPT_UNSET);
        int quiet = (dtp->dt_options[DTRACEOPT_QUIET] != DTRACEOPT_UNSET);
        int rval, i, n;
        uint64_t tracememsize = 0;
        dtrace_probedata_t data;
        uint64_t drops;

        bzero(&data, sizeof (data));
        data.dtpda_handle = dtp;
        data.dtpda_cpu = cpu;
        data.dtpda_flow = dtp->dt_flow;
        data.dtpda_indent = dtp->dt_indent;
        data.dtpda_prefix = dtp->dt_prefix;

        for (offs = buf->dtbd_oldest; offs < buf->dtbd_size; ) {
                dtrace_eprobedesc_t *epd;

                /*
                 * We're guaranteed to have an ID.
                 */
                id = *(uint32_t *)((uintptr_t)buf->dtbd_data + offs);

                if (id == DTRACE_EPIDNONE) {
                        /*
                         * This is filler to assure proper alignment of the
                         * next record; we simply ignore it.
                         */
                        offs += sizeof (id);
                        continue;
                }

                if ((rval = dt_epid_lookup(dtp, id, &data.dtpda_edesc,
                    &data.dtpda_pdesc)) != 0)
                        return (rval);

                epd = data.dtpda_edesc;
                data.dtpda_data = buf->dtbd_data + offs;

                if (data.dtpda_edesc->dtepd_uarg != DT_ECB_DEFAULT) {
                        rval = dt_handle(dtp, &data);

                        if (rval == DTRACE_CONSUME_NEXT)
                                goto nextepid;

                        if (rval == DTRACE_CONSUME_ERROR)
                                return (-1);
                }

                if (flow)
                        (void) dt_flowindent(dtp, &data, dtp->dt_last_epid,
                            buf, offs);

                rval = (*efunc)(&data, arg);

                if (flow) {
                        if (data.dtpda_flow == DTRACEFLOW_ENTRY)
                                data.dtpda_indent += 2;
                }

                if (rval == DTRACE_CONSUME_NEXT)
                        goto nextepid;

                if (rval == DTRACE_CONSUME_ABORT)
                        return (dt_set_errno(dtp, EDT_DIRABORT));

                if (rval != DTRACE_CONSUME_THIS)
                        return (dt_set_errno(dtp, EDT_BADRVAL));

                for (i = 0; i < epd->dtepd_nrecs; i++) {
                        caddr_t addr;
                        dtrace_recdesc_t *rec = &epd->dtepd_rec[i];
                        dtrace_actkind_t act = rec->dtrd_action;

                        data.dtpda_data = buf->dtbd_data + offs +
                            rec->dtrd_offset;
                        addr = data.dtpda_data;

                        if (act == DTRACEACT_LIBACT) {
                                uint64_t arg = rec->dtrd_arg;
                                dtrace_aggvarid_t id;

                                switch (arg) {
                                case DT_ACT_CLEAR:
                                        /* LINTED - alignment */
                                        id = *((dtrace_aggvarid_t *)addr);
                                        (void) dtrace_aggregate_walk(dtp,
                                            dt_clear_agg, &id);
                                        continue;

                                case DT_ACT_DENORMALIZE:
                                        /* LINTED - alignment */
                                        id = *((dtrace_aggvarid_t *)addr);
                                        (void) dtrace_aggregate_walk(dtp,
                                            dt_denormalize_agg, &id);
                                        continue;

                                case DT_ACT_FTRUNCATE:
                                        if (fp == NULL)
                                                continue;

                                        (void) fflush(fp);
                                        (void) ftruncate(fileno(fp), 0);
                                        (void) fseeko(fp, 0, SEEK_SET);
                                        continue;

                                case DT_ACT_NORMALIZE:
                                        if (i == epd->dtepd_nrecs - 1)
                                                return (dt_set_errno(dtp,
                                                    EDT_BADNORMAL));

                                        if (dt_normalize(dtp,
                                            buf->dtbd_data + offs, rec) != 0)
                                                return (-1);

                                        i++;
                                        continue;

