96 lines
2.4 KiB
C
96 lines
2.4 KiB
C
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/*
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* (C) Copyright 2002
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* Daniel Engstr<EFBFBD>m, Omicron Ceti AB, daniel@omicron.se
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <common.h>
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#include <asm/io.h>
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#include <asm/ptrace.h>
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#include <asm/realmode.h>
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#define REALMODE_BASE ((char*)0x7c0)
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#define REALMODE_MAILBOX ((char*)0xe00)
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extern char realmode_enter;
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int realmode_setup(void)
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{
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/* copy the realmode switch code */
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if (i386boot_realmode_size > (REALMODE_MAILBOX-REALMODE_BASE)) {
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printf("realmode switch too large (%ld bytes, max is %d)\n",
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i386boot_realmode_size, (REALMODE_MAILBOX-REALMODE_BASE));
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return -1;
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}
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memcpy(REALMODE_BASE, (void*)i386boot_realmode, i386boot_realmode_size);
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asm("wbinvd\n");
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return 0;
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}
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int enter_realmode(u16 seg, u16 off, struct pt_regs *in, struct pt_regs *out)
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{
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/* setup out thin bios emulation */
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if (bios_setup()) {
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return -1;
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}
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if (realmode_setup()) {
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return -1;
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}
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in->eip = off;
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in->xcs = seg;
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if (3>(in->esp & 0xffff)) {
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printf("Warning: entering realmode with sp < 4 will fail\n");
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}
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memcpy(REALMODE_MAILBOX, in, sizeof(struct pt_regs));
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asm("wbinvd\n");
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__asm__ volatile (
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"lcall $0x20,%0\n" : : "i" (&realmode_enter) );
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asm("wbinvd\n");
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memcpy(out, REALMODE_MAILBOX, sizeof(struct pt_regs));
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return out->eax;
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}
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/* This code is supposed to access a realmode interrupt
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* it does currently not work for me */
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int enter_realmode_int(u8 lvl, struct pt_regs *in, struct pt_regs *out)
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{
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/* place two instructions at 0x700 */
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writeb(0xcd, 0x700); /* int $lvl */
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writeb(lvl, 0x701);
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writeb(0xcb, 0x702); /* lret */
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asm("wbinvd\n");
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enter_realmode(0x00, 0x700, in, out);
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return out->eflags&1;
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}
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