Assembly header and main routine for new x86 setup code

The assembly header and initialization code, and the main() routine.
main.c also contains some miscellaneous very short routines.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 283 insertions, 0 deletions

diff --git a/arch/i386/boot/header.S b/arch/i386/boot/header.S
new file mode 100644
index 000000000000..6b9923fb6eae
--- /dev/null
+++ b/arch/i386/boot/header.S
@@ -0,0 +1,283 @@
+/*
+ *      header.S
+ *
+ *      Copyright (C) 1991, 1992 Linus Torvalds
+ *
+ *      Based on bootsect.S and setup.S
+ *      modified by more people than can be counted
+ *
+ *      Rewritten as a common file by H. Peter Anvin (Apr 2007)
+ *
+ * BIG FAT NOTE: We're in real mode using 64k segments.  Therefore segment
+ * addresses must be multiplied by 16 to obtain their respective linear
+ * addresses. To avoid confusion, linear addresses are written using leading
+ * hex while segment addresses are written as segment:offset.
+ *
+ */
+
+#include <asm/segment.h>
+#include <linux/utsrelease.h>
+#include <asm/boot.h>
+#include <asm/e820.h>
+#include <asm/page.h>
+#include <asm/setup.h>
+#include "boot.h"
+
+SETUPSECTS      = 4                     /* default nr of setup-sectors */
+BOOTSEG         = 0x07C0                /* original address of boot-sector */
+SYSSEG          = DEF_SYSSEG            /* system loaded at 0x10000 (65536) */
+SYSSIZE         = DEF_SYSSIZE           /* system size: # of 16-byte clicks */
+                                        /* to be loaded */
+ROOT_DEV        = 0                     /* ROOT_DEV is now written by "build" */
+SWAP_DEV        = 0                     /* SWAP_DEV is now written by "build" */
+
+#ifndef SVGA_MODE
+#define SVGA_MODE ASK_VGA
+#endif
+
+#ifndef RAMDISK
+#define RAMDISK 0
+#endif
+
+#ifndef ROOT_RDONLY
+#define ROOT_RDONLY 1
+#endif
+
+        .code16
+        .section ".bstext", "ax"
+
+        .global bootsect_start
+bootsect_start:
+
+        # Normalize the start address
+        ljmp    $BOOTSEG, $start2
+
+start2:
+        movw    %cs, %ax
+        movw    %ax, %ds
+        movw    %ax, %es
+        movw    %ax, %ss
+        xorw    %sp, %sp
+        sti
+        cld
+
+        movw    $bugger_off_msg, %si
+
+msg_loop:
+        lodsb
+        andb    %al, %al
+        jz      bs_die
+        movb    $0xe, %ah
+        movw    $7, %bx
+        int     $0x10
+        jmp     msg_loop
+
+bs_die:
+        # Allow the user to press a key, then reboot
+        xorw    %ax, %ax
+        int     $0x16
+        int     $0x19
+
+        # int 0x19 should never return.  In case it does anyway,
+        # invoke the BIOS reset code...
+        ljmp    $0xf000,$0xfff0
+
+        .section ".bsdata", "a"
+bugger_off_msg:
+        .ascii  "Direct booting from floppy is no longer supported.\r\n"
+        .ascii  "Please use a boot loader program instead.\r\n"
+        .ascii  "\n"
+        .ascii  "Remove disk and press any key to reboot . . .\r\n"
+        .byte   0
+
+
+        # Kernel attributes; used by setup.  This is part 1 of the
+        # header, from the old boot sector.
+
+        .section ".header", "a"
+        .globl  hdr
+hdr:
+setup_sects:    .byte SETUPSECTS
+root_flags:     .word ROOT_RDONLY
+syssize:        .long SYSSIZE
+ram_size:       .word RAMDISK
+vid_mode:       .word SVGA_MODE
+root_dev:       .word ROOT_DEV
+boot_flag:      .word 0xAA55
+
+        # offset 512, entry point
+
+        .globl  _start
+_start:
+                # Explicitly enter this as bytes, or the assembler
+                # tries to generate a 3-byte jump here, which causes
+                # everything else to push off to the wrong offset.
+                .byte   0xeb            # short (2-byte) jump
+                .byte   start_of_setup-1f
+1:
+
+        # Part 2 of the header, from the old setup.S
+
+                .ascii  "HdrS"          # header signature
+                .word   0x0206          # header version number (>= 0x0105)
+                                        # or else old loadlin-1.5 will fail)
+                .globl realmode_swtch
+realmode_swtch: .word   0, 0            # default_switch, SETUPSEG
+start_sys_seg:  .word   SYSSEG
+                .word   kernel_version-512 # pointing to kernel version string
+                                        # above section of header is compatible
+                                        # with loadlin-1.5 (header v1.5). Don't
+                                        # change it.
+
+type_of_loader: .byte   0               # = 0, old one (LILO, Loadlin,
+                                        #      Bootlin, SYSLX, bootsect...)
