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

/*
 * CRIS ELF shared library loader support.
 *
 * 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.
 *
 * Copyright (C) 2002, Axis Communications AB
 * All rights reserved
 *
 * Author: Tobias Anderberg, <tobiasa@axis.com>
 *
 * 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.
 */

/* Support for the LD_DEBUG variable. */
#if defined (__SUPPORT_LD_DEBUG__)
static const char *_dl_reltypes_tab[] = {
	[0]		"R_CRIS_NONE", "R_CRIS_8", "R_CRIS_16", "R_CRIS_32",
	[4]		"R_CRIS_8_PCREL", "R_CRIS_16_PCREL", "R_CRIS_32_PCREL", "R_CRIS_GNU_VTINHERIT",
	[8]		"R_CRIS_GNU_VTENTRY", "R_CRIS_COPY", "R_CRIS_GLOB_DAT", "R_CRIS_JUMP_SLOT",
	[16]	"R_CRIS_RELATIVE", "R_CRIS_16_GOT", "R_CRIS_32_GOT", "R_CRIS_16_GOTPLT",
	[32]	"R_CRIS_32_GOTPLT", "R_CRIS_32_GOTREL", "R_CRIS_32_PLT_GOTREL", "R_CRIS_32_PLT_PCREL",

};


static const char *
_dl_reltypes(int type)
{
	const char *str;
	static char buf[22];

	if (type >= (sizeof(_dl_reltypes_tab)/sizeof(_dl_reltypes_tab[0])) ||
		NULL == (str = _dl_reltypes_tab[type]))
		str = _dl_simple_ltoa(buf, (unsigned long) (type));

	return str;
}

static void
debug_sym(Elf32_Sym *symtab, char *strtab, int symtab_index)
{
	if (_dl_debug_symbols) {
		if (symtab_index) {
			_dl_dprintf(_dl_debug_file,
				"\n%s\tvalue=%x\tsize=%x\tinfo=%x\tother=%x\tshndx=%x",
				strtab + symtab[symtab_index].st_name,
				symtab[symtab_index].st_value,
				symtab[symtab_index].st_size,
				symtab[symtab_index].st_info,
				symtab[symtab_index].st_other,
				symtab[symtab_index].st_shndx);
		}
  	}
}

static void
debug_reloc(Elf32_Sym *symtab, char *strtab, ELF_RELOC *rpnt)
{
	if (_dl_debug_reloc) {
		int symtab_index;
		const char *sym;

		symtab_index = ELF32_R_SYM(rpnt->r_info);
		sym = symtab_index ? strtab + symtab[symtab_index].st_name : "sym=0x0";

		if (_dl_debug_symbols)
			_dl_dprintf(_dl_debug_file, "\n\t");
		else
			_dl_dprintf(_dl_debug_file, "\n%s\n\t", sym);

#ifdef ELF_USES_RELOCA
		_dl_dprintf(_dl_debug_file, "%s\toffset=%x\taddend=%x",
			_dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
			rpnt->r_offset,
			rpnt->r_addend);
#else
		_dl_dprintf(_dl_debug_file, "%s\toffset%x\n",
			_dl_reltypes(ELF32_R_TYPE(rpnt->r_info)),
			rpnt->r_offset);
#endif
	}
}
#endif /* __SUPPORT_LD_DEBUG__ */

/* Defined in resolve.S. */
extern int _dl_linux_resolv(void);

unsigned long
_dl_linux_resolver(struct elf_resolve *tpnt, int reloc_entry)
{
	int reloc_type;
	int symtab_index;
	char *strtab;
	char *symname;
	char *new_addr;
	char *rel_addr;
	char **got_addr;
	Elf32_Sym *symtab;
	ELF_RELOC *this_reloc;
	unsigned long instr_addr;

	rel_addr = (char *) (tpnt->dynamic_info[DT_JMPREL] + tpnt->loadaddr);