                                case DT_ACT_SETOPT: {
                                        uint64_t *opts = dtp->dt_options;
                                        dtrace_recdesc_t *valrec;
                                        uint32_t valsize;
                                        caddr_t val;
                                        int rv;

                                        if (i == epd->dtepd_nrecs - 1) {
                                                return (dt_set_errno(dtp,
                                                    EDT_BADSETOPT));
                                        }

                                        valrec = &epd->dtepd_rec[++i];
                                        valsize = valrec->dtrd_size;

                                        if (valrec->dtrd_action != act ||
                                            valrec->dtrd_arg != arg) {
                                                return (dt_set_errno(dtp,
                                                    EDT_BADSETOPT));
                                        }

                                        if (valsize > sizeof (uint64_t)) {
                                                val = buf->dtbd_data + offs +
                                                    valrec->dtrd_offset;
                                        } else {
                                                val = "1";
                                        }

                                        rv = dt_setopt(dtp, &data, addr, val);

                                        if (rv != 0)
                                                return (-1);

                                        flow = (opts[DTRACEOPT_FLOWINDENT] !=
                                            DTRACEOPT_UNSET);
                                        quiet = (opts[DTRACEOPT_QUIET] !=
                                            DTRACEOPT_UNSET);

                                        continue;
                                }

                                case DT_ACT_TRUNC:
                                        if (i == epd->dtepd_nrecs - 1)
                                                return (dt_set_errno(dtp,
                                                    EDT_BADTRUNC));

                                        if (dt_trunc(dtp,
                                            buf->dtbd_data + offs, rec) != 0)
                                                return (-1);

                                        i++;
                                        continue;

                                default:
                                        continue;
                                }
                        }

                        if (act == DTRACEACT_TRACEMEM_DYNSIZE &&
                            rec->dtrd_size == sizeof (uint64_t)) {
                                /* LINTED - alignment */
                                tracememsize = *((unsigned long long *)addr);
                                continue;
                        }

                        rval = (*rfunc)(&data, rec, arg);

                        if (rval == DTRACE_CONSUME_NEXT)
                                continue;

                        if (rval == DTRACE_CONSUME_ABORT)
                                return (dt_set_errno(dtp, EDT_DIRABORT));

                        if (rval != DTRACE_CONSUME_THIS)
                                return (dt_set_errno(dtp, EDT_BADRVAL));

                        if (act == DTRACEACT_STACK) {
                                int depth = rec->dtrd_arg;

                                if (dt_print_stack(dtp, fp, NULL, addr, depth,
                                    rec->dtrd_size / depth) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_USTACK ||
                            act == DTRACEACT_JSTACK) {
                                if (dt_print_ustack(dtp, fp, NULL,
                                    addr, rec->dtrd_arg) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_SYM) {
                                if (dt_print_sym(dtp, fp, NULL, addr) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_MOD) {
                                if (dt_print_mod(dtp, fp, NULL, addr) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_USYM || act == DTRACEACT_UADDR) {
                                if (dt_print_usym(dtp, fp, addr, act) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_UMOD) {
                                if (dt_print_umod(dtp, fp, NULL, addr) < 0)
                                        return (-1);
                                goto nextrec;
                        }

                        if (DTRACEACT_ISPRINTFLIKE(act)) {
                                void *fmtdata;
                                int (*func)(dtrace_hdl_t *, FILE *, void *,
                                    const dtrace_probedata_t *,
                                    const dtrace_recdesc_t *, uint_t,
                                    const void *buf, size_t);

                                if ((fmtdata = dt_format_lookup(dtp,
                                    rec->dtrd_format)) == NULL)
                                        goto nofmt;

                                switch (act) {
                                case DTRACEACT_PRINTF:
                                        func = dtrace_fprintf;
                                        break;
                                case DTRACEACT_PRINTA:
                                        func = dtrace_fprinta;
                                        break;
                                case DTRACEACT_SYSTEM:
                                        func = dtrace_system;
                                        break;
                                case DTRACEACT_FREOPEN:
                                        func = dtrace_freopen;
                                        break;
                                }

