protect.c 详细解释

/*++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
protect.c
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Forrest Yu, 2005
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++*/

#include "type.h"
#include "const.h"
#include "protect.h"
#include "proto.h"
#include "proc.h"
#include "global.h"

/* 本文件内函数声明 */
PRIVATE void init_idt_desc(unsigned char vector, u8 desc_type, int_handler handler, unsigned char privilege);
PRIVATE void init_descriptor(DESCRIPTOR * p_desc, u32 base, u32 limit, u16 attribute);

/* 中断处理函数 */
void divide_error();
void single_step_exception();
void nmi();
void breakpoint_exception();
void overflow();
void bounds_check();
void inval_opcode();
void copr_not_available();
void double_fault();
void copr_seg_overrun();
void inval_tss();
void segment_not_present();
void stack_exception();
void general_protection();
void page_fault();
void copr_error();
void hwint00();
void hwint01();
void hwint02();
void hwint03();
void hwint04();
void hwint05();
void hwint06();
void hwint07();
void hwint08();
void hwint09();
void hwint10();
void hwint11();
void hwint12();
void hwint13();
void hwint14();
void hwint15();

/*======================================================================*
init_prot
*----------------------------------------------------------------------*
初始化 IDT
*======================================================================*/
PUBLIC void init_prot()
{
init_8259A();

// 全部初始化成中断门(没有陷阱门)
init_idt_desc(INT_VECTOR_DIVIDE, DA_386IGate, divide_error,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_DEBUG,  DA_386IGate, single_step_exception, PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_NMI,  DA_386IGate, nmi,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_BREAKPOINT, DA_386IGate, breakpoint_exception, PRIVILEGE_USER);
init_idt_desc(INT_VECTOR_OVERFLOW, DA_386IGate, overflow,   PRIVILEGE_USER);
init_idt_desc(INT_VECTOR_BOUNDS, DA_386IGate, bounds_check,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_INVAL_OP, DA_386IGate, inval_opcode,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_COPROC_NOT, DA_386IGate, copr_not_available, PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_DOUBLE_FAULT, DA_386IGate, double_fault,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_COPROC_SEG, DA_386IGate, copr_seg_overrun,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_INVAL_TSS, DA_386IGate, inval_tss,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_SEG_NOT, DA_386IGate, segment_not_present, PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_STACK_FAULT, DA_386IGate, stack_exception,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_PROTECTION, DA_386IGate, general_protection, PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_PAGE_FAULT, DA_386IGate, page_fault,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_COPROC_ERR, DA_386IGate, copr_error,  PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 0, DA_386IGate, hwint00,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 1, DA_386IGate, hwint01,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 2, DA_386IGate, hwint02,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 3, DA_386IGate, hwint03,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 4, DA_386IGate, hwint04,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 5, DA_386IGate, hwint05,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 6, DA_386IGate, hwint06,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ0 + 7, DA_386IGate, hwint07,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 0, DA_386IGate, hwint08,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 1, DA_386IGate, hwint09,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 2, DA_386IGate, hwint10,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 3, DA_386IGate, hwint11,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 4, DA_386IGate, hwint12,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 5, DA_386IGate, hwint13,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 6, DA_386IGate, hwint14,   PRIVILEGE_KRNL);
init_idt_desc(INT_VECTOR_IRQ8 + 7, DA_386IGate, hwint15,   PRIVILEGE_KRNL);

/* 填充 GDT 中 TSS 这个描述符 */
memset(&tss, 0, sizeof(tss));
tss.ss0  = SELECTOR_KERNEL_DS;
init_descriptor(&gdt[INDEX_TSS],
   vir2phys(seg2phys(SELECTOR_KERNEL_DS), &tss),
   sizeof(tss) - 1,
   DA_386TSS);
tss.iobase = sizeof(tss); /* 没有I/O许可位图 */

// 填充 GDT 中进程的 LDT 的描述符
init_descriptor(&gdt[INDEX_LDT_FIRST],
   vir2phys(seg2phys(SELECTOR_KERNEL_DS), proc_table[0].ldts),
   LDT_SIZE * sizeof(DESCRIPTOR) - 1,
   DA_LDT);

