modules/genunix/modhash.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 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include <string.h>
#include <sys/modhash_impl.h>

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

#include "modhash.h"

/* This is passed to the modent callback; allows caller to get context */
typedef struct modent_step_data_s {
    struct mod_hash_entry   msd_mhe;    /* must be first */
    int         msd_hash_index;
    int         msd_position;   /* entry position in chain */
    uintptr_t       msd_first_addr; /* first address in chain */
} modent_step_data_t;

/* Context for a walk over a modhash (variable length) */
typedef struct hash_walk_s {
    modent_step_data_t  hwalk_msd;  /* current entry data */
    mod_hash_t      hwalk_hash; /* always last (var. len) */
} hash_walk_t;

/* Computes number of bytes to allocate for hash_walk_t structure. */
#define HW_SIZE(n)  (sizeof (modent_step_data_t) + MH_SIZE(n))

/* Used for decoding hash keys for display */
typedef struct hash_type_entry_s {
    const char *hte_type;       /* name of hash type for ::modent -t */
    const char *hte_comparator; /* name of comparator function */
    void (*hte_format)(const mod_hash_key_t, char *, size_t);
} hash_type_entry_t;

static void format_strhash(const mod_hash_key_t, char *, size_t);
static void format_ptrhash(const mod_hash_key_t, char *, size_t);
static void format_idhash(const mod_hash_key_t, char *, size_t);
static void format_default(const mod_hash_key_t, char *, size_t);

static const hash_type_entry_t hte_table[] = {
    { "str", "mod_hash_strkey_cmp", format_strhash },
    { "ptr", "mod_hash_ptrkey_cmp", format_ptrhash },
    { "id", "mod_hash_idkey_cmp", format_idhash },
    { NULL, NULL, format_default }
};

static int modent_print(uintptr_t, int, uint_t, const hash_type_entry_t *,
    boolean_t, uint_t, uint_t);

/* The information used during a walk */
typedef struct mod_walk_data_s {
    const hash_type_entry_t *mwd_hte;   /* pointer to entry type */
    int         mwd_main_flags; /* ::modhash flags */
    int         mwd_flags;  /* DCMD_* flags for looping */
    uint_t          mwd_opt_e;  /* call-modent mode */
    uint_t          mwd_opt_c;  /* chain head only mode */
    uint_t          mwd_opt_h;  /* hash index output */
    boolean_t       mwd_opt_k_set;  /* key supplied */
    boolean_t       mwd_opt_v_set;  /* value supplied */
    uintptr_t       mwd_opt_k;  /* key */
    uintptr_t       mwd_opt_v;  /* value */
    int         mwd_maxposn;    /* len of longest chain - 1 */
    int         mwd_maxidx; /* hash idx of longest chain */
    uintptr_t       mwd_maxaddr;    /* addr of 1st elem @ maxidx */
    uintptr_t       mwd_idxtoprint; /* desired hash pos to print */
    uintptr_t       mwd_addr;   /* 1st elem addr @idxtoprint */
} mod_walk_data_t;

/*
 * Initialize a walk over all the modhashes in the system.
 */
int
modhash_walk_init(mdb_walk_state_t *wsp)
{
    mod_hash_t *mh_head;

    if (mdb_readvar(&mh_head, "mh_head") == -1) {
        mdb_warn("failed to read mh_head");
        return (WALK_ERR);
    }
    wsp->walk_addr = (uintptr_t)mh_head;

    return (WALK_NEXT);
}

/*
 * Step to the next modhash in the system.
 */
int
modhash_walk_step(mdb_walk_state_t *wsp)
{
    mod_hash_t mh;
    int status;

    if (wsp->walk_addr == NULL)
        return (WALK_DONE);

    if (mdb_vread(&mh, sizeof (mh), wsp->walk_addr) == -1) {
        mdb_warn("failed to read mod_hash_t at %p", wsp->walk_addr);
        return (WALK_ERR);
    }

    status = wsp->walk_callback(wsp->walk_addr, &mh, wsp->walk_cbdata);

    wsp->walk_addr = (uintptr_t)mh.mh_next;

    return (status);
}

/*
 * Initialize a walk over the entries in a given modhash.
 */
int
modent_walk_init(mdb_walk_state_t *wsp)
{
    mod_hash_t mh;
    hash_walk_t *hwp;
    int retv;

    if (wsp->walk_addr == NULL) {
        mdb_warn("mod_hash_t address required\n");
        return (WALK_ERR);
    }

    if (mdb_vread(&mh, sizeof (mh), wsp->walk_addr) == -1) {
        mdb_warn("failed to read mod_hash_t at %p", wsp->walk_addr);
        return (WALK_ERR);
    }

    if (mh.mh_nchains <= 1) {
        mdb_warn("impossible number of chains in mod_hash_t at %p",
            wsp->walk_addr);
        return (WALK_ERR);
    }

