usr/src/cmd/sgs/librtld_db/amd64/plt64_resolution.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include        <libelf.h>
  30 #include        <sys/reg.h>
  31 #include        <rtld_db.h>
  32 #include        "_rtld_db.h"
  33 #include        "msg.h"
  34
  35
  36 /*
  37  * On amd64, basically, a PLT entry looks like this:
  38  *
  39  *      0x00  ff 25 00 00 00 00  jmpq   *func@got(%rip)  ; jmp GOT[N]
  40  *      0x06  68 01 00 00 00     pushq  $0x1           ; push index
  41  *      0x0b  e9 00 00 00 00     jmpq   .plt0          ; jmp plt[0]
  42  *      0x10  ...
  43  *
  44  *  The first time around GOT[N] contains address of pushq; this forces
  45  *      first time resolution to go thru PLT's first entry (which is a call)
  46  *  The nth time around, the GOT[N] actually contains the resolved
  47  *      address of the symbol(name), so the jmp is direct
  48  */
  49 /* ARGSUSED 3 */
  50 rd_err_e
  51 plt64_resolution(rd_agent_t *rap, psaddr_t pc, lwpid_t lwpid,
  52         psaddr_t pltbase, rd_plt_info_t *rpi)
  53 {
  54         uint32_t        pcrel;
  55         psaddr_t        destaddr;
  56         psaddr_t        pltoff, pltaddr;
  57
  58
  59         if (rtld_db_version >= RD_VERSION3) {
  60                 rpi->pi_flags = 0;
  61                 rpi->pi_baddr = 0;
  62         }
  63
  64         pltoff = pc - pltbase;
  65         pltaddr = pltbase +
  66                 ((pltoff / M_PLT_ENTSIZE) * M_PLT_ENTSIZE);
  67         /*
  68          * This is the target of the jmp instruction
  69          */
  70         if (ps_pread(rap->rd_psp, pltaddr + 2, (char *)&pcrel,
  71             sizeof (pcrel)) != PS_OK) {
  72                 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(pltaddr + 2)));
  73                 return (RD_ERR);
  74         }
  75
  76         /*
  77          * the offset to the GOT table entry is
  78          * PC-relative.
  79          */
  80         destaddr = pcrel + pltaddr + 6;
  81
  82         /*
  83          * Find out what's pointed to by @OFFSET_INTO_GOT
  84          */
  85         if (ps_pread(rap->rd_psp, destaddr, (char *)&destaddr,
  86             sizeof (destaddr)) != PS_OK) {
  87                 LOG(ps_plog(MSG_ORIG(MSG_DB_READFAIL_2), EC_ADDR(destaddr)));
  88                 return (RD_ERR);
  89         }
  90         if (destaddr == (pltaddr + 6)) {
  91                 rd_err_e        rerr;
  92                 /*
  93                  * If GOT[ind] points to PLT+6 then this is the first
  94                  * time through this PLT.
  95                  */
  96                 if ((rerr = rd_binder_exit_addr(rap, MSG_ORIG(MSG_SYM_RTBIND),
  97                     &(rpi->pi_target))) != RD_OK) {
  98                         return (rerr);
  99                 }
 100                 rpi->pi_skip_method = RD_RESOLVE_TARGET_STEP;
 101                 rpi->pi_nstep = 1;
 102         } else {
 103                 /*
 104                  * This is the n'th time through and GOT[ind] points
 105                  * to the final destination.
 106                  */
 107                 rpi->pi_skip_method = RD_RESOLVE_STEP;
 108                 rpi->pi_nstep = 1;
 109                 rpi->pi_target = 0;
 110                 if (rtld_db_version >= RD_VERSION3) {
 111                         rpi->pi_flags |= RD_FLG_PI_PLTBOUND;
 112                         rpi->pi_baddr = destaddr;
 113                 }
 114         }
 115
 116         return (RD_OK);
 117 }