V2EX = way to explore
V2EX 是一个关于分享和探索的地方
Sign Up Now
For Existing Member  Sign In
wjz

Linux0.11 内核中 kernel/traps.c 的疑问

  •  
  •   wjz · Feb 5, 2018 · 2646 views
    This topic created in 3007 days ago, the information mentioned may be changed or developed.
    kernel/traps.c 中 trap_init()函数的反汇编如下:
    00007361 <trap_init>:
    7361: 8b 0d 00 60 00 00 mov 0x6000,%ecx
    7367: b8 00 00 08 00 mov $0x80000,%eax
    736c: ba e7 72 00 00 mov $0x72e7,%edx
    7371: 66 89 d0 mov %dx,%ax
    7374: 66 ba 00 8f mov $0x8f00,%dx
    7378: 89 01 mov %eax,(%ecx)
    737a: 89 51 04 mov %edx,0x4(%ecx)

    这段汇编代码是"set_trap_gate(0, &divide_error);"的反汇编,第一行 mov 0x6000, %ecx 会将 ds:[0x6000]处的数据放入 ecx 寄存器中,导致第六行和第七行无法将中断描述符放入中断描述符表里(我的中断描述符表从地址 0x6000 开始)。我想第一行应该是 mov $0x6000, %ecx 才对,应该将立即数 0x6000 放入 ecx,然而实际情况却是如上图所示。set_tarp_gate(), _set_gate()完全参考 linux0.11 内核,如下:

    #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_table[n], 14, 0, addr) // idt_table from head.s

    #define set_trap_gate(n, addr) \
    _set_gate(&idt_table[n], 15, 0, addr) // idt_table from head.s

    环境: Ubuntu16.04, gcc-5.4.0
    No Comments Yet
    About   ·   Help   ·   Advertise   ·   Blog   ·   API   ·   FAQ   ·   Solana   ·   1449 Online   Highest 6679   ·     Select Language
    创意工作者们的社区
    World is powered by solitude
    VERSION: 3.9.8.5 · 31ms · UTC 16:44 · PVG 00:44 · LAX 09:44 · JFK 12:44
    ♥ Do have faith in what you're doing.