/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2019 Hesham Almatary
 *
 * This software was developed by SRI International and the University of
 * Cambridge Computer Laboratory (Department of Computer Science and
 * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
 * DARPA SSITH research programme.
 *
 * 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.
 */

/* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 * See https://llvm.org/LICENSE.txt for license information.
 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 */

#include <sys/cdefs.h>

#include <errno.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>

#include <rtems/rtl/rtl.h>
#include "rtl-elf.h"
#include "rtl-error.h"
#include <rtems/rtl/rtl-trace.h>
#include "rtl-unwind.h"
#include "rtl-unwind-dw2.h"

uint32_t
rtems_rtl_elf_section_flags (const rtems_rtl_obj* obj,
                             const Elf_Shdr*      shdr) {
  return 0;
}

uint32_t
rtems_rtl_elf_arch_parse_section (const rtems_rtl_obj* obj,
                                  int                  section,
                                  const char*          name,
                                  const Elf_Shdr*      shdr,
                                  const uint32_t       flags) {
  (void) obj;
  (void) section;
  (void) name;
  (void) shdr;
  return flags;
}

bool
rtems_rtl_elf_arch_section_alloc (const rtems_rtl_obj* obj,
                                  rtems_rtl_obj_sect*  sect) {
  (void) obj;
  (void) sect;
  return false;
}

bool
rtems_rtl_elf_arch_section_free (const rtems_rtl_obj* obj,
                                 rtems_rtl_obj_sect*  sect) {
  (void) obj;
  (void) sect;
  return false;
}

bool
rtems_rtl_elf_rel_resolve_sym (Elf_Word type) {
  return true;
}

size_t
rtems_rtl_elf_relocate_tramp_max_size (void) {
  /*
   * Disable by returning 0.
   */
  return 0;
}

rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rel_tramp (rtems_rtl_obj*            obj,
                                  const Elf_Rel*            rel,
                                  const rtems_rtl_obj_sect* sect,
                                  const char*               symname,
                                  const Elf_Byte            syminfo,
                                  const Elf_Word            symvalue) {
  (void) obj;
  (void) rel;
  (void) sect;
  (void) symname;
  (void) syminfo;
  (void) symvalue;
  return rtems_rtl_elf_rel_no_error;
}

// Extract bits V[Begin:End], where range is inclusive, and Begin must be < 63.
static uint32_t extractBits(uint64_t v, uint32_t begin, uint32_t end) {
  return (v & ((1ULL << (begin + 1)) - 1)) >> end;
}

static int64_t SignExtend64(uint64_t val, unsigned bits) {
  return (int64_t )(((int64_t) (val << (64 - bits))) >> (64 - bits));
}

static void write16le(void *loc, uint16_t val) {
  *((uint16_t *) loc) = val;
}

static void write32le(void *loc, uint32_t val) {
  *((uint32_t *) loc) = val;
}

static void write64le(void *loc, uint64_t val) {
  *((uint64_t *) loc) = val;
}

static uint16_t read16le(void *loc) {
  return *((uint16_t *) loc);
}

static uint32_t read32le(void *loc) {
  return *((uint32_t *) loc);
}

static uint64_t read64le(void *loc) {
  return *((uint64_t *) loc);
}

static rtems_rtl_elf_rel_status
rtems_rtl_elf_reloc_rela (rtems_rtl_obj*      obj,
                          const Elf_Rela*           rela,
                          const rtems_rtl_obj_sect* sect,
                          const char*               symname,
                          const Elf_Byte            syminfo,
                          const Elf_Word            symvalue,
                          const bool parsing) {
  Elf_Word *where;
  Elf_Word  tmp;
  Elf_Word addend = (Elf_Word) rela->r_addend;
  Elf_Word local = 0;

  char bits = (sizeof(Elf_Word) * 8);
  where = (Elf_Addr *)(sect->base + rela->r_offset);

  // Final PCREL value
  Elf_Word pcrel_val = symvalue - ((Elf_Word) where);

  if (syminfo == STT_SECTION) {
    local = 1;
    return rtems_rtl_elf_rel_no_error;
  }

  if (parsing) {
    return rtems_rtl_elf_rel_no_error;
  }

  switch (ELF_R_TYPE(rela->r_info)) {
  case R_TYPE(NONE):
    break;

  case R_TYPE(RVC_BRANCH): {
    uint16_t insn = ((*where) & 0xFFFF) & 0xE383;
    uint16_t imm8 = extractBits(pcrel_val, 8, 8) << 12;
    uint16_t imm4_3 = extractBits(pcrel_val, 4, 3) << 10;
    uint16_t imm7_6 = extractBits(pcrel_val, 7, 6) << 5;
    uint16_t imm2_1 = extractBits(pcrel_val, 2, 1) << 3;
    uint16_t imm5 = extractBits(pcrel_val, 5, 5) << 2;
    insn |= imm8 | imm4_3 | imm7_6 | imm2_1 | imm5;

