GDB之调试系统接口syscall(九)

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1.前言

本篇目的：GDB之调试系统接口。

2.系统调用和编号的映射文件

/usr/share/gdb/syscalls/amd64-linux.xml

<?xml version="1.0"?>
<!DOCTYPE syscalls_info SYSTEM "gdb-syscalls.dtd">
<!-- Copyright (C) 2009-2022 Free Software Foundation, Inc.

     Copying and distribution of this file, with or without modification,
     are permitted in any medium without royalty provided the copyright
     notice and this notice are preserved.  -->
<!-- This file was generated using the following file:
     
     /usr/src/linux/arch/x86/include/asm/unistd_64.h

     The file mentioned above belongs to the Linux Kernel.  -->
<syscalls_info>
  <syscall name="read" number="0" groups="descriptor"/>
  <syscall name="write" number="1" groups="descriptor"/>
  <syscall name="open" number="2" groups="descriptor,file"/>
  <syscall name="close" number="3" groups="descriptor"/>
  <syscall name="stat" number="4" groups="file"/>
  <syscall name="fstat" number="5" groups="descriptor"/>
  <syscall name="lstat" number="6" groups="file"/>
  <syscall name="poll" number="7" groups="descriptor"/>
  <syscall name="lseek" number="8" groups="descriptor"/>
  <syscall name="mmap" number="9" groups="descriptor,memory"/>
  <syscall name="mprotect" number="10" groups="memory"/>
  <syscall name="munmap" number="11" groups="memory"/>
  <syscall name="brk" number="12" groups="memory"/>
  <syscall name="rt_sigaction" number="13" groups="signal"/>
  <syscall name="rt_sigprocmask" number="14" groups="signal"/>
  <syscall name="rt_sigreturn" number="15" groups="signal"/>
  <syscall name="ioctl" number="16" groups="descriptor"/>
  <syscall name="pread64" number="17" groups="descriptor"/>
  <syscall name="pwrite64" number="18" groups="descriptor"/>
  <syscall name="readv" number="19" groups="descriptor"/>
  <syscall name="writev" number="20" groups="descriptor"/>
  <syscall name="access" number="21" groups="file"/>
  <syscall name="pipe" number="22" groups="descriptor"/>
  <syscall name="select" number="23" groups="descriptor"/>
  <syscall name="sched_yield" number="24"/>
  <syscall name="mremap" number="25" groups="memory"/>
  <syscall name="msync" number="26" groups="memory"/>
  <syscall name="mincore" number="27" groups="memory"/>
  <syscall name="madvise" number="28" groups="memory"/>
  <syscall name="shmget" number="29" groups="ipc"/>
  <syscall name="shmat" number="30" groups="ipc,memory"/>
  <syscall name="shmctl" number="31" groups="ipc"/>
  <syscall name="dup" number="32" groups="descriptor"/>
  <syscall name="dup2" number="33" groups="descriptor"/>
  <syscall name="pause" number="34" groups="signal"/>
  <syscall name="nanosleep" number="35"/>
  <syscall name="getitimer" number="36"/>
  <syscall name="alarm" number="37"/>
  <syscall name="setitimer" number="38"/>
  <syscall name="getpid" number="39"/>
  <syscall name="sendfile" number="40" groups="descriptor,network"/>
  <syscall name="socket" number="41" groups="network"/>
  <syscall name="connect" number="42" groups="network"/>
  <syscall name="accept" number="43" groups="network"/>
  <syscall name="sendto" number="44" groups="network"/>
  <syscall name="recvfrom" number="45" groups="network"/>
  <syscall name="sendmsg" number="46" groups="network"/>
  <syscall name="recvmsg" number="47" groups="network"/>
  <syscall name="shutdown" number="48" groups="network"/>
  <syscall name="bind" number="49" groups="network"/>
  <syscall name="listen" number="50" groups="network"/>
  <syscall name="getsockname" number="51" groups="network"/>
  <syscall name="getpeername" number="52" groups="network"/>
  <syscall name="socketpair" number="53" groups="network"/>
  <syscall name="setsockopt" number="54" groups="network"/>
  <syscall name="getsockopt" number="55" groups="network"/>
  <syscall name="clone" number="56" groups="process"/>
  <syscall name="fork" number="57" groups="process"/>