	this_reloc = (ELF_RELOC *) (intptr_t)(rel_addr + reloc_entry);
	reloc_type = ELF32_R_TYPE(this_reloc->r_info);
	symtab_index = ELF32_R_SYM(this_reloc->r_info);

	symtab = (Elf32_Sym *) (intptr_t)(tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
	strtab = (char *)(tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);
	symname = strtab + symtab[symtab_index].st_name;

	if (unlikely(reloc_type != R_CRIS_JUMP_SLOT)) {
		_dl_dprintf(2, "%s: Incorrect relocation type for jump relocations.\n",
			_dl_progname);
		_dl_exit(1);
	}

	/* Fetch the address of the jump instruction to fix up. */
	instr_addr = ((unsigned long) this_reloc->r_offset + (unsigned long) tpnt->loadaddr);
	got_addr = (char **) instr_addr;

	/* Fetch the address of the GOT entry. */
	new_addr = _dl_find_hash(symname, tpnt->symbol_scope, ELF_RTYPE_CLASS_PLT);
	if (unlikely(!new_addr)) {
	    _dl_dprintf(2, "%s: Can't resolv 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, "\tpatch %x ==> %x @ %x", *got_addr, new_addr, got_addr);
	}
#endif

	*got_addr = new_addr;
	return (unsigned long) new_addr;
}

static int
_dl_parse(struct elf_resolve *tpnt, struct dyn_elf *scope, unsigned long rel_addr,
	unsigned long rel_size, int (*reloc_fnc)(struct elf_resolve *tpnt, struct dyn_elf *scope,
	                            ELF_RELOC *rpnt, Elf32_Sym *symtab, char *strtab))
{
	int symtab_index;
	int res;
	unsigned int i;
	char *strtab;
	Elf32_Sym *symtab;
	ELF_RELOC *rpnt;

	/* Parse the relocation information. */
	rpnt = (ELF_RELOC *) (intptr_t) (rel_addr + tpnt->loadaddr);
	rel_size /= sizeof(ELF_RELOC);

	symtab = (Elf32_Sym *) (intptr_t) (tpnt->dynamic_info[DT_SYMTAB] + tpnt->loadaddr);
	strtab = (char *) (tpnt->dynamic_info[DT_STRTAB] + tpnt->loadaddr);

	for (i = 0; i < rel_size; i++, rpnt++) {
		symtab_index = ELF32_R_SYM(rpnt->r_info);
#if defined (__SUPPORT_LD_DEBUG__)
		debug_sym(symtab, strtab, symtab_index);
		debug_reloc(symtab, strtab, rpnt);
#endif

		/* Pass over to actual relocation function. */
		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 = ELF32_R_TYPE(rpnt->r_info);

#if defined (__SUPPORT_LD_DEBUG__)
			_dl_dprintf(2, "can't handle relocation type '%s'\n", _dl_reltypes(reloc_type));
#else
			_dl_dprintf(2, "can't handle relocation type %x\n", reloc_type);
#endif
			_dl_exit(-res);
		}
		if (unlikely(res > 0)) {
			_dl_dprintf(2, "can't resolv symbol\n");
			return res;
		}
	}

	return 0;
}

static int
_dl_do_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope, ELF_RELOC *rpnt,
	Elf32_Sym *symtab, char *strtab)
{
	int reloc_type;
	int symtab_index;
	char *symname;
	unsigned long *reloc_addr;
	unsigned symbol_addr;
#if defined (__SUPPORT_LD_DEBUG__)
	unsigned long old_val;
#endif

	reloc_addr = (unsigned long *)(intptr_t)(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;
	symname = strtab + symtab[symtab_index].st_name;

	if (symtab_index) {
		if (symtab[symtab_index].st_shndx != SHN_UNDEF &&
			ELF32_ST_BIND(symtab[symtab_index].st_info) == STB_LOCAL) {
			symbol_addr = (unsigned long) tpnt->loadaddr;
		}
		else {
			symbol_addr = (unsigned long) _dl_find_hash(symname, scope,
								    elf_machine_type_class(reloc_type));
		}

