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NJU-ProjectN/nemu eb63cf3568dbf4e0c3c6ef462e6ec685550fabbc Merge pull request #76 from rijuyuezhu/master
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xinyangli 2023-12-21 00:20:36 +08:00
parent 1efe03efb9
commit 2824efad33
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nemu/tools/qemu-diff/src/isa.c Normal file
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/***************************************************************************************
* Copyright (c) 2014-2022 Zihao Yu, Nanjing University
*
* NEMU is licensed under Mulan PSL v2.
* You can use this software according to the terms and conditions of the Mulan PSL v2.
* You may obtain a copy of Mulan PSL v2 at:
* http://license.coscl.org.cn/MulanPSL2
*
* THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
* EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
* MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
*
* See the Mulan PSL v2 for more details.
***************************************************************************************/
#include "common.h"
#if defined(CONFIG_ISA_x86)
bool gdb_memcpy_to_qemu(uint32_t, void *, int);
bool gdb_getregs(union isa_gdb_regs *);
bool gdb_setregs(union isa_gdb_regs *);
void difftest_exec(uint64_t n);
static uint8_t mbr[] = {
// start16:
0xfa, // cli
0x31, 0xc0, // xorw %ax,%ax
0x8e, 0xd8, // movw %ax,%ds
0x8e, 0xc0, // movw %ax,%es
0x8e, 0xd0, // movw %ax,%ss
0x0f, 0x01, 0x16, 0x44, 0x7c, // lgdt gdtdesc
0x0f, 0x20, 0xc0, // movl %cr0,%eax
0x66, 0x83, 0xc8, 0x01, // orl $CR0_PE,%eax
0x0f, 0x22, 0xc0, // movl %eax,%cr0
0xea, 0x1d, 0x7c, 0x08, 0x00, // ljmp $GDT_ENTRY(1),$start32
// start32:
0x66, 0xb8, 0x10, 0x00, // movw $0x10,%ax
0x8e, 0xd8, // movw %ax, %ds
0x8e, 0xc0, // movw %ax, %es
0x8e, 0xd0, // movw %ax, %ss
0xeb, 0xfe, // jmp 7c27
0x8d, 0x76, 0x00, // lea 0x0(%esi),%esi
// GDT
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00,
0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00,
// GDT descriptor
0x17, 0x00, 0x2c, 0x7c, 0x00, 0x00
};
void init_isa() {
// put the MBR code to QEMU to enable protected mode
bool ok = gdb_memcpy_to_qemu(0x7c00, mbr, sizeof(mbr));
assert(ok == 1);
union isa_gdb_regs r;
gdb_getregs(&r);
// set cs:eip to 0000:7c00
r.eip = 0x7c00;
r.cs = 0x0000;
ok = gdb_setregs(&r);
assert(ok == 1);
// execute enough instructions to enter protected mode
difftest_exec(20);
}
#else
void init_isa() {
}
#endif