8322 nl: misleading-indentation

[unleashed/tickless.git] / usr / src / lib / libtnfctl / probes.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (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 (c) 1994, by Sun Microsytems, Inc.
 */

/*
 * Load object and probe discovery in target process.  This file is
 * not exercised for kernel probes.
 */

#ifndef DEBUG
#define NDEBUG  1
#endif

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stddef.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <assert.h>

#include "tnfctl_int.h"
#include "kernel_int.h"
#include "dbg.h"

/*
 * Defines - Project private interfaces
 */

#define PROBE_SYMBOL    "__tnf_probe_version_1"

/*
 * Typedefs
 */

typedef struct link_args {
        char            *la_probename;
        int             ret_val;
} link_args_t;

typedef struct link_args2 {
        tnfctl_handle_t *la_hndl;
        char            *la_probename;
        objlist_t       *la_obj;
        ulong_t         la_index;
        ulong_t         la_base;
} link_args2_t;

static int per_loadobj(void *, const tnfctl_ind_obj_info_t *, void *);
static objlist_t *loadobj_find(tnfctl_handle_t *,
                        const tnfctl_ind_obj_info_t *);
static tnfctl_errcode_t get_num_probes(tnfctl_handle_t *, objlist_t *, int *);
static tnfctl_errcode_t read_probes_in_obj(tnfctl_handle_t *, objlist_t *,
                ulong_t, ulong_t);
static void free_obj_fields(objlist_t *);
static tnfctl_errcode_t count_probes(char *, uintptr_t, void *,
                                        tnfctl_elf_search_t *);
static tnfctl_errcode_t read_a_probe(char *, uintptr_t, void *,
                                        tnfctl_elf_search_t *);
static tnfctl_errcode_t link_targ_obj_probes(tnfctl_handle_t *, objlist_t *);
static tnfctl_errcode_t unlink_targ_obj_probes(tnfctl_handle_t *, objlist_t *);

/*
 * sync up our library list with that of the run time linker's
 * Returns an event indicating if a dlopen or dlclose happened.
 */
tnfctl_errcode_t
_tnfctl_lmap_update(tnfctl_handle_t *hndl, boolean_t *lmap_ok,
                                enum event_op_t *dl_evt)
{
        int             miscstat;
        objlist_t       *cur_obj;

        *lmap_ok = B_TRUE;

        /* reset old and new of current objects */
        for (cur_obj = hndl->objlist; cur_obj; cur_obj = cur_obj->next) {
                cur_obj->old = B_TRUE;
                cur_obj->new = B_FALSE;
        }

        /* read in object list */
        miscstat = hndl->p_obj_iter(hndl->proc_p, per_loadobj, hndl);
        /* reset libs_changed global var to indicated sync up done */
        _tnfctl_libs_changed = B_FALSE;
        if (miscstat) {
                /*
                 * for INDIRECT_MODE or INTERNAL_MODE, we should never get
                 * called when linkmaps are not consistent, so this is a real
                 * error - return without setting lmap_ok.
                 */
                if ((hndl->mode == INDIRECT_MODE) ||
                                (hndl->mode == INTERNAL_MODE))
                        return (TNFCTL_ERR_INTERNAL);

                assert(hndl->mode == DIRECT_MODE);
                /*
                 * in DIRECT_MODE:
                 * caller needs to call tnfctl_continue on BADLMAPSTATE
                 * XXXX - the cast from int to prb_status_t is ok as
                 * we know we are in DIRECT_MODE and we are calling our
                 * own loadobject iterator function.
                 */
                if ((prb_status_t) miscstat == PRB_STATUS_BADLMAPSTATE)
                        *lmap_ok = B_FALSE;
                return (_tnfctl_map_to_errcode((prb_status_t) miscstat));
        }

        /*
         * find out about dlopens or dlcloses - In direct mode, there
         * can only be one since we monitor all dl activity.  The dl_evt
         * field is only used by tnfctl_continue().  In proc_service
         * mode or internal mode, the new_probe member indicates new probes
         * correctly.
         */
        *dl_evt = EVT_NONE;
        for (cur_obj = hndl->objlist; cur_obj; cur_obj = cur_obj->next) {
                if (cur_obj->old == B_TRUE) {
                        *dl_evt = EVT_CLOSE;
                        break;
                }
                if (cur_obj->new == B_TRUE) {
                        *dl_evt = EVT_OPEN;
                        break;
                }
        }

