8672 proc_t changes broke genunix dmods and walker

[unleashed.git] / usr / src / cmd / mdb / common / modules / mdb_ks / mdb_ks.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 (c) 1990, 2010, Oracle and/or its affiliates. All rights reserved.
 * Copyright 2017 Joyent, Inc.
 */

/*
 * Mdb kernel support module.  This module is loaded automatically when the
 * kvm target is initialized.  Any global functions declared here are exported
 * for the resolution of symbols in subsequently loaded modules.
 *
 * WARNING: Do not assume that static variables in mdb_ks will be initialized
 * to zero.
 */

#include <mdb/mdb_target.h>
#include <mdb/mdb_param.h>
#include <mdb/mdb_modapi.h>
#include <mdb/mdb_ks.h>

#include <sys/types.h>
#include <sys/procfs.h>
#include <sys/proc.h>
#include <sys/dnlc.h>
#include <sys/autoconf.h>
#include <sys/machelf.h>
#include <sys/modctl.h>
#include <sys/hwconf.h>
#include <sys/kobj.h>
#include <sys/fs/autofs.h>
#include <sys/ddi_impldefs.h>
#include <sys/refstr_impl.h>
#include <sys/cpuvar.h>
#include <sys/dlpi.h>
#include <sys/clock_impl.h>
#include <sys/swap.h>
#include <errno.h>

#include <vm/seg_vn.h>
#include <vm/page.h>

#define MDB_PATH_NELEM  256                     /* Maximum path components */

typedef struct mdb_path {
        size_t mdp_nelem;                       /* Number of components */
        uint_t mdp_complete;                    /* Path completely resolved? */
        uintptr_t mdp_vnode[MDB_PATH_NELEM];    /* Array of vnode_t addresses */
        char *mdp_name[MDB_PATH_NELEM];         /* Array of name components */
} mdb_path_t;

static int mdb_autonode2path(uintptr_t, mdb_path_t *);
static int mdb_sprintpath(char *, size_t, mdb_path_t *);

/*
 * Kernel parameters from <sys/param.h> which we keep in-core:
 */
unsigned long _mdb_ks_pagesize;
unsigned int _mdb_ks_pageshift;
unsigned long _mdb_ks_pageoffset;
unsigned long long _mdb_ks_pagemask;
unsigned long _mdb_ks_mmu_pagesize;
unsigned int _mdb_ks_mmu_pageshift;
unsigned long _mdb_ks_mmu_pageoffset;
unsigned long _mdb_ks_mmu_pagemask;
uintptr_t _mdb_ks_kernelbase;
uintptr_t _mdb_ks_userlimit;
uintptr_t _mdb_ks_userlimit32;
uintptr_t _mdb_ks_argsbase;
unsigned long _mdb_ks_msg_bsize;
unsigned long _mdb_ks_defaultstksz;
int _mdb_ks_ncpu;
int _mdb_ks_ncpu_log2;
int _mdb_ks_ncpu_p2;

/*
 * In-core copy of DNLC information:
 */
#define MDB_DNLC_HSIZE  1024
#define MDB_DNLC_HASH(vp)       (((uintptr_t)(vp) >> 3) & (MDB_DNLC_HSIZE - 1))
#define MDB_DNLC_NCACHE_SZ(ncp) (sizeof (ncache_t) + (ncp)->namlen)
#define MDB_DNLC_MAX_RETRY 4

static ncache_t **dnlc_hash;    /* mdbs hash array of dnlc entries */

/*
 * copy of page_hash-related data
 */
static int page_hash_loaded;
static long mdb_page_hashsz;
static uint_t mdb_page_hashsz_shift;    /* Needed for PAGE_HASH_FUNC */
static uintptr_t mdb_page_hash;         /* base address of page hash */
#define page_hashsz             mdb_page_hashsz
#define page_hashsz_shift       mdb_page_hashsz_shift

/*
 * This will be the location of the vnodeops pointer for "autofs_vnodeops"
 * The pointer still needs to be read with mdb_vread() to get the location
 * of the vnodeops structure for autofs.
 */
static struct vnodeops *autofs_vnops_ptr;

/*
 * STREAMS queue registrations:
 */
typedef struct mdb_qinfo {
        const mdb_qops_t *qi_ops;       /* Address of ops vector */
        uintptr_t qi_addr;              /* Address of qinit structure (key) */
        struct mdb_qinfo *qi_next;      /* Next qinfo in list */
} mdb_qinfo_t;

static mdb_qinfo_t *qi_head;            /* Head of qinfo chain */

/*
 * Device naming callback structure:
 */
typedef struct nm_query {
        const char *nm_name;            /* Device driver name [in/out] */
        major_t nm_major;               /* Device major number [in/out] */
        ushort_t nm_found;              /* Did we find a match? [out] */
} nm_query_t;

/*
 * Address-to-modctl callback structure:
 */
typedef struct a2m_query {
        uintptr_t a2m_addr;             /* Virtual address [in] */
        uintptr_t a2m_where;            /* Modctl address [out] */
} a2m_query_t;

/*
 * Segment-to-mdb_map callback structure:
 */
typedef struct {
        struct seg_ops *asm_segvn_ops;  /* Address of segvn ops [in] */
        void (*asm_callback)(const struct mdb_map *, void *); /* Callb [in] */
        void *asm_cbdata;               /* Callback data [in] */
} asmap_arg_t;

static void
dnlc_free(void)
{
        ncache_t *ncp, *next;
        int i;

        if (dnlc_hash == NULL) {
                return;
        }

        /*
         * Free up current dnlc entries
         */
        for (i = 0; i < MDB_DNLC_HSIZE; i++) {
                for (ncp = dnlc_hash[i]; ncp; ncp = next) {
                        next = ncp->hash_next;
                        mdb_free(ncp, MDB_DNLC_NCACHE_SZ(ncp));
                }
        }
        mdb_free(dnlc_hash, MDB_DNLC_HSIZE * sizeof (ncache_t *));
        dnlc_hash = NULL;
}

char bad_dnlc[] = "inconsistent dnlc chain: %d, ncache va: %p"
        " - continuing with the rest\n";

static int
dnlc_load(void)
{
        int i; /* hash index */
        int retry_cnt = 0;
        int skip_bad_chains = 0;
        int nc_hashsz; /* kernel hash array size */
        uintptr_t nc_hash_addr; /* kernel va of ncache hash array */
        uintptr_t head; /* kernel va of head of hash chain */

        /*
         * If we've already cached the DNLC and we're looking at a dump,
         * our cache is good forever, so don't bother re-loading.
         */
        if (dnlc_hash && mdb_prop_postmortem) {
                return (0);
        }