}

/*======================================================================*
                             init_idt_desc
*----------------------------------------------------------------------*
初始化 386 中断门
*======================================================================*/
PUBLIC void init_idt_desc(unsigned char vector, u8 desc_type, int_handler handler, unsigned char privilege)
{
GATE * p_gate = &idt[vector];
u32 base = (u32)handler;
p_gate->offset_low = base & 0xFFFF;
p_gate->selector = SELECTOR_KERNEL_CS;
p_gate->dcount  = 0;
p_gate->attr  = desc_type | (privilege << 5);
p_gate->offset_high = (base >> 16) & 0xFFFF;
}

/*======================================================================*
seg2phys
*----------------------------------------------------------------------*
由段名求绝对地址
*======================================================================*/
PUBLIC u32 seg2phys(u16 seg)
{
DESCRIPTOR* p_dest = &gdt[seg >> 3];

return (p_dest->base_high << 24) | (p_dest->base_mid << 16) | (p_dest->base_low);
}

/*======================================================================*
                           init_descriptor
*----------------------------------------------------------------------*
初始化段描述符
*======================================================================*/
PRIVATE void init_descriptor(DESCRIPTOR * p_desc, u32 base, u32 limit, u16 attribute)
{
p_desc->limit_low  = limit & 0x0FFFF;  // 段界限 1  (2 字节)
p_desc->base_low  = base & 0x0FFFF;  // 段基址 1  (2 字节)
p_desc->base_mid  = (base >> 16) & 0x0FF;  // 段基址 2  (1 字节)
p_desc->attr1   = attribute & 0xFF;  // 属性 1
p_desc->limit_high_attr2 = ((limit >> 16) & 0x0F) |
      (attribute >> 8) & 0xF0;// 段界限 2 + 属性 2
p_desc->base_high  = (base >> 24) & 0x0FF;  // 段基址 3  (1 字节)
}

/*======================================================================*
                            exception_handler
*----------------------------------------------------------------------*
异常处理
*======================================================================*/
PUBLIC void exception_handler(int vec_no, int err_code, int eip, int cs, int eflags)
{
int i;
int text_color = 0x74; /* 灰底红字 */
char err_description[][64] = { "#DE Divide Error",
     "#DB RESERVED",
     "— NMI Interrupt",
     "#BP Breakpoint",
     "#OF Overflow",
     "#BR BOUND Range Exceeded",
     "#UD Invalid Opcode (Undefined Opcode)",
     "#NM Device Not Available (No Math Coprocessor)",
     "#DF Double Fault",
     "    Coprocessor Segment Overrun (reserved)",
     "#TS Invalid TSS",
     "#NP Segment Not Present",
     "#SS Stack-Segment Fault",
     "#GP General Protection",
     "#PF Page Fault",
     "— (Intel reserved. Do not use.)",
     "#MF x87 FPU Floating-Point Error (Math Fault)",
     "#AC Alignment Check",
     "#MC Machine Check",
     "#XF SIMD Floating-Point Exception"
    };

/* 通过打印空格的方式清空屏幕的前五行，并把 disp_pos 清零 */
disp_pos = 0;
for(i=0;i<80*5;i++){
disp_str(" ");
}
disp_pos = 0;

disp_color_str("Exception! --> ", text_color);
disp_color_str(err_description[vec_no], text_color);
disp_color_str("\n\n", text_color);
disp_color_str("EFLAGS:", text_color);
disp_int(eflags);
disp_color_str("CS:", text_color);
disp_int(cs);
disp_color_str("EIP:", text_color);
disp_int(eip);

if(err_code != 0xFFFFFFFF){
disp_color_str("Error code:", text_color);
disp_int(err_code);
}
}

posted on 2011-05-17 10:55 wanghj_dz 阅读(936) 评论(0) 编辑收藏举报

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protect.c 详细解释

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