sparc/dtrace/sdt.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) 2012, Joyent, Inc. All rights reserved.
 */

#include <sys/modctl.h>
#include <sys/sunddi.h>
#include <sys/dtrace.h>
#include <sys/kobj.h>
#include <sys/stat.h>
#include <sys/conf.h>
#include <vm/seg_kmem.h>
#include <sys/stack.h>
#include <sys/sdt_impl.h>

static dev_info_t       *sdt_devi;

int sdt_verbose = 0;

#define SDT_REG_G0      0
#define SDT_REG_O0      8
#define SDT_REG_O1      9
#define SDT_REG_O2      10
#define SDT_REG_O3      11
#define SDT_REG_O4      12
#define SDT_REG_O5      13
#define SDT_REG_I0      24
#define SDT_REG_I1      25
#define SDT_REG_I2      26
#define SDT_REG_I3      27
#define SDT_REG_I4      28
#define SDT_REG_I5      29

#define SDT_SIMM13_MASK     0x1fff
#define SDT_SIMM13_MAX      ((int32_t)0xfff)
#define SDT_CALL(from, to)  (((uint32_t)1 << 30) | \
                (((uintptr_t)(to) - (uintptr_t)(from) >> 2) & \
                0x3fffffff))
#define SDT_SAVE        (0x9de3a000 | (-SA(MINFRAME) & SDT_SIMM13_MASK))
#define SDT_RET         0x81c7e008
#define SDT_RESTORE     0x81e80000

#define SDT_OP_SETHI        0x1000000
#define SDT_OP_OR       0x80100000

#define SDT_FMT2_RD_SHIFT   25
#define SDT_IMM22_SHIFT     10
#define SDT_IMM22_MASK      0x3fffff
#define SDT_IMM10_MASK      0x3ff

#define SDT_FMT3_RD_SHIFT   25
#define SDT_FMT3_RS1_SHIFT  14
#define SDT_FMT3_RS2_SHIFT  0
#define SDT_FMT3_IMM        (1 << 13)

#define SDT_MOV(rs, rd) \
    (SDT_OP_OR | (SDT_REG_G0 << SDT_FMT3_RS1_SHIFT) | \
    ((rs) << SDT_FMT3_RS2_SHIFT) | ((rd) << SDT_FMT3_RD_SHIFT))

#define SDT_ORLO(rs, val, rd) \
    (SDT_OP_OR | ((rs) << SDT_FMT3_RS1_SHIFT) | \
    ((rd) << SDT_FMT3_RD_SHIFT) | SDT_FMT3_IMM | ((val) & SDT_IMM10_MASK))

#define SDT_ORSIMM13(rs, val, rd) \
    (SDT_OP_OR | ((rs) << SDT_FMT3_RS1_SHIFT) | \
    ((rd) << SDT_FMT3_RD_SHIFT) | SDT_FMT3_IMM | ((val) & SDT_SIMM13_MASK))

#define SDT_SETHI(val, reg) \
    (SDT_OP_SETHI | (reg << SDT_FMT2_RD_SHIFT) | \
    ((val >> SDT_IMM22_SHIFT) & SDT_IMM22_MASK))

#define SDT_ENTRY_SIZE  (11 * sizeof (uint32_t))

static void
sdt_initialize(sdt_probe_t *sdp, uint32_t **trampoline)
{
    uint32_t *instr = *trampoline;

    *instr++ = SDT_SAVE;

    if (sdp->sdp_id > (uint32_t)SDT_SIMM13_MAX)  {
        *instr++ = SDT_SETHI(sdp->sdp_id, SDT_REG_O0);
        *instr++ = SDT_ORLO(SDT_REG_O0, sdp->sdp_id, SDT_REG_O0);
    } else {
        *instr++ = SDT_ORSIMM13(SDT_REG_G0, sdp->sdp_id, SDT_REG_O0);
    }

    *instr++ = SDT_MOV(SDT_REG_I0, SDT_REG_O1);
    *instr++ = SDT_MOV(SDT_REG_I1, SDT_REG_O2);
    *instr++ = SDT_MOV(SDT_REG_I2, SDT_REG_O3);
    *instr++ = SDT_MOV(SDT_REG_I3, SDT_REG_O4);
    *instr = SDT_CALL(instr, dtrace_probe);
    instr++;
    *instr++ = SDT_MOV(SDT_REG_I4, SDT_REG_O5);

    *instr++ = SDT_RET;
    *instr++ = SDT_RESTORE;
    *trampoline = instr;
}

/*ARGSUSED*/
static void
sdt_provide_module(void *arg, struct modctl *ctl)
{
    struct module *mp = ctl->mod_mp;
    char *modname = ctl->mod_modname;
    int primary, nprobes = 0;
    sdt_probedesc_t *sdpd;
    sdt_probe_t *sdp, *old;
    uint32_t *tab;
    sdt_provider_t *prov;
    int len;

