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[netbsd-mini2440.git] / libexec / ld.elf_so / arch / sparc / mdreloc.c

/*      $NetBSD: mdreloc.c,v 1.41 2008/07/24 04:39:25 matt Exp $        */

/*-
 * Copyright (c) 1999, 2002 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Paul Kranenburg and by Charles M. Hannum.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND 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 FOUNDATION OR 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 <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: mdreloc.c,v 1.41 2008/07/24 04:39:25 matt Exp $");
#endif /* not lint */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>

#include "rtldenv.h"
#include "debug.h"
#include "rtld.h"

/*
 * 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_U           0x04000000              /* Unaligned */
#define _RF_SZ(s)       (((s) & 0xff) << 8)     /* memory target size */
#define _RF_RS(s)       ( (s) & 0xff)           /* right shift */
static const 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_U|  _RF_SZ(32) | _RF_RS(0),         /* UA_32 */
};

#ifdef RTLD_DEBUG_RELOC
static const char *reloc_names[] = {
        "NONE", "RELOC_8", "RELOC_16", "RELOC_32", "DISP_8",
        "DISP_16", "DISP_32", "WDISP_30", "WDISP_22", "HI22",
        "22", "13", "LO10", "GOT10", "GOT13",
        "GOT22", "PC10", "PC22", "WPLT30", "COPY",
        "GLOB_DAT", "JMP_SLOT", "RELATIVE", "UA_32"
};
#endif

#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_UNALIGNED(t)              ((reloc_target_flags[t] & _RF_U) != 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 const 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)                         /* _UA32 */
#undef _BM
};
#define RELOC_VALUE_BITMASK(t)  (reloc_target_bitmask[t])

void _rtld_bind_start(void);
void _rtld_relocate_nonplt_self(Elf_Dyn *, Elf_Addr);
caddr_t _rtld_bind(const Obj_Entry *, Elf_Word);
static inline int _rtld_relocate_plt_object(const Obj_Entry *,
    const Elf_Rela *, Elf_Addr *);

void
_rtld_setup_pltgot(const Obj_Entry *obj)
{
        /*
         * 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    0x9de3bfa0      /* i.e. `save %sp,-96,%sp' */
#define CALL    0x40000000
#define NOP     0x01000000
        obj->pltgot[0] = SAVE;
        obj->pltgot[1] = CALL |
            ((Elf_Addr) &_rtld_bind_start - (Elf_Addr) &obj->pltgot[1]) >> 2;
        obj->pltgot[2] = NOP;
        obj->pltgot[3] = (Elf_Addr) obj;
}

void
_rtld_relocate_nonplt_self(Elf_Dyn *dynp, Elf_Addr relocbase)
{
        const Elf_Rela *rela = 0, *relalim;
        Elf_Addr relasz = 0;
        Elf_Addr *where;

        for (; dynp->d_tag != DT_NULL; dynp++) {
                switch (dynp->d_tag) {
                case DT_RELA:
                        rela = (const Elf_Rela *)(relocbase + dynp->d_un.d_ptr);
                        break;
                case DT_RELASZ:
                        relasz = dynp->d_un.d_val;
                        break;
                }
        }
        relalim = (const Elf_Rela *)((const uint8_t *)rela + relasz);
        for (; rela < relalim; rela++) {
                where = (Elf_Addr *)(relocbase + rela->r_offset);
                *where += (Elf_Addr)(relocbase + rela->r_addend);
        }
}

int
_rtld_relocate_nonplt_objects(const Obj_Entry *obj)
{
        const Elf_Rela *rela;

        for (rela = obj->rela; rela < obj->relalim; rela++) {
                Elf_Addr *where;
                Elf_Word type, value, mask;
                const Elf_Sym *def = NULL;
                const Obj_Entry *defobj = NULL;
                unsigned long    symnum;

                where = (Elf_Addr *) (obj->relocbase + rela->r_offset);
                symnum = ELF_R_SYM(rela->r_info);

                type = ELF_R_TYPE(rela->r_info);
                if (type == R_TYPE(NONE))
                        continue;

                /* We do JMP_SLOTs in _rtld_bind() below */
                if (type == R_TYPE(JMP_SLOT))
                        continue;

                /* COPY relocs are also handled elsewhere */
                if (type == R_TYPE(COPY))
                        continue;

                /*
                 * We use the fact that relocation types are an `enum'
                 * Note: R_SPARC_6 is currently numerically largest.
                 */
                if (type > R_TYPE(6))
                        return (-1);

                value = rela->r_addend;

