Codice

268 volume VI os16
Script e sorgenti del kernel 269
1660098 | ;
1660099 | ; If we are here, a user process was interrupted.
1660100 | ; Switch to the kernel stack.
1660101 | ;
1660102 | mov ax, #0x0050 ; Kernel data area.
1660103 | mov ss, ax
1660104 | mov sp, __ksp
1660105 | ;
1660106 | ; Call the scheduler.
1660107 | ;
1660108 | push #proc_ss_0 ; &proc_ss_0
1660109 | push #proc_sp_0 ; &proc_sp_0
1660110 | call _proc_scheduler
1660111 | add sp, #2
1660112 | add sp, #2
1660113 | ;
1660114 | ; Restore process stack registers from kernel data segment.
1660115 | ;
1660116 | mov ss, proc_ss_0 ; Restore process stack segment.
1660117 | mov sp, proc_sp_0 ; Restore process stack pointer.
1660118 | ;
1660119 |L2: ; Restore from process stack:
1660120 | ;
1660121 | pop ax
1660122 | pop cx
1660123 | pop dx
1660124 | pop bx
1660125 | pop bp
1660126 | pop si
1660127 | pop di
1660128 | pop ds
1660129 | pop es
1660130 | ;
1660131 | ; Return from interrupt: will restore CS:IP and FLAGS
1660132 | ; from process stack.
1660133 | ;
1660134 | iret
1660135 |;-----------------------------------------------------------------------
1660136 |; Syscall.
1660137 |;-----------------------------------------------------------------------
1660138 |.align 2
1660139 |isr_80:
1660140 | ;-------------------------------------------------------------------
1660141 | ; Inside the process stack, we already have:
1660142 | ; push #message_size
1660143 | ; push &message_structure ; the relative address of it
1660144 | ; push #syscall_number
1660145 | ; push #back_address ; made by a call to _sys function
1660146 | ; push flags ; made by int #0x80
1660147 | ; push cs ; made by int #0x80
1660148 | ; push ip ; made by int #0x80
1660149 | ;-------------------------------------------------------------------
1660150 | ;
1660151 | ; Save into process stack:
1660152 | ;
1660153 | push es ; extra segment
1660154 | push ds ; data segment
1660155 | push di ; destination index
1660156 | push si ; source index
1660157 | push bp ; base pointer
1660158 | push bx ; BX
1660159 | push dx ; DX
1660160 | push cx ; CX
1660161 | push ax ; AX
1660162 | ;
1660163 | ; Set the data segments to the kernel data area,
1660164 | ; so that the following variables can be accessed.
1660165 | ;
1660166 | mov ax, #0x0050 ; DS and ES.
1660167 | mov ds, ax ;
1660168 | mov es, ax ;
1660169 | ;
1660170 | ; Save process stack registers into kernel data segment.
1660171 | ;
1660172 | mov proc_ss_1, ss ; Save process stack segment.
1660173 | mov proc_sp_1, sp ; Save process stack pointer.
1660174 | ;
1660175 | ; Save some more data, from the system call.
1660176 | ;
1660177 | mov bp, sp
1660178 | mov ax, +26[bp]
1660179 | mov proc_syscallnr, ax
1660180 | mov ax, +28[bp]
1660181 | mov proc_msg_offset, ax
1660182 | mov ax, +30[bp]
1660183 | mov proc_msg_size, ax
1660184 | ;
1660185 | ; Check if it is already the kernel stack.
1660186 | ;
1660187 | mov dx, ss
1660188 | mov ax, #0x0050 ; Kernel data area.
1660189 | cmp dx, ax
1660190 | jne L3
1660191 | ;
1660192 | ; It is already the kernel stack, so, the variable "_ksp" is
1660193 | ; aligned to current stack pointer. This way, the first syscall
1660194 | ; can work without having to set the "_ksp" variable to some
1660195 | ; reasonable value.
1660196 | ;
1660197 | mov __ksp, sp
1660198 | ;
1660199 |L3: ; Switch to the kernel stack.
1660200 | ;
1660201 | mov ax, #0x0050 ; Kernel data area.
1660202 | mov ss, ax
1660203 | mov sp, __ksp
1660204 | ;
1660205 | ; Call the external hardware interrupt handler.
