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/* $OpenBSD: self_reloc.c,v 1.2 2019/05/11 19:14:41 mlarkin Exp $ */
/*-
* Copyright (c) 2008-2010 Rui Paulo <rpaulo@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/param.h>
#include <machine/reloc.h>
#define ELFSIZE 32
#define ElfW_Rel Elf32_Rel
#define ElfW_Dyn Elf32_Dyn
#define ELFW_R_TYPE ELF32_R_TYPE
#include <sys/exec_elf.h>
#define RELOC_TYPE_NONE R_386_NONE
#define RELOC_TYPE_RELATIVE R_386_RELATIVE
/*
* A simple elf relocator.
*/
void
self_reloc(Elf_Addr baseaddr, ElfW_Dyn *dynamic)
{
Elf_Word relsz, relent;
Elf_Addr *newaddr;
ElfW_Rel *rel = NULL;
ElfW_Dyn *dynp;
/*
* Find the relocation address, its size and the relocation entry.
*/
relsz = 0;
relent = 0;
for (dynp = dynamic; dynp->d_tag != DT_NULL; dynp++) {
switch (dynp->d_tag) {
case DT_REL:
case DT_RELA:
rel = (ElfW_Rel *)(dynp->d_un.d_ptr + baseaddr);
break;
case DT_RELSZ:
case DT_RELASZ:
relsz = dynp->d_un.d_val;
break;
case DT_RELENT:
case DT_RELAENT:
relent = dynp->d_un.d_val;
break;
default:
break;
}
}
/*
* Perform the actual relocation. We rely on the object having been
* linked at 0, so that the difference between the load and link
* address is the same as the load address.
*/
for (; relsz > 0; relsz -= relent) {
switch (ELFW_R_TYPE(rel->r_info)) {
case RELOC_TYPE_NONE:
/* No relocation needs be performed. */
break;
case RELOC_TYPE_RELATIVE:
newaddr = (Elf_Addr *)(rel->r_offset + baseaddr);
#ifdef ELF_RELA
/* Addend relative to the base address. */
*newaddr = baseaddr + rel->r_addend;
#else
/* Address relative to the base address. */
*newaddr += baseaddr;
#endif
break;
default:
/* XXX: do we need other relocations ? */
break;
}
rel = (ElfW_Rel *) ((caddr_t) rel + relent);
}
}
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