                /*
                 * Handle relative relocs here, as an optimization.
                 */
                if (type == R_TYPE(RELATIVE)) {
                        *where += (Elf_Addr)(obj->relocbase + value);
                        rdbg(("RELATIVE in %s --> %p", obj->path,
                            (void *)*where));
                        continue;
                }

                if (RELOC_RESOLVE_SYMBOL(type)) {

                        /* Find the symbol */
                        def = _rtld_find_symdef(symnum, obj, &defobj, false);
                        if (def == NULL)
                                return (-1);

                        /* Add in the symbol's absolute address */
                        value += (Elf_Word)(defobj->relocbase + def->st_value);
                }

                if (RELOC_PC_RELATIVE(type)) {
                        value -= (Elf_Word)where;
                }

                if (RELOC_BASE_RELATIVE(type)) {
                        /*
                         * Note that even though sparcs use `Elf_rela'
                         * exclusively we still need the implicit memory addend
                         * in relocations referring to GOT entries.
                         * Undoubtedly, someone f*cked this up in the distant
                         * past, and now we're stuck with it in the name of
                         * compatibility for all eternity..
                         *
                         * In any case, the implicit and explicit should be
                         * mutually exclusive. We provide a check for that
                         * here.
                         */
#define DIAGNOSTIC
#ifdef DIAGNOSTIC
                        if (value != 0 && *where != 0) {
                                xprintf("BASE_REL(%s): where=%p, *where 0x%x, "
                                        "addend=0x%x, base %p\n",
                                        obj->path, where, *where,
                                        rela->r_addend, obj->relocbase);
                        }
#endif
                        value += (Elf_Word)(obj->relocbase + *where);
                }

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

                if (RELOC_UNALIGNED(type)) {
                        /* Handle unaligned relocations. */
                        Elf_Addr tmp = 0;
                        char *ptr = (char *)where;
                        int i, size = RELOC_TARGET_SIZE(type)/8;

                        /* Read it in one byte at a time. */
                        for (i=0; i<size; i++)
                                tmp = (tmp << 8) | ptr[i];

                        tmp &= ~mask;
                        tmp |= value;

                        /* Write it back out. */
                        for (i=0; i<size; i++)
                                ptr[i] = ((tmp >> (8*i)) & 0xff);
#ifdef RTLD_DEBUG_RELOC
                        value = (Elf_Word)tmp;
#endif

                } else {
                        *where &= ~mask;
                        *where |= value;
#ifdef RTLD_DEBUG_RELOC
                        value = (Elf_Word)*where;
#endif
                }
#ifdef RTLD_DEBUG_RELOC
                if (RELOC_RESOLVE_SYMBOL(type)) {
                        rdbg(("%s %s in %s --> %p in %s", reloc_names[type],
                            obj->strtab + obj->symtab[symnum].st_name,
                            obj->path, (void *)value, defobj->path));
                } else {
                        rdbg(("%s in %s --> %p", reloc_names[type],
                            obj->path, (void *)value));
                }
#endif
        }
        return (0);
}

int
_rtld_relocate_plt_lazy(const Obj_Entry *obj)
{
        return (0);
}

caddr_t
_rtld_bind(const Obj_Entry *obj, Elf_Word reloff)
{
        const Elf_Rela *rela = (const Elf_Rela *)((const uint8_t *)obj->pltrela + reloff);
        Elf_Addr value;
        int err;

        value = 0;      /* XXX gcc */

        err = _rtld_relocate_plt_object(obj, rela, &value);
        if (err || value == 0)
                _rtld_die();

        return (caddr_t)value;
}

int
_rtld_relocate_plt_objects(const Obj_Entry *obj)
{
        const Elf_Rela *rela = obj->pltrela;

        for (; rela < obj->pltrelalim; rela++)
                if (_rtld_relocate_plt_object(obj, rela, NULL) < 0)
                        return -1;

        return 0;
}

static inline int
_rtld_relocate_plt_object(const Obj_Entry *obj, const Elf_Rela *rela, Elf_Addr *tp)
{
        const Elf_Sym *def;
        const Obj_Entry *defobj;
        Elf_Word *where = (Elf_Addr *)(obj->relocbase + rela->r_offset);
        Elf_Addr value;

        /* Fully resolve procedure addresses now */

        assert(ELF_R_TYPE(rela->r_info) == R_TYPE(JMP_SLOT));

        def = _rtld_find_symdef(ELF_R_SYM(rela->r_info), obj, &defobj, true);
        if (def == NULL)
                return -1;

        value = (Elf_Addr)(defobj->relocbase + def->st_value);
        rdbg(("bind now/fixup in %s --> new=%p", 
            defobj->strtab + def->st_name, (void *)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));

        if (tp)
                *tp = value;

        return 0;
}