                                n = (*func)(dtp, fp, fmtdata, &data,
                                    rec, epd->dtepd_nrecs - i,
                                    (uchar_t *)buf->dtbd_data + offs,
                                    buf->dtbd_size - offs);

                                if (n < 0)
                                        return (-1); /* errno is set for us */

                                if (n > 0)
                                        i += n - 1;
                                goto nextrec;
                        }

                        /*
                         * If this is a DIF expression, and the record has a
                         * format set, this indicates we have a CTF type name
                         * associated with the data and we should try to print
                         * it out by type.
                         */
                        if (act == DTRACEACT_DIFEXPR) {
                                const char *strdata = dt_strdata_lookup(dtp,
                                    rec->dtrd_format);
                                if (strdata != NULL) {
                                        n = dtrace_print(dtp, fp, strdata,
                                            addr, rec->dtrd_size);

                                        /*
                                         * dtrace_print() will return -1 on
                                         * error, or return the number of bytes
                                         * consumed.  It will return 0 if the
                                         * type couldn't be determined, and we
                                         * should fall through to the normal
                                         * trace method.
                                         */
                                        if (n < 0)
                                                return (-1);

                                        if (n > 0)
                                                goto nextrec;
                                }
                        }

nofmt:
                        if (act == DTRACEACT_PRINTA) {
                                dt_print_aggdata_t pd;
                                dtrace_aggvarid_t *aggvars;
                                int j, naggvars = 0;
                                size_t size = ((epd->dtepd_nrecs - i) *
                                    sizeof (dtrace_aggvarid_t));

                                if ((aggvars = dt_alloc(dtp, size)) == NULL)
                                        return (-1);

                                /*
                                 * This might be a printa() with multiple
                                 * aggregation variables.  We need to scan
                                 * forward through the records until we find
                                 * a record from a different statement.
                                 */
                                for (j = i; j < epd->dtepd_nrecs; j++) {
                                        dtrace_recdesc_t *nrec;
                                        caddr_t naddr;

                                        nrec = &epd->dtepd_rec[j];

                                        if (nrec->dtrd_uarg != rec->dtrd_uarg)
                                                break;

                                        if (nrec->dtrd_action != act) {
                                                return (dt_set_errno(dtp,
                                                    EDT_BADAGG));
                                        }

                                        naddr = buf->dtbd_data + offs +
                                            nrec->dtrd_offset;

                                        aggvars[naggvars++] =
                                            /* LINTED - alignment */
                                            *((dtrace_aggvarid_t *)naddr);
                                }

                                i = j - 1;
                                bzero(&pd, sizeof (pd));
                                pd.dtpa_dtp = dtp;
                                pd.dtpa_fp = fp;

                                assert(naggvars >= 1);

                                if (naggvars == 1) {
                                        pd.dtpa_id = aggvars[0];
                                        dt_free(dtp, aggvars);

                                        if (dt_printf(dtp, fp, "\n") < 0 ||
                                            dtrace_aggregate_walk_sorted(dtp,
                                            dt_print_agg, &pd) < 0)
                                                return (-1);
                                        goto nextrec;
                                }

                                if (dt_printf(dtp, fp, "\n") < 0 ||
                                    dtrace_aggregate_walk_joined(dtp, aggvars,
                                    naggvars, dt_print_aggs, &pd) < 0) {
                                        dt_free(dtp, aggvars);
                                        return (-1);
                                }

                                dt_free(dtp, aggvars);
                                goto nextrec;
                        }

                        if (act == DTRACEACT_TRACEMEM) {
                                if (tracememsize == 0 ||
                                    tracememsize > rec->dtrd_size) {
                                        tracememsize = rec->dtrd_size;
                                }

                                n = dt_print_bytes(dtp, fp, addr,
                                    tracememsize, -33, quiet, 1);

                                tracememsize = 0;

                                if (n < 0)
                                        return (-1);

