/* $NetBSD: asm.S,v 1.12 1995/03/12 00:10:53 mycroft Exp $ */ /* * Ported to boot 386BSD by Julian Elischer (julian@tfs.com) Sept 1992 * * 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. */ /* 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. */ #include #define addr32 .byte 0x67 #define data32 .byte 0x66 CR0_PE = 0x1 .data .globl _ourseg _ourseg: .long 0 /* * 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 addr32 data32 lgdt _C_LABEL(Gdtr) # set the PE bit of CR0 movl %cr0, %eax data32 orl $CR0_PE, %eax movl %eax, %cr0 # make intrasegment jump to flush the processor pipeline and # reload CS register data32 ljmp $0x18, $xprot xprot: # we are in USE32 mode now # set up the protected mode segment registers : DS, SS, ES movl $0x20, %eax movl %ax, %ds movl %ax, %ss movl %ax, %es ret /* * prot_to_real() * transfer from protected mode to real mode */ ENTRY(prot_to_real) # set up a dummy stack frame for the second seg change. # Adjust the intersegment jump instruction following # the clearing of protected mode bit. # This is self-modifying code, but we need a writable # code segment, and an intersegment return does not give us that. movl _ourseg, %eax movw %ax, xreal-2 # Change to use16 mode. ljmp $0x28, $x16 x16: # clear the PE bit of CR0 movl %cr0, %eax data32 andl $~CR0_PE, %eax movl %eax, %cr0 # make intersegment jmp to flush the processor pipeline # using the fake stack frame set up earlier # and reload CS register # Here we have an 16 bits intersegment jump. .byte 0xea .word xreal .word 0 xreal: # we are in real mode now # set up the real mode segment registers : DS, SS, ES movl %cs, %ax movl %ax, %ds movl %ax, %ss movl %ax, %es sti data32 ret /* * startprog(phyaddr) * start the program on protected mode where phyaddr is the entry point */ ENTRY(startprog) pushl %ebp movl %esp, %ebp # get things we need into registers movl 8(%ebp), %ecx # entry offset movl 12(%ebp), %eax # &argv # make a new stack at 0:0x90000 (big segs) movl $0x10, %ebx movw %bx, %ss movl $0x90000, %ebx movl %ebx, %esp # push some number of args onto the stack pushl 28(%eax) # argv[7] = cnvmem pushl 32(%eax) # argv[8] = extmem pushl 16(%eax) # argv[4] = esym pushl $0 # nominally a cyl offset in the boot. pushl 8(%eax) # argv[2] = bootdev pushl 4(%eax) # argv[1] = howto pushl $0 # dummy 'return' address # push on our entry address movl $0x8, %ebx # segment pushl %ebx pushl %ecx # convert over the other data segs movl $0x10, %ebx movl %bx, %ds movl %bx, %es # convert the PC (and code seg) lret /* * pbzero(dst, cnt) * where dst is a virtual address and cnt is the length */ ENTRY(pbzero) pushl %ebp movl %esp, %ebp pushl %es pushl %edi cld # set %es to point at the flat segment movl $0x10, %eax movl %ax, %es movl 8(%ebp), %edi # destination movl 12(%ebp), %ecx # count xorl %eax, %eax # value rep stosb popl %edi popl %es popl %ebp ret /* * pcpy(src, dst, cnt) * where src is a virtual address and dst is a physical address */ ENTRY(pcpy) pushl %ebp movl %esp, %ebp pushl %es pushl %esi pushl %edi cld # set %es to point at the flat segment movl $0x10, %eax movl %ax, %es movl 8(%ebp), %esi # source movl 12(%ebp), %edi # destination movl 16(%ebp), %ecx # count rep movsb popl %edi popl %esi popl %es popl %ebp ret #ifdef CHECKSUM /* * cksum(src, cnt) * where src is a virtual address and cnt is the length */ ENTRY(cksum) pushl %ebp movl %esp, %ebp pushl %es pushl %edi cld # set %es to point at the flat segment movl $0x10, %eax movl %ax, %es movl 8(%ebp), %edi # destination movl 12(%ebp), %ecx # count shrl $2, %ecx xorl %edx, %edx # value 1: es lodsl xorl %eax, %edx loop 1b movl %edx, %eax popl %edi popl %es popl %ebp ret #endif #if 0 ENTRY(getword) pushl %ebp movl %esp, %ebp pushl %es # set %es to point at the flat segment movl $0x10, %eax movl %ax, %es movl 8(%ebp), %eax es movl (%eax), %edx movl %edx, %eax popl %es popl %ebp ret #endif