// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *  Copyright (C) 1997 Martin Mares
 *  Copyright (C) 2007 H. Peter Anvin
 */

/*
 * This file builds a disk-image from three different files:
 *
 * - setup: 8086 machine code, sets up system parm
 * - system: 80386 code for actual system
 * - zoffset.h: header with ZO_* defines
 *
 * It does some checking that all files are of the correct type, and writes
 * the result to the specified destination, removing headers and padding to
 * the right amount. It also writes some system data to stdout.
 */

/*
 * Changes by tytso to allow root device specification
 * High loaded stuff by Hans Lermen & Werner Almesberger, Feb. 1996
 * Cross compiling fixes by Gertjan van Wingerde, July 1996
 * Rewritten by Martin Mares, April 1997
 * Substantially overhauled by H. Peter Anvin, April 2007
 */

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <tools/le_byteshift.h>

typedef unsigned char  u8;
typedef unsigned short u16;
typedef unsigned int   u32;

#define DEFAULT_MAJOR_ROOT 0
#define DEFAULT_MINOR_ROOT 0
#define DEFAULT_ROOT_DEV (DEFAULT_MAJOR_ROOT << 8 | DEFAULT_MINOR_ROOT)

/* Minimal number of setup sectors */
#define SETUP_SECT_MIN 5
#define SETUP_SECT_MAX 64

/* This must be large enough to hold the entire setup */
u8 buf[SETUP_SECT_MAX*512];

#define PECOFF_RELOC_RESERVE 0x20

#ifdef CONFIG_EFI_MIXED
#define PECOFF_COMPAT_RESERVE 0x20
#else
#define PECOFF_COMPAT_RESERVE 0x0
#endif

static unsigned long efi32_stub_entry;
static unsigned long efi64_stub_entry;
static unsigned long efi_pe_entry;
static unsigned long efi32_pe_entry;
static unsigned long kernel_info;
static unsigned long startup_64;
static unsigned long _ehead;
static unsigned long _end;

/*----------------------------------------------------------------------*/

static const u32 crctab32[] = {
        0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419,
        0x706af48f, 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4,
        0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07,
        0x90bf1d91, 0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de,
        0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7, 0x136c9856,
        0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
        0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4,
        0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
        0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3,
        0x45df5c75, 0xdcd60dcf, 0xabd13d59, 0x26d930ac, 0x51de003a,
        0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599,
        0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
        0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190,
        0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f,
        0x9fbfe4a5, 0xe8b8d433, 0x7807c9a2, 0x0f00f934, 0x9609a88e,
        0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
        0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed,
        0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
        0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3,
        0xfbd44c65, 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2,
        0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a,
        0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5,
        0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa, 0xbe0b1010,
        0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
        0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17,
        0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6,
        0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615,
        0x73dc1683, 0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8,
        0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1, 0xf00f9344,
        0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
        0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a,
        0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
        0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1,
        0xa6bc5767, 0x3fb506dd, 0x48b2364b, 0xd80d2bda, 0xaf0a1b4c,
        0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef,
        0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
        0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe,
        0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31,
        0x2cd99e8b, 0x5bdeae1d, 0x9b64c2b0, 0xec63f226, 0x756aa39c,
        0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
        0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b,
        0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
        0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1,
        0x18b74777, 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c,
        0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45, 0xa00ae278,
        0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7,
        0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc, 0x40df0b66,
        0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
        0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605,
        0xcdd70693, 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8,
        0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b,
        0x2d02ef8d
};

static u32 partial_crc32_one(u8 c, u32 crc)
{
        return crctab32[(crc ^ c) & 0xff] ^ (crc >> 8);
}

static u32 partial_crc32(const u8 *s, int len, u32 crc)
{
        while (len--)
                crc = partial_crc32_one(*s++, crc);
        return crc;
}

static void die(const char * str, ...)
{
        va_list args;
        va_start(args, str);
        vfprintf(stderr, str, args);
        va_end(args);
        fputc('\n', stderr);
        exit(1);
}

static void usage(void)
{
        die("Usage: build setup system zoffset.h image");
}