  <syscall name="vfork" number="58" groups="process"/>
  <syscall name="execve" number="59" groups="file,process"/>
  <syscall name="exit" number="60" groups="process"/>
  <syscall name="wait4" number="61" groups="process"/>
  <syscall name="kill" number="62" groups="signal"/>
  <syscall name="uname" number="63"/>
  <syscall name="semget" number="64" groups="ipc"/>
  <syscall name="semop" number="65" groups="ipc"/>
  <syscall name="semctl" number="66" groups="ipc"/>
  <syscall name="shmdt" number="67" groups="ipc,memory"/>
  <syscall name="msgget" number="68" groups="ipc"/>
  <syscall name="msgsnd" number="69" groups="ipc"/>
  <syscall name="msgrcv" number="70" groups="ipc"/>
  <syscall name="msgctl" number="71" groups="ipc"/>
  <syscall name="fcntl" number="72" groups="descriptor"/>
  <syscall name="flock" number="73" groups="descriptor"/>
  <syscall name="fsync" number="74" groups="descriptor"/>
  <syscall name="fdatasync" number="75" groups="descriptor"/>
  <syscall name="truncate" number="76" groups="file"/>
  <syscall name="ftruncate" number="77" groups="descriptor"/>
  <syscall name="getdents" number="78" groups="descriptor"/>
  <syscall name="getcwd" number="79" groups="file"/>
  <syscall name="chdir" number="80" groups="file"/>
  <syscall name="fchdir" number="81" groups="descriptor"/>
  <syscall name="rename" number="82" groups="file"/>
  <syscall name="mkdir" number="83" groups="file"/>
  <syscall name="rmdir" number="84" groups="file"/>
  <syscall name="creat" number="85" groups="descriptor,file"/>
  <syscall name="link" number="86" groups="file"/>
  <syscall name="unlink" number="87" groups="file"/>
  <syscall name="symlink" number="88" groups="file"/>
  <syscall name="readlink" number="89" groups="file"/>
  <syscall name="chmod" number="90" groups="file"/>
  <syscall name="fchmod" number="91" groups="descriptor"/>
  <syscall name="chown" number="92" groups="file"/>
  <syscall name="fchown" number="93" groups="descriptor"/>
  <syscall name="lchown" number="94" groups="file"/>
  <syscall name="umask" number="95"/>
  <syscall name="gettimeofday" number="96"/>
  <syscall name="getrlimit" number="97"/>
  <syscall name="getrusage" number="98"/>
  <syscall name="sysinfo" number="99"/>
  <syscall name="times" number="100"/>
  <syscall name="ptrace" number="101"/>
  <syscall name="getuid" number="102"/>
  <syscall name="syslog" number="103"/>
  <syscall name="getgid" number="104"/>
  <syscall name="setuid" number="105"/>
  <syscall name="setgid" number="106"/>
  <syscall name="geteuid" number="107"/>
  <syscall name="getegid" number="108"/>
  <syscall name="setpgid" number="109"/>
  <syscall name="getppid" number="110"/>
  <syscall name="getpgrp" number="111"/>
  <syscall name="setsid" number="112"/>
  <syscall name="setreuid" number="113"/>
  <syscall name="setregid" number="114"/>
  <syscall name="getgroups" number="115"/>
  <syscall name="setgroups" number="116"/>
  <syscall name="setresuid" number="117"/>
  <syscall name="getresuid" number="118"/>
  <syscall name="setresgid" number="119"/>
  <syscall name="getresgid" number="120"/>
  <syscall name="getpgid" number="121"/>
  <syscall name="setfsuid" number="122"/>
  <syscall name="setfsgid" number="123"/>
  <syscall name="getsid" number="124"/>
  <syscall name="capget" number="125"/>
  <syscall name="capset" number="126"/>
  <syscall name="rt_sigpending" number="127" groups="signal"/>
  <syscall name="rt_sigtimedwait" number="128" groups="signal"/>
  <syscall name="rt_sigqueueinfo" number="129" groups="signal"/>
  <syscall name="rt_sigsuspend" number="130" groups="signal"/>
  <syscall name="sigaltstack" number="131" groups="signal"/>
  <syscall name="utime" number="132" groups="file"/>
  <syscall name="mknod" number="133" groups="file"/>
  <syscall name="uselib" number="134" groups="file"/>
  <syscall name="personality" number="135"/>
  <syscall name="ustat" number="136"/>
  <syscall name="statfs" number="137" groups="file"/>