                                goto nextrec;
                        }

                        switch (rec->dtrd_size) {
                        case sizeof (uint64_t):
                                n = dt_printf(dtp, fp,
                                    quiet ? "%lld" : " %16lld",
                                    /* LINTED - alignment */
                                    *((unsigned long long *)addr));
                                break;
                        case sizeof (uint32_t):
                                n = dt_printf(dtp, fp, quiet ? "%d" : " %8d",
                                    /* LINTED - alignment */
                                    *((uint32_t *)addr));
                                break;
                        case sizeof (uint16_t):
                                n = dt_printf(dtp, fp, quiet ? "%d" : " %5d",
                                    /* LINTED - alignment */
                                    *((uint16_t *)addr));
                                break;
                        case sizeof (uint8_t):
                                n = dt_printf(dtp, fp, quiet ? "%d" : " %3d",
                                    *((uint8_t *)addr));
                                break;
                        default:
                                n = dt_print_bytes(dtp, fp, addr,
                                    rec->dtrd_size, -33, quiet, 0);
                                break;
                        }

                        if (n < 0)
                                return (-1); /* errno is set for us */

nextrec:
                        if (dt_buffered_flush(dtp, &data, rec, NULL, 0) < 0)
                                return (-1); /* errno is set for us */
                }

                /*
                 * Call the record callback with a NULL record to indicate
                 * that we're done processing this EPID.
                 */
                rval = (*rfunc)(&data, NULL, arg);
nextepid:
                offs += epd->dtepd_size;
                dtp->dt_last_epid = id;
                if (just_one) {
                        buf->dtbd_oldest = offs;
                        break;
                }
        }

        dtp->dt_flow = data.dtpda_flow;
        dtp->dt_indent = data.dtpda_indent;
        dtp->dt_prefix = data.dtpda_prefix;

        if ((drops = buf->dtbd_drops) == 0)
                return (0);

        /*
         * Explicitly zero the drops to prevent us from processing them again.
         */
        buf->dtbd_drops = 0;

        return (dt_handle_cpudrop(dtp, cpu, DTRACEDROP_PRINCIPAL, drops));
}

/*
 * Reduce memory usage by shrinking the buffer if it's no more than half full.
 * Note, we need to preserve the alignment of the data at dtbd_oldest, which is
 * only 4-byte aligned.
 */
static void
dt_realloc_buf(dtrace_hdl_t *dtp, dtrace_bufdesc_t *buf, int cursize)
{
        uint64_t used = buf->dtbd_size - buf->dtbd_oldest;
        if (used < cursize / 2) {
                int misalign = buf->dtbd_oldest & (sizeof (uint64_t) - 1);
                char *newdata = dt_alloc(dtp, used + misalign);
                if (newdata == NULL)
                        return;
                bzero(newdata, misalign);
                bcopy(buf->dtbd_data + buf->dtbd_oldest,
                    newdata + misalign, used);
                dt_free(dtp, buf->dtbd_data);
                buf->dtbd_oldest = misalign;
                buf->dtbd_size = used + misalign;
                buf->dtbd_data = newdata;
        }
}

/*
 * If the ring buffer has wrapped, the data is not in order.  Rearrange it
 * so that it is.  Note, we need to preserve the alignment of the data at
 * dtbd_oldest, which is only 4-byte aligned.
 */
static int
dt_unring_buf(dtrace_hdl_t *dtp, dtrace_bufdesc_t *buf)
{
        int misalign;
        char *newdata, *ndp;

        if (buf->dtbd_oldest == 0)
                return (0);

        misalign = buf->dtbd_oldest & (sizeof (uint64_t) - 1);
        newdata = ndp = dt_alloc(dtp, buf->dtbd_size + misalign);

        if (newdata == NULL)
                return (-1);

        assert(0 == (buf->dtbd_size & (sizeof (uint64_t) - 1)));

        bzero(ndp, misalign);
        ndp += misalign;

        bcopy(buf->dtbd_data + buf->dtbd_oldest, ndp,
            buf->dtbd_size - buf->dtbd_oldest);
        ndp += buf->dtbd_size - buf->dtbd_oldest;

        bcopy(buf->dtbd_data, ndp, buf->dtbd_oldest);

        dt_free(dtp, buf->dtbd_data);
        buf->dtbd_oldest = 0;
        buf->dtbd_data = newdata;
        buf->dtbd_size += misalign;

        return (0);
}

static void
dt_put_buf(dtrace_hdl_t *dtp, dtrace_bufdesc_t *buf)
{
        dt_free(dtp, buf->dtbd_data);
        dt_free(dtp, buf);
}