#ifdef CONFIG_EFI_STUB

static void update_pecoff_section_header_fields(char *section_name, u32 vma, u32 size, u32 datasz, u32 offset)
{
        unsigned int pe_header;
        unsigned short num_sections;
        u8 *section;

        pe_header = get_unaligned_le32(&buf[0x3c]);
        num_sections = get_unaligned_le16(&buf[pe_header + 6]);

#ifdef CONFIG_X86_32
        section = &buf[pe_header + 0xa8];
#else
        section = &buf[pe_header + 0xb8];
#endif

        while (num_sections > 0) {
                if (strncmp((char*)section, section_name, 8) == 0) {
                        /* section header size field */
                        put_unaligned_le32(size, section + 0x8);

                        /* section header vma field */
                        put_unaligned_le32(vma, section + 0xc);

                        /* section header 'size of initialised data' field */
                        put_unaligned_le32(datasz, section + 0x10);

                        /* section header 'file offset' field */
                        put_unaligned_le32(offset, section + 0x14);

                        break;
                }
                section += 0x28;
                num_sections--;
        }
}

static void update_pecoff_section_header(char *section_name, u32 offset, u32 size)
{
        update_pecoff_section_header_fields(section_name, offset, size, size, offset);
}

static void update_pecoff_setup_and_reloc(unsigned int size)
{
        u32 setup_offset = 0x200;
        u32 reloc_offset = size - PECOFF_RELOC_RESERVE - PECOFF_COMPAT_RESERVE;
#ifdef CONFIG_EFI_MIXED
        u32 compat_offset = reloc_offset + PECOFF_RELOC_RESERVE;
#endif
        u32 setup_size = reloc_offset - setup_offset;

        update_pecoff_section_header(".setup", setup_offset, setup_size);
        update_pecoff_section_header(".reloc", reloc_offset, PECOFF_RELOC_RESERVE);

        /*
         * Modify .reloc section contents with a single entry. The
         * relocation is applied to offset 10 of the relocation section.
         */
        put_unaligned_le32(reloc_offset + 10, &buf[reloc_offset]);
        put_unaligned_le32(10, &buf[reloc_offset + 4]);

#ifdef CONFIG_EFI_MIXED
        update_pecoff_section_header(".compat", compat_offset, PECOFF_COMPAT_RESERVE);

        /*
         * Put the IA-32 machine type (0x14c) and the associated entry point
         * address in the .compat section, so loaders can figure out which other
         * execution modes this image supports.
         */
        buf[compat_offset] = 0x1;
        buf[compat_offset + 1] = 0x8;
        put_unaligned_le16(0x14c, &buf[compat_offset + 2]);
        put_unaligned_le32(efi32_pe_entry + size, &buf[compat_offset + 4]);
#endif
}

static void update_pecoff_text(unsigned int text_start, unsigned int file_sz,
                               unsigned int init_sz)
{
        unsigned int pe_header;
        unsigned int text_sz = file_sz - text_start;
        unsigned int bss_sz = init_sz - file_sz;

        pe_header = get_unaligned_le32(&buf[0x3c]);

        /*
         * The PE/COFF loader may load the image at an address which is
         * misaligned with respect to the kernel_alignment field in the setup
         * header.
         *
         * In order to avoid relocating the kernel to correct the misalignment,
         * add slack to allow the buffer to be aligned within the declared size
         * of the image.
         */
        bss_sz  += CONFIG_PHYSICAL_ALIGN;
        init_sz += CONFIG_PHYSICAL_ALIGN;

        /*
         * Size of code: Subtract the size of the first sector (512 bytes)
         * which includes the header.
         */
        put_unaligned_le32(file_sz - 512 + bss_sz, &buf[pe_header + 0x1c]);

        /* Size of image */
        put_unaligned_le32(init_sz, &buf[pe_header + 0x50]);