1660206 | ;
1660207 | push proc_msg_size
1660208 | push proc_msg_offset
1660209 | push proc_syscallnr
1660210 | push #proc_ss_1 ; &proc_ss_1
1660211 | push #proc_sp_1 ; &proc_sp_1
1660212 | call _sysroutine
1660213 | add sp, #2
1660214 | add sp, #2
1660215 | add sp, #2
1660216 | add sp, #2
1660217 | add sp, #2
1660218 | ;
1660219 | ; Restore process stack registers from kernel data segment.
1660220 | ;
1660221 | mov ss, proc_ss_1 ; Restore process stack segment.
1660222 | mov sp, proc_sp_1 ; Restore process stack pointer.
1660223 | ;
1660224 | ; Restore from process stack:
1660225 | ;
1660226 | pop ax
1660227 | pop cx
1660228 | pop dx
1660229 | pop bx
1660230 | pop bp
1660231 | pop si
1660232 | pop di
1660233 | pop ds
1660234 | pop es
1660235 | ;
1660236 | ; Return from interrupt: will restore CS:IP and FLAGS
1660237 | ; from process stack.
1660238 | ;
1660239 | iret
104.9.2 kernel/proc/_ivt_load.s
Si veda la sezione 103.8.2.
1670001 |.extern isr_1C
1670002 |.extern isr_80
1670003 |.global __ivt_load
1670004 |;-----------------------------------------------------------------------
1670005 |.text
1670006 |;-----------------------------------------------------------------------
1670007 |; Load IVT.
1670008 |;
1670009 |; Currently, only the timer function and the syscall are loaded.
1670010 |;-----------------------------------------------------------------------
1670011 |.align 2
1670012 |__ivt_load:
1670013 | enter #0, #0 ; No local variables.
1670014 | pushf
1670015 | cli
1670016 | pusha
1670017 | ;
1670018 | mov ax, #0 ; Change the DS segment to 0.
1670019 | mov ds, ax ;
1670020 | ;
1670021 | mov bx, #112 ; Timer INT 0x08 (8) --> 0x1C
1670022 | mov [bx], #isr_1C ; offset
1670023 | mov bx, #114 ;
1670024 | mov [bx], cs ; segment
1670025 | ;
1670026 | mov bx, #512 ; Syscall INT 0x80 (128)
1670027 | mov [bx], #isr_80 ; offset
1670028 | mov bx, #514 ;
1670029 | mov [bx], cs ; segment
1670030 | ;
1670031 | mov ax, #0x0050 ; Put the DS segment back to the right
1670032 | mov ds, ax ; value.
1670033 | ;
1670034 | ;
1670035 | ;
1670036 | popa
1670037 | popf
1670038 | leave
1670039 | ret
104.9.3 kernel/proc/proc_available.c
Si veda la sezione 103.8.3.
1680001 |#include
1680002 |//----------------------------------------------------------------------
1680003 |void
1680004 |proc_available (pid_t pid)
1680005 |{
1680006 | proc_table[pid].ppid = -1;
1680007 | proc_table[pid].pgrp = -1;
1680008 | proc_table[pid].uid = -1;
1680009 | proc_table[pid].euid = -1;
1680010 | proc_table[pid].suid = -1;
1680011 | proc_table[pid].sig_status = 0;
1680012 | proc_table[pid].sig_ignore = 0;
1680013 | proc_table[pid].usage = 0;
1680014 | proc_table[pid].status = PROC_EMPTY;
1680015 | proc_table[pid].wakeup_events = 0;
1680016 | proc_table[pid].wakeup_signal = 0;
1680017 | proc_table[pid].wakeup_timer = 0;
1680018 | proc_table[pid].segment_i = -1;
1680019 | proc_table[pid].address_i = -1L;
1680020 | proc_table[pid].size_i = -1;
1680021 | proc_table[pid].segment_d = -1;
1680022 | proc_table[pid].address_d = -1L;
1680023 | proc_table[pid].size_d = -1;
1680024 | proc_table[pid].sp = 0;
1680025 | proc_table[pid].ret = 0;
1680026 | proc_table[pid].inode_cwd = 0;
1680027 | proc_table[pid].path_cwd[0] = 0;
1680028 | proc_table[pid].umask = 0;
1680029 | proc_table[pid].name[0] = 0;
1680030 |}
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