/*
 * Returns 0 on success, in which case *cbp will be filled in if we retrieved
 * data, or NULL if there is no data for this CPU.
 * Returns -1 on failure and sets dt_errno.
 */
static int
dt_get_buf(dtrace_hdl_t *dtp, int cpu, dtrace_bufdesc_t **bufp)
{
        dtrace_optval_t size;
        dtrace_bufdesc_t *buf = dt_zalloc(dtp, sizeof (*buf));
        int error;

        if (buf == NULL)
                return (-1);

        (void) dtrace_getopt(dtp, "bufsize", &size);
        buf->dtbd_data = dt_alloc(dtp, size);
        if (buf->dtbd_data == NULL) {
                dt_free(dtp, buf);
                return (-1);
        }
        buf->dtbd_size = size;
        buf->dtbd_cpu = cpu;

        if (dt_ioctl(dtp, DTRACEIOC_BUFSNAP, buf) == -1) {
                dt_put_buf(dtp, buf);
                /*
                 * If we failed with ENOENT, it may be because the
                 * CPU was unconfigured -- this is okay.  Any other
                 * error, however, is unexpected.
                 */
                if (errno == ENOENT) {
                        *bufp = NULL;
                        return (0);
                }

                return (dt_set_errno(dtp, errno));
        }

        error = dt_unring_buf(dtp, buf);
        if (error != 0) {
                dt_put_buf(dtp, buf);
                return (error);
        }
        dt_realloc_buf(dtp, buf, size);

        *bufp = buf;
        return (0);
}

typedef struct dt_begin {
        dtrace_consume_probe_f *dtbgn_probefunc;
        dtrace_consume_rec_f *dtbgn_recfunc;
        void *dtbgn_arg;
        dtrace_handle_err_f *dtbgn_errhdlr;
        void *dtbgn_errarg;
        int dtbgn_beginonly;
} dt_begin_t;

static int
dt_consume_begin_probe(const dtrace_probedata_t *data, void *arg)
{
        dt_begin_t *begin = arg;
        dtrace_probedesc_t *pd = data->dtpda_pdesc;

        int r1 = (strcmp(pd->dtpd_provider, "dtrace") == 0);
        int r2 = (strcmp(pd->dtpd_name, "BEGIN") == 0);

        if (begin->dtbgn_beginonly) {
                if (!(r1 && r2))
                        return (DTRACE_CONSUME_NEXT);
        } else {
                if (r1 && r2)
                        return (DTRACE_CONSUME_NEXT);
        }

        /*
         * We have a record that we're interested in.  Now call the underlying
         * probe function...
         */
        return (begin->dtbgn_probefunc(data, begin->dtbgn_arg));
}

static int
dt_consume_begin_record(const dtrace_probedata_t *data,
    const dtrace_recdesc_t *rec, void *arg)
{
        dt_begin_t *begin = arg;

        return (begin->dtbgn_recfunc(data, rec, begin->dtbgn_arg));
}

static int
dt_consume_begin_error(const dtrace_errdata_t *data, void *arg)
{
        dt_begin_t *begin = (dt_begin_t *)arg;
        dtrace_probedesc_t *pd = data->dteda_pdesc;

        int r1 = (strcmp(pd->dtpd_provider, "dtrace") == 0);
        int r2 = (strcmp(pd->dtpd_name, "BEGIN") == 0);

        if (begin->dtbgn_beginonly) {
                if (!(r1 && r2))
                        return (DTRACE_HANDLE_OK);
        } else {
                if (r1 && r2)
                        return (DTRACE_HANDLE_OK);
        }

