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alpha_reloc.c revision 1.4 
      1 /*	$NetBSD: alpha_reloc.c,v 1.4 2002/09/05 15:38:23 mycroft Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2001 Wasabi Systems, Inc.
      5  * All rights reserved.
      6  *
      7  * Written by Jason R. Thorpe for Wasabi Systems, Inc.
      8  *
      9  * Redistribution and use in source and binary forms, with or without
     10  * modification, are permitted provided that the following conditions
     11  * are met:
     12  * 1. Redistributions of source code must retain the above copyright
     13  *    notice, this list of conditions and the following disclaimer.
     14  * 2. Redistributions in binary form must reproduce the above copyright
     15  *    notice, this list of conditions and the following disclaimer in the
     16  *    documentation and/or other materials provided with the distribution.
     17  * 3. All advertising materials mentioning features or use of this software
     18  *    must display the following acknowledgement:
     19  *	This product includes software developed for the NetBSD Project by
     20  *	Wasabi Systems, Inc.
     21  * 4. The name of Wasabi Systems, Inc. may not be used to endorse
     22  *    or promote products derived from this software without specific prior
     23  *    written permission.
     24  *
     25  * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
     26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     27  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     28  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL WASABI SYSTEMS, INC
     29  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     30  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     31  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     32  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     33  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     34  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     35  * POSSIBILITY OF SUCH DAMAGE.
     36  */
     37 
     38 #include <sys/types.h>
     39 #include <sys/stat.h>
     40 
     41 #include "rtld.h"
     42 #include "debug.h"
     43 
     44 #ifdef RTLD_DEBUG_ALPHA
     45 #define	adbg(x)		if (dodebug) xprintf x
     46 #else
     47 #define	adbg(x)		/* nothing */
     48 #endif
     49 
     50 void
     51 _rtld_setup_pltgot(const Obj_Entry *obj)
     52 {
     53 	uint32_t word0;
     54 
     55 	/*
     56 	 * The PLTGOT on the Alpha looks like this:
     57 	 *
     58 	 *	PLT HEADER
     59 	 *	.
     60 	 *	. 32 bytes
     61 	 *	.
     62 	 *	PLT ENTRY #0
     63 	 *	.
     64 	 *	. 12 bytes
     65 	 *	.
     66 	 *	PLT ENTRY #1
     67 	 *	.
     68 	 *	. 12 bytes
     69 	 *	.
     70 	 *	etc.
     71 	 *
     72 	 * The old-format entries look like (displacements filled in
     73 	 * by the linker):
     74 	 *
     75 	 *	ldah	$28, 0($31)		# 0x279f0000
     76 	 *	lda	$28, 0($28)		# 0x239c0000
     77 	 *	br	$31, plt0		# 0xc3e00000
     78 	 *
     79 	 * The new-format entries look like:
     80 	 *
     81 	 *	br	$28, plt0		# 0xc3800000
     82 	 *					# 0x00000000
     83 	 *					# 0x00000000
     84 	 *
     85 	 * What we do is fetch the first PLT entry and check to
     86 	 * see the first word of it matches the first word of the
     87 	 * old format.  If so, we use a binding routine that can
     88 	 * handle the old format, otherwise we use a binding routine
     89 	 * that handles the new format.
     90 	 *
     91 	 * Note that this is done on a per-object basis, we can mix
     92 	 * and match shared objects build with both the old and new
     93 	 * linker.
     94 	 */
     95 	word0 = *(uint32_t *)(((char *) obj->pltgot) + 32);
     96 	if ((word0 & 0xffff0000) == 0x279f0000) {
     97 		/* Old PLT entry format. */
     98 		adbg(("ALPHA: object %p has old PLT format\n", obj));
     99 		obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start_old;
    100 		obj->pltgot[3] = (Elf_Addr) obj;
    101 	} else {
    102 		/* New PLT entry format. */
    103 		adbg(("ALPHA: object %p has new PLT format\n", obj));
    104 		obj->pltgot[2] = (Elf_Addr) &_rtld_bind_start;
    105 		obj->pltgot[3] = (Elf_Addr) obj;
    106 	}
    107 
    108 	__asm __volatile("imb");
    109 }
    110