/*-
 * Copyright 1996-1998 John D. Polstra.
 * Copyright (c) 2015 Ruslan Bukin <br@bsdpad.com>
 * Copyright (c) 2016 Yukishige Shibata <y-shibat@mtd.biglobe.ne.jp>
 * All rights reserved.
 *
 * Portions of this software were developed by SRI International and the
 * University of Cambridge Computer Laboratory under DARPA/AFRL contract
 * FA8750-10-C-0237 ("CTSRD"), as part of the DARPA CRASH research programme.
 *
 * Portions of this software were developed by the University of Cambridge
 * Computer Laboratory as part of the CTSRD Project, with support from the
 * UK Higher Education Innovation Fund (HEIF).
 *
 * 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 AUTHOR 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 AUTHOR 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/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/exec.h>
#include <sys/imgact.h>
#include <sys/linker.h>
#include <sys/proc.h>
#include <sys/reg.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#include <sys/imgact_elf.h>
#include <sys/syscall.h>
#include <sys/signalvar.h>
#include <sys/vnode.h>

#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_param.h>

#include <machine/elf.h>
#include <machine/md_var.h>

u_long elf_hwcap;

static struct sysentvec elf64_freebsd_sysvec = {
        .sv_size        = SYS_MAXSYSCALL,
        .sv_table       = sysent,
        .sv_fixup       = __elfN(freebsd_fixup),
        .sv_sendsig     = sendsig,
        .sv_sigcode     = sigcode,
        .sv_szsigcode   = &szsigcode,
        .sv_name        = "FreeBSD ELF64",
        .sv_coredump    = __elfN(coredump),
        .sv_elf_core_osabi = ELFOSABI_FREEBSD,
        .sv_elf_core_abi_vendor = FREEBSD_ABI_VENDOR,
        .sv_elf_core_prepare_notes = __elfN(prepare_notes),
        .sv_minsigstksz = MINSIGSTKSZ,
        .sv_minuser     = VM_MIN_ADDRESS,
        .sv_maxuser     = 0,    /* Filled in during boot. */
        .sv_usrstack    = 0,    /* Filled in during boot. */
        .sv_psstrings   = 0,    /* Filled in during boot. */
        .sv_psstringssz = sizeof(struct ps_strings),
        .sv_stackprot   = VM_PROT_READ | VM_PROT_WRITE,
        .sv_copyout_auxargs = __elfN(freebsd_copyout_auxargs),
        .sv_copyout_strings     = exec_copyout_strings,
        .sv_setregs     = exec_setregs,
        .sv_fixlimit    = NULL,
        .sv_maxssiz     = NULL,
        .sv_flags       = SV_ABI_FREEBSD | SV_LP64 | SV_SHP | SV_TIMEKEEP |
            SV_ASLR | SV_RNG_SEED_VER | SV_SIGSYS,
        .sv_set_syscall_retval = cpu_set_syscall_retval,
        .sv_fetch_syscall_args = cpu_fetch_syscall_args,
        .sv_syscallnames = syscallnames,
        .sv_shared_page_base = 0,       /* Filled in during boot. */
        .sv_shared_page_len = PAGE_SIZE,
        .sv_schedtail   = NULL,
        .sv_thread_detach = NULL,
        .sv_trap        = NULL,
        .sv_hwcap       = &elf_hwcap,
        .sv_onexec_old  = exec_onexec_old,
        .sv_onexit      = exit_onexit,
        .sv_regset_begin = SET_BEGIN(__elfN(regset)),
        .sv_regset_end  = SET_LIMIT(__elfN(regset)),
};
INIT_SYSENTVEC(elf64_sysvec, &elf64_freebsd_sysvec);

