内核system.h

最新推荐文章于 2024-08-17 15:52:24 发布

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本文详细介绍了使用汇编语言实现系统调用的方法，包括切换到不同模式、设置中断门和陷阱门等关键操作。通过具体的宏定义展示了如何利用汇编指令进行系统级别的编程。

#define move_to_user_mode() / __asm__ ("movl %%esp,%%eax/n/t" / "pushl $0x17/n/t" / "pushl %%eax/n/t" / "pushfl/n/t" / "pushl $0x0f/n/t" / "pushl $1f/n/t" / "iret/n" / "1:/tmovl $0x17,%%eax/n/t" / "movw %%ax,%%ds/n/t" / "movw %%ax,%%es/n/t" / "movw %%ax,%%fs/n/t" / "movw %%ax,%%gs" / :::"ax") #define printt()/ __asm__ ("pushl %%eax/n/t" / "pushl %%edi/n/t" / "pushl $1f/n/t"/ "iret/n"/ "1:/tmovl $0xb8dd8,%%eax/n/t" / "movl %%eax,%%edi/n/t" / "movl $0x234,%%eax/n/t" / "movl %%eax,(%%edi)/n/t" / "popl %%edi/n/t"/ "popl %%eax/n/t"/ :::"ax" ) #define move_to_cs_mode() / __asm__ ("pushl %%edx/n/t" / "push %%ds/n/t" / "push %%es/n/t" / "push %%gs/n/t" / "push %%fs/n/t" / "pushl $1f/n/t" / "iret/n"/ "1:/tmovl $0x10,%%edx/n/t" / "mov %%dx,%%ds/n/t" / "mov %%dx,%%es/n/t" / "mov %%dx,%%gs/n/t" / "mov %%dx,%%fs/n/t" / :::"ax") #define move_to_rep_mode() / __asm__ ("pop %%fs/n/t" / "pop %%gs/n/t"/ "pop %%es/n/t"/ "pop %%ds/n/t"/ "popl %%edx/n/t" / :::"ax") #define sti() __asm__ ("sti"::) #define cli() __asm__ ("cli"::) #define nop() __asm__ ("nop"::) #define iret() __asm__ ("iret"::) #define _set_gate(gate_addr,type,dpl,addr) / __asm__ ("movw %%dx,%%ax/n/t" / "movw %0,%%dx/n/t" / "movl %%eax,%1/n/t" / "movl %%edx,%2" / : / : "i" ((short) (0x8000+(dpl<<13)+(type<<8))), / "o" (*((char *) (gate_addr))), / "o" (*(4+(char *) (gate_addr))), / "d" ((char *) (addr)),"a" (0x00080000)) #define set_intr_gate(n,addr) / _set_gate(&idt[n],14,0,addr) #define set_trap_gate(n,addr) / _set_gate(&idt[n],15,0,addr) #define set_system_gate(n,addr) / _set_gate(&idt[n],15,3,addr) #define _set_seg_desc(gate_addr,type,dpl,base,limit) {/ *(gate_addr) = ((base) & 0xff000000) | / (((base) & 0x00ff0000)>>16) | / ((limit) & 0xf0000) | / ((dpl)<<13) | / (0x00408000) | / ((type)<<8); / *((gate_addr)+1) = (((base) & 0x0000ffff)<<16) | / ((limit) & 0x0ffff); } #define _set_tssldt_desc(n,addr,type) / __asm__ ("movw $104,%1/n/t" / "movw %%ax,%2/n/t" / "rorl $16,%%eax/n/t" / "movb %%al,%3/n/t" / "movb $" type ",%4/n/t" / "movb $0x00,%5/n/t" / "movb %%ah,%6/n/t" / "rorl $16,%%eax" / ::"a" (addr), "m" (*(n)), "m" (*(n+2)), "m" (*(n+4)), / "m" (*(n+5)), "m" (*(n+6)), "m" (*(n+7)) / ) #define set_tss_desc(n,addr) _set_tssldt_desc(((char *) (n)),addr,"0x89") #define set_ldt_desc(n,addr) _set_tssldt_desc(((char *) (n)),addr,"0x82")