    /*
     * If the user presents us with a garbage pointer, and thus the number
     * of chains is just absurd, we don't want to bail out of mdb.  Fail to
     * walk instead.
     */
    hwp = mdb_alloc(HW_SIZE(mh.mh_nchains), UM_NOSLEEP);
    if (hwp == NULL) {
        mdb_warn("unable to allocate %#x bytes for mod_hash_t at %p",
            HW_SIZE(mh.mh_nchains), wsp->walk_addr);
        return (WALK_ERR);
    }

    (void) memcpy(&hwp->hwalk_hash, &mh, sizeof (hwp->hwalk_hash));

    retv = mdb_vread(hwp->hwalk_hash.mh_entries + 1,
        (mh.mh_nchains - 1) * sizeof (struct mod_hash_entry *),
        wsp->walk_addr + sizeof (mh));

    if (retv == -1) {
        mdb_free(hwp, HW_SIZE(mh.mh_nchains));
        mdb_warn("failed to read %#x mod_hash_entry pointers at %p",
            mh.mh_nchains - 1, wsp->walk_addr + sizeof (mh));
        return (WALK_ERR);
    }

    hwp->hwalk_msd.msd_hash_index = -1;
    hwp->hwalk_msd.msd_position = 0;
    hwp->hwalk_msd.msd_first_addr = NULL;

    wsp->walk_addr = NULL;
    wsp->walk_data = hwp;

    return (WALK_NEXT);
}

/*
 * Step to the next entry in the modhash.
 */
int
modent_walk_step(mdb_walk_state_t *wsp)
{
    hash_walk_t *hwp = wsp->walk_data;
    int status;

    while (wsp->walk_addr == NULL) {
        hwp->hwalk_msd.msd_position = 0;
        if (++hwp->hwalk_msd.msd_hash_index >=
            hwp->hwalk_hash.mh_nchains)
            return (WALK_DONE);
        wsp->walk_addr = hwp->hwalk_msd.msd_first_addr =
            (uintptr_t)hwp->hwalk_hash.mh_entries[
            hwp->hwalk_msd.msd_hash_index];
    }

    if (mdb_vread(&hwp->hwalk_msd.msd_mhe, sizeof (hwp->hwalk_msd.msd_mhe),
        wsp->walk_addr) == -1) {
        mdb_warn("failed to read mod_hash_entry at %p",
            wsp->walk_addr);
        return (WALK_ERR);
    }

    status = wsp->walk_callback(wsp->walk_addr, &hwp->hwalk_msd,
        wsp->walk_cbdata);

    hwp->hwalk_msd.msd_position++;
    wsp->walk_addr = (uintptr_t)hwp->hwalk_msd.msd_mhe.mhe_next;

    return (status);
}

/*
 * Clean up after walking the entries in a modhash.
 */
void
modent_walk_fini(mdb_walk_state_t *wsp)
{
    hash_walk_t *hwp = wsp->walk_data;

    mdb_free(hwp, HW_SIZE(hwp->hwalk_hash.mh_nchains));
    wsp->walk_data = NULL;
}

/*
 * Step to next entry on a hash chain.
 */
int
modchain_walk_step(mdb_walk_state_t *wsp)
{
    struct mod_hash_entry mhe;
    int status;

    if (wsp->walk_addr == NULL)
        return (WALK_DONE);

    if (mdb_vread(&mhe, sizeof (mhe), wsp->walk_addr) == -1) {
        mdb_warn("failed to read mod_hash_entry at %p",
            wsp->walk_addr);
        return (WALK_ERR);
    }

    status = wsp->walk_callback(wsp->walk_addr, &mhe, wsp->walk_cbdata);

    wsp->walk_addr = (uintptr_t)mhe.mhe_next;

    return (status);
}

/*
 * This is called by ::modhash (via a callback) when gathering data about the
 * entries in a given modhash.  It keeps track of the longest chain, finds a
 * specific entry (if the user requested one) and prints out a summary of the
 * entry or entries.
 */
static int
modent_format(uintptr_t addr, const void *data, void *private)
{
    const modent_step_data_t *msd = data;
    mod_walk_data_t *mwd = private;
    int retv = DCMD_OK;