+                                        # See Documentation/i386/boot.txt for
+                                        # assigned ids
+
+# flags, unused bits must be zero (RFU) bit within loadflags
+loadflags:
+LOADED_HIGH     = 1                     # If set, the kernel is loaded high
+CAN_USE_HEAP    = 0x80                  # If set, the loader also has set
+                                        # heap_end_ptr to tell how much
+                                        # space behind setup.S can be used for
+                                        # heap purposes.
+                                        # Only the loader knows what is free
+#ifndef __BIG_KERNEL__
+                .byte   0
+#else
+                .byte   LOADED_HIGH
+#endif
+
+setup_move_size: .word  0x8000          # size to move, when setup is not
+                                        # loaded at 0x90000. We will move setup
+                                        # to 0x90000 then just before jumping
+                                        # into the kernel. However, only the
+                                        # loader knows how much data behind
+                                        # us also needs to be loaded.
+
+code32_start:                           # here loaders can put a different
+                                        # start address for 32-bit code.
+#ifndef __BIG_KERNEL__
+                .long   0x1000          #   0x1000 = default for zImage
+#else
+                .long   0x100000        # 0x100000 = default for big kernel
+#endif
+
+ramdisk_image:  .long   0               # address of loaded ramdisk image
+                                        # Here the loader puts the 32-bit
+                                        # address where it loaded the image.
+                                        # This only will be read by the kernel.
+
+ramdisk_size:   .long   0               # its size in bytes
+
+bootsect_kludge:
+                .long   0               # obsolete
+
+heap_end_ptr:   .word   _end+1024       # (Header version 0x0201 or later)
+                                        # space from here (exclusive) down to
+                                        # end of setup code can be used by setup
+                                        # for local heap purposes.
+
+pad1:           .word   0
+cmd_line_ptr:   .long   0               # (Header version 0x0202 or later)
+                                        # If nonzero, a 32-bit pointer
+                                        # to the kernel command line.
+                                        # The command line should be
+                                        # located between the start of
+                                        # setup and the end of low
+                                        # memory (0xa0000), or it may
+                                        # get overwritten before it
+                                        # gets read.  If this field is
+                                        # used, there is no longer
+                                        # anything magical about the
+                                        # 0x90000 segment; the setup
+                                        # can be located anywhere in
+                                        # low memory 0x10000 or higher.
+
+ramdisk_max:    .long (-__PAGE_OFFSET-(512 << 20)-1) & 0x7fffffff
+                                        # (Header version 0x0203 or later)
+                                        # The highest safe address for
+                                        # the contents of an initrd
+
+kernel_alignment:  .long CONFIG_PHYSICAL_ALIGN  #physical addr alignment
+                                                #required for protected mode
+                                                #kernel
+#ifdef CONFIG_RELOCATABLE
+relocatable_kernel:    .byte 1
+#else
+relocatable_kernel:    .byte 0
+#endif
+pad2:                   .byte 0
+pad3:                   .word 0
+
+cmdline_size:   .long   COMMAND_LINE_SIZE-1     #length of the command line,
+                                                #added with boot protocol
+                                                #version 2.06
+
+# End of setup header #####################################################
+
+        .section ".inittext", "ax"
+start_of_setup:
+#ifdef SAFE_RESET_DISK_CONTROLLER
+# Reset the disk controller.
+        movw    $0x0000, %ax            # Reset disk controller
+        movb    $0x80, %dl              # All disks
+        int     $0x13
+#endif
+
+# We will have entired with %cs = %ds+0x20, normalize %cs so
+# it is on par with the other segments.
+        pushw   %ds
+        pushw   $setup2
+        lretw
+
+setup2:
+# Force %es = %ds
+        movw    %ds, %ax
+        movw    %ax, %es
+        cld
+
+# Stack paranoia: align the stack and make sure it is good
+# for both 16- and 32-bit references.  In particular, if we
+# were meant to have been using the full 16-bit segment, the
+# caller might have set %sp to zero, which breaks %esp-based
+# references.
+        andw    $~3, %sp        # dword align (might as well...)
+        jnz     1f
+        movw    $0xfffc, %sp    # Make sure we're not zero
+1:      movzwl  %sp, %esp       # Clear upper half of %esp
+        sti
+
+# Check signature at end of setup
+        cmpl    $0x5a5aaa55, setup_sig
+        jne     setup_bad
+
+# Zero the bss
+        movw    $__bss_start, %di
+        movw    $_end+3, %cx
+        xorl    %eax, %eax
+        subw    %di, %cx
+        shrw    $2, %cx
+        rep; stosl
+
+# Jump to C code (should not return)
+        calll   main
+
+# Setup corrupt somehow...
+setup_bad:
+        movl    $setup_corrupt, %eax
+        calll   puts
+        # Fall through...
+
+        .globl  die
+        .type   die, @function
+die:
+        hlt
+        jmp     die
+
+        .size   die, .-due
+
+        .section ".initdata", "a"
+setup_corrupt:
+        .byte   7
+        .string "No setup signature found..."