这里主要说说异常(cpu查出来的) 中断(狭义的指硬盘 键盘...)
1.异常的发生
2.异常的处理过程
3.异常的设置
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1.异常发生
异常通常是cpu侦测出来的
还有疑问,用户可不可以用就不知?int n 可以么?
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2.异常的处理 //先看异常的设置最下边
//set_intr_gate(n,addr) 在8295a设置对应的中断向量号 0x20-0x2f
//set_trap_gate(n,addr)
//set_system_gate(n,addr)
//lin/kernel/asm.s 分成有错误码和无错误码 两种,linux中做了统一对于没有错误码的也压入一个0x0000
/* * 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 no_error_code: xchgl %eax,(%esp) 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: pushl $_do_int3 # _do_debug jmp no_error_code _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: 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
//lin/kernel/trap.c 这里主要是异常 ,硬中断是硬件也分布在各个文件中
/* * 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):"" (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):"" (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); static void die(char * str,long esp_ptr,long nr) { long * esp = (long *) esp_ptr; int i; printk("%s: %04x ",str,nr&0xffff); printk("EIP: %04x:%p EFLAGS: %p ESP: %04x:%p ", esp[1],esp[0],esp[2],esp[4],esp[3]); printk("fs: %04x ",_fs()); printk("base: %p, limit: %p ",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(" "); } str(i); printk("Pid: %d, process nr: %d ",current->pid,0xffff & i); for(i=0;i<10;i++) printk("%02x ",0xff & get_seg_byte(esp[1],(i+(char *)esp[0]))); printk(" "); do_exit(11); /* 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); } 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)); printk("eax ebx ecx edx %8x %8x %8x %8x ", eax,ebx,ecx,edx); printk("esi edi ebp esp %8x %8x %8x %8x ", esi,edi,ebp,(long) esp); printk(" ds es fs tr %4x %4x %4x %4x ", ds,es,fs,tr); printk("EIP: %8x CS: %4x EFLAGS: %8x ",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); } void trap_init(void) { int i; set_trap_gate(0,÷_error); set_trap_gate(1,&debug); 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); }
2.异常的处理
当cpu侦测到异常后,会发出对应的中断号 ,这里已经设置好了
找到对应的处理过程处理异常
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3.异常的设置
//这里可以看到每个异常对应一个编号,这个是intel,建议使用的或者说指定的
//再看第2处异常的处理 这里以overflow()为例来说
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在traps.c中有 2个很像
void overflow(void);
//这个声明实际 实现在asm.s中因为是汇编所以以_overflow:实现,其实还是调用了了do_overflow()函数
_overflow:
pushl $_do_overflow //_overflow:函数在这里 ,压入的是_do_overflow
jmp no_error_code //通用过程的提炼部分
void do_overflow(long esp, long error_code)
{die("overflow",esp,error_code);} //overflow这个异常的实际处理过程因为最底层需要参数,所以交上层overfow()处理
overflow()函数实现在上边已经有说明
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181 void trap_init(void) 182 { 183 int i; 184 185 set_trap_gate(0,÷_error); 186 set_trap_gate(1,&debug); 187 set_trap_gate(2,&nmi); 188 set_system_gate(3,&int3); /* int3-5 can be called from all */ 189 set_system_gate(4,&overflow); 190 set_system_gate(5,&bounds); 191 set_trap_gate(6,&invalid_op); 192 set_trap_gate(7,&device_not_available); 193 set_trap_gate(8,&double_fault); 194 set_trap_gate(9,&coprocessor_segment_overrun); 195 set_trap_gate(10,&invalid_TSS); 196 set_trap_gate(11,&segment_not_present); 197 set_trap_gate(12,&stack_segment); 198 set_trap_gate(13,&general_protection); 199 set_trap_gate(14,&page_fault); 200 set_trap_gate(15,&reserved); 201 set_trap_gate(16,&coprocessor_error); 202 for (i=17;i<48;i++) 203 set_trap_gate(i,&reserved); 204 set_trap_gate(45,&irq13); 205 outb_p(inb_p(0x21)&0xfb,0x21); 206 outb(inb_p(0xA1)&0xdf,0xA1); 207 set_trap_gate(39,¶llel_interrupt); 208 }
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