Linux 核心中斷體系結構 (1)
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目錄0. 目的:
1.硬體的中斷響應 ---> 核心驅動中的中斷
2.系統呼叫的函式響應(sys call) --->系統呼叫
3.自定義中斷 --->軟體的軟中斷模式
4.訊號中斷 (kill -signalnum)
5.系統的異常和錯誤 ---> 系統異常處理獲取 瞭解系統異常的作用
1. Linux的中斷機制
1.1 分類:
硬體中斷 軟體中斷
硬中斷:由電腦主機的8259A類似的硬體中斷控制晶片發出的中斷
AR中斷控制器發出的中斷
軟中斷:異常第一類:CPU自行保留的中斷
系統呼叫異常
1.2 程式碼結構:
asm.s -> trap.c
system_call.s -> fork.c signal.c exit.c sys.c
2. 中斷的工作流程:
2.1: 回憶
- 做CPU工作模式的轉化
- 進行暫存器的拷貝與壓棧
- 設定中斷異常向量表
- 儲存正常執行的函式返回值
- 跳轉到對應的中斷服務函式上執行
- 進行模式的復原以及暫存器的復原
- 跳轉回正常工作的函式地址繼續執行
2.2 Linux 中中斷的工作流程
-
將所有暫存器的值入棧(切換CPU模式)
SS EFLAGS ESP CS EIP -
將異常碼入棧(中斷號:哪個裝置產生的中斷,如果發生錯誤能找到誰發出的中斷處理)
他這裡異常碼是中斷號,中斷處理過程中的c程式碼要靠這個號找到中斷處理函式 -
將當前的函式返回值進行入棧(為了在中斷執行後能夠找到在哪裡中斷,能夠復原)
-
調出 對應的中斷服務函式
-
暫存器復原
如圖所示:
中斷前的處理過程,中斷的回覆過程 中斷的執行過程
硬體中斷的處理過程 asm.s trap.c
軟體及系統呼叫的處理過程 system call.s fork.csignal .cexit.c sys.c
3. 中斷的程式碼實現過程
中斷前的處理過程,中斷的回覆過程 中斷的執行過程
硬體中斷的處理過程 asm.s trap.c
EIP暫存器,用來儲存CPU要讀取指令的地址,CPU通過EIP暫存器讀取即將要執行的指令。每次CPU執行完相應的彙編指令之後,EIP暫存器的值就會增加。
老師說的其實不準確,實際上是eax和(esp指向的記憶體)兩個東西交換了,esp存的是記憶體地址,而加括號就是取這個地址對應的記憶體值,並不是操作的esp
CS(code segment)程式碼段地址暫存器,存放程式碼段的起始地址
DS(data segment)資料段地址暫存器,存放資料段的起始地址
SS(stack segment)堆疊段地址暫存器,存放堆疊段的起始地址(每個程序都有自己的棧空間)
ES(extra segment)附加段地址暫存器,存放附加段的起始地址
/*
* linux/kernel/asm.s
*
* (C) 1991 Linus Torvalds
*/
/*
* asm.s contains the low-level code for most hardware faults.
* page_exception is handled by the mm, so that isn't here. This
* file also handles (hopefully) fpu-exceptions due to TS-bit, as
* the fpu must be properly saved/resored. This hasn't been tested.