        /*
         * For a core dump, retries wont help.
         * Just print and skip any bad chains.
         */
        if (mdb_prop_postmortem) {
                skip_bad_chains = 1;
        }
retry:
        if (retry_cnt++ >= MDB_DNLC_MAX_RETRY) {
                /*
                 * Give up retrying the rapidly changing dnlc.
                 * Just print and skip any bad chains
                 */
                skip_bad_chains = 1;
        }

        dnlc_free(); /* Free up the mdb hashed dnlc - if any */

        /*
         * Although nc_hashsz and the location of nc_hash doesn't currently
         * change, it may do in the future with a more dynamic dnlc.
         * So always read these values afresh.
         */
        if (mdb_readvar(&nc_hashsz, "nc_hashsz") == -1) {
                mdb_warn("failed to read nc_hashsz");
                return (-1);
        }
        if (mdb_readvar(&nc_hash_addr, "nc_hash") == -1) {
                mdb_warn("failed to read nc_hash");
                return (-1);
        }

        /*
         * Allocate the mdb dnlc hash array
         */
        dnlc_hash = mdb_zalloc(MDB_DNLC_HSIZE * sizeof (ncache_t *), UM_SLEEP);

        /* for each kernel hash chain */
        for (i = 0, head = nc_hash_addr; i < nc_hashsz;
            i++, head += sizeof (nc_hash_t)) {
                nc_hash_t nch; /* kernel hash chain header */
                ncache_t *ncp; /* name cache pointer */
                int hash; /* mdb hash value */
                uintptr_t nc_va; /* kernel va of next ncache */
                uintptr_t ncprev_va; /* kernel va of previous ncache */
                int khash; /* kernel dnlc hash value */
                uchar_t namelen; /* name length */
                ncache_t nc; /* name cache entry */
                int nc_size; /* size of a name cache entry */

                /*
                 * We read each element of the nc_hash array individually
                 * just before we process the entries in its chain. This is
                 * because the chain can change so rapidly on a running system.
                 */
                if (mdb_vread(&nch, sizeof (nc_hash_t), head) == -1) {
                        mdb_warn("failed to read nc_hash chain header %d", i);
                        dnlc_free();
                        return (-1);
                }

                ncprev_va = head;
                nc_va = (uintptr_t)(nch.hash_next);
                /* for each entry in the chain */
                while (nc_va != head) {
                        /*
                         * The size of the ncache entries varies
                         * because the name is appended to the structure.
                         * So we read in the structure then re-read
                         * for the structure plus name.
                         */
                        if (mdb_vread(&nc, sizeof (ncache_t), nc_va) == -1) {
                                if (skip_bad_chains) {
                                        mdb_warn(bad_dnlc, i, nc_va);
                                        break;
                                }
                                goto retry;
                        }
                        nc_size = MDB_DNLC_NCACHE_SZ(&nc);
                        ncp = mdb_alloc(nc_size, UM_SLEEP);
                        if (mdb_vread(ncp, nc_size - 1, nc_va) == -1) {
                                mdb_free(ncp, nc_size);
                                if (skip_bad_chains) {
                                        mdb_warn(bad_dnlc, i, nc_va);
                                        break;
                                }
                                goto retry;
                        }

                        /*
                         * Check for chain consistency
                         */
                        if ((uintptr_t)ncp->hash_prev != ncprev_va) {
                                mdb_free(ncp, nc_size);
                                if (skip_bad_chains) {
                                        mdb_warn(bad_dnlc, i, nc_va);
                                        break;
                                }
                                goto retry;
                        }
                        /*
                         * Terminate the new name with a null.
                         * Note, we allowed space for this null when
                         * allocating space for the entry.
                         */
                        ncp->name[ncp->namlen] = '\0';

                        /*
                         * Validate new entry by re-hashing using the
                         * kernel dnlc hash function and comparing the hash
                         */
                        DNLCHASH(ncp->name, ncp->dp, khash, namelen);
                        if ((namelen != ncp->namlen) ||
                            (khash != ncp->hash)) {
                                mdb_free(ncp, nc_size);
                                if (skip_bad_chains) {
                                        mdb_warn(bad_dnlc, i, nc_va);
                                        break;
                                }
                                goto retry;
                        }

                        /*
                         * Finally put the validated entry into the mdb
                         * hash chains. Reuse the kernel next hash field
                         * for the mdb hash chain pointer.
                         */
                        hash = MDB_DNLC_HASH(ncp->vp);
                        ncprev_va = nc_va;
                        nc_va = (uintptr_t)(ncp->hash_next);
                        ncp->hash_next = dnlc_hash[hash];
                        dnlc_hash[hash] = ncp;
                }
        }
        return (0);
}

/*ARGSUSED*/
int
dnlcdump(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
        ncache_t *ent;
        int i;

        if ((flags & DCMD_ADDRSPEC) || argc != 0)
                return (DCMD_USAGE);

        if (dnlc_load() == -1)
                return (DCMD_ERR);

        mdb_printf("%<u>%-?s %-?s %-32s%</u>\n", "VP", "DVP", "NAME");

        for (i = 0; i < MDB_DNLC_HSIZE; i++) {
                for (ent = dnlc_hash[i]; ent != NULL; ent = ent->hash_next) {
                        mdb_printf("%0?p %0?p %s\n",
                            ent->vp, ent->dp, ent->name);
                }
        }

        return (DCMD_OK);
}

static int
mdb_sprintpath(char *buf, size_t len, mdb_path_t *path)
{
        char *s = buf;
        int i;

        if (len < sizeof ("/..."))
                return (-1);

        if (!path->mdp_complete) {
                (void) strcpy(s, "??");
                s += 2;

                if (path->mdp_nelem == 0)
                        return (-1);
        }

        if (path->mdp_nelem == 0) {
                (void) strcpy(s, "/");
                return (0);
        }

        for (i = path->mdp_nelem - 1; i >= 0; i--) {
                /*
                 * Number of bytes left is the distance from where we
                 * are to the end, minus 2 for '/' and '\0'
                 */
                ssize_t left = (ssize_t)(&buf[len] - s) - 2;

                if (left <= 0)
                        break;

                *s++ = '/';
                (void) strncpy(s, path->mdp_name[i], left);
                s[left - 1] = '\0';
                s += strlen(s);

                if (left < strlen(path->mdp_name[i]))
                        break;
        }

        if (i >= 0)
                (void) strcpy(&buf[len - 4], "...");

        return (0);
}

static int
mdb_autonode2path(uintptr_t addr, mdb_path_t *path)
{
        fninfo_t fni;
        fnnode_t fn;

        vnode_t vn;
        vfs_t vfs;
        struct vnodeops *autofs_vnops = NULL;

