[理工] [計系]-師大100-資工

看板Grad-ProbAsk作者love5566188 (I'dont kown)時間12年前 (2012/02/06 21:08)推噓3(3推 0噓 12→)

留言15則, 3人參與討論串1/1

第四題我想要觀念釐清 4.The processing times needed for the five stages in a pipelined datapath are 400ps, 150ps, 200ps, 350ps,and 150ps,respectively.A register with 50ps access time is needed between consecutive stages. (a) What is the fastest clock frequency this datapath can operate? (b) What is the maximum speed-up when compared to the single cycle implementation of the datapath? 請問(a)小題是要直接算整個IF,ID,EX,MEM,WB的clock frequency為1450ps,還是要比較 lw,R-type,branch指令誰執行最少的clock? (b)小題的single cycle是取決於最大指令clock cycle 還是說取決於最大執行stage 400ps然後再乘以五(個stages)? 第11題我就真的不太會了 11.Buffer overflow is one of the most common attack to operating systems. Please explain how a hacker can use the code below to gain a system shell and enter the system. #include <stdio.h> #define BUFFER_SIZE 256 int main(int argc, char *argv[]) { char buffer[BUFFER_SIZE]; if (argc < 2) return -1; else { strcpy(buffer,argv[1]); return 0; } } 他給的圖: bottom ＿＿＿＿＿＿＿＿＿＿＿＿＿ frame pointer ∣ ∣ return address ∣ ←————— ∣ ∣————————————∣ ∣ ∣ saved frame pointer ∣ ∣ ∣————————————∣ ∣ ∣ ∣ ∣ ∣————————————∣ ∣ ∣automatic variables ∣ ∣ ∣————————————∣ ↓ ∣ parameters ∣ top ∣＿＿＿＿＿＿＿＿＿＿＿＿∣ 請高手幫幫忙 -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 175.98.50.200

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pikachu123

02/06 22:13, , 1^F

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