1 /* ----------------------------------------------------------------------- 2 * 3 * Copyright 2003-2009 H. Peter Anvin - All Rights Reserved 4 * Copyright 2009 Intel Corporation; author: H. Peter Anvin 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, 9 * Boston MA 02110-1301, USA; either version 2 of the License, or 10 * (at your option) any later version; incorporated herein by reference. 11 * 12 * ----------------------------------------------------------------------- */ 13 14 /* 15 * Simple stub to get us to the right point in the 32-bit code; 16 * this module must be linked first 17 */ 18 19 .section ".init", "ax" 20 .globl _start 21 _start: 22 /* Zero the bss */ 23 cld 24 movl $__bss_start, %edi 25 movl $__bss_end, %ecx 26 subl %edi, %ecx 27 xorl %eax, %eax 28 shrl $2, %ecx 29 rep ; stosl 30 31 /* Set up the protected-mode IDT and the interrupt jump buffers */ 32 movl $idt, %edi 33 movl $ijb, %eax 34 movl $0xee000000, %ebx /* Interrupt gate */ 35 movw %cs, %bx /* Target segment */ 36 37 /* Make the IDT */ 38 movl $256, %ecx 39 1: 40 stosl 41 stosl 42 movl %ebx, -6(%edi) 43 addl $8, %eax 44 loop 1b 45 46 /* 47 * Each entry in the interrupt jump buffer contains the following 48 * instructions: 49 * 50 * 60 pushal 51 * b0xx movb $xx, %al # interrupt number 52 * e9xxxxxxxx jmp handle_interrupt 53 */ 54 movl $0xe900b060, %eax 55 movl $256, %ecx 56 1: 57 movl %eax, (%edi) 58 addl $(1 << 16), %eax 59 movl $handle_interrupt-8, %edx 60 subl %edi, %edx 61 movl %edx, 4(%edi) 62 addl $8, %edi 63 loop 1b 64 65 #if __SIZEOF_POINTER__ == 4 66 lidtl idt_ptr 67 #elif __SIZEOF_POINTER__ == 8 68 lidt idt_ptr 69 #else 70 #error "unsupported architecture" 71 #endif 72 73 /* Save arguments, switch stacks */ 74 movl %esp, %eax /* Pointer to arguments */ 75 movl $__stack_end, %esp 76 77 call setup 78 jmp *(rm_args) /* First argument is return */ 79 80 .section ".text","ax" 81 .globl intcall 82 .type intcall, @function 83 intcall: 84 jmp *(rm_args+1*4) /* Intcall is argument 1 */ 85 .size intcall, .-intcall 86 87 .type handle_interrupt, @function 88 handle_interrupt: 89 jmp *(rm_args+4*4) /* Interrupt pointer is argument 4 */ 90 .size handle_interrupt, .-handle_interrupt 91 92 .section ".rodata","a" 93 idt_ptr: 94 .word 8*256-1 95 .long idt 96 .word 0 97 98 .section ".bss.large","aw" 99 .balign 2048 100 idt: 101 .space 8*256 102 ijb: 103 .space 8*256 104 105 __stack: 106 .space 65536 107 __stack_end: 108