        /*
         * "autofs_vnops_ptr" is the address of the pointer to the vnodeops
         * structure for autofs.  We want to read it each time we access
         * it since autofs could (in theory) be unloaded and reloaded.
         */
        if (mdb_vread(&autofs_vnops, sizeof (autofs_vnops),
            (uintptr_t)autofs_vnops_ptr) == -1)
                return (-1);

        if (mdb_vread(&vn, sizeof (vn), addr) == -1)
                return (-1);

        if (autofs_vnops == NULL || vn.v_op != autofs_vnops)
                return (-1);

        addr = (uintptr_t)vn.v_data;

        if (mdb_vread(&vfs, sizeof (vfs), (uintptr_t)vn.v_vfsp) == -1 ||
            mdb_vread(&fni, sizeof (fni), (uintptr_t)vfs.vfs_data) == -1 ||
            mdb_vread(&vn, sizeof (vn), (uintptr_t)fni.fi_rootvp) == -1)
                return (-1);

        for (;;) {
                size_t elem = path->mdp_nelem++;
                char elemstr[MAXNAMELEN];
                char *c, *p;

                if (elem == MDB_PATH_NELEM) {
                        path->mdp_nelem--;
                        return (-1);
                }

                if (mdb_vread(&fn, sizeof (fn), addr) != sizeof (fn)) {
                        path->mdp_nelem--;
                        return (-1);
                }

                if (mdb_readstr(elemstr, sizeof (elemstr),
                    (uintptr_t)fn.fn_name) <= 0) {
                        (void) strcpy(elemstr, "?");
                }

                c = mdb_alloc(strlen(elemstr) + 1, UM_SLEEP | UM_GC);
                (void) strcpy(c, elemstr);

                path->mdp_vnode[elem] = (uintptr_t)fn.fn_vnode;

                if (addr == (uintptr_t)fn.fn_parent) {
                        path->mdp_name[elem] = &c[1];
                        path->mdp_complete = TRUE;
                        break;
                }

                if ((p = strrchr(c, '/')) != NULL)
                        path->mdp_name[elem] = p + 1;
                else
                        path->mdp_name[elem] = c;

                addr = (uintptr_t)fn.fn_parent;
        }

        return (0);
}

int
mdb_vnode2path(uintptr_t addr, char *buf, size_t buflen)
{
        uintptr_t rootdir;
        ncache_t *ent;
        vnode_t vp;
        mdb_path_t path;

        /*
         * Check to see if we have a cached value for this vnode
         */
        if (mdb_vread(&vp, sizeof (vp), addr) != -1 &&
            vp.v_path != NULL &&
            mdb_readstr(buf, buflen, (uintptr_t)vp.v_path) != -1)
                return (0);

        if (dnlc_load() == -1)
                return (-1);

        if (mdb_readvar(&rootdir, "rootdir") == -1) {
                mdb_warn("failed to read 'rootdir'");
                return (-1);
        }

        bzero(&path, sizeof (mdb_path_t));
again:
        if ((addr == NULL) && (path.mdp_nelem == 0)) {
                /*
                 * 0 elems && complete tells sprintpath to just print "/"
                 */
                path.mdp_complete = TRUE;
                goto out;
        }

        if (addr == rootdir) {
                path.mdp_complete = TRUE;
                goto out;
        }

        for (ent = dnlc_hash[MDB_DNLC_HASH(addr)]; ent; ent = ent->hash_next) {
                if ((uintptr_t)ent->vp == addr) {
                        if (strcmp(ent->name, "..") == 0 ||
                            strcmp(ent->name, ".") == 0)
                                continue;

                        path.mdp_vnode[path.mdp_nelem] = (uintptr_t)ent->vp;
                        path.mdp_name[path.mdp_nelem] = ent->name;
                        path.mdp_nelem++;

                        if (path.mdp_nelem == MDB_PATH_NELEM) {
                                path.mdp_nelem--;
                                mdb_warn("path exceeded maximum expected "
                                    "elements\n");
                                return (-1);
                        }

                        addr = (uintptr_t)ent->dp;
                        goto again;
                }
        }

        (void) mdb_autonode2path(addr, &path);

out:
        return (mdb_sprintpath(buf, buflen, &path));
}


uintptr_t
mdb_pid2proc(pid_t pid, proc_t *proc)
{
        int pid_hashsz, hash;
        uintptr_t paddr, pidhash, procdir;
        struct pid pidp;

        if (mdb_readvar(&pidhash, "pidhash") == -1)
                return (0);

        if (mdb_readvar(&pid_hashsz, "pid_hashsz") == -1)
                return (0);

        if (mdb_readvar(&procdir, "procdir") == -1)
                return (0);

        hash = pid & (pid_hashsz - 1);

        if (mdb_vread(&paddr, sizeof (paddr),
            pidhash + (hash * sizeof (paddr))) == -1)
                return (0);

        while (paddr != 0) {
                if (mdb_vread(&pidp, sizeof (pidp), paddr) == -1)
                        return (0);

                if (pidp.pid_id == pid) {
                        uintptr_t procp;

                        if (mdb_vread(&procp, sizeof (procp), procdir +
                            (pidp.pid_prslot * sizeof (procp))) == -1)
                                return (0);

                        if (proc != NULL)
                                (void) mdb_vread(proc, sizeof (proc_t), procp);

                        return (procp);
                }
                paddr = (uintptr_t)pidp.pid_link;
        }
        return (0);
}

int
mdb_cpu2cpuid(uintptr_t cpup)
{
        cpu_t cpu;

        if (mdb_vread(&cpu, sizeof (cpu_t), cpup) != sizeof (cpu_t))
                return (-1);

        return (cpu.cpu_id);
}

int
mdb_cpuset_find(uintptr_t cpusetp)
{
        ulong_t *cpuset;
        size_t nr_words = BT_BITOUL(NCPU);
        size_t sz = nr_words * sizeof (ulong_t);
        size_t  i;
        int cpu = -1;

        cpuset = mdb_alloc(sz, UM_SLEEP);

        if (mdb_vread((void *)cpuset, sz, cpusetp) != sz)
                goto out;

        for (i = 0; i < nr_words; i++) {
                size_t j;
                ulong_t m;

                for (j = 0, m = 1; j < BT_NBIPUL; j++, m <<= 1) {
                        if (cpuset[i] & m) {
                                cpu = i * BT_NBIPUL + j;
                                goto out;
                        }
                }
        }

out:
        mdb_free(cpuset, sz);
        return (cpu);
}

static int
page_hash_load(void)
{
        if (page_hash_loaded) {
                return (1);
        }

        if (mdb_readvar(&mdb_page_hashsz, "page_hashsz") == -1) {
                mdb_warn("unable to read page_hashsz");
                return (0);
        }
        if (mdb_readvar(&mdb_page_hashsz_shift, "page_hashsz_shift") == -1) {
                mdb_warn("unable to read page_hashsz_shift");
                return (0);
        }
        if (mdb_readvar(&mdb_page_hash, "page_hash") == -1) {
                mdb_warn("unable to read page_hash");
                return (0);
        }

        page_hash_loaded = 1;   /* zeroed on state change */
        return (1);
}

uintptr_t
mdb_page_lookup(uintptr_t vp, u_offset_t offset)
{
        size_t ndx;
        uintptr_t page_hash_entry, pp;

        if (!page_hash_loaded && !page_hash_load()) {
                return (NULL);
        }

        ndx = PAGE_HASH_FUNC(vp, offset);
        page_hash_entry = mdb_page_hash + ndx * sizeof (uintptr_t);

        if (mdb_vread(&pp, sizeof (pp), page_hash_entry) < 0) {
                mdb_warn("unable to read page_hash[%ld] (%p)", ndx,
                    page_hash_entry);
                return (NULL);
        }

        while (pp != NULL) {
                page_t page;
                long nndx;

                if (mdb_vread(&page, sizeof (page), pp) < 0) {
                        mdb_warn("unable to read page_t at %p", pp);
                        return (NULL);
                }

                if ((uintptr_t)page.p_vnode == vp &&
                    (uint64_t)page.p_offset == offset)
                        return (pp);

