librtld/amd64/_relocate.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    <string.h>
#include    "machdep.h"
#include    "reloc.h"
#include    "_librtld.h"
#include    "_elf.h"

/*
 * Undo relocations that have been applied to a memory image.  Basically this
 * involves copying the original files relocation offset into the new image
 * being created.
 */
/* ARGSUSED3 */
void
undo_reloc(void *vrel, uchar_t *oaddr, uchar_t *iaddr, Reloc *reloc)
{
    Rela        *rel = vrel;
    Xword       rtype = ELF_R_TYPE(rel->r_info, M_MACH);

    switch (rtype) {
    case R_AMD64_NONE:
        break;
    case R_AMD64_COPY:
        (void) memset((void *)oaddr, 0, (size_t)reloc->r_size);
        break;
    case R_AMD64_JUMP_SLOT:
        {
            /* LINTED */
            ulong_t *_oaddr = (ulong_t *)oaddr;
            /* LINTED */
            ulong_t *_iaddr = (ulong_t *)iaddr;

            if (_iaddr)
                *_oaddr = *_iaddr + reloc->r_value;
            else
                *_oaddr = reloc->r_value;
        }
        break;
    default:
        {
            size_t re_fsize = reloc_table[rtype].re_fsize;

            if (iaddr)
                (void) memcpy(oaddr, iaddr, re_fsize);
            else
                (void) memset(oaddr, 0, re_fsize);
        }
    }
}

/*
 * Copy a relocation record and increment its value.  The record must reflect
 * the new address to which this image is fixed. Note that .got entries
 * associated with .plt's must be fixed to the new base address.
 */
/* ARGSUSED3 */
void
inc_reloc(void *vnrel, void *vorel, Reloc *reloc, uchar_t *oaddr,
    uchar_t *iaddr)
{
    Rela    *nrel = vnrel;
    Rela    *orel = vorel;

    if (ELF_R_TYPE(nrel->r_info, M_MACH) == R_AMD64_JUMP_SLOT) {
        /* LINTED */
        ulong_t *_oaddr = (ulong_t *)oaddr;
        /* LINTED */
        ulong_t *_iaddr = (ulong_t *)iaddr;

        if (_iaddr)
            *_oaddr = *_iaddr + reloc->r_value;
        else
            *_oaddr = reloc->r_value;
    }

    *nrel = *orel;
    nrel->r_offset += reloc->r_value;
}

/*
 * Clear a relocation record.  The relocation has been applied to the image and
 * thus the relocation must not occur again.
 */
void
clear_reloc(void *vrel)
{
    Rela    *rel = vrel;

    rel->r_offset = 0;
    rel->r_info = ELF_R_INFO(0, R_AMD64_NONE);
    rel->r_addend = 0;
}

/*
 * Apply a relocation to an image being built from an input file.  Use the
 * runtime linkers routines to do the necessary magic.
 */
void
apply_reloc(void *vrel, Reloc *reloc, const char *name, uchar_t *oaddr,
    Rt_map *lmp)
{
    Rela    *rel = vrel;
    Xword   type = ELF_R_TYPE(rel->r_info, M_MACH);
    Xword   value = reloc->r_value + rel->r_addend;

    if (type == R_AMD64_JUMP_SLOT) {
        uintptr_t   addr, vaddr;

        if (FLAGS(lmp) & FLG_RT_FIXED)
            vaddr = 0;
        else
            vaddr = ADDR(lmp);

        addr = (uintptr_t)oaddr - rel->r_offset;
        /* LINTED */
        (void) elf_plt_write((uintptr_t)addr, vaddr, rel,
            (uintptr_t)value, reloc->r_pltndx);

    } else if (type == R_AMD64_COPY) {
        (void) memcpy((void *)oaddr, (void *)value,
            (size_t)reloc->r_size);
    } else {
        (void) do_reloc_rtld(type, oaddr, &value, reloc->r_name, name,
            LIST(lmp));
    }
}