path: root/libexec/ld.so/sparc/rtld_machine.c

/*	$OpenBSD: rtld_machine.c,v 1.2 2002/07/27 16:56:01 art Exp $ */

/*
 * Copyright (c) 1999 Dale Rahn
 * Copyright (c) 2001 Niklas Hallqvist
 * Copyright (c) 2001 Artur Grabowski
 *
 * 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed under OpenBSD by
 *	Dale Rahn.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
 */

#define _DYN_LOADER

#include <sys/types.h>
#include <sys/cdefs.h>
#include <sys/mman.h>

#include <nlist.h>
#include <link.h>

#include "syscall.h"
#include "archdep.h"
#include "resolve.h"

void
_dl_bcopy(const void *src, void *dest, int size)
{
	const unsigned char *psrc = src;
	unsigned char *pdest = dest;
	int i;

	for (i = 0; i < size; i++)
		pdest[i] = psrc[i];
}

/*
 * The following table holds for each relocation type:
 *	- the width in bits of the memory location the relocation
 *	  applies to (not currently used)
 *	- the number of bits the relocation value must be shifted to the
 *	  right (i.e. discard least significant bits) to fit into
 *	  the appropriate field in the instruction word.
 *	- flags indicating whether
 *		* the relocation involves a symbol
 *		* the relocation is relative to the current position
 *		* the relocation is for a GOT entry
 *		* the relocation is relative to the load address
 *
 */
#define _RF_S		0x80000000		/* Resolve symbol */
#define _RF_A		0x40000000		/* Use addend */
#define _RF_P		0x20000000		/* Location relative */
#define _RF_G		0x10000000		/* GOT offset */
#define _RF_B		0x08000000		/* Load address relative */
#define _RF_SZ(s)	(((s) & 0xff) << 8)	/* memory target size */
#define _RF_RS(s)	((s) & 0xff)		/* right shift */
static int reloc_target_flags[] = {
	0,							/* NONE */
	_RF_S|_RF_A|		_RF_SZ(8)  | _RF_RS(0),		/* RELOC_8 */
	_RF_S|_RF_A|		_RF_SZ(16) | _RF_RS(0),		/* RELOC_16 */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* RELOC_32 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(8)  | _RF_RS(0),		/* DISP_8 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(16) | _RF_RS(0),		/* DISP_16 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(0),		/* DISP_32 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(2),		/* WDISP_30 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(2),		/* WDISP_22 */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(10),	/* HI22 */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* 22 */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* 13 */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* LO10 */
	_RF_G|			_RF_SZ(32) | _RF_RS(0),		/* GOT10 */
	_RF_G|			_RF_SZ(32) | _RF_RS(0),		/* GOT13 */
	_RF_G|			_RF_SZ(32) | _RF_RS(10),	/* GOT22 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(0),		/* PC10 */
	_RF_S|_RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(10),	/* PC22 */
	      _RF_A|_RF_P|	_RF_SZ(32) | _RF_RS(2),		/* WPLT30 */
				_RF_SZ(32) | _RF_RS(0),		/* COPY */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* GLOB_DAT */
				_RF_SZ(32) | _RF_RS(0),		/* JMP_SLOT */
	      _RF_A|	_RF_B|	_RF_SZ(32) | _RF_RS(0),		/* RELATIVE */
	_RF_S|_RF_A|		_RF_SZ(32) | _RF_RS(0),		/* UA_32 */

	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* PLT32 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* HIPLT22 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* LOPLT10 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* LOPLT10 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* PCPLT22 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* PCPLT32 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* 10 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* 11 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* 64 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* OLO10 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* HH22 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* HM10 */
	_RF_S|_RF_A|/*unknown*/	_RF_SZ(32) | _RF_RS(0),		/* LM22 */
	_RF_S|_RF_A|_RF_P|/*unknown*/	_RF_SZ(32) | _RF_RS(0),	/* WDISP16 */
	_RF_S|_RF_A|_RF_P|/*unknown*/	_RF_SZ(32) | _RF_RS(0),	/* WDISP19 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* GLOB_JMP */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* 7 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* 5 */
	/*unknown*/		_RF_SZ(32) | _RF_RS(0),		/* 6 */
};