                /*
                 * Double check that the pages actually hash to the
                 * bucket we're searching.  If not, our version of
                 * PAGE_HASH_FUNC() doesn't match the kernel's, and we're
                 * not going to be able to find the page.  The most
                 * likely reason for this that mdb_ks doesn't match the
                 * kernel we're running against.
                 */
                nndx = PAGE_HASH_FUNC(page.p_vnode, page.p_offset);
                if (page.p_vnode != NULL && nndx != ndx) {
                        mdb_warn("mdb_page_lookup: mdb_ks PAGE_HASH_FUNC() "
                            "mismatch: in bucket %ld, but page %p hashes to "
                            "bucket %ld\n", ndx, pp, nndx);
                        return (NULL);
                }

                pp = (uintptr_t)page.p_hash;
        }

        return (NULL);
}

char
mdb_vtype2chr(vtype_t type, mode_t mode)
{
        static const char vttab[] = {
                ' ',    /* VNON */
                ' ',    /* VREG */
                '/',    /* VDIR */
                ' ',    /* VBLK */
                ' ',    /* VCHR */
                '@',    /* VLNK */
                '|',    /* VFIFO */
                '>',    /* VDOOR */
                ' ',    /* VPROC */
                '=',    /* VSOCK */
                ' ',    /* VBAD */
        };

        if (type < 0 || type >= sizeof (vttab) / sizeof (vttab[0]))
                return ('?');

        if (type == VREG && (mode & 0111) != 0)
                return ('*');

        return (vttab[type]);
}

struct pfn2page {
        pfn_t pfn;
        page_t *pp;
};

/*ARGSUSED*/
static int
pfn2page_cb(uintptr_t addr, const struct memseg *msp, void *data)
{
        struct pfn2page *p = data;

        if (p->pfn >= msp->pages_base && p->pfn < msp->pages_end) {
                p->pp = msp->pages + (p->pfn - msp->pages_base);
                return (WALK_DONE);
        }

        return (WALK_NEXT);
}

uintptr_t
mdb_pfn2page(pfn_t pfn)
{
        struct pfn2page arg;
        struct page     page;

        arg.pfn = pfn;
        arg.pp = NULL;

        if (mdb_walk("memseg", (mdb_walk_cb_t)pfn2page_cb, &arg) == -1) {
                mdb_warn("pfn2page: can't walk memsegs");
                return (0);
        }
        if (arg.pp == NULL) {
                mdb_warn("pfn2page: unable to find page_t for pfn %lx\n",
                    pfn);
                return (0);
        }

        if (mdb_vread(&page, sizeof (page_t), (uintptr_t)arg.pp) == -1) {
                mdb_warn("pfn2page: can't read page 0x%lx at %p", pfn, arg.pp);
                return (0);
        }
        if (page.p_pagenum != pfn) {
                mdb_warn("pfn2page: page_t 0x%p should have PFN 0x%lx, "
                    "but actually has 0x%lx\n", arg.pp, pfn, page.p_pagenum);
                return (0);
        }

        return ((uintptr_t)arg.pp);
}

pfn_t
mdb_page2pfn(uintptr_t addr)
{
        struct page     page;

        if (mdb_vread(&page, sizeof (page_t), addr) == -1) {
                mdb_warn("pp2pfn: can't read page at %p", addr);
                return ((pfn_t)(-1));
        }

        return (page.p_pagenum);
}

static int
a2m_walk_modctl(uintptr_t addr, const struct modctl *m, a2m_query_t *a2m)
{
        struct module mod;

        if (m->mod_mp == NULL)
                return (0);

        if (mdb_vread(&mod, sizeof (mod), (uintptr_t)m->mod_mp) == -1) {
                mdb_warn("couldn't read modctl %p's module", addr);
                return (0);
        }

        if (a2m->a2m_addr >= (uintptr_t)mod.text &&
            a2m->a2m_addr < (uintptr_t)mod.text + mod.text_size)
                goto found;

        if (a2m->a2m_addr >= (uintptr_t)mod.data &&
            a2m->a2m_addr < (uintptr_t)mod.data + mod.data_size)
                goto found;

        return (0);

found:
        a2m->a2m_where = addr;
        return (-1);
}

uintptr_t
mdb_addr2modctl(uintptr_t addr)
{
        a2m_query_t a2m;

        a2m.a2m_addr = addr;
        a2m.a2m_where = NULL;

        (void) mdb_walk("modctl", (mdb_walk_cb_t)a2m_walk_modctl, &a2m);
        return (a2m.a2m_where);
}

static mdb_qinfo_t *
qi_lookup(uintptr_t qinit_addr)
{
        mdb_qinfo_t *qip;

        for (qip = qi_head; qip != NULL; qip = qip->qi_next) {
                if (qip->qi_addr == qinit_addr)
                        return (qip);
        }

        return (NULL);
}

void
mdb_qops_install(const mdb_qops_t *qops, uintptr_t qinit_addr)
{
        mdb_qinfo_t *qip = qi_lookup(qinit_addr);

        if (qip != NULL) {
                qip->qi_ops = qops;
                return;
        }

        qip = mdb_alloc(sizeof (mdb_qinfo_t), UM_SLEEP);

        qip->qi_ops = qops;
        qip->qi_addr = qinit_addr;
        qip->qi_next = qi_head;

        qi_head = qip;
}

void
mdb_qops_remove(const mdb_qops_t *qops, uintptr_t qinit_addr)
{
        mdb_qinfo_t *qip, *p = NULL;

        for (qip = qi_head; qip != NULL; p = qip, qip = qip->qi_next) {
                if (qip->qi_addr == qinit_addr && qip->qi_ops == qops) {
                        if (qi_head == qip)
                                qi_head = qip->qi_next;
                        else
                                p->qi_next = qip->qi_next;
                        mdb_free(qip, sizeof (mdb_qinfo_t));
                        return;
                }
        }
}

char *
mdb_qname(const queue_t *q, char *buf, size_t nbytes)
{
        struct module_info mi;
        struct qinit qi;

        if (mdb_vread(&qi, sizeof (qi), (uintptr_t)q->q_qinfo) == -1) {
                mdb_warn("failed to read qinit at %p", q->q_qinfo);
                goto err;
        }

        if (mdb_vread(&mi, sizeof (mi), (uintptr_t)qi.qi_minfo) == -1) {
                mdb_warn("failed to read module_info at %p", qi.qi_minfo);
                goto err;
        }

        if (mdb_readstr(buf, nbytes, (uintptr_t)mi.mi_idname) <= 0) {
                mdb_warn("failed to read mi_idname at %p", mi.mi_idname);
                goto err;
        }

        return (buf);

