/*
 * 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 2006 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

#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;


        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);
}