path: root/ldso/ldso/xtensa/elfinterp.c

/* vi: set sw=4 ts=4: */
/* Xtensa ELF shared library loader suppport
 *
 * Copyright (C) 2007 Tensilica Inc.
 * Copyright (c) 1994-2000 Eric Youngdale, Peter MacDonald,
 *                              David Engel, Hongjiu Lu and Mitch D'Souza
 * Copyright (C) 2001-2004 Erik Andersen
 *
 * 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. The name of the above contributors may not be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE 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 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 "ldso.h"

unsigned long
_dl_linux_resolver (struct elf_resolve *tpnt, int reloc_entry)
{
	ELF_RELOC *this_reloc;
	char *strtab;
	ElfW(Sym) *symtab;
	int symtab_index;
	char *rel_addr;
	char *new_addr;
	char **got_addr;
	char *symname;

	rel_addr = (char *) tpnt->dynamic_info[DT_JMPREL];
	this_reloc = (ELF_RELOC *) (rel_addr + reloc_entry);
	symtab_index = ELF_R_SYM (this_reloc->r_info);

	symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB];
	strtab = (char *) tpnt->dynamic_info[DT_STRTAB];
	symname = strtab + symtab[symtab_index].st_name;

	/* Address of the literal to fix up.  */
	got_addr = (char **) (this_reloc->r_offset + tpnt->loadaddr);

	/* Get the address of the GOT entry.  */
	new_addr = _dl_find_hash (symname, &_dl_loaded_modules->symbol_scope, tpnt,
							  ELF_RTYPE_CLASS_PLT, NULL);
	if (unlikely (!new_addr)) {
		_dl_dprintf (2, "%s: can't resolve symbol '%s'\n",
					 _dl_progname, symname);
		_dl_exit (1);
	}

#if defined (__SUPPORT_LD_DEBUG__)
	if (_dl_debug_bindings) {
		_dl_dprintf (_dl_debug_file, "\nresolve function: %s", symname);
		if (_dl_debug_detail)
			_dl_dprintf (_dl_debug_file, "\n\tpatched %x ==> %x @ %x\n",
						 *got_addr, new_addr, got_addr);
	}
	if (!_dl_debug_nofixups)
		*got_addr = new_addr;
#else
	*got_addr = new_addr;
#endif

	return (unsigned long) new_addr;
}


static int
_dl_parse (struct elf_resolve *tpnt, struct r_scope_elem *scope,
		   unsigned long rel_addr, unsigned long rel_size,
		   int (*reloc_fnc) (struct elf_resolve *tpnt, struct r_scope_elem *scope,
							 ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab))
{
	unsigned int i;
	char *strtab;
	ElfW(Sym) *symtab;
	ELF_RELOC *rpnt;
	int symtab_index;

	/* Parse the relocation information.  */
	rpnt = (ELF_RELOC *) rel_addr;
	rel_size /= sizeof (ELF_RELOC);

	symtab = (ElfW(Sym) *) tpnt->dynamic_info[DT_SYMTAB];
	strtab = (char *) tpnt->dynamic_info[DT_STRTAB];

	for (i = 0; i < rel_size; i++, rpnt++) {
		int res;

		symtab_index = ELF_R_SYM (rpnt->r_info);

		debug_sym (symtab, strtab, symtab_index);
		debug_reloc (symtab, strtab, rpnt);

		res = reloc_fnc (tpnt, scope, rpnt, symtab, strtab);

		if (res == 0)
			continue;

		_dl_dprintf (2, "\n%s: ", _dl_progname);

		if (symtab_index)
			_dl_dprintf (2, "symbol '%s': ",
						 strtab + symtab[symtab_index].st_name);

		if (unlikely (res < 0)) {
			int reloc_type = ELF_R_TYPE (rpnt->r_info);
#if defined (__SUPPORT_LD_DEBUG__)
			_dl_dprintf (2, "can't handle reloc type %s\n",
						 _dl_reltypes (reloc_type));
#else
			_dl_dprintf (2, "can't handle reloc type %x\n", reloc_type);
#endif
			_dl_exit (-res);
		}
		if (unlikely (res > 0)) {
			_dl_dprintf (2, "can't resolve symbol\n");
			return res;
		}
	}

	return 0;
}


static int
_dl_do_reloc (struct elf_resolve *tpnt, struct r_scope_elem *scope,
			  ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
{
	int reloc_type;
	int symtab_index;
	char *symname;
	struct symbol_ref sym_ref;
	ElfW(Addr) *reloc_addr;
	ElfW(Addr) symbol_addr;
#if defined (__SUPPORT_LD_DEBUG__)
	ElfW(Addr) old_val;
#endif