    /* If this chain is longest seen, then save start of chain */
    if (msd->msd_position > mwd->mwd_maxposn) {
        mwd->mwd_maxposn = msd->msd_position;
        mwd->mwd_maxidx = msd->msd_hash_index;
        mwd->mwd_maxaddr = msd->msd_first_addr;
    }

    /* If the user specified a particular chain, then ignore others */
    if (mwd->mwd_idxtoprint != (uintptr_t)-1) {
        /* Save address of *first* entry */
        if (mwd->mwd_idxtoprint == msd->msd_hash_index)
            mwd->mwd_addr = msd->msd_first_addr;
        else
            return (retv);
    }

    /* If the user specified a particular key, ignore others. */
    if (mwd->mwd_opt_k_set &&
        (uintptr_t)msd->msd_mhe.mhe_key != mwd->mwd_opt_k)
        return (retv);

    /* If the user specified a particular value, ignore others. */
    if (mwd->mwd_opt_v_set &&
        (uintptr_t)msd->msd_mhe.mhe_val != mwd->mwd_opt_v)
        return (retv);

    /* If the user just wants the chain heads, skip intermediate nodes. */
    if (mwd->mwd_opt_c && msd->msd_position != 0)
        return (retv);

    /* If the user asked to have the entries printed, then do that. */
    if (mwd->mwd_opt_e) {
        /* If the output is to a pipeline, just print addresses */
        if (mwd->mwd_main_flags & DCMD_PIPE_OUT)
            mdb_printf("%p\n", addr);
        else
            retv = modent_print(addr, msd->msd_hash_index,
                mwd->mwd_flags, mwd->mwd_hte, mwd->mwd_opt_h, 0, 0);
        mwd->mwd_flags &= ~DCMD_LOOPFIRST;
    }
    return (retv);
}

void
modhash_help(void)
{
    mdb_printf("Prints information about one or all mod_hash_t databases "
        "in the system.\n"
        "This command has three basic forms, summarized below.\n\n"
        "  ::modhash [-t]\n  <addr>::modhash\n"
        "  <addr>::modhash -e [-ch] [-k key] [-v val] [-i index]\n\n"
        "In the first form, no address is provided, and a summary of all "
        "registered\n"
        "hashes in the system is printed; adding the '-t' option shows"
        " the hash\n"
        "type instead of the limits.  In the second form, the address of a"
        " mod_hash_t\n"
        "is provided, and the output is in a verbose format.  The final "
        "form prints\n"
        "the elements of the hash, optionally selecting just those with a "
        "particular\n"
        "key, value, and/or hash index, or just the chain heads (-c).  "
        "The -h option\n"
        "shows hash indices instead of addresses.\n");
}

int
modhash(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    mod_hash_t mh;
    char name[256];
    int len;
    mod_walk_data_t mwd;
    uint_t opt_s = FALSE;
    uint_t opt_t = FALSE;
    char kfunc[MDB_SYM_NAMLEN];
    const hash_type_entry_t *htep;
    boolean_t elem_flags;

    (void) memset(&mwd, 0, sizeof (mwd));
    mwd.mwd_main_flags = flags;
    mwd.mwd_flags = DCMD_ADDRSPEC | DCMD_LOOP | DCMD_LOOPFIRST;
    mwd.mwd_maxposn = -1;
    mwd.mwd_idxtoprint = (uintptr_t)-1;

    len = mdb_getopts(argc, argv,
        's', MDB_OPT_SETBITS, TRUE, &opt_s,
        't', MDB_OPT_SETBITS, TRUE, &opt_t,
        'c', MDB_OPT_SETBITS, TRUE, &mwd.mwd_opt_c,
        'e', MDB_OPT_SETBITS, TRUE, &mwd.mwd_opt_e,
        'h', MDB_OPT_SETBITS, TRUE, &mwd.mwd_opt_h,
        'i', MDB_OPT_UINTPTR, &mwd.mwd_idxtoprint,
        'k', MDB_OPT_UINTPTR_SET, &mwd.mwd_opt_k_set, &mwd.mwd_opt_k,
        'v', MDB_OPT_UINTPTR_SET, &mwd.mwd_opt_v_set, &mwd.mwd_opt_v,
        NULL);

    if (len < argc) {
        argv += len;
        if (argv->a_type == MDB_TYPE_STRING)
            mdb_warn("unexpected argument: %s\n",
                argv->a_un.a_str);
        else
            mdb_warn("unexpected argument(s)\n");
        return (DCMD_USAGE);
    }