		if (!symbol_addr && ELF32_ST_BIND(symtab[symtab_index].st_info) == STB_GLOBAL) {
#if defined (__SUPPORT_LD_DEBUG__)
			_dl_dprintf(2, "\tglobal symbol '%s' already defined in '%s'\n",
				symname, tpnt->libname);
#endif
			return 0;
		}

		symbol_addr += rpnt->r_addend;
	}

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

	switch (reloc_type) {
		case R_CRIS_NONE:
			break;
		case R_CRIS_GLOB_DAT:
		case R_CRIS_JUMP_SLOT:
		case R_CRIS_32:
		case R_CRIS_COPY:
			*reloc_addr = symbol_addr;
			break;
		case R_CRIS_RELATIVE:
			*reloc_addr = (unsigned long) tpnt->loadaddr + rpnt->r_addend;
			break;
		default:
			return -1;	/* Call _dl_exit(1). */
	}

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

	return 0;
}

static int
_dl_do_lazy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope, ELF_RELOC *rpnt,
	Elf32_Sym *symtab, char *strtab)
{
	int reloc_type;
	unsigned long *reloc_addr;
#if defined (__SUPPORT_LD_DEBUG__)
	unsigned long old_val;
#endif

	/* Don't care about these, just keep the compiler happy. */
	(void) scope;
	(void) symtab;
	(void) strtab;

	reloc_addr = (unsigned long *)(intptr_t)(tpnt->loadaddr + (unsigned long) rpnt->r_offset);
	reloc_type = ELF32_R_TYPE(rpnt->r_info);

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

	switch (reloc_type) {
		case R_CRIS_NONE:
			break;
		case R_CRIS_JUMP_SLOT:
			*reloc_addr += (unsigned long) tpnt->loadaddr;
			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", old_val, *reloc_addr, reloc_addr);
#endif

	return 0;
}

static int
_dl_do_copy_reloc(struct elf_resolve *tpnt, struct dyn_elf *scope, ELF_RELOC *rpnt,
	Elf32_Sym *symtab, char *strtab)
{
	int goof;
	int reloc_type;
	int symtab_index;
	char *symname;
	unsigned long *reloc_addr;
	unsigned long symbol_addr;

	reloc_addr = (unsigned long *)(intptr_t) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
	reloc_type = ELF32_R_TYPE(rpnt->r_info);

	if (reloc_type != R_CRIS_COPY)
		return 0;

	symtab_index = ELF32_R_SYM(rpnt->r_info);
	symbol_addr = 0;
	symname = strtab + symtab[symtab_index].st_name;
	goof = 0;

	if (symtab_index) {
		symbol_addr = (unsigned long) _dl_find_hash(symname, scope, ELF_RTYPE_CLASS_COPY);

		if (!symbol_addr)
			goof++;
	}

	if (!goof) {
#if defined (__SUPPORT_LD_DEBUG__)
		if (_dl_debug_move)
			_dl_dprintf(_dl_debug_file, "\n%s move %x bytes from %x to %x",
				symname, symtab[symtab_index].st_size, symbol_addr, symtab[symtab_index].st_value);
#endif
			_dl_memcpy((char *) symtab[symtab_index].st_value,
				(char *) symbol_addr, symtab[symtab_index].st_size);
	}

	return goof;
}

/* External interface to the generic part of the dynamic linker. */

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,
	unsigned long rel_addr, unsigned long rel_size)
{
	return _dl_parse(rpnt->dyn, rpnt->dyn->symbol_scope, rel_addr, rel_size, _dl_do_reloc);
}

int _dl_parse_copy_information(struct dyn_elf *rpnt,
	unsigned long rel_addr, unsigned long rel_size)
{
	return _dl_parse(rpnt->dyn, rpnt->next, rel_addr, rel_size, _dl_do_copy_reloc);
}