        return (begin->dtbgn_errhdlr(data, begin->dtbgn_errarg));
}

static int
dt_consume_begin(dtrace_hdl_t *dtp, FILE *fp,
    dtrace_consume_probe_f *pf, dtrace_consume_rec_f *rf, void *arg)
{
        /*
         * There's this idea that the BEGIN probe should be processed before
         * everything else, and that the END probe should be processed after
         * anything else.  In the common case, this is pretty easy to deal
         * with.  However, a situation may arise where the BEGIN enabling and
         * END enabling are on the same CPU, and some enabling in the middle
         * occurred on a different CPU.  To deal with this (blech!) we need to
         * consume the BEGIN buffer up until the end of the BEGIN probe, and
         * then set it aside.  We will then process every other CPU, and then
         * we'll return to the BEGIN CPU and process the rest of the data
         * (which will inevitably include the END probe, if any).  Making this
         * even more complicated (!) is the library's ERROR enabling.  Because
         * this enabling is processed before we even get into the consume call
         * back, any ERROR firing would result in the library's ERROR enabling
         * being processed twice -- once in our first pass (for BEGIN probes),
         * and again in our second pass (for everything but BEGIN probes).  To
         * deal with this, we interpose on the ERROR handler to assure that we
         * only process ERROR enablings induced by BEGIN enablings in the
         * first pass, and that we only process ERROR enablings _not_ induced
         * by BEGIN enablings in the second pass.
         */

        dt_begin_t begin;
        processorid_t cpu = dtp->dt_beganon;
        int rval, i;
        static int max_ncpus;
        dtrace_bufdesc_t *buf;

        dtp->dt_beganon = -1;

        if (dt_get_buf(dtp, cpu, &buf) != 0)
                return (-1);
        if (buf == NULL)
                return (0);

        if (!dtp->dt_stopped || buf->dtbd_cpu != dtp->dt_endedon) {
                /*
                 * This is the simple case.  We're either not stopped, or if
                 * we are, we actually processed any END probes on another
                 * CPU.  We can simply consume this buffer and return.
                 */
                rval = dt_consume_cpu(dtp, fp, cpu, buf, B_FALSE,
                    pf, rf, arg);
                dt_put_buf(dtp, buf);
                return (rval);
        }

        begin.dtbgn_probefunc = pf;
        begin.dtbgn_recfunc = rf;
        begin.dtbgn_arg = arg;
        begin.dtbgn_beginonly = 1;

        /*
         * We need to interpose on the ERROR handler to be sure that we
         * only process ERRORs induced by BEGIN.
         */
        begin.dtbgn_errhdlr = dtp->dt_errhdlr;
        begin.dtbgn_errarg = dtp->dt_errarg;
        dtp->dt_errhdlr = dt_consume_begin_error;
        dtp->dt_errarg = &begin;

        rval = dt_consume_cpu(dtp, fp, cpu, buf, B_FALSE,
            dt_consume_begin_probe, dt_consume_begin_record, &begin);

        dtp->dt_errhdlr = begin.dtbgn_errhdlr;
        dtp->dt_errarg = begin.dtbgn_errarg;

        if (rval != 0) {
                dt_put_buf(dtp, buf);
                return (rval);
        }

        if (max_ncpus == 0)
                max_ncpus = dt_sysconf(dtp, _SC_CPUID_MAX) + 1;

        for (i = 0; i < max_ncpus; i++) {
                dtrace_bufdesc_t *nbuf;
                if (i == cpu)
                        continue;

                if (dt_get_buf(dtp, i, &nbuf) != 0) {
                        dt_put_buf(dtp, buf);
                        return (-1);
                }
                if (nbuf == NULL)
                        continue;

                rval = dt_consume_cpu(dtp, fp, i, nbuf, B_FALSE,
                    pf, rf, arg);
                dt_put_buf(dtp, nbuf);
                if (rval != 0) {
                        dt_put_buf(dtp, buf);
                        return (rval);
                }
        }