static const Elf64_Brandinfo freebsd_brand_info = {
        .brand          = ELFOSABI_FREEBSD,
        .machine        = EM_RISCV,
        .compat_3_brand = "FreeBSD",
        .interp_path    = "/libexec/ld-elf.so.1",
        .sysvec         = &elf64_freebsd_sysvec,
        .interp_newpath = NULL,
        .brand_note     = &elf64_freebsd_brandnote,
        .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
};
C_SYSINIT(elf64, SI_SUB_EXEC, SI_ORDER_FIRST,
    (sysinit_cfunc_t)elf64_insert_brand_entry, &freebsd_brand_info);

static void
elf64_register_sysvec(void *arg)
{
        struct sysentvec *sv;

        sv = arg;
        switch (pmap_mode) {
        case PMAP_MODE_SV48:
                sv->sv_maxuser = VM_MAX_USER_ADDRESS_SV48;
                sv->sv_usrstack = USRSTACK_SV48;
                sv->sv_psstrings = PS_STRINGS_SV48;
                sv->sv_shared_page_base = SHAREDPAGE_SV48;
                break;
        case PMAP_MODE_SV39:
                sv->sv_maxuser = VM_MAX_USER_ADDRESS_SV39;
                sv->sv_usrstack = USRSTACK_SV39;
                sv->sv_psstrings = PS_STRINGS_SV39;
                sv->sv_shared_page_base = SHAREDPAGE_SV39;
                break;
        }
}
SYSINIT(elf64_register_sysvec, SI_SUB_VM, SI_ORDER_ANY, elf64_register_sysvec,
    &elf64_freebsd_sysvec);

static bool debug_kld;
SYSCTL_BOOL(_debug, OID_AUTO, kld_reloc, CTLFLAG_RW, &debug_kld, 0,
    "Activate debug prints in elf_reloc_internal()");

struct type2str_ent {
        int type;
        const char *str;
};

void
elf64_dump_thread(struct thread *td, void *dst, size_t *off)
{

}

/*
 * Following 4 functions are used to manipulate bits on 32bit integer value.
 * FIXME: I implemetend for ease-to-understand rather than for well-optimized.
 */
static uint32_t
gen_bitmask(int msb, int lsb)
{
        uint32_t mask;

        if (msb == sizeof(mask) * 8 - 1)
                mask = ~0;
        else
                mask = (1U << (msb + 1)) - 1;

        if (lsb > 0)
                mask &= ~((1U << lsb) - 1);

        return (mask);
}

static uint32_t
extract_bits(uint32_t x, int msb, int lsb)
{
        uint32_t mask;

        mask = gen_bitmask(msb, lsb);

        x &= mask;
        x >>= lsb;

        return (x);
}

static uint32_t
insert_bits(uint32_t d, uint32_t s, int msb, int lsb)
{
        uint32_t mask;

        mask = gen_bitmask(msb, lsb);

        d &= ~mask;

        s <<= lsb;
        s &= mask;

        return (d | s);
}

static uint32_t
insert_imm(uint32_t insn, uint32_t imm, int imm_msb, int imm_lsb,
    int insn_lsb)
{
        int insn_msb;
        uint32_t v;

        v = extract_bits(imm, imm_msb, imm_lsb);
        insn_msb = (imm_msb - imm_lsb) + insn_lsb;

        return (insert_bits(insn, v, insn_msb, insn_lsb));
}

/*
 * The RISC-V ISA is designed so that all of immediate values are
 * sign-extended.
 * An immediate value is sometimes generated at runtime by adding
 * 12bit sign integer and 20bit signed integer. This requests 20bit
 * immediate value to be ajusted if the MSB of the 12bit immediate
 * value is asserted (sign-extended value is treated as negative value).
 *
 * For example, 0x123800 can be calculated by adding upper 20 bit of
 * 0x124000 and sign-extended 12bit immediate whose bit pattern is
 * 0x800 as follows:
 *   0x123800
 *     = 0x123000 + 0x800
 *     = (0x123000 + 0x1000) + (-0x1000 + 0x800)
 *     = (0x123000 + 0x1000) + (0xff...ff800)
 *     = 0x124000            + sign-extention(0x800)
 */
static uint32_t
calc_hi20_imm(uint32_t value)
{
        /*
         * There is the arithmetical hack that can remove conditional
         * statement. But I implement it in straightforward way.
         */
        if ((value & 0x800) != 0)
                value += 0x1000;
        return (value & ~0xfff);
}

