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/* Run an ELF binary on a linux system.
Copyright (C) 1993, Eric Youngdale.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#ifndef VERBOSE_DLINKER
#define VERBOSE_DLINKER
#endif
#ifdef VERBOSE_DLINKER
static const char *_dl_reltypes[] =
{ "R_386_NONE", "R_386_32", "R_386_PC32", "R_386_GOT32",
"R_386_PLT32", "R_386_COPY", "R_386_GLOB_DAT",
"R_386_JMP_SLOT", "R_386_RELATIVE", "R_386_GOTOFF",
"R_386_GOTPC", "R_386_NUM"
};
#endif
/* Program to load an ELF binary on a linux system, and run it.
References to symbols in sharable libraries can be resolved by either
an ELF sharable library or a linux style of shared library. */
/* Disclaimer: I have never seen any AT&T source code for SVr4, nor have
I ever taken any courses on internals. This program was developed using
information available through the book "UNIX SYSTEM V RELEASE 4,
Programmers guide: Ansi C and Programming Support Tools", which did
a more than adequate job of explaining everything required to get this
working. */
extern int _dl_linux_resolve(void);
unsigned long _dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
{
int reloc_type;
Elf32_Rel *this_reloc;
char *strtab;
Elf32_Sym *symtab;
Elf32_Rel *rel_addr;
int symtab_index;
char *new_addr;
char **got_addr;
unsigned long instr_addr;
rel_addr = (Elf32_Rel *) (tpnt->dynamic_info[DT_JMPREL] + tpnt->loadaddr);
this_reloc = rel_addr + (reloc_entry >> 3);
reloc_type = ELF32_R_TYPE(this_reloc->r_info);
symtab_index = ELF32_R_SYM(this_reloc->r_info);
symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
if (reloc_type != R_386_JMP_SLOT) {
_dl_dprintf(2, "%s: Incorrect relocation type in jump relocations\n",
_dl_progname);
_dl_exit(1);
};
/* Address of jump instruction to fix up */
instr_addr = ((unsigned long) this_reloc->r_offset +
(unsigned long) tpnt->loadaddr);
got_addr = (char **) instr_addr;
#ifdef DL_DEBUG_SYMBOLS
_dl_dprintf(2, "Resolving symbol %s\n",
strtab + symtab[symtab_index].st_name);
#endif
/* Get the address of the GOT entry */
new_addr = _dl_find_hash(strtab + symtab[symtab_index].st_name,
tpnt->symbol_scope, tpnt, 0);
if (!new_addr) {
_dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
_dl_progname, strtab + symtab[symtab_index].st_name);
_dl_exit(1);
};
#ifdef DL_NEVER_FIXUP_SYMBOLS
if ((unsigned long) got_addr < 0x40000000) {
_dl_dprintf(2, "Calling library function: %s\n",
strtab + symtab[symtab_index].st_name);
} else {
*got_addr = new_addr;
}
#else
*got_addr = new_addr;
#endif
return (unsigned long) new_addr;
}
void _dl_parse_lazy_relocation_information(struct elf_resolve *tpnt,
unsigned long rel_addr, unsigned long rel_size, int type)
{
int i;
char *strtab;
int reloc_type;
int symtab_index;
Elf32_Sym *symtab;
Elf32_Rel *rpnt;
unsigned long *reloc_addr;
/* Now parse the relocation information */
rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
rel_size = rel_size / sizeof(Elf32_Rel);
symtab =
(Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
for (i = 0; i < rel_size; i++, rpnt++) {
reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
reloc_type = ELF32_R_TYPE(rpnt->r_info);
symtab_index = ELF32_R_SYM(rpnt->r_info);
/* When the dynamic linker bootstrapped itself, it resolved some symbols.
