xref: /freebsd/usr.sbin/kldxref/ef_amd64.c (revision 2a622f14)

/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2003 Jake Burkholder.
 * Copyright 1996-1998 John D. Polstra.
 * 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/endian.h>

#include <err.h>
#include <errno.h>
#include <gelf.h>

#include "ef.h"

/*
 * Apply relocations to the values obtained from the file. `relbase' is the
 * target relocation address of the section, and `dataoff/len' is the region
 * that is to be relocated, and has been copied to *dest
 */
static int
ef_amd64_reloc(struct elf_file *ef, const void *reldata, Elf_Type reltype,
    GElf_Addr relbase, GElf_Addr dataoff, size_t len, void *dest)
{
	char *where;
	GElf_Addr addr, addend;
	GElf_Size rtype, symidx;
	const GElf_Rel *rel;
	const GElf_Rela *rela;

	switch (reltype) {
	case ELF_T_REL:
		rel = (const GElf_Rel *)reldata;
		where = (char *)dest + (relbase + rel->r_offset - dataoff);
		addend = 0;
		rtype = GELF_R_TYPE(rel->r_info);
		symidx = GELF_R_SYM(rel->r_info);
		break;
	case ELF_T_RELA:
		rela = (const GElf_Rela *)reldata;
		where = (char *)dest + (relbase + rela->r_offset - dataoff);
		addend = rela->r_addend;
		rtype = GELF_R_TYPE(rela->r_info);
		symidx = GELF_R_SYM(rela->r_info);
		break;
	default:
		return (EINVAL);
	}

	if (where < (char *)dest || where >= (char *)dest + len)
		return (0);

	if (reltype == ELF_T_REL) {
		/* Addend is 32 bit on 32 bit relocs */
		switch (rtype) {
		case R_X86_64_PC32:
		case R_X86_64_32S:
			addend = le32dec(where);
			break;
		default:
			addend = le64dec(where);
			break;
		}
	}

	switch (rtype) {
	case R_X86_64_NONE:	/* none */
		break;
	case R_X86_64_64:	/* S + A */
		addr = EF_SYMADDR(ef, symidx) + addend;
		le64enc(where, addr);
		break;
	case R_X86_64_32S:	/* S + A sign extend */
		addr = EF_SYMADDR(ef, symidx) + addend;
		le32enc(where, addr);
		break;
	case R_X86_64_GLOB_DAT:	/* S */
		addr = EF_SYMADDR(ef, symidx);
		le64enc(where, addr);
		break;
	case R_X86_64_RELATIVE:	/* B + A */
		addr = relbase + addend;
		le64enc(where, addr);
		break;
	default:
		warnx("unhandled relocation type %d", (int)rtype);
	}
	return (0);
}

ELF_RELOC(ELFCLASS64, ELFDATA2LSB, EM_X86_64, ef_amd64_reloc);