    /* true if any element-related flags are set */
    elem_flags = mwd.mwd_opt_c || mwd.mwd_opt_e || mwd.mwd_opt_h ||
        mwd.mwd_opt_k_set || mwd.mwd_opt_v_set ||
        mwd.mwd_idxtoprint != (uintptr_t)-1;

    if (!(flags & DCMD_ADDRSPEC)) {
        mdb_arg_t new_argv[1];

        if (elem_flags) {
            /*
             * This isn't allowed so that the output doesn't become
             * a confusing mix of hash table descriptions and
             * element entries.
             */
            mdb_warn("printing elements from all hashes is not "
                "permitted\n");
            return (DCMD_USAGE);
        }
        /* we force short mode here, no matter what he says */
        new_argv[0].a_type = MDB_TYPE_STRING;
        new_argv[0].a_un.a_str = opt_t ? "-st" : "-s";
        if (mdb_walk_dcmd("modhash", "modhash", 1, new_argv) == -1) {
            mdb_warn("can't walk mod_hash structures");
            return (DCMD_ERR);
        }
        return (DCMD_OK);
    }

    if (mwd.mwd_opt_e) {
        if (opt_s | opt_t) {
            mdb_warn("hash summary options not permitted when "
                "displaying elements\n");
            return (DCMD_USAGE);
        }
    } else {
        if (elem_flags) {
            /*
             * This isn't allowed so that the output doesn't become
             * a confusing mix of hash table description and
             * element entries.
             */
            mdb_warn("printing elements requires -e\n");
            return (DCMD_USAGE);
        }
    }

    if (mdb_vread(&mh, sizeof (mh), addr) == -1) {
        mdb_warn("failed to read mod_hash_t at %p", addr);
        return (DCMD_ERR);
    }

    if (mwd.mwd_idxtoprint != (uintptr_t)-1 &&
        mwd.mwd_idxtoprint >= mh.mh_nchains) {
        mdb_warn("mod_hash chain index %x out of range 0..%x\n",
            mwd.mwd_idxtoprint, mh.mh_nchains - 1);
        return (DCMD_ERR);
    }

    if (DCMD_HDRSPEC(flags) && opt_s) {
        if (opt_t != 0) {
            mdb_printf("%<u>%?s %6s %5s %?s %s%</u>\n",
                "ADDR", "CHAINS", "ELEMS", "TYPE", "NAME");
        } else {
            mdb_printf("%<u>%?s %6s %5s %6s %6s %s%</u>\n",
                "ADDR", "CHAINS", "ELEMS", "MAXLEN", "MAXIDX",
                "NAME");
        }
    }

    len = mdb_readstr(name, sizeof (name), (uintptr_t)mh.mh_name);
    if (len < 0)
        (void) strcpy(name, "??");

    if (mdb_lookup_by_addr((uintptr_t)mh.mh_keycmp, MDB_SYM_EXACT, kfunc,
        sizeof (kfunc), NULL) == -1)
        kfunc[0] = '\0';
    for (htep = hte_table; htep->hte_type != NULL; htep++)
        if (strcmp(kfunc, htep->hte_comparator) == 0)
            break;
    mwd.mwd_hte = htep;

    if (!mwd.mwd_opt_e && !opt_s) {
        mdb_printf("mod_hash_t %?p %s%s:\n", addr, name,
            len == sizeof (name) ? "..." : "");
        mdb_printf("\tKey comparator: %?p %s\n",
            mh.mh_keycmp, kfunc);
        mdb_printf("\tType: %s\n",
            htep->hte_type == NULL ? "unknown" : htep->hte_type);
        mdb_printf("\tSleep flag = %s, alloc failed = %#x\n",
            mh.mh_sleep ? "true" : "false",
            mh.mh_stat.mhs_nomem);
        mdb_printf("\tNumber of chains = %#x, elements = %#x\n",
            mh.mh_nchains, mh.mh_stat.mhs_nelems);
        mdb_printf("\tHits = %#x, misses = %#x, dups = %#x\n",
            mh.mh_stat.mhs_hit, mh.mh_stat.mhs_miss,
            mh.mh_stat.mhs_coll);
    }
    if (mdb_pwalk("modent", modent_format, &mwd, addr) == -1) {
        mdb_warn("can't walk mod_hash entries");
        return (DCMD_ERR);
    }
    if (opt_s) {
        const char *tname;
        char tbuf[64];

        if (htep->hte_type == NULL) {
            (void) mdb_snprintf(tbuf, sizeof (tbuf), "%p",
                mh.mh_keycmp);
            tname = tbuf;
        } else {
            tname = htep->hte_type;
        }
        mdb_printf("%?p %6x %5x ", addr, mh.mh_nchains,
            mh.mh_stat.mhs_nelems);
        if (opt_t != 0) {
            mdb_printf("%?s", tname);
        } else {
            mdb_printf("%6x %6x", mwd.mwd_maxposn + 1,
                mwd.mwd_maxidx);
        }
        mdb_printf(" %s%s\n", name, len == sizeof (name) ? "..." : "");
    } else if (!mwd.mwd_opt_e) {
        mdb_printf("\tMaximum chain length = %x (at index %x, first "
            "entry %p)\n", mwd.mwd_maxposn + 1, mwd.mwd_maxidx,
            mwd.mwd_maxaddr);
    }
    return (DCMD_OK);
}

static void
format_strhash(const mod_hash_key_t key, char *keystr, size_t keystrlen)
{
    int len;

