rtld/common/tls.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#include <stdio.h>
#include <strings.h>
#include <sys/types.h>
#include <dlfcn.h>
#include <libc_int.h>
#include <_rtld.h>
#include <_elf.h>
#include <msg.h>
#include <debug.h>

#define TLSBLOCKCNT 16  /* number of blocks of tmi_bits to allocate */
                /* at a time. */
typedef struct {
    uint_t  *tmi_bits;
    ulong_t tmi_lowfree;
    ulong_t tmi_cnt;
} Tlsmodid;

static Tlsmodid tmid = {0, 0, 0};

static ulong_t
tls_getmodid()
{
    ulong_t ndx, cnt;

    if (tmid.tmi_bits == 0) {
        if ((tmid.tmi_bits =
            calloc(TLSBLOCKCNT, sizeof (uint_t))) == NULL)
            return ((ulong_t)-1);
        tmid.tmi_bits[0] = 1;
        tmid.tmi_lowfree = 1;
        tmid.tmi_cnt = TLSBLOCKCNT;
        return (0);
    }

    for (cnt = tmid.tmi_lowfree / (sizeof (uint_t) * 8);
        cnt < tmid.tmi_cnt; cnt++) {
        uint_t  bits;

        /*
         * If all bits are assigned - move on.
         */
        if ((tmid.tmi_bits[cnt] ^ ~((uint_t)0)) == 0)
            continue;

        for (ndx = 0, bits = 1; bits; bits = bits << 1, ndx++) {
            if ((tmid.tmi_bits[cnt] & bits) == 0) {
                tmid.tmi_bits[cnt] |= bits;
                ndx = (cnt * (sizeof (uint_t)) * 8) + ndx;
                tmid.tmi_lowfree = ndx + 1;
                return (ndx);
            }
        }
    }

    /*
     * All bits taken - must allocate a new block
     */
    if ((tmid.tmi_bits = realloc(tmid.tmi_bits,
        ((tmid.tmi_cnt * sizeof (uint_t)) +
        (TLSBLOCKCNT * sizeof (uint_t))))) == NULL)
        return ((ulong_t)-1);

    /*
     * Clear out the tail of the new allocation.
     */
    bzero(&(tmid.tmi_bits[tmid.tmi_cnt]), TLSBLOCKCNT * sizeof (uint_t));
    tmid.tmi_bits[tmid.tmi_cnt] = 1;
    ndx = (tmid.tmi_cnt * sizeof (uint_t)) * 8;
    tmid.tmi_lowfree = ndx + 1;
    tmid.tmi_cnt += TLSBLOCKCNT;

    return (ndx);
}

void
tls_freemodid(ulong_t modid)
{
    ulong_t i;
    uint_t  j;

    i = modid / (sizeof (uint_t) * 8);
    /* LINTED */
    j = modid % (sizeof (uint_t) * 8);
    j = ~(1 << j);
    tmid.tmi_bits[i] &= j;
    if (modid < tmid.tmi_lowfree)
        tmid.tmi_lowfree = modid;
}

void
tls_modaddrem(Rt_map *lmp, uint_t flag)
{
    Lm_list     *lml = LIST(lmp);
    TLS_modinfo tmi;
    Phdr        *tlsphdr;
    void        (*fptr)(TLS_modinfo *);

    if (flag & TM_FLG_MODADD) {
        fptr = (void (*)())lml->lm_lcs[CI_TLS_MODADD].lc_un.lc_func;
    } else if (FLAGS1(lmp) & FL1_RT_TLSADD) {
        fptr = (void (*)())lml->lm_lcs[CI_TLS_MODREM].lc_un.lc_func;
    } else {
        return;
    }

    tlsphdr = PTTLS(lmp);

    bzero(&tmi, sizeof (tmi));
    tmi.tm_modname = PATHNAME(lmp);
    tmi.tm_modid = TLSMODID(lmp);
    tmi.tm_tlsblock = (void *)(tlsphdr->p_vaddr);

    if (!(FLAGS(lmp) & FLG_RT_FIXED))
        tmi.tm_tlsblock = (void *)((uintptr_t)tmi.tm_tlsblock +
            ADDR(lmp));

    tmi.tm_filesz = tlsphdr->p_filesz;
    tmi.tm_memsz = tlsphdr->p_memsz;
    tmi.tm_flags = 0;
    tmi.tm_stattlsoffset = 0;

