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/*
* ELF object format helpers - x86:x32
*
* Copyright (C) 2012 Michael Urman and H.J. Lu
*
* 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 OTHER 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 OTHER 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 <util.h>
#include <libyasm.h>
#define YASM_OBJFMT_ELF_INTERNAL
#include "elf.h"
#include "elf-machine.h"
static elf_machine_ssym elf_x86_x32_ssyms[] = {
{"plt", ELF_SSYM_SYM_RELATIVE, R_X86_64_PLT32, 32},
{"gotpcrel", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOTPCREL, 32},
{"tlsgd", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_TLSGD, 32},
{"tlsld", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_TLSLD, 32},
{"gottpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_GOTTPOFF, 32},
{"tpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_TPOFF32, 32},
{"dtpoff", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_DTPOFF32, 32},
{"got", ELF_SSYM_SYM_RELATIVE, R_X86_64_GOT32, 32},
{"tlsdesc", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_GOTPC32_TLSDESC, 32},
{"tlscall", ELF_SSYM_SYM_RELATIVE|ELF_SSYM_THREAD_LOCAL,
R_X86_64_TLSDESC_CALL, 32}
};
static int
elf_x86_x32_accepts_reloc(size_t val, yasm_symrec *wrt)
{
if (wrt) {
const elf_machine_ssym *ssym = (elf_machine_ssym *)
yasm_symrec_get_data(wrt, &elf_ssym_symrec_data);
if (!ssym || val != ssym->size)
return 0;
return 1;
}
return (val&(val-1)) ? 0 : ((val & (8|16|32)) != 0);
}
static void
elf_x86_x32_write_symtab_entry(unsigned char *bufp,
elf_symtab_entry *entry,
yasm_intnum *value_intn,
yasm_intnum *size_intn)
{
YASM_WRITE_32_L(bufp, entry->name ? entry->name->index : 0);
YASM_WRITE_32I_L(bufp, value_intn);
YASM_WRITE_32I_L(bufp, size_intn);
YASM_WRITE_8(bufp, ELF32_ST_INFO(entry->bind, entry->type));
YASM_WRITE_8(bufp, ELF32_ST_OTHER(entry->vis));
if (entry->sect) {
elf_secthead *shead =
yasm_section_get_data(entry->sect, &elf_section_data);
if (!shead)
yasm_internal_error(N_("symbol references section without data"));
YASM_WRITE_16_L(bufp, shead->index);
} else {
YASM_WRITE_16_L(bufp, entry->index);
}
}
static void
elf_x86_x32_write_secthead(unsigned char *bufp, elf_secthead *shead)
{
YASM_WRITE_32_L(bufp, shead->name ? shead->name->index : 0);
YASM_WRITE_32_L(bufp, shead->type);
YASM_WRITE_32_L(bufp, shead->flags);
YASM_WRITE_32_L(bufp, 0); /* vmem address */
YASM_WRITE_32_L(bufp, shead->offset);
YASM_WRITE_32I_L(bufp, shead->size);
YASM_WRITE_32_L(bufp, shead->link);
YASM_WRITE_32_L(bufp, shead->info);
YASM_WRITE_32_L(bufp, shead->align);
YASM_WRITE_32_L(bufp, shead->entsize);
}
static void
elf_x86_x32_write_secthead_rel(unsigned char *bufp,
elf_secthead *shead,
elf_section_index symtab_idx,
elf_section_index sindex)
{
yasm_intnum *nreloc;
yasm_intnum *relocsize;
YASM_WRITE_32_L(bufp, shead->rel_name ? shead->rel_name->index : 0);
YASM_WRITE_32_L(bufp, SHT_RELA);
YASM_WRITE_32_L(bufp, 0);
YASM_WRITE_32_L(bufp, 0);
YASM_WRITE_32_L(bufp, shead->rel_offset);
nreloc = yasm_intnum_create_uint(shead->nreloc);
relocsize = yasm_intnum_create_uint(RELOC32A_SIZE);
yasm_intnum_calc(relocsize, YASM_EXPR_MUL, nreloc);
YASM_WRITE_32I_L(bufp, relocsize); /* size */
yasm_intnum_destroy(nreloc);
yasm_intnum_destroy(relocsize);
YASM_WRITE_32_L(bufp, symtab_idx); /* link: symtab index */
YASM_WRITE_32_L(bufp, shead->index); /* info: relocated's index */
YASM_WRITE_32_L(bufp, RELOC32_ALIGN); /* align */
YASM_WRITE_32_L(bufp, RELOC32A_SIZE); /* entity size */
}
static void
elf_x86_x32_handle_reloc_addend(yasm_intnum *intn,
elf_reloc_entry *reloc,
unsigned long offset)
{
