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001 /* Copyright (C) 2000-2004, The KOS team 002 Copyright (C) 1999 Free Software Foundation, Inc. 003 004 This program is free software; you can redistribute it and/or 005 modify it under the terms of the GNU General Public License 006 as published by the Free Software Foundation; either version 2 007 of the License, or (at your option) any later version. 008 009 This program is distributed in the hope that it will be useful, 010 but WITHOUT ANY WARRANTY; without even the implied warranty of 011 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 012 GNU General Public License for more details. 013 014 You should have received a copy of the GNU General Public License 015 along with this program; if not, write to the Free Software 016 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 017 USA. 018 */ 019 #define ASM_SOURCE 1 020 021 .file "cpu_context_switch.S" 022 023 .text 024 025 026 .globl sos_cpu_kstate_switch 027 .type sos_cpu_kstate_switch, @function 028 sos_cpu_kstate_switch: 029 // arg2= to_context -- esp+64 030 // arg1= from_context -- esp+60 031 // caller ip -- esp+56 032 pushf // (eflags) esp+52 033 pushl %cs // (cs) esp+48 034 pushl $resume_pc // (ip) esp+44 035 pushl $0 // (error code) esp+40 036 pushl %ebp // esp+36 037 pushl %edi // esp+32 038 pushl %esi // esp+28 039 pushl %edx // esp+24 040 pushl %ecx // esp+20 041 pushl %ebx // esp+16 042 pushl %eax // esp+12 043 subl $2, %esp // (alignment) esp+10 044 pushw %ss // esp+8 045 pushw %ds // esp+6 046 pushw %es // esp+4 047 pushw %fs // esp+2 048 pushw %gs // esp 049 050 /* 051 * Now that the original eax/ebx are store, we can use them safely 052 */ 053 054 /* Store the address of the saved context */ 055 movl 60(%esp), %ebx 056 movl %esp, (%ebx) 057 058 /* This is the proper context switch ! We change the stack here */ 059 movl 64(%esp), %esp 060 061 /* Restore the CPU context */ 062 popw %gs 063 popw %fs 064 popw %es 065 popw %ds 066 popw %ss 067 addl $2,%esp 068 popl %eax 069 popl %ebx 070 popl %ecx 071 popl %edx 072 popl %esi 073 popl %edi 074 popl %ebp 075 addl $4, %esp /* Ignore "error code" */ 076 077 /* This restores the eflags, the cs and the eip registers */ 078 iret /* equivalent to: popfl ; ret */ 079 080 resume_pc: 081 // Same context as that when sos_cpu_kstate_switch got called 082 // arg2= to_context -- esp+8 083 // arg1= from_context -- esp+4 084 // caller ip -- esp 085 ret 086 087 088 089 /* ------------------------- */ 090 .globl sos_cpu_kstate_exit_to 091 .type sos_cpu_kstate_exit_to, @function 092 sos_cpu_kstate_exit_to: 093 // arg3= reclaiming_arg -- esp+12 094 // arg2= reclaiming_func -- esp+8 095 // arg1= to_context -- esp+4 096 // caller ip -- esp 097 098 /* Store the current SP in a temporary register */ 099 movl %esp, %eax 100 101 /* This is the proper context switch ! We change the stack here */ 102 movl 4(%eax), %esp 103 104 /* Call the reclaiming function (remember: the old frame address 105 is stored in eax) */ 106 pushl 12(%eax) 107 call *8(%eax) 108 addl $4, %esp 109 110 /* Restore the CPU context */ 111 popw %gs 112 popw %fs 113 popw %es 114 popw %ds 115 popw %ss 116 addl $2,%esp 117 popl %eax 118 popl %ebx 119 popl %ecx 120 popl %edx 121 popl %esi 122 popl %edi 123 popl %ebp 124 addl $4, %esp /* Ignore "error code" */ 125 126 /* This restores the eflags, the cs and the eip registers */ 127 iret /* equivalent to: popfl ; ret */ 128
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