Linux Strace tool

user guide

2017-10-13

Linux Strace tool user guide

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Reversion Record

Date Rev Change Description Author

2017-10-13 V0.1 Initial Zhang Yongchang

Linux Strace tool user guide

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catalog 1 PURPOSE ...............................................................................................................................................................4

2 TERMINOLOGY ......................................................................................................................................................4

3 ENVIRONMENT ......................................................................................................................................................4

3.1 HARDWARE PLATFORM .......................................................................................................................................4 3.2 SOFTWARE PLATFORM ........................................................................................................................................4

4 INSTALL GUIDE .....................................................................................................................................................4

4.1 DOWNLOAD THE STRACE .....................................................................................................................................4 4.2 ENVIRONMENT PREPARED ...................................................................................................................................5 4.3 COMPILE STRACE ...............................................................................................................................................5

5 USE GUIDE .............................................................................................................................................................5

5.1 SIMPLE EXAMPLE ................................................................................................................................................5 5.1.1 Trace system call ......................................................................................................................................6 5.1.2 Trace signal ..............................................................................................................................................7

5.2 STATISTICAL SYSTEM CALL ..................................................................................................................................8 5.3 OTHER OPTIONS DESCRIPTION ............................................................................................................................8 5.4 TRACE A EXIST PROCESS .....................................................................................................................................8

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Figure index Figure 1 trace system call ...................................................................................................................................6

Figure 2 trace signal (1) ......................................................................................................................................7

Figure 3 trace signal (2) ......................................................................................................................................8

Figure 4 statistical system call .............................................................................................................................8

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1 Purpose

This guide help user install the strace on ARM, and show how to use Strace to intercept and record the system calls.

2 Terminology

strace: strace is a diagnostic, debugging and instructional user space utility for Linux. It

is used to monitor and tamper with interactions between processes and the Linux

kernel, which include system calls, signal deliveries, and changes of process state. The

operation of strace is made possible by the kernel feature known as ptrace.

3 Environment

3.1 Hardware Platform

SOC: Rockchip RK3399

GPU: Mali T864 (800MHz)

CPU: Dual-core Cortex-A72 up to 2.0GHz (real frequency is 1.8GHz) Quad-core Cortex-A53 up to 1.5GHz (real frequency is 1.4GHz)

3.2 Software Platform

OS: Ubuntu 16.04 （32bit）

4 Install Guide

4.1 Download the strace

wget https://nchc.dl.sourceforge.net/project/strace/strace/4.19/strace-4.19.tar.xz

tar -xvf strace-4.19.tar.xz

cd ~/

mkdir -p build-starce

To assume the code directory:

strace source code：~/strace-4.19

strace build：~/build-strace

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4.2 Environment Prepared

sudo apt-get install flex bison libelf-dev libaudit-dev libdw-dev libunwind-dev python-dev

sudo apt-get install libnuma-dev libunwind8 libunwind8-dev

sudo apt-get install libslang2 libslang2-dev

sudo apt-get install binutils-multiarch-dev elfutils libiberty-dev

sudo apt-get install gcc-arm-linux-gnueabihf

4.3 Compile Strace

cd ~/build-strace

CC=arm-linux-gnueabihf-gcc LD=arm-linux-gnueabifh-ld RANLIB=arm-linux-gnueabihf-ranlib ../strace-

4.19/configure --host=arm-linux --target=arm-linux --prefix=/usr/

make –j4

sudo make install

• If your system is 64bit, you should specific --target=aarch64-linux, --host=aarch64-linux.

5 Use Guide

5.1 Simple example

Create a test file test.c:

#include <stdio.h>

int main()

{

int num = 0;

printf(“Please input number: ”);

scanf(“%d”, &num);

printf(“%09d\n”, num);

return 0;

}

Compile test:

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gcc –o test test.c

5.1.1 Trace system call

Figure 1 trace system call

From the output we can know:

1. The system calls the exec to start a new process, then to prepare the environment. 2. Pause at "read (0,", and wait for input the number.

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3. Input the number “99”, the writer function output “000000099\n” to the screen. 4. Call exit_group() to complete the entire process

5.1.2 Trace signal

Figure 2 trace signal (1)

Now, we don’t input anything, it block at the read function. Start a new terminal:

killall test

And you can see the strace output:

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Figure 3 trace signal (2)

The test process receives the “SIFTERM” signal, it will be terminated.

5.2 Statistical system call

Strace can count times, calls and errors for the system call, and report a summary.

Figure 4 statistical system call

5.3 Other Options description

Please read Strace command manual

man strace

5.4 Trace a exist process

Attach to the process with the process ID “pid” and begin tracing. The trace may be terminated at any time by a keyboard interrupt signal (CTRL-C). Strace will respond by detaching itself from the traced process(es) leaving it (them) to continue running. Multiple -p options can be used to attach to many processes in addition to command (which is optional if at least one -p option is given). -p "`pidof PROG`" syntax is supported.

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strace –p pid