*/
.globl _divide_error,_debug,_nmi,_int3,_overflow,_bounds,_invalid_op
.globl _double_fault,_coprocessor_segment_overrun
.globl _invalid_TSS,_segment_not_present,_stack_segment
.globl _general_protection,_coprocessor_error,_irq13,_reserved
_divide_error:
pushl $_do_divide_error//把一個c語言函式入棧
no_error_code://無錯誤碼中斷
xchgl %eax,(%esp) // 此時%esp指向的地址裡面的值是$_do_divide_error 的函式地址
pushl %ebx
pushl %ecx
pushl %edx
pushl %edi
pushl %esi
pushl %ebp
push %ds
push %es
push %fs
pushl $0 # "error code"
lea 44(%esp),%edx
pushl %edx
movl $0x10,%edx
mov %dx,%ds
mov %dx,%es
mov %dx,%fs
call *%eax
addl $8,%esp
pop %fs
pop %es
pop %ds
popl %ebp
popl %esi
popl %edi
popl %edx
popl %ecx
popl %ebx
popl %eax
iret
_debug://這是一箇中斷
pushl $_do_int3 # _do_debug
jmp no_error_code//跳轉
_nmi:
pushl $_do_nmi
jmp no_error_code
_int3:
pushl $_do_int3
jmp no_error_code
_overflow:
pushl $_do_overflow
jmp no_error_code
_bounds:
pushl $_do_bounds
jmp no_error_code
_invalid_op:
pushl $_do_invalid_op
jmp no_error_code
_coprocessor_segment_overrun:
pushl $_do_coprocessor_segment_overrun
jmp no_error_code
_reserved:
pushl $_do_reserved
jmp no_error_code
_irq13:
pushl %eax
xorb %al,%al
outb %al,$0xF0
movb $0x20,%al
outb %al,$0x20
jmp 1f
1: jmp 1f
1: outb %al,$0xA0
popl %eax
jmp _coprocessor_error
_double_fault:
pushl $_do_double_fault
error_code://有中斷碼中斷
xchgl %eax,4(%esp) # error code <-> %eax
xchgl %ebx,(%esp) # &function <-> %ebx
pushl %ecx
pushl %edx
pushl %edi
pushl %esi
pushl %ebp
push %ds
push %es
push %fs
pushl %eax # error code
lea 44(%esp),%eax # offset
pushl %eax
movl $0x10,%eax
mov %ax,%ds
mov %ax,%es
mov %ax,%fs
call *%ebx
addl $8,%esp
pop %fs
pop %es
pop %ds
popl %ebp
popl %esi
popl %edi
popl %edx
popl %ecx
popl %ebx
popl %eax
iret
_invalid_TSS:
pushl $_do_invalid_TSS
jmp error_code
_segment_not_present:
pushl $_do_segment_not_present
jmp error_code
_stack_segment:
pushl $_do_stack_segment
jmp error_code
_general_protection:
pushl $_do_general_protection
jmp error_code
trap.c
/*
* linux/kernel/traps.c
*
* (C) 1991 Linus Torvalds
*/
/*
* 'Traps.c' handles hardware traps and faults after we have saved some
* state in 'asm.s'. Currently mostly a debugging-aid, will be extended
* to mainly kill the offending process (probably by giving it a signal,
* but possibly by killing it outright if necessary).
*/
#include <string.h>
#include <linux/head.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/io.h>
#define get_seg_byte(seg,addr) ({ \
register char __res; \
__asm__("push %%fs;mov %%ax,%%fs;movb %%fs:%2,%%al;pop %%fs" \
:"=a" (__res):"0" (seg),"m" (*(addr))); \
__res;})
#define get_seg_long(seg,addr) ({ \
register unsigned long __res; \
__asm__("push %%fs;mov %%ax,%%fs;movl %%fs:%2,%%eax;pop %%fs" \
:"=a" (__res):"0" (seg),"m" (*(addr))); \
__res;})
#define _fs() ({ \
register unsigned short __res; \
__asm__("mov %%fs,%%ax":"=a" (__res):); \
__res;})
int do_exit(long code);
void page_exception(void);
void divide_error(void);
void debug(void);
void nmi(void);
void int3(void);
void overflow(void);
void bounds(void);
void invalid_op(void);
void device_not_available(void);
void double_fault(void);
void coprocessor_segment_overrun(void);
void invalid_TSS(void);
void segment_not_present(void);
void stack_segment(void);
void general_protection(void);
void page_fault(void);
void coprocessor_error(void);
void reserved(void);
void parallel_interrupt(void);
void irq13(void);
//esp_ptr 段指標
//nr 出錯的段號
//總的來說die函式就是用來列印錯誤資訊