	reloc_addr = (ElfW(Addr) *) (tpnt->loadaddr + rpnt->r_offset);
	reloc_type = ELF_R_TYPE (rpnt->r_info);
	symtab_index = ELF_R_SYM (rpnt->r_info);
	sym_ref.sym = &symtab[symtab_index];
	sym_ref.tpnt = NULL;
	symbol_addr = 0;
	symname = strtab + sym_ref.sym->st_name;

	if (symtab_index) {
		symbol_addr = (ElfW(Addr))
			_dl_find_hash (symname, scope, tpnt,
						   elf_machine_type_class (reloc_type), &sym_ref);

		/*
		 * 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 (unlikely (!symbol_addr &&
					  ELF_ST_BIND (sym_ref.sym->st_info) != STB_WEAK)) {
			_dl_dprintf (2, "%s: can't resolve symbol '%s'\n",
						 _dl_progname, symname);
			_dl_exit (1);
		}
		if (_dl_trace_prelink) {
			_dl_debug_lookup (symname, tpnt, &symtab[symtab_index],
						&sym_ref, elf_machine_type_class(reloc_type));
		}
	}

#if defined (__SUPPORT_LD_DEBUG__)
	old_val = *reloc_addr;
#endif

	switch (reloc_type) {
	case R_XTENSA_NONE:
		break;

	case R_XTENSA_GLOB_DAT:
	case R_XTENSA_JMP_SLOT:
		*reloc_addr = symbol_addr + rpnt->r_addend;
		break;

	case R_XTENSA_RTLD:
		if (rpnt->r_addend == 1) {
			/* Grab the function pointer stashed at the beginning of the
			   GOT by the GOT_INIT function.  */
			*reloc_addr = *(ElfW(Addr) *) tpnt->dynamic_info[DT_PLTGOT];
		} else if (rpnt->r_addend == 2) {
			/* Store the link map for the object.  */
			*reloc_addr = (ElfW(Addr)) tpnt;
		} else {
			_dl_exit (1);
		}
		break;

	case R_XTENSA_RELATIVE:
		*reloc_addr += tpnt->loadaddr + rpnt->r_addend;
		break;

	default:
		return -1; /* Calls _dl_exit(1).  */
	}
#if defined (__SUPPORT_LD_DEBUG__)
	if (_dl_debug_reloc && _dl_debug_detail)
		_dl_dprintf (_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
					 old_val, *reloc_addr, reloc_addr);
#endif

	return 0;
}


static int
_dl_do_lazy_reloc (struct elf_resolve *tpnt, struct r_scope_elem *scope,
				   ELF_RELOC *rpnt, ElfW(Sym) *symtab, char *strtab)
{
	int reloc_type;
	ElfW(Addr) *reloc_addr;
#if defined (__SUPPORT_LD_DEBUG__)
	ElfW(Addr) old_val;
#endif

	reloc_addr = (ElfW(Addr) *) (tpnt->loadaddr + rpnt->r_offset);
	reloc_type = ELF_R_TYPE (rpnt->r_info);

#if defined (__SUPPORT_LD_DEBUG__)
	old_val = *reloc_addr;
#endif

	switch (reloc_type) {
	case R_XTENSA_JMP_SLOT:
		/* Perform a RELATIVE reloc on the GOT entry that transfers
		   to the stub function.  */
		*reloc_addr += tpnt->loadaddr;
		break;
	case R_XTENSA_NONE:
		break;
	default:
		_dl_exit (1);
	}

#if defined (__SUPPORT_LD_DEBUG__)
	if (_dl_debug_reloc && _dl_debug_detail)
		_dl_dprintf (_dl_debug_file, "\tpatched: %x ==> %x @ %x\n",
					 old_val, *reloc_addr, reloc_addr);
#endif
	return 0;

}

void
_dl_parse_lazy_relocation_information (struct dyn_elf *rpnt,
									   unsigned long rel_addr,
									   unsigned long rel_size)
{
	(void) _dl_parse (rpnt->dyn, NULL, rel_addr, rel_size, _dl_do_lazy_reloc);
}

int
_dl_parse_relocation_information (struct dyn_elf *rpnt,
								  struct r_scope_elem *scope,
								  unsigned long rel_addr,
								  unsigned long rel_size)
{
	return _dl_parse (rpnt->dyn, scope, rel_addr, rel_size,
					  _dl_do_reloc);
}