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Diffstat (limited to 'sys/boot/pc98/boot2/asm.S')
| -rw-r--r-- | sys/boot/pc98/boot2/asm.S | 258 |
1 files changed, 258 insertions, 0 deletions
diff --git a/sys/boot/pc98/boot2/asm.S b/sys/boot/pc98/boot2/asm.S new file mode 100644 index 0000000..de51618 --- /dev/null +++ b/sys/boot/pc98/boot2/asm.S @@ -0,0 +1,258 @@ +/* + * Mach Operating System + * Copyright (c) 1992, 1991 Carnegie Mellon University + * All Rights Reserved. + * + * Permission to use, copy, modify and distribute this software and its + * documentation is hereby granted, provided that both the copyright + * notice and this permission notice appear in all copies of the + * software, derivative works or modified versions, and any portions + * thereof, and that both notices appear in supporting documentation. + * + * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" + * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR + * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. + * + * Carnegie Mellon requests users of this software to return to + * + * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU + * School of Computer Science + * Carnegie Mellon University + * Pittsburgh PA 15213-3890 + * + * any improvements or extensions that they make and grant Carnegie Mellon + * the rights to redistribute these changes. + * + * from: Mach, Revision 2.2 92/04/04 11:34:13 rpd + * $FreeBSD$ + */ + + +/* + Copyright 1988, 1989, 1990, 1991, 1992 + by Intel Corporation, Santa Clara, California. + + All Rights Reserved + +Permission to use, copy, modify, and distribute this software and +its documentation for any purpose and without fee is hereby +granted, provided that the above copyright notice appears in all +copies and that both the copyright notice and this permission notice +appear in supporting documentation, and that the name of Intel +not be used in advertising or publicity pertaining to distribution +of the software without specific, written prior permission. + +INTEL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE +INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, +IN NO EVENT SHALL INTEL BE LIABLE FOR ANY SPECIAL, INDIRECT, OR +CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM +LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT, +NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION +WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. +*/ + + .file "asm.s" + +#include "asm.h" + + +CR0_PE_ON = 0x1 +CR0_PE_OFF = 0xfffffffe + .code16 + .text + +/* + * + * real_to_prot() + * transfer from real mode to protected mode. + */ + +ENTRY(real_to_prot) + /* guarantee that interrupt is disabled when in prot mode */ + cli + + /* load the gdtr */ + .code32 + addr32 + data32 + lgdt EXT(Gdtr) + .code16 + + /* set the PE bit of CR0 */ + mov %cr0, %eax + + or $CR0_PE_ON, %eax + mov %eax, %cr0 + + /* + * make intrasegment jump to flush the processor pipeline and + * reload CS register + */ + .code32 + data32 + ljmp $0x18, $xprot + .code16 +xprot: + + /* + * we are in USE32 mode now + * set up the protected mode segment registers : DS, SS, ES, FS + */ + data32 + movw $0x20, %ax /* data segment */ + mov %ax, %ds /* gas would waste a prefix byte for movw */ + mov %ax, %ss + mov %ax, %es + data32 + movw $0x10, %ax /* flat segment */ + mov %ax, %fs + +#ifdef BDE_DEBUGGER + /* load idtr so we can debug */ + lidt EXT(Idtr_prot) +#endif + + ret + +/* + * + * prot_to_real() + * transfer from protected mode to real mode + * + */ + +ENTRY(prot_to_real) + + /* Prepare %ax while we're still in a mode that gas understands. */ + data32 + movw $0x30, %ax + + /* Change to use16 mode. */ + .code32 + ljmp $0x28, $x16 + .code16 +x16: + + mov %ax, %ds + mov %ax, %ss + mov %ax, %es + mov %ax, %fs + + /* clear the PE bit of CR0 */ + mov %cr0, %eax + and $CR0_PE_OFF, %eax + mov %eax, %cr0 + + /* + * make intersegment jmp to flush the processor pipeline + * and reload CS register + */ + .code32 + data32 + ljmp $BOOTSEG, $xreal + .code16 +xreal: + + /* + * we are in real mode now + * set up the real mode segment registers : DS, SS, ES, FS + */ + mov %cs, %ax + mov %ax, %ds + mov %ax, %ss + mov %ax, %es + mov %ax, %fs + +#ifdef BDE_DEBUGGER + /* load idtr so we can debug */ + addr32 + data32 + lidt EXT(Idtr_real) +#endif + + data32 + ret + +/* + * startprog(phyaddr) + * start the program on protected mode where phyaddr is the entry point + * + * XXX This whole mess should go away and we should run the boot code in + * flat 32 bit mode with it linked -T BOOTSEG. See the netboot code for + * how this is done. + */ + +ENTRY(startprog) + .code32 + push %ebp + mov %esp, %ebp + movl %esp, %eax /* Use eax as the old stack pointer */ + + /* convert the current stack to a 32 bit flat model */ + movw $0x10, %bx + data32 + mov %bx, %ss + addl $(BOOTSEG<<4),%esp + + /* copy the arguments from the old stack to the new stack */ + pushl 0x14(%eax) /* &bootinfo */ + pushl $0 /* was &nfsdiskless */ + pushl $0 /* was esym */ + pushl $0 /* was cyloffset */ + pushl 0x10(%eax) /* bootdev */ + pushl 0x0C(%eax) /* howto */ + movl $(ourreturn),%ebx + addl $(BOOTSEG<<4),%ebx /* Fix it up for flat segments */ + pushl %ebx /* our return address */ + + /* push on our entry address */ + pushl $0x08 /* segment selector */ + pushl 0x08(%eax) /* kernel entry address */ + + /* convert over the other data segs */ + movw $0x10, %bx + data32 + mov %bx, %ds + data32 + mov %bx, %es + + /* convert the PC (and code seg) */ + lret +ourreturn: + /* For now there is not much we can do, just lock in a loop */ + jmp ourreturn + +/* + * pcpy(src, dst, cnt) + * where src is a virtual address and dst is a physical address + */ + +ENTRY(pcpy) + .code32 + push %ebp + mov %esp, %ebp + push %es + push %esi + push %edi + push %ecx + + cld + + /* set %es to point at the flat segment */ + movw $0x10, %ax + mov %ax, %es + + mov 0x8(%ebp), %esi /* source */ + mov 0xc(%ebp), %edi /* destination */ + mov 0x10(%ebp), %ecx /* count */ + + rep + movsb + + pop %ecx + pop %edi + pop %esi + pop %es + pop %ebp + + ret |