    DBG_CALL(Dbg_tls_modactivity(LIST(lmp), &tmi, flag));
    (*fptr)(&tmi);

    /*
     * Tag that this link-map has registered its TLS, and, if this object
     * is being removed, free up the module id.
     */
    FLAGS1(lmp) |= FL1_RT_TLSADD;

    if (flag & TM_FLG_MODREM)
        tls_freemodid(TLSMODID(lmp));
}

static ulong_t  tls_static_size = 0;    /* static TLS buffer size */
static ulong_t  tls_static_resv = 512;  /* (extra) static TLS reservation */

/*
 * Track any static TLS use, retain the TLS header, and assign a TLS module
 * identifier.
 */
int
tls_assign(Lm_list *lml, Rt_map *lmp, Phdr *phdr)
{
    ulong_t memsz = S_ROUND(phdr->p_memsz, M_TLSSTATALIGN);
    ulong_t filesz = phdr->p_filesz;
    ulong_t resv = tls_static_resv;

    /*
     * If this object explicitly references static TLS, then there are some
     * limitations.
     */
    if (FLAGS1(lmp) & FL1_RT_TLSSTAT) {
        /*
         * Static TLS is only available to objects on the primary
         * link-map list.
         */
        if (((lml->lm_flags & LML_FLG_BASELM) == 0) ||
            ((rtld_flags2 & RT_FL2_NOPLM) != 0)) {
            eprintf(lml, ERR_FATAL, MSG_INTL(MSG_TLS_STATBASE),
                NAME(lmp));
            return (0);
        }

        /*
         * All TLS blocks that are processed before thread
         * initialization, are registered with libc.  This
         * initialization is carried out through a handshake with libc
         * prior to executing any user code (ie. before the first .init
         * sections are called).  As part of this initialization, a
         * small backup TLS reservation is added (tls_static_resv).
         * Only explicit static TLS references that can be satisfied by
         * this TLS backup reservation can be satisfied.
         */
        if (rtld_flags2 & RT_FL2_PLMSETUP) {
            /*
             * Initialized static TLS can not be satisfied from the
             * TLS backup reservation.
             */
            if (filesz) {
                eprintf(lml, ERR_FATAL,
                    MSG_INTL(MSG_TLS_STATINIT), NAME(lmp));
                return (0);
            }

            /*
             * Make sure the backup reservation is sufficient.
             */
            if (memsz > tls_static_resv) {
                eprintf(lml, ERR_FATAL,
                    MSG_INTL(MSG_TLS_STATSIZE), NAME(lmp),
                    EC_XWORD(memsz), EC_XWORD(tls_static_resv));
                return (0);
            }

            tls_static_resv -= memsz;
        }
    }

    /*
     * If we haven't yet initialized threads, or this static reservation can
     * be satisfied from the TLS backup reservation, determine the total
     * static TLS size, and assign this object a static TLS offset.
     */
    if (((rtld_flags2 & RT_FL2_PLMSETUP) == 0) ||
        (FLAGS1(lmp) & FL1_RT_TLSSTAT)) {
        tls_static_size += memsz;
        TLSSTATOFF(lmp) = tls_static_size;
    }

    /*
     * Retain the PT_TLS header, obtain a new module identifier, and
     * indicate that this link-map list contains a new TLS object.
     */
    PTTLS(lmp) = phdr;
    TLSMODID(lmp) = tls_getmodid();