    write16le(where, insn);
  }
  break;

  case R_TYPE(RVC_JUMP): {
    uint16_t insn = ((*where) & 0xFFFF) & 0xE003;
    uint16_t imm11 = extractBits(pcrel_val, 11, 11) << 12;
    uint16_t imm4 = extractBits(pcrel_val, 4, 4) << 11;
    uint16_t imm9_8 = extractBits(pcrel_val, 9, 8) << 9;
    uint16_t imm10 = extractBits(pcrel_val, 10, 10) << 8;
    uint16_t imm6 = extractBits(pcrel_val, 6, 6) << 7;
    uint16_t imm7 = extractBits(pcrel_val, 7, 7) << 6;
    uint16_t imm3_1 = extractBits(pcrel_val, 3, 1) << 3;
    uint16_t imm5 = extractBits(pcrel_val, 5, 5) << 2;
    insn |= imm11 | imm4 | imm9_8 | imm10 | imm6 | imm7 | imm3_1 | imm5;

    write16le(where, insn);
  }
  break;

  case R_TYPE(RVC_LUI): {
    int64_t imm = SignExtend64(symvalue + 0x800, bits) >> 12;
    if (imm == 0) { // `c.lui rd, 0` is illegal, convert to `c.li rd, 0`
      write16le(where, (read16le(where) & 0x0F83) | 0x4000);
    } else {
      uint16_t imm17 = extractBits(symvalue + 0x800, 17, 17) << 12;
      uint16_t imm16_12 = extractBits(symvalue + 0x800, 16, 12) << 2;
      write16le(where, (read16le(where) & 0xEF83) | imm17 | imm16_12);
    }
  }
  break;

  case R_TYPE(JAL): {
    uint32_t insn = read32le(where) & 0xFFF;
    uint32_t imm20 = extractBits(pcrel_val, 20, 20) << 31;
    uint32_t imm10_1 = extractBits(pcrel_val, 10, 1) << 21;
    uint32_t imm11 = extractBits(pcrel_val, 11, 11) << 20;
    uint32_t imm19_12 = extractBits(pcrel_val, 19, 12) << 12;
    insn |= imm20 | imm10_1 | imm11 | imm19_12;

    write32le(where, insn);
  }
  break;

  case R_TYPE(BRANCH): {

    uint32_t insn = read32le(where) & 0x1FFF07F;
    uint32_t imm12 = extractBits(pcrel_val, 12, 12) << 31;
    uint32_t imm10_5 = extractBits(pcrel_val, 10, 5) << 25;
    uint32_t imm4_1 = extractBits(pcrel_val, 4, 1) << 8;
    uint32_t imm11 = extractBits(pcrel_val, 11, 11) << 7;
    insn |= imm12 | imm10_5 | imm4_1 | imm11;

    write32le(where, insn);
  }
  break;

  case R_TYPE(64):
    write64le(where, symvalue);
    break;
  case R_TYPE(32):
    write32le(where, symvalue);
    break;

  case R_TYPE(SET6):
    *((uint8_t *) where) = (*where & 0xc0) | (symvalue & 0x3f);
    break;
  case R_TYPE(SET8):
    *((uint8_t *) where) = symvalue;
    break;
  case R_TYPE(SET16):
    write16le(where, symvalue);
    break;
  case R_TYPE(SET32):
    write32le(where, symvalue);
    break;

  case R_TYPE(ADD8):
    *((uint8_t *) where) = *((uint8_t *) where) + symvalue;
    break;
  case R_TYPE(ADD16):
    write16le(where, read16le(where) + symvalue);
    break;
  case R_TYPE(ADD32):
    write32le(where, read32le(where) + symvalue);
    break;
  case R_TYPE(ADD64):
    write64le(where, read64le(where) + symvalue);
    break;

  case R_TYPE(SUB6):
    *((uint8_t *) where) = (*where & 0xc0) | (((*where & 0x3f) - symvalue) & 0x3f);
    break;
  case R_TYPE(SUB8):
    *((uint8_t *) where) = *((uint8_t *) where) - symvalue;
    break;
  case R_TYPE(SUB16):
    write16le(where, read16le(where) - symvalue);
    break;
  case R_TYPE(SUB32):
    write32le(where, read32le(where) - symvalue);
    break;
  case R_TYPE(SUB64):
    write64le(where, read64le(where) - symvalue);
    break;

  case R_TYPE(32_PCREL): {
    write32le(where, pcrel_val);

    if (rtems_rtl_trace (RTEMS_RTL_TRACE_RELOC))
      printf ("rtl: R_RISCV_32_PCREL %p @ %p in %s\n",
              (void *) * (where), where, rtems_rtl_obj_oname (obj));