Make sure we do not do them again */
if (!symtab_index && tpnt->libtype == program_interpreter)
continue;
if (symtab_index && tpnt->libtype == program_interpreter &&
_dl_symbol(strtab + symtab[symtab_index].st_name))
continue;
switch (reloc_type) {
case R_386_NONE:
break;
case R_386_JMP_SLOT:
*reloc_addr += (unsigned long) tpnt->loadaddr;
break;
default:
_dl_dprintf(2, "%s: (LAZY) can't handle reloc type ",
_dl_progname);
#ifdef VERBOSE_DLINKER
_dl_dprintf(2, "%s ", _dl_reltypes[reloc_type]);
#endif
if (symtab_index)
_dl_dprintf(2, "'%s'\n", strtab + symtab[symtab_index].st_name);
_dl_exit(1);
};
};
}
int _dl_parse_relocation_information(struct elf_resolve *tpnt,
unsigned long rel_addr, unsigned long rel_size, int type)
{
int i;
char *strtab;
int reloc_type;
int goof = 0;
Elf32_Sym *symtab;
Elf32_Rel *rpnt;
unsigned long *reloc_addr;
unsigned long symbol_addr;
int symtab_index;
/* Now parse the relocation information */
rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
rel_size = rel_size / sizeof(Elf32_Rel);
symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
for (i = 0; i < rel_size; i++, rpnt++) {
reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
reloc_type = ELF32_R_TYPE(rpnt->r_info);
symtab_index = ELF32_R_SYM(rpnt->r_info);
symbol_addr = 0;
if (!symtab_index && tpnt->libtype == program_interpreter)
continue;
if (symtab_index) {
if (tpnt->libtype == program_interpreter &&
_dl_symbol(strtab + symtab[symtab_index].st_name))
continue;
symbol_addr = (unsigned long) _dl_find_hash(strtab + symtab[symtab_index].st_name,
tpnt->symbol_scope,
(reloc_type == R_386_JMP_SLOT ? tpnt : NULL), 0);
/*
* We want to allow undefined references to weak symbols - this might
* have been intentional. We should not be linking local symbols
* here, so all bases should be covered.
*/
if (!symbol_addr &&
ELF32_ST_BIND(symtab[symtab_index].st_info) == STB_GLOBAL) {
_dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
_dl_progname, strtab + symtab[symtab_index].st_name);
goof++;
}
}
switch (reloc_type) {
case R_386_NONE:
break;
case R_386_32:
*reloc_addr += symbol_addr;
break;
case R_386_PC32:
*reloc_addr += symbol_addr - (unsigned long) reloc_addr;
break;
case R_386_GLOB_DAT:
case R_386_JMP_SLOT:
*reloc_addr = symbol_addr;
break;
case R_386_RELATIVE:
*reloc_addr += (unsigned long) tpnt->loadaddr;
break;
case R_386_COPY:
#if 0
/* Do this later */
_dl_dprintf(2, "Doing copy for symbol ");
if (symtab_index) _dl_dprintf(2, strtab + symtab[symtab_index].st_name);
_dl_dprintf(2, "\n");
_dl_memcpy((void *) symtab[symtab_index].st_value,
(void *) symbol_addr, symtab[symtab_index].st_size);
#endif
break;
default:
_dl_dprintf(2, "%s: can't handle reloc type ", _dl_progname);
#ifdef VERBOSE_DLINKER
_dl_dprintf(2, "%s ", _dl_reltypes[reloc_type]);
#endif
if (symtab_index)
_dl_dprintf(2, "'%s'\n", strtab + symtab[symtab_index].st_name);
_dl_exit(1);
};
};
return goof;
}
/* This is done as a separate step, because there are cases where
information is first copied and later initialized. This results in
the wrong information being copied. Someone at Sun was complaining about
a bug in the handling of _COPY by SVr4, and this may in fact be what he
was talking about. Sigh. */
/* No, there are cases where the SVr4 linker fails to emit COPY relocs
at all */
int _dl_parse_copy_information(struct dyn_elf *xpnt, unsigned long rel_addr,
unsigned long rel_size, int type)
{
int i;
char *strtab;
int reloc_type;
int goof = 0;
Elf32_Sym *symtab;
Elf32_Rel *rpnt;
unsigned long *reloc_addr;
unsigned long symbol_addr;
struct elf_resolve *tpnt;
int symtab_index;
/* Now parse the relocation information */
tpnt = xpnt->dyn;
rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);
rel_size = rel_size / sizeof(Elf32_Rel);
symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
for (i = 0; i < rel_size; i++, rpnt++) {
reloc_addr = (unsigned long *) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
reloc_type = ELF32_R_TYPE(rpnt->r_info);
if (reloc_type != R_386_COPY)
continue;
symtab_index = ELF32_R_SYM(rpnt->r_info);
symbol_addr = 0;
if (!symtab_index && tpnt->libtype == program_interpreter)
continue;
if (symtab_index) {
if (tpnt->libtype == program_interpreter &&
_dl_symbol(strtab + symtab[symtab_index].st_name))
continue;
symbol_addr = (unsigned long) _dl_find_hash(strtab +
symtab[symtab_index].st_name, xpnt->next,
NULL, 1);
if (!symbol_addr) {
_dl_dprintf(2, "%s: can't resolve symbol '%s'\n",
_dl_progname, strtab + symtab[symtab_index].st_name);
goof++;
};
};
if (!goof) {
_dl_memcpy((char *) symtab[symtab_index].st_value,
(char *) symbol_addr, symtab[symtab_index].st_size);
}
};
return goof;
}
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