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