err:
        (void) mdb_snprintf(buf, nbytes, "???");
        return (buf);
}

void
mdb_qinfo(const queue_t *q, char *buf, size_t nbytes)
{
        mdb_qinfo_t *qip = qi_lookup((uintptr_t)q->q_qinfo);
        buf[0] = '\0';

        if (qip != NULL)
                qip->qi_ops->q_info(q, buf, nbytes);
}

uintptr_t
mdb_qrnext(const queue_t *q)
{
        mdb_qinfo_t *qip = qi_lookup((uintptr_t)q->q_qinfo);

        if (qip != NULL)
                return (qip->qi_ops->q_rnext(q));

        return (NULL);
}

uintptr_t
mdb_qwnext(const queue_t *q)
{
        mdb_qinfo_t *qip = qi_lookup((uintptr_t)q->q_qinfo);

        if (qip != NULL)
                return (qip->qi_ops->q_wnext(q));

        return (NULL);
}

uintptr_t
mdb_qrnext_default(const queue_t *q)
{
        return ((uintptr_t)q->q_next);
}

uintptr_t
mdb_qwnext_default(const queue_t *q)
{
        return ((uintptr_t)q->q_next);
}

/*
 * The following three routines borrowed from modsubr.c
 */
static int
nm_hash(const char *name)
{
        char c;
        int hash = 0;

        for (c = *name++; c; c = *name++)
                hash ^= c;

        return (hash & MOD_BIND_HASHMASK);
}

static uintptr_t
find_mbind(const char *name, uintptr_t *hashtab)
{
        int hashndx;
        uintptr_t mb;
        struct bind mb_local;
        char node_name[MAXPATHLEN + 1];

        hashndx = nm_hash(name);
        mb = hashtab[hashndx];
        while (mb) {
                if (mdb_vread(&mb_local, sizeof (mb_local), mb) == -1) {
                        mdb_warn("failed to read struct bind at %p", mb);
                        return (NULL);
                }
                if (mdb_readstr(node_name, sizeof (node_name),
                    (uintptr_t)mb_local.b_name) == -1) {
                        mdb_warn("failed to read node name string at %p",
                            mb_local.b_name);
                        return (NULL);
                }

                if (strcmp(name, node_name) == 0)
                        break;

                mb = (uintptr_t)mb_local.b_next;
        }
        return (mb);
}

int
mdb_name_to_major(const char *name, major_t *major)
{
        uintptr_t       mbind;
        uintptr_t       mb_hashtab[MOD_BIND_HASHSIZE];
        struct bind     mbind_local;


        if (mdb_readsym(mb_hashtab, sizeof (mb_hashtab), "mb_hashtab") == -1) {
                mdb_warn("failed to read symbol 'mb_hashtab'");
                return (-1);
        }

        if ((mbind = find_mbind(name, mb_hashtab)) != NULL) {
                if (mdb_vread(&mbind_local, sizeof (mbind_local), mbind) ==
                    -1) {
                        mdb_warn("failed to read mbind struct at %p", mbind);
                        return (-1);
                }

                *major = (major_t)mbind_local.b_num;
                return (0);
        }
        return (-1);
}

const char *
mdb_major_to_name(major_t major)
{
        static char name[MODMAXNAMELEN + 1];

        uintptr_t devnamesp;
        struct devnames dn;
        uint_t devcnt;

        if (mdb_readvar(&devcnt, "devcnt") == -1 || major >= devcnt ||
            mdb_readvar(&devnamesp, "devnamesp") == -1)
                return (NULL);

        if (mdb_vread(&dn, sizeof (struct devnames), devnamesp +
            major * sizeof (struct devnames)) != sizeof (struct devnames))
                return (NULL);

        if (mdb_readstr(name, MODMAXNAMELEN + 1, (uintptr_t)dn.dn_name) == -1)
                return (NULL);

        return ((const char *)name);
}

/*
 * Return the name of the driver attached to the dip in drivername.
 */
int
mdb_devinfo2driver(uintptr_t dip_addr, char *drivername, size_t namebufsize)
{
        struct dev_info devinfo;
        char bind_name[MAXPATHLEN + 1];
        major_t major;
        const char *namestr;


        if (mdb_vread(&devinfo, sizeof (devinfo), dip_addr) == -1) {
                mdb_warn("failed to read devinfo at %p", dip_addr);
                return (-1);
        }

        if (mdb_readstr(bind_name, sizeof (bind_name),
            (uintptr_t)devinfo.devi_binding_name) == -1) {
                mdb_warn("failed to read binding name at %p",
                    devinfo.devi_binding_name);
                return (-1);
        }

        /*
         * Many->one relation: various names to one major number
         */
        if (mdb_name_to_major(bind_name, &major) == -1) {
                mdb_warn("failed to translate bind name to major number\n");
                return (-1);
        }

        /*
         * One->one relation: one major number corresponds to one driver
         */
        if ((namestr = mdb_major_to_name(major)) == NULL) {
                (void) strncpy(drivername, "???", namebufsize);
                return (-1);
        }

        (void) strncpy(drivername, namestr, namebufsize);
        return (0);
}

/*
 * Find the name of the driver attached to this dip (if any), given:
 * - the address of a dip (in core)
 * - the NAME of the global pointer to the driver's i_ddi_soft_state struct
 * - pointer to a pointer to receive the address
 */
int
mdb_devinfo2statep(uintptr_t dip_addr, char *soft_statep_name,
    uintptr_t *statep)
{
        struct dev_info dev_info;


        if (mdb_vread(&dev_info, sizeof (dev_info), dip_addr) == -1) {
                mdb_warn("failed to read devinfo at %p", dip_addr);
                return (-1);
        }

        return (mdb_get_soft_state_byname(soft_statep_name,
            dev_info.devi_instance, statep, NULL, 0));
}

/*
 * Returns a pointer to the top of the soft state struct for the instance
 * specified (in state_addr), given the address of the global soft state
 * pointer and size of the struct.  Also fills in the buffer pointed to by
 * state_buf_p (if non-NULL) with the contents of the state struct.
 */
int
mdb_get_soft_state_byaddr(uintptr_t ssaddr, uint_t instance,
    uintptr_t *state_addr, void *state_buf_p, size_t sizeof_state)
{
        struct i_ddi_soft_state ss;
        void *statep;


        if (mdb_vread(&ss, sizeof (ss), ssaddr) == -1)
                return (-1);

        if (instance >= ss.n_items)
                return (-1);

        if (mdb_vread(&statep, sizeof (statep), (uintptr_t)ss.array +
            (sizeof (statep) * instance)) == -1)
                return (-1);

        if (state_addr != NULL)
                *state_addr = (uintptr_t)statep;

        if (statep == NULL) {
                errno = ENOENT;
                return (-1);
        }

        if (state_buf_p != NULL) {

                /* Read the state struct into the buffer in local space. */
                if (mdb_vread(state_buf_p, sizeof_state,
                    (uintptr_t)statep) == -1)
                        return (-1);
        }

        return (0);
}


/*
 * Returns a pointer to the top of the soft state struct for the instance
 * specified (in state_addr), given the name of the global soft state pointer
 * and size of the struct.  Also fills in the buffer pointed to by
 * state_buf_p (if non-NULL) with the contents of the state struct.
 */
int
mdb_get_soft_state_byname(char *softstatep_name, uint_t instance,
    uintptr_t *state_addr, void *state_buf_p, size_t sizeof_state)
{
        uintptr_t ssaddr;

        if (mdb_readvar((void *)&ssaddr, softstatep_name) == -1)
                return (-1);

        return (mdb_get_soft_state_byaddr(ssaddr, instance, state_addr,
            state_buf_p, sizeof_state));
}

static const mdb_dcmd_t dcmds[] = {
        { "dnlc", NULL, "print DNLC contents", dnlcdump },
        { NULL }
};

static const mdb_modinfo_t modinfo = { MDB_API_VERSION, dcmds };

