1/* $OpenBSD: run_i386.S,v 1.1 2015/09/02 01:52:26 yasuoka Exp $ */ 2 3/* 4 * Copyright (c) 2015 YASUOKA Masahiko <yasuoka@yasuoka.net> 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19#include <machine/asm.h> 20#include <machine/specialreg.h> 21 22#define CODE_SEGMENT 0x10 23#define DATA_SEGMENT 0x18 24 25 .globl _C_LABEL(run_i386_size) 26_C_LABEL(run_i386_size): 27 .long run_i386_end - _C_LABEL(run_i386_start) 28 29 .align 4 30 .text 31 .globl _C_LABEL(run_i386_start) 32_C_LABEL(run_i386_start): 33start: 34 /* 35 * run_i386(_start) is to call the loaded kernel's start() with 36 * 32bit segment mode from x64 mode. 37 * %rdi == loaded start address, %rsi == kernel start address 38 */ 39 40 /* re-arrange the parameters for the x86 calling convension */ 41 mov %edx, (run_i386_end - start - 0x20)(%rdi) 42 mov %ecx, (run_i386_end - start - 0x1c)(%rdi) 43 mov %r8d, (run_i386_end - start - 0x18)(%rdi) 44 mov %r9d, (run_i386_end - start - 0x14)(%rdi) 45 mov 0x8(%rsp), %edx 46 mov %edx, (run_i386_end - start - 0x10)(%rdi) 47 mov 0x10(%rsp), %edx 48 mov %edx, (run_i386_end - start - 0xc)(%rdi) 49 mov 0x18(%rsp), %edx 50 mov %edx, (run_i386_end - start - 0x8)(%rdi) 51 mov 0x20(%rsp), %edx 52 mov %edx, (run_i386_end - start - 0x4)(%rdi) 53 54 /* Prepare jump address */ 55 lea (start32a - start)(%rdi), %rax 56 movl %eax, (start32r - start)(%rdi) 57 58 cli 59 60 /* Setup GDT */ 61 lea (gdt - start)(%rdi), %rax 62 mov %rax, (gdtrr - start)(%rdi) 63 lgdt (gdtr - start)(%rdi) 64 65 /* Jump to set %cs */ 66 ljmp *(start32r - start)(%rdi) 67 68 .align 4 69start32a: 70 .code32 71 movl $DATA_SEGMENT, %eax 72 movl %eax, %ds 73 movl %eax, %es 74 movl %eax, %fs 75 movl %eax, %gs 76 movl %eax, %ss 77 78 lea (run_i386_end - start - 0x20)(%edi), %eax 79 mov %eax, %esp 80 81 /* Disable Paging in CR0 */ 82 movl %cr0, %eax 83 andl $(~CR0_PG), %eax 84 movl %eax, %cr0 85 86 /* Disable PAE in CR4 */ 87 movl %cr4, %eax 88 andl $(~CR4_PAE), %eax 89 movl %eax, %cr4 90 91 jmp start32b 92start32b: 93 .code32 94 95 call *%esi 96 97 .align 4 98start32r: 99 .long 0 100 .long CODE_SEGMENT 101 .align 4 102gdt: 103 .long 0, 0 104 .long 0, 0 105 .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x9f, 0xcf, 0x00 106 .byte 0xff, 0xff, 0x00, 0x00, 0x00, 0x93, 0xcf, 0x00 107gdtr: 108 .word gdtr - gdt 109gdtrr: 110 .quad 111start32end: 112 /* Space for the stack */ 113 .align 4 114 .space 8192 115run_i386_end: 116