  }
  break;

  case R_TYPE(PCREL_HI20): {
    int64_t hi = SignExtend64(pcrel_val + 0x800, bits); //pcrel_val + 0x800;
    write32le(where, (read32le(where) & 0xFFF) | (hi & 0xFFFFF000));

  }
  break;

  case R_TYPE(GOT_HI20):
  case R_TYPE(HI20): {

    uint64_t hi = symvalue + 0x800;
    write32le(where, (read32le(where) & 0xFFF) | (hi & 0xFFFFF000));
  }
  break;

  case R_TYPE(PCREL_LO12_I): {
    uint64_t hi = (pcrel_val + 0x800) >> 12;
    uint64_t lo = pcrel_val - (hi << 12);
    write32le(where, (read32le(where) & 0xFFFFF) | ((lo & 0xFFF) << 20));
  }
  break;

  case R_TYPE(LO12_I): {

    uint64_t hi = (symvalue + 0x800) >> 12;
    uint64_t lo = symvalue - (hi << 12);
    write32le(where, (read32le(where) & 0xFFFFF) | ((lo & 0xFFF) << 20));

  }
  break;

  case R_TYPE(PCREL_LO12_S): {
    uint64_t hi = (pcrel_val + 0x800) >> 12;
    uint64_t lo = pcrel_val - (hi << 12);
    uint32_t imm11_5 = extractBits(lo, 11, 5) << 25;
    uint32_t imm4_0 = extractBits(lo, 4, 0) << 7;
    write32le(where, (read32le(where) & 0x1FFF07F) | imm11_5 | imm4_0);

  }
  break;

  case R_TYPE(LO12_S): {
    uint64_t hi = (symvalue + 0x800) >> 12;
    uint64_t lo = symvalue - (hi << 12);
    uint32_t imm11_5 = extractBits(lo, 11, 5) << 25;
    uint32_t imm4_0 = extractBits(lo, 4, 0) << 7;
    write32le(where, (read32le(where) & 0x1FFF07F) | imm11_5 | imm4_0);
  }
  break;

  case R_TYPE(CALL_PLT):
  case R_TYPE(CALL): {
    int64_t hi = SignExtend64(pcrel_val + 0x800, bits);
    write32le(where, (read32le(where) & 0xFFF) | (hi & 0xFFFFF000));
    int64_t hi20 = SignExtend64(pcrel_val + 0x800, bits);
    int64_t lo = pcrel_val - (hi20 << 12);
    write32le(((char *) where) + 4, (read32le(((char *) where) + 4) & 0xFFFFF) | ((lo & 0xFFF) << 20));
  }
  break;

  default:
    rtems_rtl_set_error (EINVAL,
                         "%s: Unsupported relocation type %ld "
                         "in non-PLT relocations",
                         sect->name, (uint32_t) ELF_R_TYPE(rela->r_info));
    return rtems_rtl_elf_rel_failure;
  }

  return rtems_rtl_elf_rel_no_error;
}

rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rela (rtems_rtl_obj*            obj,
                             const Elf_Rela*           rela,
                             const rtems_rtl_obj_sect* sect,
                             const char*               symname,
                             const Elf_Byte            syminfo,
                             const Elf_Word            symvalue) {
  return rtems_rtl_elf_reloc_rela (obj,
                                   rela,
                                   sect,
                                   symname,
                                   syminfo,
                                   symvalue,
                                   false);
}

rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rela_tramp (rtems_rtl_obj*            obj,
                                   const Elf_Rela*           rela,
                                   const rtems_rtl_obj_sect* sect,
                                   const char*               symname,
                                   const Elf_Byte            syminfo,
                                   const Elf_Word            symvalue) {
  return rtems_rtl_elf_reloc_rela (obj,
                                   rela,
                                   sect,
                                   symname,
                                   syminfo,
                                   symvalue,
                                   true);
}

rtems_rtl_elf_rel_status
rtems_rtl_elf_relocate_rel (rtems_rtl_obj*      obj,
                            const Elf_Rel*            rel,
                            const rtems_rtl_obj_sect* sect,
                            const char*               symname,
                            const Elf_Byte            syminfo,
                            const Elf_Word            symvalue) {
  rtems_rtl_set_error (EINVAL, "rel type record not supported");
  return rtems_rtl_elf_rel_failure;
}

bool
rtems_rtl_elf_unwind_parse (const rtems_rtl_obj* obj,
                            const char*          name,
                            uint32_t             flags) {
  return rtems_rtl_elf_unwind_dw2_parse (obj, name, flags);
}

bool
rtems_rtl_elf_unwind_register (rtems_rtl_obj* obj) {
  return rtems_rtl_elf_unwind_dw2_register (obj);
}

bool
rtems_rtl_elf_unwind_deregister (rtems_rtl_obj* obj) {
  return rtems_rtl_elf_unwind_dw2_deregister (obj);
}