BYR Achieve · 镜像论坛

【求助】小小跳转跳出了神（汇编简单问题）

2008/8/14镜像同步4 回复

又碰上一个低级问题：就是一个简单的长跳转，跳转后，eip却不是变成正常的0x7d61，却到了别处，程序也因此崩溃，不知道为啥？（实模式，x86） bochs的调试信息： (0) Breakpoint 1, 0x00000000000032a4 in ?? () Next at t=32586615 (0) [0x000032a4] 0000:32a4 (unk. ctxt): jmp word ptr es:[eax] ; 2667ff20------------------这是下一条要执行的指令，跳转到es:eax之处 <bochs:3> sreg cs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1 ds:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=3 ss:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=7 es:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1------------es为0x0 fs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1 gs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1 ldtr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0 tr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0 gdtr:base=0x00070000, limit=0xfffe idtr:base=0x00000000, limit=0x3ff <bochs:4> r rax: 0x00000000:00007d61 rcx: 0x00000000:00009000---------ax为0x7d61：目的地址 rdx: 0x00000000:00003404 rbx: 0x00000000:00000000 rsp: 0x00000000:0000ffda rbp: 0x00000000:00000000 rsi: 0x00000000:ffff0000 rdi: 0x00000000:0008ffac r8 : 0x00000000:00000000 r9 : 0x00000000:00000000 r10: 0x00000000:00000000 r11: 0x00000000:00000000 r12: 0x00000000:00000000 r13: 0x00000000:00000000 r14: 0x00000000:00000000 r15: 0x00000000:00000000 rip: 0x00000000:000032a4 eflags 0x00000002 id vip vif ac vm rf nt IOPL=0 of df if tf sf zf af pf cf <bochs:5> s---------------------------------------------------执行了这一句之后 Next at t=32586616 (0) [0x000092e4] 0000:92e4 (unk. ctxt): add byte ptr ds:[bx+si], al ; 0000 <bochs:6> r rax: 0x00000000:00007d61 rcx: 0x00000000:00009000 rdx: 0x00000000:00003404 rbx: 0x00000000:00000000 rsp: 0x00000000:0000ffda rbp: 0x00000000:00000000 rsi: 0x00000000:ffff0000 rdi: 0x00000000:0008ffac r8 : 0x00000000:00000000 r9 : 0x00000000:00000000 r10: 0x00000000:00000000 r11: 0x00000000:00000000 r12: 0x00000000:00000000 r13: 0x00000000:00000000 r14: 0x00000000:00000000 r15: 0x00000000:00000000 rip: 0x00000000:000092e4-------------------------------------eip变成了这个数，不是0x7d61，我猜测发生了中断 eflags 0x00000002 id vip vif ac vm rf nt IOPL=0 of df if tf sf zf af pf cf <bochs:7> sreg cs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1-----------cs倒是变成了0 ds:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=3 ss:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=7 es:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=3 fs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1 gs:s=0x0000, dl=0x0000ffff, dh=0x00009300, valid=1 ldtr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0 tr:s=0x0000, dl=0x00000000, dh=0x00000000, valid=0 gdtr:base=0x00070000, limit=0xfffe idtr:base=0x00000000, limit=0x3ff 不知道为什么，请大家帮助[em18]

订阅后，新回复会通过你的通知中心匿名送达。