/*ARGSUSED*/
static void
update_vars(void *arg)
{
        GElf_Sym sym;

        if (mdb_lookup_by_name("auto_vnodeops", &sym) == 0)
                autofs_vnops_ptr = (struct vnodeops *)(uintptr_t)sym.st_value;
        else
                autofs_vnops_ptr = NULL;

        (void) mdb_readvar(&_mdb_ks_pagesize, "_pagesize");
        (void) mdb_readvar(&_mdb_ks_pageshift, "_pageshift");
        (void) mdb_readvar(&_mdb_ks_pageoffset, "_pageoffset");
        (void) mdb_readvar(&_mdb_ks_pagemask, "_pagemask");
        (void) mdb_readvar(&_mdb_ks_mmu_pagesize, "_mmu_pagesize");
        (void) mdb_readvar(&_mdb_ks_mmu_pageshift, "_mmu_pageshift");
        (void) mdb_readvar(&_mdb_ks_mmu_pageoffset, "_mmu_pageoffset");
        (void) mdb_readvar(&_mdb_ks_mmu_pagemask, "_mmu_pagemask");
        (void) mdb_readvar(&_mdb_ks_kernelbase, "_kernelbase");

        (void) mdb_readvar(&_mdb_ks_userlimit, "_userlimit");
        (void) mdb_readvar(&_mdb_ks_userlimit32, "_userlimit32");
        (void) mdb_readvar(&_mdb_ks_argsbase, "_argsbase");
        (void) mdb_readvar(&_mdb_ks_msg_bsize, "_msg_bsize");
        (void) mdb_readvar(&_mdb_ks_defaultstksz, "_defaultstksz");
        (void) mdb_readvar(&_mdb_ks_ncpu, "_ncpu");
        (void) mdb_readvar(&_mdb_ks_ncpu_log2, "_ncpu_log2");
        (void) mdb_readvar(&_mdb_ks_ncpu_p2, "_ncpu_p2");

        page_hash_loaded = 0;   /* invalidate cached page_hash state */
}

const mdb_modinfo_t *
_mdb_init(void)
{
        /*
         * When used with mdb, mdb_ks is a separate dmod.  With kmdb, however,
         * mdb_ks is compiled into the debugger module.  kmdb cannot
         * automatically modunload itself when it exits.  If it restarts after
         * debugger fault, static variables may not be initialized to zero.
         * They must be manually reinitialized here.
         */
        dnlc_hash = NULL;
        qi_head = NULL;

        mdb_callback_add(MDB_CALLBACK_STCHG, update_vars, NULL);

        update_vars(NULL);

        return (&modinfo);
}

void
_mdb_fini(void)
{
        dnlc_free();
        while (qi_head != NULL) {
                mdb_qinfo_t *qip = qi_head;
                qi_head = qip->qi_next;
                mdb_free(qip, sizeof (mdb_qinfo_t));
        }
}

/*
 * Interface between MDB kproc target and mdb_ks.  The kproc target relies
 * on looking up and invoking these functions in mdb_ks so that dependencies
 * on the current kernel implementation are isolated in mdb_ks.
 */

/*
 * Given the address of a proc_t, return the p.p_as pointer; return NULL
 * if we were unable to read a proc structure from the given address.
 */
uintptr_t
mdb_kproc_as(uintptr_t proc_addr)
{
        proc_t p;

        if (mdb_vread(&p, sizeof (p), proc_addr) == sizeof (p))
                return ((uintptr_t)p.p_as);

        return (NULL);
}

/*
 * Given the address of a proc_t, return the p.p_model value; return
 * PR_MODEL_UNKNOWN if we were unable to read a proc structure or if
 * the model value does not match one of the two known values.
 */
uint_t
mdb_kproc_model(uintptr_t proc_addr)
{
        proc_t p;

        if (mdb_vread(&p, sizeof (p), proc_addr) == sizeof (p)) {
                switch (p.p_model) {
                case DATAMODEL_ILP32:
                        return (PR_MODEL_ILP32);
                case DATAMODEL_LP64:
                        return (PR_MODEL_LP64);
                }
        }

        return (PR_MODEL_UNKNOWN);
}

/*
 * Callback function for walking process's segment list.  For each segment,
 * we fill in an mdb_map_t describing its properties, and then invoke
 * the callback function provided by the kproc target.
 */
static int
asmap_step(uintptr_t addr, const struct seg *seg, asmap_arg_t *asmp)
{
        struct segvn_data svd;
        mdb_map_t map;

        if (seg->s_ops == asmp->asm_segvn_ops && mdb_vread(&svd,
            sizeof (svd), (uintptr_t)seg->s_data) == sizeof (svd)) {

                if (svd.vp != NULL) {
                        if (mdb_vnode2path((uintptr_t)svd.vp, map.map_name,
                            MDB_TGT_MAPSZ) != 0) {
                                (void) mdb_snprintf(map.map_name,
                                    MDB_TGT_MAPSZ, "[ vnode %p ]", svd.vp);
                        }
                } else
                        (void) strcpy(map.map_name, "[ anon ]");

        } else {
                (void) mdb_snprintf(map.map_name, MDB_TGT_MAPSZ,
                    "[ seg %p ]", addr);
        }

        map.map_base = (uintptr_t)seg->s_base;
        map.map_size = seg->s_size;
        map.map_flags = 0;

        asmp->asm_callback((const struct mdb_map *)&map, asmp->asm_cbdata);
        return (WALK_NEXT);
}