static const struct type2str_ent t2s[] = {
        { R_RISCV_NONE,         "R_RISCV_NONE"          },
        { R_RISCV_64,           "R_RISCV_64"            },
        { R_RISCV_JUMP_SLOT,    "R_RISCV_JUMP_SLOT"     },
        { R_RISCV_RELATIVE,     "R_RISCV_RELATIVE"      },
        { R_RISCV_JAL,          "R_RISCV_JAL"           },
        { R_RISCV_CALL,         "R_RISCV_CALL"          },
        { R_RISCV_PCREL_HI20,   "R_RISCV_PCREL_HI20"    },
        { R_RISCV_PCREL_LO12_I, "R_RISCV_PCREL_LO12_I"  },
        { R_RISCV_PCREL_LO12_S, "R_RISCV_PCREL_LO12_S"  },
        { R_RISCV_HI20,         "R_RISCV_HI20"          },
        { R_RISCV_LO12_I,       "R_RISCV_LO12_I"        },
        { R_RISCV_LO12_S,       "R_RISCV_LO12_S"        },
};

static const char *
reloctype_to_str(int type)
{
        int i;

        for (i = 0; i < sizeof(t2s) / sizeof(t2s[0]); ++i) {
                if (type == t2s[i].type)
                        return t2s[i].str;
        }

        return "*unknown*";
}

bool
elf_is_ifunc_reloc(Elf_Size r_info)
{

        return (ELF_R_TYPE(r_info) == R_RISCV_IRELATIVE);
}

/*
 * Currently kernel loadable module for RISCV is compiled with -fPIC option.
 * (see also additional CFLAGS definition for RISCV in sys/conf/kmod.mk)
 * Only R_RISCV_64, R_RISCV_JUMP_SLOT and RISCV_RELATIVE are emitted in
 * the module. Other relocations will be processed when kernel loadable
 * modules are built in non-PIC.
 *
 * FIXME: only RISCV64 is supported.
 */
static int
elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data,
    int type, int local, elf_lookup_fn lookup)
{
        Elf_Size rtype, symidx;
        const Elf_Rela *rela;
        Elf_Addr val, addr;
        Elf64_Addr *where;
        Elf_Addr addend;
        uint32_t before32_1;
        uint32_t before32;
        uint64_t before64;
        uint32_t *insn32p;
        uint32_t imm20;
        int error;

        switch (type) {
        case ELF_RELOC_RELA:
                rela = (const Elf_Rela *)data;
                where = (Elf_Addr *)(relocbase + rela->r_offset);
                insn32p = (uint32_t *)where;
                addend = rela->r_addend;
                rtype = ELF_R_TYPE(rela->r_info);
                symidx = ELF_R_SYM(rela->r_info);
                break;
        default:
                printf("%s:%d unknown reloc type %d\n",
                    __FUNCTION__, __LINE__, type);
                return (-1);
        }

        switch (rtype) {
        case R_RISCV_NONE:
                break;

        case R_RISCV_64:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                before64 = *where;
                *where = addr + addend;
                if (debug_kld)
                        printf("%p %c %-24s %016lx -> %016lx\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before64, *where);
                break;

        case R_RISCV_JUMP_SLOT:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                before64 = *where;
                *where = addr;
                if (debug_kld)
                        printf("%p %c %-24s %016lx -> %016lx\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before64, *where);
                break;

        case R_RISCV_RELATIVE:
                before64 = *where;
                *where = elf_relocaddr(lf, relocbase + addend);
                if (debug_kld)
                        printf("%p %c %-24s %016lx -> %016lx\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before64, *where);
                break;

        case R_RISCV_JAL:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr - (Elf_Addr)where;
                if (val <= -(1UL << 20) || (1UL << 20) <= val) {
                        printf("kldload: huge offset against R_RISCV_JAL\n");
                        return (-1);
                }

