libld/common/groups.c

	groups.c revision 1007fd6fd24227460e77ce89f5ca85641a85a576
/*
 * 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) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
 */

#include    <stdio.h>
#include    <string.h>
#include    <link.h>
#include    <debug.h>
#include    "msg.h"
#include    "_libld.h"

/*
 * Determine whether a (COMDAT) group has already been encountered.  If so,
 * indicate that the group descriptor has an overriding group (gd_oisc).  This
 * indication triggers the ld_place_section() to discard this group, while the
 * gd_oisc information provides for complete diagnostics of the override.
 * Otherwise, this is the first occurrence of this group, therefore the group
 * descriptor is saved for future comparisons.
 */
static uintptr_t
gpavl_loaded(Ofl_desc *ofl, Group_desc *gdp)
{
    Isd_node    isd, *isdp;
    avl_tree_t  *avlt;
    avl_index_t where;

    /*
     * Create a groups avl tree if required.
     */
    if ((avlt = ofl->ofl_groups) == NULL) {
        if ((avlt = libld_calloc(sizeof (avl_tree_t), 1)) == NULL)
            return (S_ERROR);
        avl_create(avlt, isdavl_compare, sizeof (Isd_node),
            SGSOFFSETOF(Isd_node, isd_avl));
        ofl->ofl_groups = avlt;
    }

    /*
     * An SHT_GROUP section is identified by the name of its signature
     * symbol rather than section name. Although the section names are
     * often unique, this is not required, and some compilers set it to
     * a generic name like ".group".
     */
    isd.isd_name = gdp->gd_name;
    isd.isd_hash = sgs_str_hash(isd.isd_name);

    if ((isdp = avl_find(avlt, &isd, &where)) != NULL) {
        gdp->gd_oisc = isdp->isd_isp;
        return (1);
    }

    /*
     * This is a new group - so keep it.
     */
    if ((isdp = libld_calloc(sizeof (Isd_node), 1)) == NULL)
        return (S_ERROR);

    isdp->isd_name = isd.isd_name;
    isdp->isd_hash = isd.isd_hash;
    isdp->isd_isp = gdp->gd_isc;

    avl_insert(avlt, isdp, where);
    return (0);
}

Group_desc *
ld_get_group(Ofl_desc *ofl, Is_desc *isp)
{
    Ifl_desc    *ifl = isp->is_file;
    uint_t      scnndx = isp->is_scnndx;
    Group_desc  *gdp;
    Aliste      idx;

    /*
     * Scan the GROUP sections associated with this file to find the
     * matching group section.
     */
    for (ALIST_TRAVERSE(ifl->ifl_groups, idx, gdp)) {
        size_t  ndx;
        Word    *data;

        if (isp->is_shdr->sh_type == SHT_GROUP) {
            if (isp->is_scnndx == gdp->gd_isc->is_scnndx)
                return (gdp);
            continue;
        }

        data = gdp->gd_data;
        for (ndx = 1; ndx < gdp->gd_cnt; ndx++) {
            if (data[ndx] == scnndx)
                return (gdp);
        }
    }

    ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_ELF_NOGROUPSECT),
        ifl->ifl_name, EC_WORD(isp->is_scnndx), isp->is_name);
    return (NULL);
}

uintptr_t
ld_group_process(Is_desc *gisc, Ofl_desc *ofl)
{
    Ifl_desc    *gifl = gisc->is_file;
    Shdr        *sshdr, *gshdr = gisc->is_shdr;
    Is_desc     *isc;
    Sym     *sym;
    const char  *str;
    Group_desc  gd;
    size_t      ndx;
    int     gnu_stt_section;

    /*
     * Confirm that the sh_link points to a valid section.
     */
    if ((gshdr->sh_link == SHN_UNDEF) ||
        (gshdr->sh_link >= gifl->ifl_shnum) ||
        ((isc = gifl->ifl_isdesc[gshdr->sh_link]) == NULL)) {
        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHLINK),
            gifl->ifl_name, EC_WORD(gisc->is_scnndx),
            gisc->is_name, EC_XWORD(gshdr->sh_link));
        return (0);
    }
    if (gshdr->sh_entsize == 0) {
        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHENTSIZE),
            gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
            EC_XWORD(gshdr->sh_entsize));
        return (0);
    }

