/*
 * Copyright 2013 Freescale Semiconductor, Inc.
 *
 * SPDX-License-Identifier:     GPL-2.0+ BSD-2-Clause
 *
 * 64-bit and little-endian target only until we need to support a different
 * arch that needs this.
 */

#include <elf.h>
#include <errno.h>
#include <inttypes.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#ifndef R_AARCH64_RELATIVE
#define R_AARCH64_RELATIVE      1027
#endif

static const bool debug_en;

static void debug(const char *fmt, ...)
{
        va_list args;

        va_start(args, fmt);
        if (debug_en)
                vprintf(fmt, args);
}

static bool supported_rela(Elf64_Rela *rela)
{
        uint64_t mask = 0xffffffffULL; /* would be different on 32-bit */
        uint32_t type = rela->r_info & mask;

        switch (type) {
#ifdef R_AARCH64_RELATIVE
        case R_AARCH64_RELATIVE:
                return true;
#endif
        default:
                fprintf(stderr, "warning: unsupported relocation type %"
                                PRIu32 " at %" PRIx64 "\n",
                        type, rela->r_offset);

                return false;
        }
}

static inline uint64_t swap64(uint64_t val)
{
        return ((val >> 56) & 0x00000000000000ffULL) |
               ((val >> 40) & 0x000000000000ff00ULL) |
               ((val >> 24) & 0x0000000000ff0000ULL) |
               ((val >>  8) & 0x00000000ff000000ULL) |
               ((val <<  8) & 0x000000ff00000000ULL) |
               ((val << 24) & 0x0000ff0000000000ULL) |
               ((val << 40) & 0x00ff000000000000ULL) |
               ((val << 56) & 0xff00000000000000ULL);
}

#if __BYTE_ORDER == __LITTLE_ENDIAN
static inline uint64_t be64(uint64_t val)
{
        return swap64(val);
}

static inline uint64_t le64(uint64_t val)
{
        return val;
}
#else
static inline uint64_t le64(uint64_t val)
{
        return swap64(val);
}

static inline uint64_t be64(uint64_t val)
{
        return val;
}
#endif

static bool read_num(const char *str, uint64_t *num)
{
        char *endptr;
        *num = strtoull(str, &endptr, 16);
        return str[0] && !endptr[0];
}

int main(int argc, char **argv)
{
        FILE *f;
        int i, num;
        uint64_t rela_start, rela_end, text_base;

        if (argc != 5) {
                fprintf(stderr, "Statically apply ELF rela relocations\n");
                fprintf(stderr, "Usage: %s <bin file> <text base> " \
                                "<rela start> <rela end>\n", argv[0]);
                fprintf(stderr, "All numbers in hex.\n");
                return 1;
        }

        f = fopen(argv[1], "r+b");
        if (!f) {
                fprintf(stderr, "%s: Cannot open %s: %s\n",
                        argv[0], argv[1], strerror(errno));
                return 2;
        }

        if (!read_num(argv[2], &text_base) ||
            !read_num(argv[3], &rela_start) ||
            !read_num(argv[4], &rela_end)) {
                fprintf(stderr, "%s: bad number\n", argv[0]);
                return 3;
        }

        if (rela_start > rela_end || rela_start < text_base ||
            (rela_end - rela_start) % sizeof(Elf64_Rela)) {
                fprintf(stderr, "%s: bad rela bounds\n", argv[0]);
                return 3;
        }

        rela_start -= text_base;
        rela_end -= text_base;

        num = (rela_end - rela_start) / sizeof(Elf64_Rela);

        for (i = 0; i < num; i++) {
                Elf64_Rela rela, swrela;
                uint64_t pos = rela_start + sizeof(Elf64_Rela) * i;
                uint64_t addr;

                if (fseek(f, pos, SEEK_SET) < 0) {
                        fprintf(stderr, "%s: %s: seek to %" PRIx64
                                        " failed: %s\n",
                                argv[0], argv[1], pos, strerror(errno));
                }

                if (fread(&rela, sizeof(rela), 1, f) != 1) {
                        fprintf(stderr, "%s: %s: read rela failed at %"
                                        PRIx64 "\n",
                                argv[0], argv[1], pos);
                        return 4;
                }

                swrela.r_offset = le64(rela.r_offset);
                swrela.r_info = le64(rela.r_info);
                swrela.r_addend = le64(rela.r_addend);

                if (!supported_rela(&swrela))
                        continue;

                debug("Rela %" PRIx64 " %" PRIu64 " %" PRIx64 "\n",
                      swrela.r_offset, swrela.r_info, swrela.r_addend);

                if (swrela.r_offset < text_base) {
                        fprintf(stderr, "%s: %s: bad rela at %" PRIx64 "\n",
                                argv[0], argv[1], pos);
                        return 4;
                }

                addr = swrela.r_offset - text_base;

                if (fseek(f, addr, SEEK_SET) < 0) {
                        fprintf(stderr, "%s: %s: seek to %"
                                        PRIx64 " failed: %s\n",
                                argv[0], argv[1], addr, strerror(errno));
                }

                if (fwrite(&rela.r_addend, sizeof(rela.r_addend), 1, f) != 1) {
                        fprintf(stderr, "%s: %s: write failed at %" PRIx64 "\n",
                                argv[0], argv[1], addr);
                        return 4;
                }
        }

        if (fclose(f) < 0) {
                fprintf(stderr, "%s: %s: close failed: %s\n",
                        argv[0], argv[1], strerror(errno));
                return 4;
        }

        return 0;
}