intel/dtrace/sdt.c

	sdt.c revision b0f673c4626e4cb1db7785287eaeed2731dfefe8
/*
 * 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/frame.h>
#include <sys/dtrace_impl.h>
#include <sys/cmn_err.h>
#include <sys/sysmacros.h>
#include <sys/privregs.h>
#include <sys/sdt_impl.h>

#define SDT_PATCHVAL    0xf0
#define SDT_ADDR2NDX(addr)  ((((uintptr_t)(addr)) >> 4) & sdt_probetab_mask)
#define SDT_PROBETAB_SIZE   0x1000      /* 4k entries -- 16K total */

static dev_info_t       *sdt_devi;
static int          sdt_verbose = 0;
static sdt_probe_t      **sdt_probetab;
static int          sdt_probetab_size;
static int          sdt_probetab_mask;

/*ARGSUSED*/
static int
sdt_invop(uintptr_t addr, uintptr_t *stack, uintptr_t eax)
{
    uintptr_t stack0, stack1, stack2, stack3, stack4;
    int i = 0;
    sdt_probe_t *sdt = sdt_probetab[SDT_ADDR2NDX(addr)];

#ifdef __amd64
    /*
     * On amd64, stack[0] contains the dereferenced stack pointer,
     * stack[1] contains savfp, stack[2] contains savpc.  We want
     * to step over these entries.
     */
    i += 3;
#endif

    for (; sdt != NULL; sdt = sdt->sdp_hashnext) {
        if ((uintptr_t)sdt->sdp_patchpoint == addr) {
            /*
             * When accessing the arguments on the stack, we must
             * protect against accessing beyond the stack.  We can
             * safely set NOFAULT here -- we know that interrupts
             * are already disabled.
             */
            DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
            stack0 = stack[i++];
            stack1 = stack[i++];
            stack2 = stack[i++];
            stack3 = stack[i++];
            stack4 = stack[i++];
            DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT |
                CPU_DTRACE_BADADDR);

            dtrace_probe(sdt->sdp_id, stack0, stack1,
                stack2, stack3, stack4);

            return (DTRACE_INVOP_NOP);
        }
    }

    return (0);
}

/*ARGSUSED*/
static void
sdt_provide_module(void *arg, struct modctl *ctl)
{
    struct module *mp = ctl->mod_mp;
    char *modname = ctl->mod_modname;
    sdt_probedesc_t *sdpd;
    sdt_probe_t *sdp, *old;
    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;

    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_ctl = ctl;
        sdp->sdp_name = nname;
        sdp->sdp_namelen = len;
        sdp->sdp_provider = prov;

        func = kobj_searchsym(mp, sdpd->sdpd_offset, &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, 3, sdp);

            mp->sdt_nprobes++;
        }

        sdp->sdp_hashnext =
            sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)];
        sdt_probetab[SDT_ADDR2NDX(sdpd->sdpd_offset)] = sdp;

        sdp->sdp_patchval = SDT_PATCHVAL;
        sdp->sdp_patchpoint = (uint8_t *)sdpd->sdpd_offset;
        sdp->sdp_savedval = *sdp->sdp_patchpoint;
    }
}

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

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

    while (sdp != NULL) {
        old = sdp;

        /*
         * Now we need to remove this probe from the sdt_probetab.
         */
        ndx = SDT_ADDR2NDX(sdp->sdp_patchpoint);
        last = NULL;
        hash = sdt_probetab[ndx];

        while (hash != sdp) {
            ASSERT(hash != NULL);
            last = hash;
            hash = hash->sdp_hashnext;
        }

        if (last != NULL) {
            last->sdp_hashnext = sdp->sdp_hashnext;
        } else {
            sdt_probetab[ndx] = sdp->sdp_hashnext;
        }

        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 (!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;

    ctl->mod_nenabled--;

    if (!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:
    ;
}

/*ARGSUSED*/
uint64_t
sdt_getarg(void *arg, dtrace_id_t id, void *parg, int argno, int aframes)
{
    uintptr_t val;
    struct frame *fp = (struct frame *)dtrace_getfp();
    uintptr_t *stack;
    int i;
#if defined(__amd64)
    /*
     * A total of 6 arguments are passed via registers; any argument with
     * index of 5 or lower is therefore in a register.
     */
    int inreg = 5;
#endif

    for (i = 1; i <= aframes; i++) {
        fp = (struct frame *)(fp->fr_savfp);

        if (fp->fr_savpc == (pc_t)dtrace_invop_callsite) {
#if !defined(__amd64)
            /*
             * If we pass through the invalid op handler, we will
             * use the pointer that it passed to the stack as the
             * second argument to dtrace_invop() as the pointer to
             * the stack.
             */
            stack = ((uintptr_t **)&fp[1])[1];
#else
            /*
             * In the case of amd64, we will use the pointer to the
             * regs structure that was pushed when we took the
             * trap.  To get this structure, we must increment
             * beyond the frame structure.  If the argument that
             * we're seeking is passed on the stack, we'll pull
             * the true stack pointer out of the saved registers
             * and decrement our argument by the number of
             * arguments passed in registers; if the argument
             * we're seeking is passed in regsiters, we can just
             * load it directly.
             */
            struct regs *rp = (struct regs *)((uintptr_t)&fp[1] +
                sizeof (uintptr_t));

            if (argno <= inreg) {
                stack = (uintptr_t *)&rp->r_rdi;
            } else {
                stack = (uintptr_t *)(rp->r_rsp);
                argno -= (inreg + 1);
            }
#endif
            goto load;
        }
    }

    /*
     * We know that we did not come through a trap to get into
     * dtrace_probe() -- the provider simply called dtrace_probe()
     * directly.  As this is the case, we need to shift the argument
     * that we're looking for:  the probe ID is the first argument to
     * dtrace_probe(), so the argument n will actually be found where
     * one would expect to find argument (n + 1).
     */
    argno++;

#if defined(__amd64)
    if (argno <= inreg) {
        /*
         * This shouldn't happen.  If the argument is passed in a
         * register then it should have been, well, passed in a
         * register...
         */
        DTRACE_CPUFLAG_SET(CPU_DTRACE_ILLOP);
        return (0);
    }

    argno -= (inreg + 1);
#endif
    stack = (uintptr_t *)&fp[1];

load:
    DTRACE_CPUFLAG_SET(CPU_DTRACE_NOFAULT);
    val = stack[argno];
    DTRACE_CPUFLAG_CLEAR(CPU_DTRACE_NOFAULT);

    return (val);
}

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

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

    if (ddi_create_minor_node(devi, "sdt", S_IFCHR,
        0, DDI_PSEUDO, NULL) == DDI_FAILURE) {
        cmn_err(CE_NOTE, "/dev/sdt couldn't create minor node");
        ddi_remove_minor_node(devi, NULL);
        return (DDI_FAILURE);
    }

    ddi_report_dev(devi);
    sdt_devi = devi;

    if (sdt_probetab_size == 0)
        sdt_probetab_size = SDT_PROBETAB_SIZE;

    sdt_probetab_mask = sdt_probetab_size - 1;
    sdt_probetab =
        kmem_zalloc(sdt_probetab_size * sizeof (sdt_probe_t *), KM_SLEEP);
    dtrace_invop_add(sdt_invop);

    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);
}

/*ARGSUSED*/
static int
sdt_detach(dev_info_t *dip, 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;
        }
    }

    dtrace_invop_remove(sdt_invop);
    kmem_free(sdt_probetab, sdt_probetab_size * sizeof (sdt_probe_t *));

    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));
}