        /*
         * Address of entry point for PE/COFF executable
         */
        put_unaligned_le32(text_start + efi_pe_entry, &buf[pe_header + 0x28]);

        update_pecoff_section_header_fields(".text", text_start, text_sz + bss_sz,
                                            text_sz, text_start);
}

static int reserve_pecoff_reloc_section(int c)
{
        /* Reserve 0x20 bytes for .reloc section */
        memset(buf+c, 0, PECOFF_RELOC_RESERVE);
        return PECOFF_RELOC_RESERVE;
}

static void efi_stub_defaults(void)
{
        /* Defaults for old kernel */
#ifdef CONFIG_X86_32
        efi_pe_entry = 0x10;
#else
        efi_pe_entry = 0x210;
        startup_64 = 0x200;
#endif
}

static void efi_stub_entry_update(void)
{
        unsigned long addr = efi32_stub_entry;

#ifdef CONFIG_X86_64
        /* Yes, this is really how we defined it :( */
        addr = efi64_stub_entry - 0x200;
#endif

#ifdef CONFIG_EFI_MIXED
        if (efi32_stub_entry != addr)
                die("32-bit and 64-bit EFI entry points do not match\n");
#endif
        put_unaligned_le32(addr, &buf[0x264]);
}

#else

static inline void update_pecoff_setup_and_reloc(unsigned int size) {}
static inline void update_pecoff_text(unsigned int text_start,
                                      unsigned int file_sz,
                                      unsigned int init_sz) {}
static inline void efi_stub_defaults(void) {}
static inline void efi_stub_entry_update(void) {}

static inline int reserve_pecoff_reloc_section(int c)
{
        return 0;
}
#endif /* CONFIG_EFI_STUB */

static int reserve_pecoff_compat_section(int c)
{
        /* Reserve 0x20 bytes for .compat section */
        memset(buf+c, 0, PECOFF_COMPAT_RESERVE);
        return PECOFF_COMPAT_RESERVE;
}

/*
 * Parse zoffset.h and find the entry points. We could just #include zoffset.h
 * but that would mean tools/build would have to be rebuilt every time. It's
 * not as if parsing it is hard...
 */
#define PARSE_ZOFS(p, sym) do { \
        if (!strncmp(p, "#define ZO_" #sym " ", 11+sizeof(#sym)))       \
                sym = strtoul(p + 11 + sizeof(#sym), NULL, 16);         \
} while (0)

static void parse_zoffset(char *fname)
{
        FILE *file;
        char *p;
        int c;

        file = fopen(fname, "r");
        if (!file)
                die("Unable to open `%s': %m", fname);
        c = fread(buf, 1, sizeof(buf) - 1, file);
        if (ferror(file))
                die("read-error on `zoffset.h'");
        fclose(file);
        buf[c] = 0;

        p = (char *)buf;

        while (p && *p) {
                PARSE_ZOFS(p, efi32_stub_entry);
                PARSE_ZOFS(p, efi64_stub_entry);
                PARSE_ZOFS(p, efi_pe_entry);
                PARSE_ZOFS(p, efi32_pe_entry);
                PARSE_ZOFS(p, kernel_info);
                PARSE_ZOFS(p, startup_64);
                PARSE_ZOFS(p, _ehead);
                PARSE_ZOFS(p, _end);

                p = strchr(p, '\n');
                while (p && (*p == '\r' || *p == '\n'))
                        p++;
        }
}

int main(int argc, char ** argv)
{
        unsigned int i, sz, setup_sectors, init_sz;
        int c;
        u32 sys_size;
        struct stat sb;
        FILE *file, *dest;
        int fd;
        void *kernel;
        u32 crc = 0xffffffffUL;

        efi_stub_defaults();

        if (argc != 5)
                usage();
        parse_zoffset(argv[3]);

        dest = fopen(argv[4], "w");
        if (!dest)
                die("Unable to write `%s': %m", argv[4]);