        /*
         * reset new_probe field only if there was a dlopen or dlclose
         */
        if (*dl_evt != EVT_NONE) {
                for (cur_obj = hndl->objlist; cur_obj;
                                cur_obj = cur_obj->next) {
                        cur_obj->new_probe = cur_obj->new;
                }
        }

        return (TNFCTL_ERR_NONE);
}


/*
 * search through all libraries and discover all probes in target
 * This function assumes all objects have been found and marked as
 * appropriate (new, old, or neither)
 */
tnfctl_errcode_t
_tnfctl_find_all_probes(tnfctl_handle_t *hndl)
{
        tnfctl_errcode_t        prexstat;
        int             num_probes, j;
        objlist_t       *cur_obj, *prev_obj, *tmp_obj;
        boolean_t       saw_new_probes = B_FALSE;

        prev_obj = NULL;
        cur_obj = hndl->objlist;
        while (cur_obj) {
                if (cur_obj->old == B_TRUE) {
                        /* dlclosed library : stitch out probes in target */

                        DBG_TNF_PROBE_3(_tnfctl_find_all_probes_1, "libtnfctl",
                                "sunw%verbosity 1; sunw%debug 'lib dlclosed'",
                                tnf_opaque, lib_baseaddr, cur_obj->baseaddr,
                                tnf_string, lib_name, cur_obj->objname,
                                tnf_long, lib_fd, cur_obj->objfd);

                        prexstat = unlink_targ_obj_probes(hndl, cur_obj);
                        if (prexstat)
                                return (prexstat);
                        free_obj_fields(cur_obj);
                        /* remove this object from linked list */
                        tmp_obj = cur_obj;
                        cur_obj = cur_obj->next;
                        if (prev_obj == NULL)
                                hndl->objlist = cur_obj;
                        else
                                prev_obj->next = cur_obj;
                        free(tmp_obj);
                        continue;
                }

                if (cur_obj->new == B_TRUE) {
                        /* dlopened library : read in probes */
                        prexstat = get_num_probes(hndl, cur_obj, &num_probes);
                        if (prexstat)
                                return (prexstat);
                        if (num_probes) {
                                saw_new_probes = B_TRUE;
                                cur_obj->probes = malloc(num_probes *
                                        sizeof (prbctlref_t));
                                if (cur_obj->probes == NULL)
                                        return (TNFCTL_ERR_ALLOCFAIL);
                                prexstat = read_probes_in_obj(hndl, cur_obj,
                                        num_probes, hndl->num_probes);
                                if (prexstat)
                                        return (prexstat);
                                cur_obj->min_probe_num = hndl->num_probes;
                                /* increment num_probes */
                                hndl->num_probes += num_probes;
                                cur_obj->probecnt = num_probes;
                                prexstat = link_targ_obj_probes(hndl, cur_obj);
                                if (prexstat)
                                        return (prexstat);
                        }
                }
                prev_obj = cur_obj;
                cur_obj = cur_obj->next;
        }

#if 0
        for (cur_obj = hndl->objlist; cur_obj; cur_obj = cur_obj->next) {
                        (void) fprintf(stderr, "%s 0x%08x %s fd=%d\n",
                                (cur_obj->new) ? "*" : " ",
                                cur_obj->baseaddr, cur_obj->objname,
                                cur_obj->objfd);
        }
#endif

        /* call create_func for client data if we saw new probes */
        if (saw_new_probes && hndl->create_func) {
                for (cur_obj = hndl->objlist; cur_obj;
                                                cur_obj = cur_obj->next) {
                        tnfctl_probe_t *probe_handle;

                        if (cur_obj->new == B_FALSE)
                                continue;
                        /* new object */
                        for (j = 0; j < cur_obj->probecnt; j++) {
                                probe_handle = cur_obj->probes[j].probe_handle;
                                probe_handle->client_registered_data =
                                        hndl->create_func(hndl, probe_handle);
                        }
                }
        }

        return (TNFCTL_ERR_NONE);
}

/*
 * _tnfctl_free_objs_and_probes() - cleans up objects and probes
 */
void
_tnfctl_free_objs_and_probes(tnfctl_handle_t *hndl)
{
        objlist_t *obj, *tmp;

        obj = hndl->objlist;
        while (obj) {
                free_obj_fields(obj);
                tmp = obj;
                obj = obj->next;
                free(tmp);
        }
        hndl->objlist = NULL;
}