/*
 * Given a process address space, walk its segment list using the seg walker,
 * convert the segment data to an mdb_map_t, and pass this information
 * back to the kproc target via the given callback function.
 */
int
mdb_kproc_asiter(uintptr_t as,
    void (*func)(const struct mdb_map *, void *), void *p)
{
        asmap_arg_t arg;
        GElf_Sym sym;

        arg.asm_segvn_ops = NULL;
        arg.asm_callback = func;
        arg.asm_cbdata = p;

        if (mdb_lookup_by_name("segvn_ops", &sym) == 0)
                arg.asm_segvn_ops = (struct seg_ops *)(uintptr_t)sym.st_value;

        return (mdb_pwalk("seg", (mdb_walk_cb_t)asmap_step, &arg, as));
}

/*
 * Copy the auxv array from the given process's u-area into the provided
 * buffer.  If the buffer is NULL, only return the size of the auxv array
 * so the caller knows how much space will be required.
 */
int
mdb_kproc_auxv(uintptr_t proc, auxv_t *auxv)
{
        if (auxv != NULL) {
                proc_t p;

                if (mdb_vread(&p, sizeof (p), proc) != sizeof (p))
                        return (-1);

                bcopy(p.p_user.u_auxv, auxv,
                    sizeof (auxv_t) * __KERN_NAUXV_IMPL);
        }

        return (__KERN_NAUXV_IMPL);
}

/*
 * Given a process address, return the PID.
 */
pid_t
mdb_kproc_pid(uintptr_t proc_addr)
{
        struct pid pid;
        proc_t p;

        if (mdb_vread(&p, sizeof (p), proc_addr) == sizeof (p) &&
            mdb_vread(&pid, sizeof (pid), (uintptr_t)p.p_pidp) == sizeof (pid))
                return (pid.pid_id);

        return (-1);
}

/*
 * Interface between the MDB kvm target and mdb_ks.  The kvm target relies
 * on looking up and invoking these functions in mdb_ks so that dependencies
 * on the current kernel implementation are isolated in mdb_ks.
 */

/*
 * Determine whether or not the thread that panicked the given kernel was a
 * kernel thread (panic_thread->t_procp == &p0).
 */
void
mdb_dump_print_content(dumphdr_t *dh, pid_t content)
{
        GElf_Sym sym;
        uintptr_t pt;
        uintptr_t procp;
        int expcont = 0;
        int actcont;

        (void) mdb_readvar(&expcont, "dump_conflags");
        actcont = dh->dump_flags & DF_CONTENT;

        if (actcont == DF_ALL) {
                mdb_printf("dump content: all kernel and user pages\n");
                return;
        } else if (actcont == DF_CURPROC) {
                mdb_printf("dump content: kernel pages and pages from "
                    "PID %d", content);
                return;
        }

        mdb_printf("dump content: kernel pages only\n");
        if (!(expcont & DF_CURPROC))
                return;

        if (mdb_readvar(&pt, "panic_thread") != sizeof (pt) || pt == NULL)
                goto kthreadpanic_err;

        if (mdb_vread(&procp, sizeof (procp), pt + OFFSETOF(kthread_t,
            t_procp)) == -1 || procp == NULL)
                goto kthreadpanic_err;

        if (mdb_lookup_by_name("p0", &sym) != 0)
                goto kthreadpanic_err;

        if (procp == (uintptr_t)sym.st_value) {
                mdb_printf("  (curproc requested, but a kernel thread "
                    "panicked)\n");
        } else {
                mdb_printf("  (curproc requested, but the process that "
                    "panicked could not be dumped)\n");
        }

        return;

kthreadpanic_err:
        mdb_printf("  (curproc requested, but the process that panicked could "
            "not be found)\n");
}

/*
 * Determine the process that was saved in a `curproc' dump.  This process will
 * be recorded as the first element in dump_pids[].
 */
int
mdb_dump_find_curproc(void)
{
        uintptr_t pidp;
        pid_t pid = -1;

        if (mdb_readvar(&pidp, "dump_pids") == sizeof (pidp) &&
            mdb_vread(&pid, sizeof (pid), pidp) == sizeof (pid) &&
            pid > 0)
                return (pid);
        else
                return (-1);
}


/*
 * Following three funcs extracted from sunddi.c
 */

/*
 * Return core address of root node of devinfo tree
 */
static uintptr_t
mdb_ddi_root_node(void)
{
        uintptr_t       top_devinfo_addr;

        /* return (top_devinfo);   */
        if (mdb_readvar(&top_devinfo_addr, "top_devinfo") == -1) {
                mdb_warn("failed to read top_devinfo");
                return (NULL);
        }
        return (top_devinfo_addr);
}

/*
 * Return the name of the devinfo node pointed at by 'dip_addr' in the buffer
 * pointed at by 'name.'
 *
 * - dip_addr is a pointer to a dev_info struct in core.
 */
static char *
mdb_ddi_deviname(uintptr_t dip_addr, char *name, size_t name_size)
{
        uintptr_t addrname;
        ssize_t length;
        char *local_namep = name;
        size_t local_name_size = name_size;
        struct dev_info local_dip;


        if (dip_addr == mdb_ddi_root_node()) {
                if (name_size < 1) {
                        mdb_warn("failed to get node name: buf too small\n");
                        return (NULL);
                }

                *name = '\0';
                return (name);
        }

        if (name_size < 2) {
                mdb_warn("failed to get node name: buf too small\n");
                return (NULL);
        }

        local_namep = name;
        *local_namep++ = '/';
        *local_namep = '\0';
        local_name_size--;

        if (mdb_vread(&local_dip, sizeof (struct dev_info), dip_addr) == -1) {
                mdb_warn("failed to read devinfo struct");
        }

        length = mdb_readstr(local_namep, local_name_size,
            (uintptr_t)local_dip.devi_node_name);
        if (length == -1) {
                mdb_warn("failed to read node name");
                return (NULL);
        }
        local_namep += length;
        local_name_size -= length;
        addrname = (uintptr_t)local_dip.devi_addr;

        if (addrname != NULL) {

                if (local_name_size < 2) {
                        mdb_warn("not enough room for node address string");
                        return (name);
                }
                *local_namep++ = '@';
                *local_namep = '\0';
                local_name_size--;

                length = mdb_readstr(local_namep, local_name_size, addrname);
                if (length == -1) {
                        mdb_warn("failed to read name");
                        return (NULL);
                }
        }

        return (name);
}

/*
 * Generate the full path under the /devices dir to the device entry.
 *
 * dip is a pointer to a devinfo struct in core (not in local memory).
 */
char *
mdb_ddi_pathname(uintptr_t dip_addr, char *path, size_t pathlen)
{
        struct dev_info local_dip;
        uintptr_t       parent_dip;
        char            *bp;
        size_t          buf_left;


        if (dip_addr == mdb_ddi_root_node()) {
                *path = '\0';
                return (path);
        }


        if (mdb_vread(&local_dip, sizeof (struct dev_info), dip_addr) == -1) {
                mdb_warn("failed to read devinfo struct");
        }

        parent_dip = (uintptr_t)local_dip.devi_parent;
        (void) mdb_ddi_pathname(parent_dip, path, pathlen);

        bp = path + strlen(path);
        buf_left = pathlen - strlen(path);
        (void) mdb_ddi_deviname(dip_addr, bp, buf_left);
        return (path);
}


/*
 * Read in the string value of a refstr, which is appended to the end of
 * the structure.
 */
ssize_t
mdb_read_refstr(uintptr_t refstr_addr, char *str, size_t nbytes)
{
        struct refstr *r = (struct refstr *)refstr_addr;

        return (mdb_readstr(str, nbytes, (uintptr_t)r->rs_string));
}

/*
 * Chase an mblk list by b_next and return the length.
 */
int
mdb_mblk_count(const mblk_t *mb)
{
        int count;
        mblk_t mblk;

        if (mb == NULL)
                return (0);

        count = 1;
        while (mb->b_next != NULL) {
                count++;
                if (mdb_vread(&mblk, sizeof (mblk), (uintptr_t)mb->b_next) ==
                    -1)
                        break;
                mb = &mblk;
        }
        return (count);
}