        /*
         * Okay -- we're done with the other buffers.  Now we want to
         * reconsume the first buffer -- but this time we're looking for
         * everything _but_ BEGIN.  And of course, in order to only consume
         * those ERRORs _not_ associated with BEGIN, we need to reinstall our
         * ERROR interposition function...
         */
        begin.dtbgn_beginonly = 0;

        assert(begin.dtbgn_errhdlr == dtp->dt_errhdlr);
        assert(begin.dtbgn_errarg == dtp->dt_errarg);
        dtp->dt_errhdlr = dt_consume_begin_error;
        dtp->dt_errarg = &begin;

        rval = dt_consume_cpu(dtp, fp, cpu, buf, B_FALSE,
            dt_consume_begin_probe, dt_consume_begin_record, &begin);

        dtp->dt_errhdlr = begin.dtbgn_errhdlr;
        dtp->dt_errarg = begin.dtbgn_errarg;

        return (rval);
}

/* ARGSUSED */
static uint64_t
dt_buf_oldest(void *elem, void *arg)
{
        dtrace_bufdesc_t *buf = elem;
        size_t offs = buf->dtbd_oldest;

        while (offs < buf->dtbd_size) {
                dtrace_rechdr_t *dtrh =
                    /* LINTED - alignment */
                    (dtrace_rechdr_t *)(buf->dtbd_data + offs);
                if (dtrh->dtrh_epid == DTRACE_EPIDNONE) {
                        offs += sizeof (dtrace_epid_t);
                } else {
                        return (DTRACE_RECORD_LOAD_TIMESTAMP(dtrh));
                }
        }

        /* There are no records left; use the time the buffer was retrieved. */
        return (buf->dtbd_timestamp);
}

int
dtrace_consume(dtrace_hdl_t *dtp, FILE *fp,
    dtrace_consume_probe_f *pf, dtrace_consume_rec_f *rf, void *arg)
{
        dtrace_optval_t size;
        static int max_ncpus;
        int i, rval;
        dtrace_optval_t interval = dtp->dt_options[DTRACEOPT_SWITCHRATE];
        hrtime_t now = gethrtime();

        if (dtp->dt_lastswitch != 0) {
                if (now - dtp->dt_lastswitch < interval)
                        return (0);

                dtp->dt_lastswitch += interval;
        } else {
                dtp->dt_lastswitch = now;
        }

        if (!dtp->dt_active)
                return (dt_set_errno(dtp, EINVAL));

        if (max_ncpus == 0)
                max_ncpus = dt_sysconf(dtp, _SC_CPUID_MAX) + 1;

        if (pf == NULL)
                pf = (dtrace_consume_probe_f *)dt_nullprobe;

        if (rf == NULL)
                rf = (dtrace_consume_rec_f *)dt_nullrec;

        if (dtp->dt_options[DTRACEOPT_TEMPORAL] == DTRACEOPT_UNSET) {
                /*
                 * The output will not be in the order it was traced.  Rather,
                 * we will consume all of the data from each CPU's buffer in
                 * turn.  We apply special handling for the records from BEGIN
                 * and END probes so that they are consumed first and last,
                 * respectively.
                 *
                 * If we have just begun, we want to first process the CPU that
                 * executed the BEGIN probe (if any).
                 */
                if (dtp->dt_active && dtp->dt_beganon != -1 &&
                    (rval = dt_consume_begin(dtp, fp, pf, rf, arg)) != 0)
                        return (rval);

                for (i = 0; i < max_ncpus; i++) {
                        dtrace_bufdesc_t *buf;

                        /*
                         * If we have stopped, we want to process the CPU on
                         * which the END probe was processed only _after_ we
                         * have processed everything else.
                         */
                        if (dtp->dt_stopped && (i == dtp->dt_endedon))
                                continue;

                        if (dt_get_buf(dtp, i, &buf) != 0)
                                return (-1);
                        if (buf == NULL)
                                continue;

                        dtp->dt_flow = 0;
                        dtp->dt_indent = 0;
                        dtp->dt_prefix = NULL;
                        rval = dt_consume_cpu(dtp, fp, i,
                            buf, B_FALSE, pf, rf, arg);
                        dt_put_buf(dtp, buf);
                        if (rval != 0)
                                return (rval);
                }
                if (dtp->dt_stopped) {
                        dtrace_bufdesc_t *buf;