/*
 * Free members of objlist_t
 */
static void
free_obj_fields(objlist_t *obj)
{
        int i;
        prbctlref_t *probe_p;

        for (i = 0; i < obj->probecnt; i++) {
                probe_p = &(obj->probes[i]);
                if (probe_p->attr_string)
                        free(probe_p->attr_string);
                if (probe_p->probe_handle)
                        probe_p->probe_handle->valid = B_FALSE;
        }
        if (obj->probes)
                free(obj->probes);
        obj->probecnt = 0;
        if (obj->objname)
                free(obj->objname);
        if (obj->objfd != -1)
                close(obj->objfd);
}

/*
 * _tnfctl_probes_traverse() - iterate over all probes by calling the
 * callback function supplied.
 */
tnfctl_errcode_t
_tnfctl_probes_traverse(tnfctl_handle_t *hndl,
        _tnfctl_traverse_probe_func_t func_p, void *calldata_p)
{
        tnfctl_errcode_t        prexstat;
        boolean_t       release_lock;
        objlist_t       *obj;
        int             j;

        /*LINTED statement has no consequent: else*/
        LOCK_SYNC(hndl, prexstat, release_lock);

        for (obj = hndl->objlist; obj; obj = obj->next) {
                for (j = 0; j < obj->probecnt; j++) {
                        prexstat = (*func_p) (hndl, &(obj->probes[j]),
                                                        calldata_p);
                        if (prexstat) {
                                /*LINTED statement has no consequent: else*/
                                UNLOCK(hndl, release_lock);
                                return (prexstat);
                        }
                }
        }

        /*LINTED statement has no consequent: else*/
        UNLOCK(hndl, release_lock);

        return (TNFCTL_ERR_NONE);
}

/*
 * function that is called by loadobject iterator function for every
 * loadobject.  If a new loadobject, add it to to our list.
 */
static int
per_loadobj(void *proc_p, const tnfctl_ind_obj_info_t *obj, void *cd)
{
        tnfctl_handle_t *hndl = cd;
        objlist_t       *entry_p, *cur_p, *next_p;

        if (entry_p = loadobj_find(hndl, obj)) {
                /* loadobject already exists */
                entry_p->old = B_FALSE;
                /* no need to close the objfd because iterator func will */

                /* successful return */
                return (0);
        }

        /* add new loadobject */
        entry_p = calloc(1, sizeof (objlist_t));

        entry_p->old = B_FALSE;
        entry_p->new = B_TRUE;
        entry_p->new_probe = B_TRUE;
        entry_p->objname = strdup(obj->objname);
        if (entry_p->objname == NULL)
                return (1);
        entry_p->baseaddr = obj->text_base;
        /* may have to actually open the fd */
        if (obj->objfd == -1) {
                entry_p->objfd = open(obj->objname, O_RDONLY);
                if (entry_p->objfd == -1)
                        return (1);
        } else {
                /* dup the fd because iterator function will close it */
                entry_p->objfd = dup(obj->objfd);
                if (entry_p->objfd == -1)
                        return (1);
        }

        entry_p->min_probe_num = 0;
        entry_p->probecnt = 0;
        entry_p->probes = NULL;
        entry_p->next = NULL;

        if (hndl->objlist == NULL) {
                hndl->objlist = entry_p;
        } else {
                /* add to end of list */
                next_p = hndl->objlist;
                while (next_p) {
                        cur_p = next_p;
                        next_p = next_p->next;
                }
                /* cur_p now points to last element on list */
                cur_p->next = entry_p;
        }

        return (0);
}

/*
 * check if this loadobject already exists in our linked list.
 */
static objlist_t *
loadobj_find(tnfctl_handle_t *hndl, const tnfctl_ind_obj_info_t *this_obj)
{
        objlist_t *obj;

        for (obj = hndl->objlist; obj; obj = obj->next) {
                if (obj->baseaddr == this_obj->text_base)
                        return (obj);
        }
        return (NULL);
}

