arch/arm64/start.S

	start.S revision 199767f8919635c4928607450d9e0abb932109ce
/*-
 * Copyright (c) 2014 Andrew Turner
 * All rights reserved.
 *
 * 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.
 *
 * $FreeBSD$
 */

/*
 * We need to be a PE32+ file for EFI. On some architectures we can use
 * objcopy to create the correct file, however on arm64 we need to do
 * it ourselves.
 */

#define IMAGE_FILE_MACHINE_ARM64    0xaa64

#define IMAGE_SCN_CNT_CODE      0x00000020
#define IMAGE_SCN_CNT_INITIALIZED_DATA  0x00000040
#define IMAGE_SCN_MEM_DISCARDABLE   0x02000000
#define IMAGE_SCN_MEM_EXECUTE       0x20000000
#define IMAGE_SCN_MEM_READ      0x40000000

    .section .peheader
efi_start:
    /* The MS-DOS Stub, only used to get the offset of the COFF header */
    .ascii  "MZ"
    .short  0
    .space  0x38
    .long   pe_sig - efi_start

    /* The PE32 Signature. Needs to be 8-byte aligned */
    .align  3
pe_sig:
    .ascii  "PE"
    .short  0
coff_head:
    .short  IMAGE_FILE_MACHINE_ARM64    /* AArch64 file */
    .short  2               /* 2 Sections */
    .long   0               /* Timestamp */
    .long   0               /* No symbol table */
    .long   0               /* No symbols */
    .short  section_table - optional_header /* Optional header size */
    .short  0   /* Characteristics TODO: Fill in */

optional_header:
    .short  0x020b              /* PE32+ (64-bit addressing) */
    .byte   0               /* Major linker version */
    .byte   0               /* Minor linker version */
    .long   _edata - _end_header        /* Code size */
    .long   0               /* No initialized data */
    .long   0               /* No uninitialized data */
    .long   _start - efi_start      /* Entry point */
    .long   _end_header - efi_start     /* Start of code */

optional_windows_header:
    .quad   0               /* Image base */
    .long   32              /* Section Alignment */
    .long   8               /* File alignment */
    .short  0               /* Major OS version */
    .short  0               /* Minor OS version */
    .short  0               /* Major image version */
    .short  0               /* Minor image version */
    .short  0               /* Major subsystem version */
    .short  0               /* Minor subsystem version */
    .long   0               /* Win32 version */
    .long   _edata - efi_start      /* Image size */
    .long   _end_header - efi_start     /* Header size */
    .long   0               /* Checksum */
    .short  0xa             /* Subsystem (EFI app) */
    .short  0               /* DLL Characteristics */
    .quad   0               /* Stack reserve */
    .quad   0               /* Stack commit */
    .quad   0               /* Heap reserve */
    .quad   0               /* Heap commit */
    .long   0               /* Loader flags */
    .long   6               /* Number of RVAs */

    /* RVAs: */
    .quad   0
    .quad   0
    .quad   0
    .quad   0
    .quad   0
    .quad   0

section_table:
    /* We need a .reloc section for EFI */
    .ascii  ".reloc"
    .byte   0
    .byte   0               /* Pad to 8 bytes */
    .long   0               /* Virtual size */
    .long   0               /* Virtual address */
    .long   0               /* Size of raw data */
    .long   0               /* Pointer to raw data */
    .long   0               /* Pointer to relocations */
    .long   0               /* Pointer to line numbers */
    .short  0               /* Number of relocations */
    .short  0               /* Number of line numbers */
    .long   (IMAGE_SCN_CNT_INITIALIZED_DATA | IMAGE_SCN_MEM_READ | \
         IMAGE_SCN_MEM_DISCARDABLE) /* Characteristics */

    /* The contents of the loader */
    .ascii  ".text"
    .byte   0
    .byte   0
    .byte   0               /* Pad to 8 bytes */
    .long   _edata - _end_header        /* Virtual size */
    .long   _end_header - efi_start     /* Virtual address */
    .long   _edata - _end_header        /* Size of raw data */
    .long   _end_header - efi_start     /* Pointer to raw data */
    .long   0               /* Pointer to relocations */
    .long   0               /* Pointer to line numbers */
    .short  0               /* Number of relocations */
    .short  0               /* Number of line numbers */
    .long   (IMAGE_SCN_CNT_CODE | IMAGE_SCN_MEM_EXECUTE | \
         IMAGE_SCN_MEM_READ)        /* Characteristics */
_end_header:

    .text
    .globl  _start
_start:
    /* Save the boot params to the stack */
    stp x0, x1, [sp, #-16]!

    adr x0, __bss_start
    adr x1, __bss_end

    b 2f

1:
    stp xzr, xzr, [x0], #16
2:
    cmp x0, x1
    b.lo    1b

    adr x0, ImageBase
    adr x1, _DYNAMIC

    bl  self_reloc

    ldp x0, x1, [sp], #16

    bl  efi_main

1:  b   1b