#define RELOC_RESOLVE_SYMBOL(t)		((reloc_target_flags[t] & _RF_S) != 0)
#define RELOC_PC_RELATIVE(t)		((reloc_target_flags[t] & _RF_P) != 0)
#define RELOC_BASE_RELATIVE(t)		((reloc_target_flags[t] & _RF_B) != 0)
#define RELOC_USE_ADDEND(t)		((reloc_target_flags[t] & _RF_A) != 0)
#define RELOC_TARGET_SIZE(t)		((reloc_target_flags[t] >> 8) & 0xff)
#define RELOC_VALUE_RIGHTSHIFT(t)	(reloc_target_flags[t] & 0xff)

static int reloc_target_bitmask[] = {
#define _BM(x)	(~(-(1ULL << (x))))
	0,				/* NONE */
	_BM(8), _BM(16), _BM(32),	/* RELOC_8, _16, _32 */
	_BM(8), _BM(16), _BM(32),	/* DISP8, DISP16, DISP32 */
	_BM(30), _BM(22),		/* WDISP30, WDISP22 */
	_BM(22), _BM(22),		/* HI22, _22 */
	_BM(13), _BM(10),		/* RELOC_13, _LO10 */
	_BM(10), _BM(13), _BM(22),	/* GOT10, GOT13, GOT22 */
	_BM(10), _BM(22),		/* _PC10, _PC22 */
	_BM(30), 0,			/* _WPLT30, _COPY */
	-1, -1, -1,			/* _GLOB_DAT, JMP_SLOT, _RELATIVE */
	_BM(32), _BM(32),		/* _UA32, PLT32 */
	_BM(22), _BM(10),		/* _HIPLT22, LOPLT10 */
	_BM(32), _BM(22), _BM(10),	/* _PCPLT32, _PCPLT22, _PCPLT10 */
	_BM(10), _BM(11), -1,		/* _10, _11, _64 */
	_BM(10), _BM(22),		/* _OLO10, _HH22 */
	_BM(10), _BM(22),		/* _HM10, _LM22 */
	_BM(16), _BM(19),		/* _WDISP16, _WDISP19 */
	-1,				/* GLOB_JMP */
	_BM(7), _BM(5), _BM(6)		/* _7, _5, _6 */
#undef _BM
};
#define RELOC_VALUE_BITMASK(t)	(reloc_target_bitmask[t])

void _dl_reloc_plt(Elf_Word *where, Elf_Addr value);

int
_dl_md_reloc(elf_object_t *object, int rel, int relasz)
{
	long	i;
	long	numrela;
	long	fails = 0;
	Elf_Addr loff;
	Elf_RelA *relas;
	struct load_list *llist;

	loff = object->load_offs;
	numrela = object->Dyn.info[relasz] / sizeof(Elf_RelA);
	relas = (Elf_RelA *)(object->Dyn.info[rel]);

	if (relas == NULL)
		return(0);

	/*
	 * unprotect some segments if we need it.
	 */
	if ((rel == DT_REL || rel == DT_RELA)) {
		for (llist = object->load_list; llist != NULL; llist = llist->next) {
			if (!(llist->prot & PROT_WRITE))
				_dl_mprotect(llist->start, llist->size,
				    llist->prot|PROT_WRITE);
		}
	}

	for (i = 0; i < numrela; i++, relas++) {
		Elf_Addr *where, value, ooff, mask;
		Elf_Word type;
		const Elf_Sym *sym, *this;
		const char *symn;

		type = ELF_R_TYPE(relas->r_info);

		if (type == R_TYPE(NONE))
			continue;

		if (type == R_TYPE(JMP_SLOT) && rel != DT_JMPREL)
			continue;

		where = (Elf_Addr *)(relas->r_offset + loff);

		if (RELOC_USE_ADDEND(type))
			value = relas->r_addend;
		else
			value = 0;

		sym = NULL;
		symn = NULL;
		if (RELOC_RESOLVE_SYMBOL(type)) {
			sym = object->dyn.symtab;
			sym += ELF_R_SYM(relas->r_info);
			symn = object->dyn.strtab + sym->st_name;

			if (sym->st_shndx != SHN_UNDEF &&
			    ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
				value += loff;
			} else {
				this = NULL;
				ooff = _dl_find_symbol(symn, _dl_objects,
				    &this, 0, 1);
				if (this == NULL) {
resolve_failed:
					_dl_printf("%s: %s: can't resolve "
					    "reference '%s'\n",
					    _dl_progname, object->load_name,
					    symn);
					fails++;
					continue;
				}
				value += (Elf_Addr)(ooff + this->st_value);
#ifdef notyet
/*
 * XXX Hmm, we should change the API of _dl_find_symbol and do this in there,
 * XXX or maybe make a wrapper.
 */
				if (this->st_size != sym->st_size &&
				    sym->st_size != 0) {
					_dl_printf("%s: %s : WARNING: "
					    "symbol(%s) size mismatch ",
					    _dl_progname, object->load_name,
					    symn);
					_dl_printf("relink your program\n");
				}
#endif
			}
		}