/*
 * find the number of probes in a loadobject
 */
static tnfctl_errcode_t
get_num_probes(tnfctl_handle_t *hndl, objlist_t *obj, int *num_probes)
{
        tnfctl_errcode_t        prexstat;
        link_args_t     largs;
        tnfctl_elf_search_t search_info;

        DBG_TNF_PROBE_0(get_num_probes_1, "libtnfctl", "sunw%verbosity 1");

        largs.la_probename = PROBE_SYMBOL;
        largs.ret_val = 0;

        search_info.section_func = _tnfctl_traverse_rela;
        search_info.record_func = count_probes;
        search_info.record_data = &largs;

        prexstat = _tnfctl_traverse_object(obj->objfd, obj->baseaddr,
                                                &search_info);
        if (prexstat)
                return (prexstat);

        DBG_TNF_PROBE_2(get_num_probes_2, "libtnfctl", "sunw%verbosity 1",
                        tnf_long, num_probes, largs.ret_val,
                        tnf_string, obj_name, obj->objname);

        *num_probes = largs.ret_val;
        return (TNFCTL_ERR_NONE);
}

/*
 * discover all probes in a loadobject and read it into our array.
 */
static tnfctl_errcode_t
read_probes_in_obj(tnfctl_handle_t *hndl, objlist_t *obj, ulong_t num_probes,
                        ulong_t probe_base_num)
{
        tnfctl_errcode_t        prexstat;
        link_args2_t    largs2;
        tnfctl_elf_search_t search_info;

        DBG_TNF_PROBE_0(read_probes_in_obj_1, "libtnfctl", "sunw%verbosity 2");

        largs2.la_hndl = hndl;
        largs2.la_probename = PROBE_SYMBOL;
        largs2.la_obj = obj;
        largs2.la_index = 0;
        largs2.la_base = probe_base_num;

        search_info.section_func = _tnfctl_traverse_rela;
        search_info.record_func = read_a_probe;
        search_info.record_data = &largs2;

        prexstat = _tnfctl_traverse_object(obj->objfd, obj->baseaddr,
                                                &search_info);
        if (prexstat)
                return (prexstat);

        return (TNFCTL_ERR_NONE);
}

/*
 * checks if this relocation entry is a probe and if so,
 * increments a counter for every probe seen
 */
/*ARGSUSED*/
static tnfctl_errcode_t
count_probes(char *name, uintptr_t addr, void *rel_entry,
        tnfctl_elf_search_t * search_info_p)
{
        link_args_t     *largs_p = (link_args_t *) search_info_p->record_data;

        if (strcmp(name, largs_p->la_probename) == 0) {
                largs_p->ret_val++;
        }
        return (TNFCTL_ERR_NONE);
}

/*
 * checks if this relocation entry is a probe and if so, reads in info
 * on this probe
 */
/*ARGSUSED*/
static tnfctl_errcode_t
read_a_probe(char *name, uintptr_t addr, void *rel_entry,
        tnfctl_elf_search_t * search_info_p)
{
        link_args2_t    *largs2_p = (link_args2_t *) search_info_p->record_data;
        ulong_t         index = largs2_p->la_index;
        prbctlref_t     *prbctl_p;
        tnfctl_handle_t *hndl = largs2_p->la_hndl;
        tnfctl_errcode_t        prexstat;
        int             miscstat;
        uintptr_t       attrs;

        assert((hndl->mode == INTERNAL_MODE) ?
                (MUTEX_HELD(&_tnfctl_lmap_lock)) : 1);

        if (strcmp(name, largs2_p->la_probename) != 0)
                return (TNFCTL_ERR_NONE);

        /* found a probe */
        prbctl_p = &(largs2_p->la_obj->probes[index]);
        prbctl_p->addr = addr;
        prbctl_p->probe_id = largs2_p->la_base + index;
        prbctl_p->obj = largs2_p->la_obj;
        largs2_p->la_index++;

        /* read in probe structure */
        miscstat = hndl->p_read(hndl->proc_p, addr,
                &prbctl_p->wrkprbctl, sizeof (prbctl_p->wrkprbctl));
        if (miscstat) {
                DBG((void) fprintf(stderr,
                        "read_a_probe: read from target failed: %d\n",
                        miscstat));
                return (TNFCTL_ERR_INTERNAL);
        }

