/*      $NetBSD: kobj_machdep.c,v 1.6 2023/04/28 07:33:56 skrll Exp $   */

/*-
 * Copyright (c) 1999, 2002, 2008 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.
 */

#define ELFSIZE         ARCH_ELFSIZE

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kobj.h>
#include <sys/exec.h>
#include <sys/exec_elf.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])

int
kobj_reloc(kobj_t ko, uintptr_t relocbase, const void *data,
           bool isrela, bool local)
{
        const Elf_Rela *rela;
        Elf_Addr *where, addr;
        Elf_Word value, mask;
        uintptr_t tmp;
        u_int symidx, type;
        int error;

        rela = data;
        where = (Elf_Addr *) (relocbase + rela->r_offset);
        symidx = ELF_R_SYM(rela->r_info);
        type = ELF_R_TYPE(rela->r_info);
        value = rela->r_addend;

        const Elf_Sym *sym = kobj_symbol(ko, symidx);

        if (!local && ELF_ST_BIND(sym->st_info) == STB_LOCAL) {
                return 0;
        }

        if (type == R_TYPE(NONE))
                return 0;

        if (!isrela) {
                printf("kobj_reloc: only support RELA relocations\n");
                return -1;
        }

        if (type == R_TYPE(JMP_SLOT) || type == R_TYPE(COPY) ||
            type > R_TYPE(6)) {
                printf("kobj_reloc: unexpected reloc type %d\n", type);
                return -1;
        }

        if (type == R_TYPE(RELATIVE)) {
                *where += (Elf_Addr)(relocbase + value);
                return 0;
        }

        if (RELOC_RESOLVE_SYMBOL(type)) {
                error = kobj_sym_lookup(ko, symidx, &addr);
                if (error)
                        return -1;
                value += addr;
        }

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

        if (RELOC_BASE_RELATIVE(type)) {
                value += (Elf_Word)(relocbase + *where);
        }

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

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

                /* Read it in one byte at a time. */
                for (i = 0, tmp = 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);

        } else {
                *where &= ~mask;
                *where |= value;
        }

        return 0;
}

int
kobj_machdep(kobj_t ko, void *base, size_t size, bool load)
{

        return 0;
}