librtld_db/amd64/plt64_resolution.c

	plt64_resolution.c revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
 * 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 2004 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

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

#include    <libelf.h>
#include    <sys/reg.h>
#include    <rtld_db.h>
#include    "_rtld_db.h"
#include    "msg.h"


/*
 * On amd64, basically, a PLT entry looks like this:
 *
 *  0x00  ff 25 00 00 00 00  jmpq   *func@got(%rip)  ; jmp GOT[N]
 *  0x06  68 01 00 00 00     pushq  $0x1           ; push index
 *  0x0b  e9 00 00 00 00     jmpq   .plt0          ; jmp plt[0]
 *  0x10  ...
 *
 *  The first time around GOT[N] contains address of pushq; this forces
 *  first time resolution to go thru PLT's first entry (which is a call)
 *  The nth time around, the GOT[N] actually contains the resolved
 *  address of the symbol(name), so the jmp is direct
 */
/* ARGSUSED 3 */
rd_err_e
plt64_resolution(rd_agent_t *rap, psaddr_t pc, lwpid_t lwpid,
    psaddr_t pltbase, rd_plt_info_t *rpi)
{
    uint32_t    pcrel;
    psaddr_t    destaddr;
    psaddr_t    pltoff, pltaddr;
    prgregset_t gr;


    if (rtld_db_version >= RD_VERSION3) {
        rpi->pi_flags = 0;
        rpi->pi_baddr = 0;
    }

    pltoff = pc - pltbase;
    pltaddr = pltbase +
        ((pltoff / M_PLT_ENTSIZE) * M_PLT_ENTSIZE);
    /*
     * This is the target of the jmp instruction
     */
    if (ps_pread(rap->rd_psp, pltaddr + 2, (char *)&pcrel,
        sizeof (pcrel)) != PS_OK) {
        LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 2)));
        return (RD_ERR);
    }

    /*
     * the offset to the GOT table entry is
     * PC-relative.
     */
    destaddr = pcrel + pltaddr + 6;

    /*
     * Find out what's pointed to by @OFFSET_INTO_GOT
     */
    if (ps_pread(rap->rd_psp, destaddr, (char *)&destaddr,
        sizeof (destaddr)) != PS_OK) {
        LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(destaddr)));
        return (RD_ERR);
    }
    if (destaddr == (pltaddr + 6)) {
        rd_err_e    rerr;
        /*
         * If GOT[ind] points to PLT+6 then this is the first
         * time through this PLT.
         */
        if ((rerr = rd_binder_exit_addr(rap, MSG_ORIG(MSG_SYM_RTBIND),
            &(rpi->pi_target))) != RD_OK) {
            return (rerr);
        }
        rpi->pi_skip_method = RD_RESOLVE_TARGET_STEP;
        rpi->pi_nstep = 1;
    } else {
        /*
         * This is the n'th time through and GOT[ind] points
         * to the final destination.
         */
        rpi->pi_skip_method = RD_RESOLVE_STEP;
        rpi->pi_nstep = 1;
        rpi->pi_target = 0;
        if (rtld_db_version >= RD_VERSION3) {
            rpi->pi_flags |= RD_FLG_PI_PLTBOUND;
            rpi->pi_baddr = destaddr;
        }
    }

    return (RD_OK);
}