        /*
         * dereference the attrs (read it into our address space only for
         * working copy)
         */
        attrs = (uintptr_t) prbctl_p->wrkprbctl.attrs;
        prexstat = _tnfctl_readstr_targ(hndl, attrs, &prbctl_p->attr_string);
        if (prexstat) {
                DBG((void) fprintf(stderr,
                    "read_a_probe: _tnfctl_readstr_targ (attrs) failed: %s\n",
                                tnfctl_strerror(prexstat)));
                return (prexstat);
        }

        DBG_TNF_PROBE_1(read_a_probe_2, "libtnfctl",
                "sunw%verbosity 1; sunw%debug 'found a probe'",
                tnf_string, probe, prbctl_p->attr_string);

        /* create probe handle */
        prbctl_p->probe_handle = calloc(1, sizeof (tnfctl_probe_t));
        if (prbctl_p->probe_handle == NULL)
                return (TNFCTL_ERR_ALLOCFAIL);
        prbctl_p->probe_handle->valid = B_TRUE;
        prbctl_p->probe_handle->probe_p = prbctl_p;
        /* link in probe handle into chain off tnfctl_handle_t */
        prbctl_p->probe_handle->next = hndl->probe_handle_list_head;
        hndl->probe_handle_list_head = prbctl_p->probe_handle;

        /*
         * if this is a "virgin" probe, set up probe to initial state
         * REMIND: Could defer this target write till we link the probes
         * together in target process in link_targ_obj_probes() i.e.
         * do the "write" only once.
         */
        if (prbctl_p->wrkprbctl.commit_func == NULL) {
                prbctl_p->wrkprbctl.probe_func =
                                (tnf_probe_func_t) hndl->endfunc;
                prbctl_p->wrkprbctl.commit_func =
                                (tnf_probe_func_t) hndl->commitfunc;
                prbctl_p->wrkprbctl.alloc_func =
                                (tnf_probe_alloc_func_t) hndl->allocfunc;
                /*
                 * update the probe in target to its initial state
                 * Since the probe is disabled, it is ok to write it one
                 * write command as opposed to updating each word individually
                 */
                miscstat = hndl->p_write(hndl->proc_p, addr,
                        &prbctl_p->wrkprbctl, sizeof (prbctl_p->wrkprbctl));
                if (miscstat)
                        return (TNFCTL_ERR_INTERNAL);
        }

        return (TNFCTL_ERR_NONE);
}

/*
 * Link all the probes in a linked list in the target image in specified
 * object.  Also, link probes from previous object and next object into
 * this list.  The only
 * reason this is needed is because internally in the process,
 * tnf_probe_notify() that is called from libthread walks through all
 * probes substituting the test function
 * REMIND: find a way that we don't have to walk through probes internally.
 */
static tnfctl_errcode_t
link_targ_obj_probes(tnfctl_handle_t *hndl, objlist_t *cur)
{
        int i;
        prbctlref_t *probe_p;
        tnf_probe_control_t *next_probe;
        int miscstat;
        objlist_t *cur_tmp, *prev_w_probes, *next_w_probes;
        uintptr_t next_addr;

        /* find previous object that has probes */
        prev_w_probes = NULL;
        cur_tmp = hndl->objlist;
        while (cur_tmp != cur) {
                if (cur_tmp->probecnt != 0)
                        prev_w_probes = cur_tmp;
                cur_tmp = cur_tmp->next;
        }

        /* find next object with probes */
        next_w_probes = NULL;
        cur_tmp = cur->next;
        while (cur_tmp != NULL) {
                if (cur_tmp->probecnt != 0)
                        next_w_probes = cur_tmp;
                cur_tmp = cur_tmp->next;
        }

        /* link probes (except for last one) in order */
        for (i = 0; i < (cur->probecnt - 1); i++) {
                probe_p = &(cur->probes[i]);
                next_probe = (tnf_probe_control_t *) cur->probes[i+1].addr;
                probe_p->wrkprbctl.next = next_probe;
                miscstat = hndl->p_write(hndl->proc_p, probe_p->addr +
                                offsetof(struct tnf_probe_control, next),
                                &next_probe, sizeof (next_probe));
                if (miscstat)
                        return (TNFCTL_ERR_INTERNAL);
        }

        next_probe = (tnf_probe_control_t *) cur->probes[0].addr;
        if (prev_w_probes == NULL) {
                /* adding as first object in list */
                next_addr = hndl->probelist_head;
        } else {
                probe_p = &(prev_w_probes->probes[prev_w_probes->probecnt - 1]);
                probe_p->wrkprbctl.next = next_probe;
                next_addr = probe_p->addr +
                                offsetof(struct tnf_probe_control, next);
        }