    /*
     * Get the associated symbol table.  Sanity check the sh_info field
     * (which points to the signature symbol table entry) against the size
     * of the symbol table.
     */
    sshdr = isc->is_shdr;
    sym = (Sym *)isc->is_indata->d_buf;

    if ((sshdr->sh_info == SHN_UNDEF) ||
        (gshdr->sh_info >= (Word)(sshdr->sh_size / sshdr->sh_entsize)) ||
        ((isc = gifl->ifl_isdesc[sshdr->sh_link]) == NULL)) {
        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_FIL_INVSHINFO),
            gifl->ifl_name, EC_WORD(gisc->is_scnndx), gisc->is_name,
            EC_XWORD(gshdr->sh_info));
        return (0);
    }

    sym += gshdr->sh_info;

    /*
     * Get the symbol name from the associated string table.
     */
    str = (char *)isc->is_indata->d_buf;
    str += sym->st_name;

    /*
     * The GNU assembler can use section symbols as the signature symbol
     * as described by this comment in the gold linker (found via google):
     *
     *  It seems that some versions of gas will create a section group
     *  associated with a section symbol, and then fail to give a name
     *  to the section symbol.  In such a case, use the name of the
     *  section.
     *
     * In order to support such objects, we do the same.
     */
    gnu_stt_section = ((sym->st_name == 0) || (*str == '\0')) &&
        (ELF_ST_TYPE(sym->st_info) == STT_SECTION);
    if (gnu_stt_section)
        str = gisc->is_name;


    /*
     * Generate a group descriptor.
     */
    gd.gd_isc = gisc;
    gd.gd_oisc = NULL;
    gd.gd_name = str;
    gd.gd_data = gisc->is_indata->d_buf;
    gd.gd_cnt = gisc->is_indata->d_size / sizeof (Word);

    /*
     * If this group is a COMDAT group, validate the signature symbol.
     */
    if ((gd.gd_data[0] & GRP_COMDAT) && !gnu_stt_section &&
        ((ELF_ST_BIND(sym->st_info) == STB_LOCAL) ||
        (sym->st_shndx == SHN_UNDEF))) {
        /* If section symbol, construct a printable name for it */
        if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) {
            if (gisc->is_sym_name == NULL)
                (void) ld_stt_section_sym_name(gisc);

            if (gisc->is_sym_name != NULL)
                str = gisc->is_sym_name;
        }

        ld_eprintf(ofl, ERR_FATAL, MSG_INTL(MSG_GRP_INVALSYM),
            gifl->ifl_name, EC_WORD(gisc->is_scnndx),
            gisc->is_name, str);
        return (0);
    }

    /*
     * Validate the section indices within the group.  If this is a COMDAT
     * group, mark each section as COMDAT.
     */
    for (ndx = 1; ndx < gd.gd_cnt; ndx++) {
        Word    gndx;

        if ((gndx = gd.gd_data[ndx]) >= gifl->ifl_shnum) {
            ld_eprintf(ofl, ERR_FATAL,
                MSG_INTL(MSG_GRP_INVALNDX), gifl->ifl_name,
                EC_WORD(gisc->is_scnndx), gisc->is_name, ndx, gndx);
            return (0);
        }

        if (gd.gd_data[0] & GRP_COMDAT)
            gifl->ifl_isdesc[gndx]->is_flags |= FLG_IS_COMDAT;
    }

    /*
     * If this is a COMDAT group, determine whether this group has already
     * been encountered, or whether this is the first instance of the group.
     */
    if ((gd.gd_data[0] & GRP_COMDAT) &&
        (gpavl_loaded(ofl, &gd) == S_ERROR))
        return (S_ERROR);

    /*
     * Associate the group descriptor with this input file.
     */
    if (alist_append(&(gifl->ifl_groups), &gd, sizeof (Group_desc),
        AL_CNT_IFL_GROUPS) == NULL)
        return (S_ERROR);

    return (1);
}