uclibc-ng/ldso/ldso/mips/elfinterp.c

/* vi: set sw=4 ts=4: */

/* Run an ELF binary on a linux system.

   Copyright (C) 2002, Steven J. Hill (sjhill@realitydiluted.com)

   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.  */


/* 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);

#define OFFSET_GP_GOT 0x7ff0

unsigned long _dl_linux_resolver(unsigned long sym_index,
	unsigned long old_gpreg)
{
	unsigned long *got = (unsigned long *) (old_gpreg - OFFSET_GP_GOT);
	struct elf_resolve *tpnt = (struct elf_resolve *) got[1];
	Elf32_Sym *sym;
	char *strtab;
	unsigned long local_gotno;
	unsigned long gotsym;
	unsigned long value;

	gotsym = tpnt->mips_gotsym;
	local_gotno = tpnt->mips_local_gotno;

	sym = ((Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr)) +
		sym_index;

	strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);

	value = (unsigned long) _dl_find_hash(strtab + sym->st_name,
		 tpnt->symbol_scope, tpnt, 1);

	*(got + local_gotno + sym_index - gotsym) = value;

#ifdef DL_DEBUG
	_dl_dprintf(2, "---RESOLVER---\n");
	_dl_dprintf(2, "SYMTAB INDEX: %i\n", sym_index);
	_dl_dprintf(2, "      GOTSYM: %i\n", gotsym);
	_dl_dprintf(2, " LOCAL GOTNO: %i\n", local_gotno);
	_dl_dprintf(2, "       VALUE: %x\n", value);
	_dl_dprintf(2, "      SYMBOL: %s\n\n", strtab + sym->st_name);
#endif

	return value;
}

void _dl_parse_lazy_relocation_information(struct elf_resolve *tpnt,
	unsigned long rel_addr, unsigned long rel_size, int type)
{
	/* Nothing to do */
	return;
}

int _dl_parse_copy_information(struct dyn_elf *xpnt, unsigned long rel_addr,
	unsigned long rel_size, int type)
{
	/* Nothing to do */
	return 0;
}
        
int _dl_parse_relocation_information(struct elf_resolve *tpnt, 
	unsigned long rel_addr, unsigned long rel_size, int type)
{
	Elf32_Sym *symtab;
	Elf32_Rel *rpnt;
	char *strtab;
	unsigned long *got;
	unsigned long *reloc_addr;
	unsigned long symbol_addr;
	int i, reloc_type, symtab_index;

	/* Now parse the relocation information */
	rel_size = rel_size / sizeof(Elf32_Rel);
	rpnt = (Elf32_Rel *) (rel_addr + tpnt->loadaddr);

	symtab = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
	strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
	got = (unsigned long *) (tpnt->dynamic_info[DT_PLTGOT] + 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;

		switch (reloc_type) {
		case R_MIPS_REL32:
			if (symtab_index) {
				if (symtab_index < tpnt->mips_gotsym)
					*reloc_addr +=
						symtab[symtab_index].st_value +
						(unsigned long) tpnt->loadaddr;
				else {
					*reloc_addr += got[symtab_index + tpnt->mips_local_gotno -
						tpnt->mips_gotsym];
				}
			}
			else {
				*reloc_addr += (unsigned long) tpnt->loadaddr;
			}
			break;
		case R_MIPS_NONE:
			break;
		default:
			_dl_dprintf(2, "%s: can't handle reloc type ", _dl_progname);
			if (symtab_index)
				_dl_dprintf(2, "'%s'\n", strtab + symtab[symtab_index].st_name);
			_dl_exit(1);
		};

	};
	return 0;
}

void _dl_perform_mips_global_got_relocations(struct elf_resolve *tpnt)
{
	Elf32_Sym *sym;
	char *strtab;
	unsigned long i;
	unsigned long *got_entry;

	for (; tpnt ; tpnt = tpnt->next) {

		/* We don't touch the dynamic linker */
		if (tpnt->libtype == program_interpreter)
			continue;

		/* Setup the loop variables */
		got_entry = (unsigned long *) (tpnt->loadaddr +
			tpnt->dynamic_info[DT_PLTGOT]) + tpnt->mips_local_gotno;
		sym = (Elf32_Sym *) (tpnt->dynamic_info[DT_SYMTAB] +
			(unsigned long) tpnt->loadaddr) + tpnt->mips_gotsym;
		strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] +
			(unsigned long) tpnt->loadaddr);
		i = tpnt->mips_symtabno - tpnt->mips_gotsym;

		/* Relocate the global GOT entries for the object */
		while(i--) {
			if (sym->st_shndx == SHN_UNDEF) {
				if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC && sym->st_value)
					*got_entry = sym->st_value + (unsigned long) tpnt->loadaddr;
				else {
					*got_entry = (unsigned long) _dl_find_hash(strtab +
						sym->st_name, tpnt->symbol_scope, NULL, 1);
				}
			}
			else if (sym->st_shndx == SHN_COMMON) {
				*got_entry = (unsigned long) _dl_find_hash(strtab +
					sym->st_name, tpnt->symbol_scope, NULL, 1);
			}
			else if (ELF32_ST_TYPE(sym->st_info) == STT_FUNC &&
				*got_entry != sym->st_value)
				*got_entry += (unsigned long) tpnt->loadaddr;
			else if (ELF32_ST_TYPE(sym->st_info) == STT_SECTION) {
				if (sym->st_other == 0)
					*got_entry += (unsigned long) tpnt->loadaddr;
			}
			else {
				*got_entry = (unsigned long) _dl_find_hash(strtab +
					sym->st_name, tpnt->symbol_scope, NULL, 1);
			}

#ifdef DL_DEBUG
			if (*got_entry == 0)
				_dl_dprintf(2,"ZERO: %s\n", strtab + sym->st_name);
#endif

			got_entry++;
			sym++;
		}
	}
}