/* .rela: copy value out as addend, replace original with 0 */
reloc->addend = yasm_intnum_copy(intn);
yasm_intnum_zero(intn);
}
static unsigned int
elf_x86_x32_map_reloc_info_to_type(elf_reloc_entry *reloc)
{
if (reloc->wrt) {
const elf_machine_ssym *ssym = (elf_machine_ssym *)
yasm_symrec_get_data(reloc->wrt, &elf_ssym_symrec_data);
if (!ssym || reloc->valsize != ssym->size)
yasm_internal_error(N_("Unsupported WRT"));
/* Force TLS type; this is required by the linker. */
if (ssym->sym_rel & ELF_SSYM_THREAD_LOCAL) {
elf_symtab_entry *esym;
esym = yasm_symrec_get_data(reloc->reloc.sym, &elf_symrec_data);
if (esym)
esym->type = STT_TLS;
}
/* Map PC-relative GOT to appropriate relocation */
if (reloc->rtype_rel && ssym->reloc == R_X86_64_GOT32)
return (unsigned char) R_X86_64_GOTPCREL;
return (unsigned char) ssym->reloc;
} else if (reloc->is_GOT_sym && reloc->valsize == 32) {
return (unsigned char) R_X86_64_GOTPC32;
} else if (reloc->is_GOT_sym && reloc->valsize == 64) {
yasm_internal_error(N_("Unsupported relocation size"));
} else if (reloc->rtype_rel) {
switch (reloc->valsize) {
case 8: return (unsigned char) R_X86_64_PC8;
case 16: return (unsigned char) R_X86_64_PC16;
case 32: return (unsigned char) R_X86_64_PC32;
default: yasm_internal_error(N_("Unsupported relocation size"));
}
} else {
switch (reloc->valsize) {
case 8: return (unsigned char) R_X86_64_8;
case 16: return (unsigned char) R_X86_64_16;
case 32: return (unsigned char) R_X86_64_32;
case 64: return (unsigned char) R_X86_64_64;
default: yasm_internal_error(N_("Unsupported relocation size"));
}
}
return 0;
}
static void
elf_x86_x32_write_reloc(unsigned char *bufp, elf_reloc_entry *reloc,
unsigned int r_type, unsigned int r_sym)
{
YASM_WRITE_32I_L(bufp, reloc->reloc.addr);
YASM_WRITE_32_L(bufp, ELF32_R_INFO((unsigned long)r_sym, (unsigned char)r_type));
if (reloc->addend)
YASM_WRITE_32I_L(bufp, reloc->addend);
else {
YASM_WRITE_32_L(bufp, 0);
}
}
static void
elf_x86_x32_write_proghead(unsigned char **bufpp,
elf_offset secthead_addr,
unsigned long secthead_count,
elf_section_index shstrtab_index)
{
unsigned char *bufp = *bufpp;
unsigned char *buf = bufp-4;
YASM_WRITE_8(bufp, ELFCLASS32); /* elf class */
YASM_WRITE_8(bufp, ELFDATA2LSB); /* data encoding :: MSB? */
YASM_WRITE_8(bufp, EV_CURRENT); /* elf version */
YASM_WRITE_8(bufp, ELFOSABI_SYSV); /* os/abi */
YASM_WRITE_8(bufp, 0); /* SYSV v3 ABI=0 */
while (bufp-buf < EI_NIDENT) /* e_ident padding */
YASM_WRITE_8(bufp, 0);
YASM_WRITE_16_L(bufp, ET_REL); /* e_type - object file */
YASM_WRITE_16_L(bufp, EM_X86_64); /* e_machine - or others */
YASM_WRITE_32_L(bufp, EV_CURRENT); /* elf version */
YASM_WRITE_32_L(bufp, 0); /* e_entry */
YASM_WRITE_32_L(bufp, 0); /* e_phoff */
YASM_WRITE_32_L(bufp, secthead_addr); /* e_shoff secthead off */
YASM_WRITE_32_L(bufp, 0); /* e_flags */
YASM_WRITE_16_L(bufp, EHDR32_SIZE); /* e_ehsize */
YASM_WRITE_16_L(bufp, 0); /* e_phentsize */
YASM_WRITE_16_L(bufp, 0); /* e_phnum */
YASM_WRITE_16_L(bufp, SHDR32_SIZE); /* e_shentsize */
YASM_WRITE_16_L(bufp, secthead_count); /* e_shnum */
YASM_WRITE_16_L(bufp, shstrtab_index); /* e_shstrndx */
*bufpp = bufp;
}
const elf_machine_handler
elf_machine_handler_x86_x32 = {
"x86", "x32", ".rela",
SYMTAB32_SIZE, SYMTAB32_ALIGN, RELOC32A_SIZE, SHDR32_SIZE, EHDR32_SIZE,
elf_x86_x32_accepts_reloc,
elf_x86_x32_write_symtab_entry,
elf_x86_x32_write_secthead,
elf_x86_x32_write_secthead_rel,
elf_x86_x32_handle_reloc_addend,
elf_x86_x32_map_reloc_info_to_type,
elf_x86_x32_write_reloc,
elf_x86_x32_write_proghead,
elf_x86_x32_ssyms,
sizeof(elf_x86_x32_ssyms)/sizeof(elf_x86_x32_ssyms[0]),
32
};
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