    (void) mdb_snprintf(keystr, keystrlen, "%?p ", key);
    len = strlen(keystr);
    (void) mdb_readstr(keystr + len, keystrlen - len, (uintptr_t)key);
}

static void
format_ptrhash(const mod_hash_key_t key, char *keystr, size_t keystrlen)
{
    int len;

    (void) mdb_snprintf(keystr, keystrlen, "%?p ", key);
    len = strlen(keystr);
    (void) mdb_lookup_by_addr((uintptr_t)key, MDB_SYM_EXACT, keystr + len,
        keystrlen - len, NULL);
}

static void
format_idhash(const mod_hash_key_t key, char *keystr, size_t keystrlen)
{
    (void) mdb_snprintf(keystr, keystrlen, "%?x", (uint_t)(uintptr_t)key);
}

static void
format_default(const mod_hash_key_t key, char *keystr, size_t keystrlen)
{
    (void) mdb_snprintf(keystr, keystrlen, "%?p", key);
}

void
modent_help(void)
{
    mdb_printf("Options are mutually exclusive:\n"
        "  -t <type>  print key in symbolic form; <type> is one of str, "
        "ptr, or id\n"
        "  -v         print value pointer alone\n"
        "  -k         print key pointer alone\n");
}

static int
modent_print(uintptr_t addr, int hidx, uint_t flags,
    const hash_type_entry_t *htep, boolean_t prtidx, uint_t opt_k,
    uint_t opt_v)
{
    char keystr[256];
    struct mod_hash_entry mhe;

    if (DCMD_HDRSPEC(flags) && opt_k == 0 && opt_v == 0) {
        mdb_printf("%<u>%?s %?s %?s%</u>\n",
            prtidx ? "HASH_IDX" : "ADDR", "VAL", "KEY");
    }

    if (mdb_vread(&mhe, sizeof (mhe), addr) == -1) {
        mdb_warn("failed to read mod_hash_entry at %p", addr);
        return (DCMD_ERR);
    }

    if (opt_k) {
        mdb_printf("%p\n", mhe.mhe_key);
    } else if (opt_v) {
        mdb_printf("%p\n", mhe.mhe_val);
    } else {
        htep->hte_format(mhe.mhe_key, keystr, sizeof (keystr));
        if (prtidx)
            mdb_printf("%?x", hidx);
        else
            mdb_printf("%?p", addr);
        mdb_printf(" %?p %s\n", mhe.mhe_val, keystr);
    }

    return (DCMD_OK);
}

/*
 * This prints out a single mod_hash element, showing its value and its key.
 * The key is decoded based on the type of hash keys in use.
 */
int
modent(uintptr_t addr, uint_t flags, int argc, const mdb_arg_t *argv)
{
    const char *opt_t = NULL;
    const hash_type_entry_t *htep;
    int len;
    uint_t opt_k = 0;
    uint_t opt_v = 0;

    if (!(flags & DCMD_ADDRSPEC)) {
        mdb_warn("address of mod_hash_entry must be specified\n");
        return (DCMD_ERR);
    }

    len = mdb_getopts(argc, argv,
        't', MDB_OPT_STR, &opt_t,
        'k', MDB_OPT_SETBITS, 1, &opt_k,
        'v', MDB_OPT_SETBITS, 1, &opt_v,
        NULL);

    /* options are mutually exclusive */
    if ((opt_k && opt_v) || (opt_t != NULL && (opt_k || opt_v)) ||
        len < argc) {
        return (DCMD_USAGE);
    }

    for (htep = hte_table; htep->hte_type != NULL; htep++)
        if (opt_t != NULL && strcmp(opt_t, htep->hte_type) == 0)
            break;

    if (opt_t != NULL && htep->hte_type == NULL) {
        mdb_warn("unknown hash type %s\n", opt_t);
        return (DCMD_ERR);
    }

    return (modent_print(addr, 0, flags, htep, FALSE, opt_k, opt_v));
}