    /*
     * One for all, and all for one:  if we haven't yet registered all of
     * our providers, we'll refuse to provide anything.
     */
    for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
        if (prov->sdtp_id == DTRACE_PROVNONE)
            return;
    }

    if (mp->sdt_nprobes != 0 || (sdpd = mp->sdt_probes) == NULL)
        return;

    kobj_textwin_alloc(mp);

    /*
     * Hack to identify unix/genunix/krtld.
     */
    primary = vmem_contains(heap_arena, (void *)ctl,
        sizeof (struct modctl)) == 0;

    /*
     * If there hasn't been an sdt table allocated, we'll do so now.
     */
    if (mp->sdt_tab == NULL) {
        for (; sdpd != NULL; sdpd = sdpd->sdpd_next) {
            nprobes++;
        }

        /*
         * We could (should?) determine precisely the size of the
         * table -- but a reasonable maximum will suffice.
         */
        mp->sdt_size = nprobes * SDT_ENTRY_SIZE;
        mp->sdt_tab = kobj_texthole_alloc(mp->text, mp->sdt_size);

        if (mp->sdt_tab == NULL) {
            cmn_err(CE_WARN, "couldn't allocate SDT table "
                "for module %s", modname);
            return;
        }
    }

    tab = (uint32_t *)mp->sdt_tab;

    for (sdpd = mp->sdt_probes; sdpd != NULL; sdpd = sdpd->sdpd_next) {
        char *name = sdpd->sdpd_name, *func, *nname;
        int i, j;
        sdt_provider_t *prov;
        ulong_t offs;
        dtrace_id_t id;

        for (prov = sdt_providers; prov->sdtp_prefix != NULL; prov++) {
            char *prefix = prov->sdtp_prefix;

            if (strncmp(name, prefix, strlen(prefix)) == 0) {
                name += strlen(prefix);
                break;
            }
        }

        nname = kmem_alloc(len = strlen(name) + 1, KM_SLEEP);

        for (i = 0, j = 0; name[j] != '\0'; i++) {
            if (name[j] == '_' && name[j + 1] == '_') {
                nname[i] = '-';
                j += 2;
            } else {
                nname[i] = name[j++];
            }
        }

        nname[i] = '\0';

        sdp = kmem_zalloc(sizeof (sdt_probe_t), KM_SLEEP);
        sdp->sdp_loadcnt = ctl->mod_loadcnt;
        sdp->sdp_primary = primary;
        sdp->sdp_ctl = ctl;
        sdp->sdp_name = nname;
        sdp->sdp_namelen = len;
        sdp->sdp_provider = prov;

        func = kobj_searchsym(mp, sdpd->sdpd_offset +
            (uintptr_t)mp->text, &offs);

        if (func == NULL)
            func = "<unknown>";

        /*
         * We have our provider.  Now create the probe.
         */
        if ((id = dtrace_probe_lookup(prov->sdtp_id, modname,
            func, nname)) != DTRACE_IDNONE) {
            old = dtrace_probe_arg(prov->sdtp_id, id);
            ASSERT(old != NULL);

            sdp->sdp_next = old->sdp_next;
            sdp->sdp_id = id;
            old->sdp_next = sdp;
        } else {
            sdp->sdp_id = dtrace_probe_create(prov->sdtp_id,
                modname, func, nname, 1, sdp);

            mp->sdt_nprobes++;
        }

        sdp->sdp_patchval = SDT_CALL((uintptr_t)mp->text +
            sdpd->sdpd_offset, tab);
        sdp->sdp_patchpoint = (uint32_t *)((uintptr_t)mp->textwin +
            sdpd->sdpd_offset);
        sdp->sdp_savedval = *sdp->sdp_patchpoint;
        sdt_initialize(sdp, &tab);
    }
}

/*ARGSUSED*/
static void
sdt_destroy(void *arg, dtrace_id_t id, void *parg)
{
    sdt_probe_t *sdp = parg, *old;
    struct modctl *ctl = sdp->sdp_ctl;

    if (ctl != NULL && ctl->mod_loadcnt == sdp->sdp_loadcnt) {
        if ((ctl->mod_loadcnt == sdp->sdp_loadcnt &&
            ctl->mod_loaded) || sdp->sdp_primary) {
            ((struct module *)(ctl->mod_mp))->sdt_nprobes--;
        }
    }

    while (sdp != NULL) {
        old = sdp;
        kmem_free(sdp->sdp_name, sdp->sdp_namelen);
        sdp = sdp->sdp_next;
        kmem_free(old, sizeof (sdt_probe_t));
    }
}