                before32 = *insn32p;
                *insn32p = insert_imm(*insn32p, val, 20, 20, 31);
                *insn32p = insert_imm(*insn32p, val, 10,  1, 21);
                *insn32p = insert_imm(*insn32p, val, 11, 11, 20);
                *insn32p = insert_imm(*insn32p, val, 19, 12, 12);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_CALL:
                /*
                 * R_RISCV_CALL relocates 8-byte region that consists
                 * of the sequence of AUIPC and JALR.
                 */
                /* Calculate and check the pc relative offset. */
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr - (Elf_Addr)where;
                if (val <= -(1UL << 32) || (1UL << 32) <= val) {
                        printf("kldload: huge offset against R_RISCV_CALL\n");
                        return (-1);
                }

                /* Relocate AUIPC. */
                before32 = insn32p[0];
                imm20 = calc_hi20_imm(val);
                insn32p[0] = insert_imm(insn32p[0], imm20, 31, 12, 12);

                /* Relocate JALR. */
                before32_1 = insn32p[1];
                insn32p[1] = insert_imm(insn32p[1], val, 11,  0, 20);
                if (debug_kld)
                        printf("%p %c %-24s %08x %08x -> %08x %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, insn32p[0], before32_1, insn32p[1]);
                break;

        case R_RISCV_PCREL_HI20:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr - (Elf_Addr)where;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                imm20 = calc_hi20_imm(val);
                *insn32p = insert_imm(*insn32p, imm20, 31, 12, 12);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_PCREL_LO12_I:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr - (Elf_Addr)where;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                *insn32p = insert_imm(*insn32p, addr, 11,  0, 20);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_PCREL_LO12_S:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr - (Elf_Addr)where;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                *insn32p = insert_imm(*insn32p, addr, 11,  5, 25);
                *insn32p = insert_imm(*insn32p, addr,  4,  0,  7);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_HI20:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                imm20 = calc_hi20_imm(val);
                *insn32p = insert_imm(*insn32p, imm20, 31, 12, 12);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_LO12_I:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                *insn32p = insert_imm(*insn32p, addr, 11,  0, 20);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;

        case R_RISCV_LO12_S:
                error = lookup(lf, symidx, 1, &addr);
                if (error != 0)
                        return (-1);

                val = addr;
                insn32p = (uint32_t *)where;
                before32 = *insn32p;
                *insn32p = insert_imm(*insn32p, addr, 11,  5, 25);
                *insn32p = insert_imm(*insn32p, addr,  4,  0,  7);
                if (debug_kld)
                        printf("%p %c %-24s %08x -> %08x\n", where,
                            (local ? 'l' : 'g'), reloctype_to_str(rtype),
                            before32, *insn32p);
                break;
        case R_RISCV_IRELATIVE:
                addr = relocbase + addend;
                val = ((Elf64_Addr (*)(void))addr)();
                if (*where != val)
                        *where = val;
                break;
        default:
                printf("kldload: unexpected relocation type %ld, "
                    "symbol index %ld\n", rtype, symidx);
                return (-1);
        }

        return (0);
}

int
elf_reloc(linker_file_t lf, Elf_Addr relocbase, const void *data, int type,
    elf_lookup_fn lookup)
{

        return (elf_reloc_internal(lf, relocbase, data, type, 0, lookup));
}

int
elf_reloc_local(linker_file_t lf, Elf_Addr relocbase, const void *data,
    int type, elf_lookup_fn lookup)
{

        return (elf_reloc_internal(lf, relocbase, data, type, 1, lookup));
}

int
elf_cpu_load_file(linker_file_t lf __unused)
{

        return (0);
}

int
elf_cpu_unload_file(linker_file_t lf __unused)
{

        return (0);
}

int
elf_cpu_parse_dynamic(caddr_t loadbase __unused, Elf_Dyn *dynamic __unused)
{

        return (0);
}