        /* point next_addr to first probe in this object */
        miscstat = hndl->p_write(hndl->proc_p, next_addr,
                        &next_probe, sizeof (next_probe));
        if (miscstat)
                return (TNFCTL_ERR_INTERNAL);

        /* link last probe in object */
        if (next_w_probes == NULL)
                next_probe = NULL;
        else {
                next_probe = (tnf_probe_control_t *)
                                next_w_probes->probes[0].addr;
        }
        probe_p = &(cur->probes[cur->probecnt - 1]);
        probe_p->wrkprbctl.next = next_probe;
        miscstat = hndl->p_write(hndl->proc_p, probe_p->addr +
                        offsetof(struct tnf_probe_control, next),
                        &next_probe, sizeof (next_probe));
        if (miscstat)
                return (TNFCTL_ERR_INTERNAL);
        return (TNFCTL_ERR_NONE);
}

/*
 * An object has been closed.  Stitch probes around this object in
 * target image.
 */
static tnfctl_errcode_t
unlink_targ_obj_probes(tnfctl_handle_t *hndl, objlist_t *cur)
{
        prbctlref_t *probe_p;
        tnf_probe_control_t *next_probe;
        int miscstat;
        objlist_t *cur_tmp, *prev_w_probes, *next_w_probes;
        uintptr_t next_addr;

        /* find previous object that has probes */
        prev_w_probes = NULL;
        cur_tmp = hndl->objlist;
        while (cur_tmp != cur) {
                if (cur_tmp->probecnt != 0)
                        prev_w_probes = cur_tmp;
                cur_tmp = cur_tmp->next;
        }

        /* find next object with probes */
        next_w_probes = NULL;
        cur_tmp = cur->next;
        while (cur_tmp != NULL) {
                if (cur_tmp->probecnt != 0)
                        next_w_probes = cur_tmp;
                cur_tmp = cur_tmp->next;
        }

        if (next_w_probes == NULL)
                next_probe = NULL;
        else {
                next_probe = (tnf_probe_control_t *)
                                next_w_probes->probes[0].addr;
        }

        if (prev_w_probes == NULL) {
                /* removing first object in list */
                next_addr = hndl->probelist_head;
        } else {
                probe_p = &(prev_w_probes->probes[prev_w_probes->probecnt - 1]);
                probe_p->wrkprbctl.next = next_probe;
                next_addr = probe_p->addr +
                                offsetof(struct tnf_probe_control, next);
        }

        /* point next_addr to next_probe */
        miscstat = hndl->p_write(hndl->proc_p, next_addr,
                        &next_probe, sizeof (next_probe));
        if (miscstat)
                return (TNFCTL_ERR_INTERNAL);
        return (TNFCTL_ERR_NONE);
}

/*
 * _tnfctl_flush_a_probe() - write a changed probe into the target process'
 * address space.
 */
tnfctl_errcode_t
_tnfctl_flush_a_probe(tnfctl_handle_t *hndl, prbctlref_t *ref_p, size_t offset,
                        size_t size)
{
        tnfctl_errcode_t        prexstat;
        int                     miscstat;

        /*
         * For internal control:
         * There is *no race* for finding the test function (between the time
         * we call find_test_func() and the time we assign it to a probe),
         * because tnfctl_internal_open() cannot be called from an init section
         * (look at man page of tnfctl_internal_open()).  And, after the init
         * section of libthread has run, we will always use the MT test
         * function.
         */

        if (hndl->mode == KERNEL_MODE) {
                prexstat = _tnfctl_prbk_flush(hndl, ref_p);
                if (prexstat)
                        return (prexstat);
        } else {
                miscstat = hndl->p_write(hndl->proc_p,
                        ref_p->addr + offset,
                        ((char *)&(ref_p->wrkprbctl)) + offset, size);
                if (miscstat)
                        return (TNFCTL_ERR_INTERNAL);
        }

        return (TNFCTL_ERR_NONE);
}