		if (type == R_TYPE(JMP_SLOT)) {
			_dl_reloc_plt((Elf_Word *)where, value);
			continue;
		}

		if (type == R_TYPE(COPY)) {
			void *dstaddr = where;
			const void *srcaddr;
			const Elf_Sym *dstsym = sym, *srcsym = NULL;
			size_t size = dstsym->st_size;
			Elf_Addr soff;

			soff = _dl_find_symbol(symn, object->next, &srcsym,
				0, 2);
			if (srcsym == NULL)
				goto resolve_failed;

			srcaddr = (void *)(soff + srcsym->st_value);
			_dl_bcopy(srcaddr, dstaddr, size);
			continue;
		}

		if (RELOC_PC_RELATIVE(type))
			value -= (Elf_Addr)where;
		if (RELOC_BASE_RELATIVE(type))
			value += loff + *where;

		mask = RELOC_VALUE_BITMASK(type);
		value >>= RELOC_VALUE_RIGHTSHIFT(type);
		value &= mask;

		/* We ignore alignment restrictions here */
		*where &= ~mask;
		*where |= value;

	}

	/* reprotect the unprotected segments */
	if ((rel == DT_REL || rel == DT_RELA)) {
		for (llist = object->load_list; llist != NULL; llist = llist->next) {
			if (!(llist->prot & PROT_WRITE))
				_dl_mprotect(llist->start, llist->size,
				    llist->prot);
		}
	}

	return (fails);
}

void
_dl_reloc_plt(Elf_Word *where, Elf_Addr value)
{
	/*
	 * At the PLT entry pointed at by `where', we now construct
	 * a direct transfer to the now fully resolved function
	 * address.  The resulting code in the jump slot is:
	 *
	 *	sethi	%hi(roffset), %g1
	 *	sethi	%hi(addr), %g1
	 *	jmp	%g1+%lo(addr)
	 *
	 * We write the third instruction first, since that leaves the
	 * previous `b,a' at the second word in place. Hence the whole
	 * PLT slot can be atomically change to the new sequence by
	 * writing the `sethi' instruction at word 2.
	 */
#define SETHI	0x03000000
#define JMP	0x81c06000
#define NOP	0x01000000
	where[2] = JMP   | (value & 0x000003ff);
	where[1] = SETHI | ((value >> 10) & 0x003fffff);
	__asm __volatile("iflush %0+8" : : "r" (where));
	__asm __volatile("iflush %0+4" : : "r" (where));
}

/*
 * Resolve a symbol at run-time.
 */
void *
_dl_bind(elf_object_t *object, Elf_Word reloff)
{
	Elf_RelA *rela;
	Elf_Addr *addr, ooff;
	const Elf_Sym *sym, *this;
	const char *symn;

	rela = (Elf_RelA *)(object->Dyn.info[DT_JMPREL] + reloff);

	sym = object->dyn.symtab;
	sym += ELF_R_SYM(rela->r_info);
	symn = object->dyn.strtab + sym->st_name;

DL_DEB(("_dl_bind %s\n", symn));

	addr = (Elf_Addr *)(object->load_offs + rela->r_offset);
	ooff = _dl_find_symbol(symn, _dl_objects, &this, 0, 1);
	if (this == NULL) {
		_dl_printf("lazy binding failed!\n");
		*((int *)0) = 0;	/* XXX */
	}

	_dl_reloc_plt(addr, ooff + this->st_value);

	return (void *)ooff + this->st_value;
}

void
_dl_md_reloc_got(elf_object_t *object, int lazy)
{
	Elf_Addr *pltgot;
	extern void _dl_bind_start(void);	/* XXX */

	pltgot = (Elf_Addr *)object->Dyn.info[DT_PLTGOT];

	if (object->obj_type == OBJTYPE_LDR || !lazy || pltgot == NULL) {
		_dl_md_reloc(object, DT_JMPREL, DT_PLTRELSZ);
		return;
	}

	/*
	 * PLTGOT is the PLT on the sparc.
	 * The first entry holds the call the dynamic linker.
	 * We construct a `call' sequence that transfers
	 * to `_rtld_bind_start()'.
	 * The second entry holds the object identification.
	 * Note: each PLT entry is three words long.
	 */
#define SAVE    0x9de3bfc0      /* i.e. `save %sp,-64,%sp' */
#define CALL    0x40000000
#define NOP     0x01000000
	pltgot[0] = SAVE;
	pltgot[1] = CALL |
	    ((Elf_Addr)&_dl_bind_start -
	     (Elf_Addr)&pltgot[1]) >> 2;
	pltgot[2] = NOP;
	pltgot[3] = (Elf_Addr) object;
}