    /*
     * Now that we have a TLS module id, generate any static TLS reservation
     * diagnostic.
     */
    if (resv != tls_static_resv)
        DBG_CALL(Dbg_tls_static_resv(lmp, memsz, tls_static_resv));

    return (++lml->lm_tls);
}

int
tls_statmod(Lm_list *lml, Rt_map *lmp)
{
    uint_t      tlsmodndx, tlsmodcnt = lml->lm_tls;
    TLS_modinfo **tlsmodlist, *tlsbuflist;
    Phdr        *tlsphdr;
    void        (*fptr)(TLS_modinfo **, ulong_t);

    fptr = (void (*)())lml->lm_lcs[CI_TLS_STATMOD].lc_un.lc_func;

    /*
     * Allocate a buffer to report the TLS modules, the buffer consists of:
     *
     *  TLS_modinfo *   ptrs[tlsmodcnt + 1]
     *  TLS_modinfo bufs[tlsmodcnt]
     *
     * The ptrs are initialized to the bufs - except the last one which
     * null terminates the array.
     *
     * Note, even if no TLS has yet been observed, we still supply a
     * TLS buffer with a single null entry.  This allows us to initialize
     * the backup TLS reservation.
     */
    if ((tlsmodlist = calloc((sizeof (TLS_modinfo *) * (tlsmodcnt + 1)) +
        (sizeof (TLS_modinfo) * tlsmodcnt), 1)) == NULL)
        return (0);

    lml->lm_tls = 0;

    /*
     * If we don't have any TLS modules - report that and return.
     */
    if (tlsmodcnt == 0) {
        if (fptr)
            (*fptr)(tlsmodlist, tls_static_resv);
        DBG_CALL(Dbg_tls_static_block(&lml_main, 0, 0,
            tls_static_resv));
        return (1);
    }

    /*
     * Initialize the TLS buffer.
     */
    tlsbuflist = (TLS_modinfo *)((uintptr_t)tlsmodlist +
        ((tlsmodcnt + 1) * sizeof (TLS_modinfo *)));

    for (tlsmodndx = 0; tlsmodndx < tlsmodcnt; tlsmodndx++)
        tlsmodlist[tlsmodndx] = &tlsbuflist[tlsmodndx];

    /*
     * Account for the initial dtv ptr in the TLSSIZE calculation.
     */
    tlsmodndx = 0;
    for (lmp = lml->lm_head; lmp; lmp = NEXT_RT_MAP(lmp)) {
        if (THIS_IS_NOT_ELF(lmp) ||
            (PTTLS(lmp) == 0) || (PTTLS(lmp)->p_memsz == 0))
            continue;

        tlsphdr = PTTLS(lmp);

        tlsmodlist[tlsmodndx]->tm_modname = PATHNAME(lmp);
        tlsmodlist[tlsmodndx]->tm_modid = TLSMODID(lmp);
        tlsmodlist[tlsmodndx]->tm_tlsblock = (void *)(tlsphdr->p_vaddr);

        if (!(FLAGS(lmp) & FLG_RT_FIXED)) {
            tlsmodlist[tlsmodndx]->tm_tlsblock = (void *)
                ((uintptr_t)tlsmodlist[tlsmodndx]->tm_tlsblock +
                ADDR(lmp));
        }
        tlsmodlist[tlsmodndx]->tm_filesz = tlsphdr->p_filesz;
        tlsmodlist[tlsmodndx]->tm_memsz = tlsphdr->p_memsz;
        tlsmodlist[tlsmodndx]->tm_flags = TM_FLG_STATICTLS;
        tlsmodlist[tlsmodndx]->tm_stattlsoffset = TLSSTATOFF(lmp);
        tlsmodndx++;
    }

    DBG_CALL(Dbg_tls_static_block(&lml_main, (void *)tlsmodlist,
        tls_static_size, tls_static_resv));
    (*fptr)(tlsmodlist, (tls_static_size + tls_static_resv));

    /*
     * We're done with the list - clean it up.
     */
    free(tlsmodlist);
    return (1);
}