        /* Copy the setup code */
        file = fopen(argv[1], "r");
        if (!file)
                die("Unable to open `%s': %m", argv[1]);
        c = fread(buf, 1, sizeof(buf), file);
        if (ferror(file))
                die("read-error on `setup'");
        if (c < 1024)
                die("The setup must be at least 1024 bytes");
        if (get_unaligned_le16(&buf[510]) != 0xAA55)
                die("Boot block hasn't got boot flag (0xAA55)");
        fclose(file);

        c += reserve_pecoff_compat_section(c);
        c += reserve_pecoff_reloc_section(c);

        /* Pad unused space with zeros */
        setup_sectors = (c + 511) / 512;
        if (setup_sectors < SETUP_SECT_MIN)
                setup_sectors = SETUP_SECT_MIN;
        i = setup_sectors*512;
        memset(buf+c, 0, i-c);

        update_pecoff_setup_and_reloc(i);

        /* Set the default root device */
        put_unaligned_le16(DEFAULT_ROOT_DEV, &buf[508]);

        /* Open and stat the kernel file */
        fd = open(argv[2], O_RDONLY);
        if (fd < 0)
                die("Unable to open `%s': %m", argv[2]);
        if (fstat(fd, &sb))
                die("Unable to stat `%s': %m", argv[2]);
        sz = sb.st_size;
        kernel = mmap(NULL, sz, PROT_READ, MAP_SHARED, fd, 0);
        if (kernel == MAP_FAILED)
                die("Unable to mmap '%s': %m", argv[2]);
        /* Number of 16-byte paragraphs, including space for a 4-byte CRC */
        sys_size = (sz + 15 + 4) / 16;
#ifdef CONFIG_EFI_STUB
        /*
         * COFF requires minimum 32-byte alignment of sections, and
         * adding a signature is problematic without that alignment.
         */
        sys_size = (sys_size + 1) & ~1;
#endif

        /* Patch the setup code with the appropriate size parameters */
        buf[0x1f1] = setup_sectors-1;
        put_unaligned_le32(sys_size, &buf[0x1f4]);

        init_sz = get_unaligned_le32(&buf[0x260]);
#ifdef CONFIG_EFI_STUB
        /*
         * The decompression buffer will start at ImageBase. When relocating
         * the compressed kernel to its end, we must ensure that the head
         * section does not get overwritten.  The head section occupies
         * [i, i + _ehead), and the destination is [init_sz - _end, init_sz).
         *
         * At present these should never overlap, because 'i' is at most 32k
         * because of SETUP_SECT_MAX, '_ehead' is less than 1k, and the
         * calculation of INIT_SIZE in boot/header.S ensures that
         * 'init_sz - _end' is at least 64k.
         *
         * For future-proofing, increase init_sz if necessary.
         */

        if (init_sz - _end < i + _ehead) {
                init_sz = (i + _ehead + _end + 4095) & ~4095;
                put_unaligned_le32(init_sz, &buf[0x260]);
        }
#endif
        update_pecoff_text(setup_sectors * 512, i + (sys_size * 16), init_sz);

        efi_stub_entry_update();

        /* Update kernel_info offset. */
        put_unaligned_le32(kernel_info, &buf[0x268]);

        crc = partial_crc32(buf, i, crc);
        if (fwrite(buf, 1, i, dest) != i)
                die("Writing setup failed");

        /* Copy the kernel code */
        crc = partial_crc32(kernel, sz, crc);
        if (fwrite(kernel, 1, sz, dest) != sz)
                die("Writing kernel failed");

        /* Add padding leaving 4 bytes for the checksum */
        while (sz++ < (sys_size*16) - 4) {
                crc = partial_crc32_one('\0', crc);
                if (fwrite("\0", 1, 1, dest) != 1)
                        die("Writing padding failed");
        }

        /* Write the CRC */
        put_unaligned_le32(crc, buf);
        if (fwrite(buf, 1, 4, dest) != 4)
                die("Writing CRC failed");

        /* Catch any delayed write failures */
        if (fclose(dest))
                die("Writing image failed");

        close(fd);

        /* Everything is OK */
        return 0;
}