static void die(char * str,long esp_ptr,long nr)
{
long * esp = (long *) esp_ptr;
int i;
//以下基本在列印棧資訊
printk("%s: %04x\n\r",str,nr&0xffff);
printk("EIP:\t%04x:%p\nEFLAGS:\t%p\nESP:\t%04x:%p\n",
esp[1],esp[0],esp[2],esp[4],esp[3]);
printk("fs: %04x\n",_fs());
printk("base: %p, limit: %p\n",get_base(current->ldt[1]),get_limit(0x17));
if (esp[4] == 0x17) {
printk("Stack: ");
for (i=0;i<4;i++)
printk("%p ",get_seg_long(0x17,i+(long *)esp[3]));
printk("\n");
}
str(i);
printk("Pid: %d, process nr: %d\n\r",current->pid,0xffff & i);
for(i=0;i<10;i++)
printk("%02x ",0xff & get_seg_byte(esp[1],(i+(char *)esp[0])));
printk("\n\r");
do_exit(11);//退出中斷 /* play segment exception */
}
void do_double_fault(long esp, long error_code)
{
die("double fault",esp,error_code);
}
void do_general_protection(long esp, long error_code)
{
die("general protection",esp,error_code);
}
//asm.s呼叫的第一個函式在這裡
void do_divide_error(long esp, long error_code)
{
die("divide error",esp,error_code);
}
void do_int3(long * esp, long error_code,
long fs,long es,long ds,
long ebp,long esi,long edi,
long edx,long ecx,long ebx,long eax)
{
int tr;
__asm__("str %%ax":"=a" (tr):"0" (0));
printk("eax\t\tebx\t\tecx\t\tedx\n\r%8x\t%8x\t%8x\t%8x\n\r",
eax,ebx,ecx,edx);
printk("esi\t\tedi\t\tebp\t\tesp\n\r%8x\t%8x\t%8x\t%8x\n\r",
esi,edi,ebp,(long) esp);
printk("\n\rds\tes\tfs\ttr\n\r%4x\t%4x\t%4x\t%4x\n\r",
ds,es,fs,tr);
printk("EIP: %8x CS: %4x EFLAGS: %8x\n\r",esp[0],esp[1],esp[2]);
}
void do_nmi(long esp, long error_code)
{
die("nmi",esp,error_code);
}
void do_debug(long esp, long error_code)
{
die("debug",esp,error_code);
}
void do_overflow(long esp, long error_code)
{
die("overflow",esp,error_code);
}
void do_bounds(long esp, long error_code)
{
die("bounds",esp,error_code);
}
void do_invalid_op(long esp, long error_code)
{
die("invalid operand",esp,error_code);
}
void do_device_not_available(long esp, long error_code)
{
die("device not available",esp,error_code);
}
void do_coprocessor_segment_overrun(long esp, long error_code)
{
die("coprocessor segment overrun",esp,error_code);
}
void do_invalid_TSS(long esp,long error_code)
{
die("invalid TSS",esp,error_code);
}
void do_segment_not_present(long esp,long error_code)
{
die("segment not present",esp,error_code);
}
void do_stack_segment(long esp,long error_code)
{
die("stack segment",esp,error_code);
}
void do_coprocessor_error(long esp, long error_code)
{
if (last_task_used_math != current)
return;
die("coprocessor error",esp,error_code);
}
void do_reserved(long esp, long error_code)
{
die("reserved (15,17-47) error",esp,error_code);
}
//中斷的初始化函式
//set_trap_gate 優先順序較低 只能由使用者程式來呼叫
//set_system_gate 優先順序很高 能由系統和使用者所有的程式呼叫
void trap_init(void)
{
int i;
set_trap_gate(0,÷_error);//如果被除數是0就會產生這個中斷
set_trap_gate(1,&debug);//單步除錯的時候呼叫這個中斷
set_trap_gate(2,&nmi);
set_system_gate(3,&int3); /* int3-5 can be called from all */
set_system_gate(4,&overflow);
set_system_gate(5,&bounds);
set_trap_gate(6,&invalid_op);
set_trap_gate(7,&device_not_available);
set_trap_gate(8,&double_fault);
set_trap_gate(9,&coprocessor_segment_overrun);
set_trap_gate(10,&invalid_TSS);
set_trap_gate(11,&segment_not_present);
set_trap_gate(12,&stack_segment);
set_trap_gate(13,&general_protection);
set_trap_gate(14,&page_fault);
set_trap_gate(15,&reserved);
set_trap_gate(16,&coprocessor_error);
for (i=17;i<48;i++)
set_trap_gate(i,&reserved);
set_trap_gate(45,&irq13);
outb_p(inb_p(0x21)&0xfb,0x21);
outb(inb_p(0xA1)&0xdf,0xA1);
set_trap_gate(39,¶llel_interrupt);
}