                        if (dt_get_buf(dtp, dtp->dt_endedon, &buf) != 0)
                                return (-1);
                        if (buf == NULL)
                                return (0);

                        rval = dt_consume_cpu(dtp, fp, dtp->dt_endedon,
                            buf, B_FALSE, pf, rf, arg);
                        dt_put_buf(dtp, buf);
                        return (rval);
                }
        } else {
                /*
                 * The output will be in the order it was traced (or for
                 * speculations, when it was committed).  We retrieve a buffer
                 * from each CPU and put it into a priority queue, which sorts
                 * based on the first entry in the buffer.  This is sufficient
                 * because entries within a buffer are already sorted.
                 *
                 * We then consume records one at a time, always consuming the
                 * oldest record, as determined by the priority queue.  When
                 * we reach the end of the time covered by these buffers,
                 * we need to stop and retrieve more records on the next pass.
                 * The kernel tells us the time covered by each buffer, in
                 * dtbd_timestamp.  The first buffer's timestamp tells us the
                 * time covered by all buffers, as subsequently retrieved
                 * buffers will cover to a more recent time.
                 */

                uint64_t *drops = alloca(max_ncpus * sizeof (uint64_t));
                uint64_t first_timestamp = 0;
                uint_t cookie = 0;
                dtrace_bufdesc_t *buf;

                bzero(drops, max_ncpus * sizeof (uint64_t));

                if (dtp->dt_bufq == NULL) {
                        dtp->dt_bufq = dt_pq_init(dtp, max_ncpus * 2,
                            dt_buf_oldest, NULL);
                        if (dtp->dt_bufq == NULL) /* ENOMEM */
                                return (-1);
                }

                /* Retrieve data from each CPU. */
                (void) dtrace_getopt(dtp, "bufsize", &size);
                for (i = 0; i < max_ncpus; i++) {
                        dtrace_bufdesc_t *buf;

                        if (dt_get_buf(dtp, i, &buf) != 0)
                                return (-1);
                        if (buf != NULL) {
                                if (first_timestamp == 0)
                                        first_timestamp = buf->dtbd_timestamp;
                                assert(buf->dtbd_timestamp >= first_timestamp);

                                dt_pq_insert(dtp->dt_bufq, buf);
                                drops[i] = buf->dtbd_drops;
                                buf->dtbd_drops = 0;
                        }
                }

                /* Consume records. */
                for (;;) {
                        dtrace_bufdesc_t *buf = dt_pq_pop(dtp->dt_bufq);
                        uint64_t timestamp;

                        if (buf == NULL)
                                break;

                        timestamp = dt_buf_oldest(buf, dtp);
                        assert(timestamp >= dtp->dt_last_timestamp);
                        dtp->dt_last_timestamp = timestamp;

                        if (timestamp == buf->dtbd_timestamp) {
                                /*
                                 * We've reached the end of the time covered
                                 * by this buffer.  If this is the oldest
                                 * buffer, we must do another pass
                                 * to retrieve more data.
                                 */
                                dt_put_buf(dtp, buf);
                                if (timestamp == first_timestamp &&
                                    !dtp->dt_stopped)
                                        break;
                                continue;
                        }

                        if ((rval = dt_consume_cpu(dtp, fp,
                            buf->dtbd_cpu, buf, B_TRUE, pf, rf, arg)) != 0)
                                return (rval);
                        dt_pq_insert(dtp->dt_bufq, buf);
                }

                /* Consume drops. */
                for (i = 0; i < max_ncpus; i++) {
                        if (drops[i] != 0) {
                                int error = dt_handle_cpudrop(dtp, i,
                                    DTRACEDROP_PRINCIPAL, drops[i]);
                                if (error != 0)
                                        return (error);
                        }
                }

                /*
                 * Reduce memory usage by re-allocating smaller buffers
                 * for the "remnants".
                 */
                while (buf = dt_pq_walk(dtp->dt_bufq, &cookie))
                        dt_realloc_buf(dtp, buf, buf->dtbd_size);
        }

        return (0);
}