I117 II I117 PROGRAMMING PRACTICE II DEBUG Research Center for Advanced Computing Infrastructure (RCACI) / Yasuhiro Ohara

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1 I117 II I117 PROGRAMMING PRACTICE II DEBUG Research Center for Advanced Computing Infrastructure (RCACI) / Yasuhiro Ohara yasu@jaist.ac.jp

2 / SCHEDULE /06/07(Tue) / Basic of Programming /06/09(Thu) / Fundamental data structures /06/14(Tue) / Memory Management /06/16(Thu) / Memory Management /06/21(Tue) / Debugging /06/23(Thu) / Software Development Env /06/28(Tue) / Software Development Env /06/30(Thu) / Data Structure : Tree /07/05(Tue) / Data Structure: Hash /07/07(Thu) / Understanding Programs /07/12(Tue) / Understanding Programs /07/14(Thu) / Script Language /07/19(Tue) / Script Language /07/21(Thu) / Other Languages /07/26(Tue) / Examination

3 / FINAL REPORT free topic : decide topic by 7/5(Tue) report us of the topic by i117report@jaist.ac.jp / Sound file converter / web crawler (CalDAV) calendar program new shell, editor, window manager rsync encrypt/decrypt, rsync markov-chain program choose good theme TAask TA and me The final report must have deep consideration

4 / TODAY'S INDEX / queue, stack / debug / how program runs / memory location, call stack, stack trace / debug method printf / printf debug /debugger / memory checker

5 / QUEUE, STACK

6 FIFOFIRST IN FIRST OUT queue / queue is an array / FIFO enqueue: / insert data dequeue: / extract data / pseudo code enqueue(data) queue q; q.enqueue(1); q.enqueue(2); q.enqueue(3); q.enqueue(4); q.dequeue(); /* 1/ result is 1 */ q.dequeue(); /* 2/ result is 2 */ dequeue()

7 LIFOLAST IN FIRST OUT / stack / LIFO push: / insert data pop: / extract data push(data) / pseudo code pop() stack s; s.push(1); s.push(2); s.push(3); s.push(4); s.pop(); /* 4/ result is 4 */ s.pop(); /* 3/ result is 3 */

8 / HOW PROGRAM RUNS

9 / COMPONENTS OF COMPUTER SYSTEMS CPU / processing unit SPARC, x86, MIPS,POWER,,, / memory CPU / main, cache memory HDD / storage I/O / I/O Devices / HDD, Network I/F, Keyboard, mouse, display I/O / Memory mapped I/O I/O CPU

10 CPU / CPU ACTIONS / control fetch, decode, execute, write back / instructions / arithmetic instruction / shift instruction / jump instruction / compare instruction / I/O instruction / instruction, operand / A book.

11 CPU / CPU ACTIONSCONT / instruction cycles (Fetch) (Decode) (Execute) (Writeback / sequential control FDEW / FDEW for one instruction / one instruction each. F D E W F D E W F D E W

12 CPU / CPU ACTIONS (CONT) / advanced control / pipeline / constant time for each instruction / gain thruput by shifting instruction stages F D E W F D E W F D E W 4 F D E W 5 F D E W 6 F D E W

13 / MEMORY ASSIGNMENT, CALL STACK

14 / MEMORY RANGE / physical memory Kernel / memory mapping in kernel / logical memory virtual memory / logical memory address spaces / paging

15 / MEMORY MAPPING / segment / text segment / data segment DATA BSS HEAP / common library segment / stack segment / protection SIGSEGV / send SIGSEGV upon accessing other than the segment. low-address high-address

16 TEXT / TEXT SEGMENT / a program in a machine code is located / function pointers point an address within this area. TEXT / protected against write x86 CPU / recent CPU does not execute other than this area. / buffer overrun : NX bit (AMD), XD bit (Intel) / bits in a page table entry to select whether the data is executable

17 DATA DATA / initialized static and global variables / the initial value is described BSSBlock Started by Symbol / uninitialized static and global variables BSS / the executable file does not have BSS area BSS0 / allocated before run HEAP malloc / used by malloc

18 STACK / HOW STACK WORKS PUSH POP SPARC : SP x86 : SP(16bit)/ESP(32bit)/RSP(64bit) SPARC: FP x86 : BP(16bit)/EBP(32bit)/RBP(64bit) high-address

19 / EXAMPLE PROCESS MEMORY MAPPING pmap display information about the address space of a process TEXT DATA LIBRARY STACK libc TEXT libc DATA Shared Mapping ld TEXT ld DATA

20 / PROCESS RESOURCE LIMITATION csh/sh limit/ulimit

/ SCHEDULE /06/07(Tue) / Basic of Programming /06/09(Thu) / Fundamental structures /06/14(Tue) / Memory Management /06/1

/ SCHEDULE /06/07(Tue) / Basic of Programming /06/09(Thu) / Fundamental structures /06/14(Tue) / Memory Management /06/1 I117 II I117 PROGRAMMING PRACTICE II 2 MEMORY MANAGEMENT 2 Research Center for Advanced Computing Infrastructure (RCACI) / Yasuhiro Ohara yasu@jaist.ac.jp / SCHEDULE 1. 2011/06/07(Tue) / Basic of Programming