/*ARGSUSED*/
static int
sdt_enable(void *arg, dtrace_id_t id, void *parg)
{
    sdt_probe_t *sdp = parg;
    struct modctl *ctl = sdp->sdp_ctl;

    ctl->mod_nenabled++;

    /*
     * If this module has disappeared since we discovered its probes,
     * refuse to enable it.
     */
    if (!sdp->sdp_primary && !ctl->mod_loaded) {
        if (sdt_verbose) {
            cmn_err(CE_NOTE, "sdt is failing for probe %s "
                "(module %s unloaded)",
                sdp->sdp_name, ctl->mod_modname);
        }
        goto err;
    }

    /*
     * Now check that our modctl has the expected load count.  If it
     * doesn't, this module must have been unloaded and reloaded -- and
     * we're not going to touch it.
     */
    if (ctl->mod_loadcnt != sdp->sdp_loadcnt) {
        if (sdt_verbose) {
            cmn_err(CE_NOTE, "sdt is failing for probe %s "
                "(module %s reloaded)",
                sdp->sdp_name, ctl->mod_modname);
        }
        goto err;
    }

    while (sdp != NULL) {
        *sdp->sdp_patchpoint = sdp->sdp_patchval;
        sdp = sdp->sdp_next;
    }

err:
    return (0);
}

/*ARGSUSED*/
static void
sdt_disable(void *arg, dtrace_id_t id, void *parg)
{
    sdt_probe_t *sdp = parg;
    struct modctl *ctl = sdp->sdp_ctl;

    ASSERT(ctl->mod_nenabled > 0);
    ctl->mod_nenabled--;

    if ((!sdp->sdp_primary && !ctl->mod_loaded) ||
        (ctl->mod_loadcnt != sdp->sdp_loadcnt))
        goto err;

    while (sdp != NULL) {
        *sdp->sdp_patchpoint = sdp->sdp_savedval;
        sdp = sdp->sdp_next;
    }

err:
    ;
}

static dtrace_pops_t sdt_pops = {
    NULL,
    sdt_provide_module,
    sdt_enable,
    sdt_disable,
    NULL,
    NULL,
    sdt_getargdesc,
    NULL,
    NULL,
    sdt_destroy
};

static int
sdt_attach(dev_info_t *devi, ddi_attach_cmd_t cmd)
{
    sdt_provider_t *prov;

    switch (cmd) {
    case DDI_ATTACH:
        break;
    case DDI_RESUME:
        return (DDI_SUCCESS);
    default:
        return (DDI_FAILURE);
    }

    if (ddi_create_minor_node(devi, "sdt", S_IFCHR, 0,
        DDI_PSEUDO, NULL) == DDI_FAILURE) {
        ddi_remove_minor_node(devi, NULL);
        return (DDI_FAILURE);
    }

    ddi_report_dev(devi);
    sdt_devi = devi;

    for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
        uint32_t priv;

        if (prov->sdtp_priv == DTRACE_PRIV_NONE) {
            priv = DTRACE_PRIV_KERNEL;
            sdt_pops.dtps_mode = NULL;
        } else {
            priv = prov->sdtp_priv;
            ASSERT(priv == DTRACE_PRIV_USER);
            sdt_pops.dtps_mode = sdt_mode;
        }

        if (dtrace_register(prov->sdtp_name, prov->sdtp_attr,
            priv, NULL, &sdt_pops, prov, &prov->sdtp_id) != 0) {
            cmn_err(CE_WARN, "failed to register sdt provider %s",
                prov->sdtp_name);
        }
    }

    return (DDI_SUCCESS);
}

static int
sdt_detach(dev_info_t *devi, ddi_detach_cmd_t cmd)
{
    sdt_provider_t *prov;

    switch (cmd) {
    case DDI_DETACH:
        break;
    case DDI_SUSPEND:
        return (DDI_SUCCESS);
    default:
        return (DDI_FAILURE);
    }

    for (prov = sdt_providers; prov->sdtp_name != NULL; prov++) {
        if (prov->sdtp_id != DTRACE_PROVNONE) {
            if (dtrace_unregister(prov->sdtp_id) != 0)
                return (DDI_FAILURE);
            prov->sdtp_id = DTRACE_PROVNONE;
        }
    }

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

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

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

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

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

static struct dev_ops sdt_ops = {
    DEVO_REV,       /* devo_rev, */
    0,          /* refcnt  */
    sdt_info,       /* get_dev_info */
    nulldev,        /* identify */
    nulldev,        /* probe */
    sdt_attach,     /* attach */
    sdt_detach,     /* detach */
    nodev,          /* reset */
    &sdt_cb_ops,        /* driver operations */
    NULL,           /* bus operations */
    nodev,          /* dev power */
    ddi_quiesce_not_needed,     /* quiesce */
};

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

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

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

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

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