/*
 * Write the given MAC address as a printable string in the usual colon-
 * separated format.  Assumes that buflen is at least 2.
 */
void
mdb_mac_addr(const uint8_t *addr, size_t alen, char *buf, size_t buflen)
{
        int slen;

        if (alen == 0 || buflen < 4) {
                (void) strcpy(buf, "?");
                return;
        }
        for (;;) {
                /*
                 * If there are more MAC address bytes available, but we won't
                 * have any room to print them, then add "..." to the string
                 * instead.  See below for the 'magic number' explanation.
                 */
                if ((alen == 2 && buflen < 6) || (alen > 2 && buflen < 7)) {
                        (void) strcpy(buf, "...");
                        break;
                }
                slen = mdb_snprintf(buf, buflen, "%02x", *addr++);
                buf += slen;
                if (--alen == 0)
                        break;
                *buf++ = ':';
                buflen -= slen + 1;
                /*
                 * At this point, based on the first 'if' statement above,
                 * either alen == 1 and buflen >= 3, or alen > 1 and
                 * buflen >= 4.  The first case leaves room for the final "xx"
                 * number and trailing NUL byte.  The second leaves room for at
                 * least "...".  Thus the apparently 'magic' numbers chosen for
                 * that statement.
                 */
        }
}

/*
 * Produce a string that represents a DLPI primitive, or NULL if no such string
 * is possible.
 */
const char *
mdb_dlpi_prim(int prim)
{
        switch (prim) {
        case DL_INFO_REQ:       return ("DL_INFO_REQ");
        case DL_INFO_ACK:       return ("DL_INFO_ACK");
        case DL_ATTACH_REQ:     return ("DL_ATTACH_REQ");
        case DL_DETACH_REQ:     return ("DL_DETACH_REQ");
        case DL_BIND_REQ:       return ("DL_BIND_REQ");
        case DL_BIND_ACK:       return ("DL_BIND_ACK");
        case DL_UNBIND_REQ:     return ("DL_UNBIND_REQ");
        case DL_OK_ACK:         return ("DL_OK_ACK");
        case DL_ERROR_ACK:      return ("DL_ERROR_ACK");
        case DL_ENABMULTI_REQ:  return ("DL_ENABMULTI_REQ");
        case DL_DISABMULTI_REQ: return ("DL_DISABMULTI_REQ");
        case DL_PROMISCON_REQ:  return ("DL_PROMISCON_REQ");
        case DL_PROMISCOFF_REQ: return ("DL_PROMISCOFF_REQ");
        case DL_UNITDATA_REQ:   return ("DL_UNITDATA_REQ");
        case DL_UNITDATA_IND:   return ("DL_UNITDATA_IND");
        case DL_UDERROR_IND:    return ("DL_UDERROR_IND");
        case DL_PHYS_ADDR_REQ:  return ("DL_PHYS_ADDR_REQ");
        case DL_PHYS_ADDR_ACK:  return ("DL_PHYS_ADDR_ACK");
        case DL_SET_PHYS_ADDR_REQ:      return ("DL_SET_PHYS_ADDR_REQ");
        case DL_NOTIFY_REQ:     return ("DL_NOTIFY_REQ");
        case DL_NOTIFY_ACK:     return ("DL_NOTIFY_ACK");
        case DL_NOTIFY_IND:     return ("DL_NOTIFY_IND");
        case DL_NOTIFY_CONF:    return ("DL_NOTIFY_CONF");
        case DL_CAPABILITY_REQ: return ("DL_CAPABILITY_REQ");
        case DL_CAPABILITY_ACK: return ("DL_CAPABILITY_ACK");
        case DL_CONTROL_REQ:    return ("DL_CONTROL_REQ");
        case DL_CONTROL_ACK:    return ("DL_CONTROL_ACK");
        case DL_PASSIVE_REQ:    return ("DL_PASSIVE_REQ");
        default:                return (NULL);
        }
}

/*
 * mdb_gethrtime() returns the hires system time. This will be the timestamp at
 * which we dropped into, if called from, kmdb(1); the core dump's hires time
 * if inspecting one; or the running system's hires time if we're inspecting
 * a live kernel.
 */
hrtime_t
mdb_gethrtime(void)
{
        uintptr_t ptr;
        GElf_Sym sym;
        lbolt_info_t lbi;
        hrtime_t ts;

        /*
         * We first check whether the lbolt info structure has been allocated
         * and initialized. If not, lbolt_hybrid will be pointing at
         * lbolt_bootstrap.
         */
        if (mdb_lookup_by_name("lbolt_bootstrap", &sym) == -1)
                return (0);

        if (mdb_readvar(&ptr, "lbolt_hybrid") == -1)
                return (0);

        if (ptr == (uintptr_t)sym.st_value)
                return (0);

#ifdef _KMDB
        if (mdb_readvar(&ptr, "lb_info") == -1)
                return (0);

        if (mdb_vread(&lbi, sizeof (lbolt_info_t), ptr) !=
            sizeof (lbolt_info_t))
                return (0);

        ts = lbi.lbi_debug_ts;
#else
        if (mdb_prop_postmortem) {
                if (mdb_readvar(&ptr, "lb_info") == -1)
                        return (0);

                if (mdb_vread(&lbi, sizeof (lbolt_info_t), ptr) !=
                    sizeof (lbolt_info_t))
                        return (0);

                ts = lbi.lbi_debug_ts;
        } else {
                ts = gethrtime();
        }
#endif
        return (ts);
}

/*
 * mdb_get_lbolt() returns the number of clock ticks since system boot.
 * Depending on the context in which it's called, the value will be derived
 * from different sources per mdb_gethrtime(). If inspecting a panicked
 * system, the routine returns the 'panic_lbolt64' variable from the core file.
 */
int64_t
mdb_get_lbolt(void)
{
        lbolt_info_t lbi;
        uintptr_t ptr;
        int64_t pl;
        hrtime_t ts;
        int nsec;

        if (mdb_readvar(&pl, "panic_lbolt64") != -1 && pl > 0)
                return (pl);

        /*
         * mdb_gethrtime() will return zero if the lbolt info structure hasn't
         * been allocated and initialized yet, or if it fails to read it.
         */
        if ((ts = mdb_gethrtime()) <= 0)
                return (0);

        /*
         * Load the time spent in kmdb, if any.
         */
        if (mdb_readvar(&ptr, "lb_info") == -1)
                return (0);

        if (mdb_vread(&lbi, sizeof (lbolt_info_t), ptr) !=
            sizeof (lbolt_info_t))
                return (0);

        if (mdb_readvar(&nsec, "nsec_per_tick") == -1 || nsec == 0) {
                mdb_warn("failed to read 'nsec_per_tick'");
                return (-1);
        }

        return ((ts/nsec) - lbi.lbi_debug_time);
}