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entry.S
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entry.S
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/*
* entry.S - Entry point to system mode from user mode
*/
#include <asm.h>
#include <segment.h>
#include <errno.h>
/**************************************************/
/**** Save & Restore ******************************/
/** **/
/** When we change to privilege level 0 (kernel) **/
/** (through an interrupt, a system call, an **/
/** exception ...) we must save the state of the **/
/** currently running task (save). **/
/** **/
/** Stack layout in 'systemCall': **/
/** **/
/** 0(%esp) - %edx \ **/
/** 4(%esp) - %ecx | **/
/** 8(%esp) - %ebx | **/
/** C(%esp) - %esi | Register saved **/
/** 10(%esp) - %edi | by 'save' **/
/** 14(%esp) - %ebp | **/
/** 18(%esp) - %eax | **/
/** 1C(%esp) - %ds | **/
/** 20(%esp) - %es | **/
/** 24(%esp) - %fs | **/
/** 28(%esp) - %gs / **/
/** 2C(%esp) - %eip \ **/
/** 30(%esp) - %cs | **/
/** 34(%esp) - %eflags | Return context saved **/
/** 38(%esp) - %oldesp | by the processor. **/
/** 3C(%esp) - %oldss / **/
/** **/
/**************************************************/
#define SAVE_ALL \
pushl %gs; \
pushl %fs; \
pushl %es; \
pushl %ds; \
pushl %eax; \
pushl %ebp; \
pushl %edi; \
pushl %esi; \
pushl %ebx; \
pushl %ecx; \
pushl %edx; \
movl $__KERNEL_DS, %edx; \
movl %edx, %ds; \
movl %edx, %es
#define RESTORE_ALL \
popl %edx; \
popl %ecx; \
popl %ebx; \
popl %esi; \
popl %edi; \
popl %ebp; \
popl %eax; \
popl %ds; \
popl %es; \
popl %fs; \
popl %gs
#define EOI \
movb $0x20, %al ; \
outb %al, $0x20 ;
ENTRY(keyboard_handler)
SAVE_ALL
call user_to_system
EOI
call keyboard_routine
call system_to_user
RESTORE_ALL
iret
ENTRY(clock_handler)
SAVE_ALL
call user_to_system
EOI
call clock_routine
call system_to_user
RESTORE_ALL
iret
ENTRY(system_call_handler)
SAVE_ALL
pushl %eax
call user_to_system
popl %eax
cmpl $0, %eax /* posible entrada negativa */
jl error
cmpl $MAX_SYSCALL, %eax /* posible entrada superior a la última */
jge error
call *sys_call_table(, %eax, 0x04)
jmp end
error:
movl $-ENOSYS, %eax
end:
movl %eax, 0x18(%esp)
call system_to_user
RESTORE_ALL
iret
ENTRY(custom_page_fault_handler)
call custom_page_fault_routine
iret
ENTRY(setMSR)
push %ebp
mov %esp, %ebp
mov 0x8(%ebp), %ecx # Paso de primer parametro = numero MSR
movl $0, %edx # Paso de la parte baja del segundo parametro
mov 0xc(%ebp), %eax
wrmsr
pop %ebp
ret
ENTRY(syscall_handler_sysenter)
push $__USER_DS
push %ebp # direccion stack del usuario
pushfl
push $__USER_CS
push 4(%ebp) # direccion de retorno
SAVE_ALL
cmpl $0, %eax
jl sysenter_error
cmpl $MAX_SYSCALL, %eax
jg sysenter_error
call *sys_call_table(, %eax, 0x04)
jmp sysenter_end
sysenter_error:
movl $-ENOSYS, %eax # Si no existe la funcion
sysenter_end:
movl %eax, 0x18(%esp)
RESTORE_ALL
movl (%esp), %edx # direcion de retorno
movl 12(%esp), %ecx # direccion de la stack del usuario
sti
sysexit