  <syscall name="fstatfs" number="138" groups="descriptor"/>
  <syscall name="sysfs" number="139"/>
  <syscall name="getpriority" number="140"/>
  <syscall name="setpriority" number="141"/>
  <syscall name="sched_setparam" number="142"/>
  <syscall name="sched_getparam" number="143"/>
  <syscall name="sched_setscheduler" number="144"/>
  <syscall name="sched_getscheduler" number="145"/>
  <syscall name="sched_get_priority_max" number="146"/>
  <syscall name="sched_get_priority_min" number="147"/>
  <syscall name="sched_rr_get_interval" number="148"/>
  <syscall name="mlock" number="149" groups="memory"/>
  <syscall name="munlock" number="150" groups="memory"/>
  <syscall name="mlockall" number="151" groups="memory"/>
  <syscall name="munlockall" number="152" groups="memory"/>
  <syscall name="vhangup" number="153"/>
  <syscall name="modify_ldt" number="154"/>
  <syscall name="pivot_root" number="155" groups="file"/>
  <syscall name="_sysctl" number="156"/>
  <syscall name="prctl" number="157"/>
  <syscall name="arch_prctl" number="158" groups="process"/>
  <syscall name="adjtimex" number="159"/>
  <syscall name="setrlimit" number="160"/>
  <syscall name="chroot" number="161" groups="file"/>
  <syscall name="sync" number="162"/>
  <syscall name="acct" number="163" groups="file"/>
  <syscall name="settimeofday" number="164"/>
  <syscall name="mount" number="165" groups="file"/>
  <syscall name="umount2" number="166" groups="file"/>
  <syscall name="swapon" number="167" groups="file"/>
  <syscall name="swapoff" number="168" groups="file"/>
  <syscall name="reboot" number="169"/>
  <syscall name="sethostname" number="170"/>
  <syscall name="setdomainname" number="171"/>
  <syscall name="iopl" number="172"/>
  <syscall name="ioperm" number="173"/>
  <syscall name="create_module" number="174"/>
  <syscall name="init_module" number="175"/>
  <syscall name="delete_module" number="176"/>
  <syscall name="get_kernel_syms" number="177"/>
  <syscall name="query_module" number="178"/>
  <syscall name="quotactl" number="179" groups="file"/>
  <syscall name="nfsservctl" number="180"/>
  <syscall name="getpmsg" number="181"/>
  <syscall name="putpmsg" number="182"/>
  <syscall name="afs_syscall" number="183"/>
  <syscall name="tuxcall" number="184"/>
  <syscall name="security" number="185"/>
  <syscall name="gettid" number="186"/>
  <syscall name="readahead" number="187" groups="descriptor"/>
  <syscall name="setxattr" number="188" groups="file"/>
  <syscall name="lsetxattr" number="189" groups="file"/>
  <syscall name="fsetxattr" number="190" groups="descriptor"/>
  <syscall name="getxattr" number="191" groups="file"/>
  <syscall name="lgetxattr" number="192" groups="file"/>
  <syscall name="fgetxattr" number="193" groups="descriptor"/>
  <syscall name="listxattr" number="194" groups="file"/>
  <syscall name="llistxattr" number="195" groups="file"/>
  <syscall name="flistxattr" number="196" groups="descriptor"/>
  <syscall name="removexattr" number="197" groups="file"/>
  <syscall name="lremovexattr" number="198" groups="file"/>
  <syscall name="fremovexattr" number="199" groups="descriptor"/>
  <syscall name="tkill" number="200" groups="signal"/>
  <syscall name="time" number="201"/>
  <syscall name="futex" number="202"/>
  <syscall name="sched_setaffinity" number="203"/>
  <syscall name="sched_getaffinity" number="204"/>
  <syscall name="set_thread_area" number="205"/>
  <syscall name="io_setup" number="206"/>
  <syscall name="io_destroy" number="207"/>
  <syscall name="io_getevents" number="208"/>
  <syscall name="io_submit" number="209"/>
  <syscall name="io_cancel" number="210"/>
  <syscall name="get_thread_area" number="211"/>
  <syscall name="lookup_dcookie" number="212"/>
  <syscall name="epoll_create" number="213" groups="descriptor"/>
  <syscall name="epoll_ctl_old" number="214"/>
  <syscall name="epoll_wait_old" number="215"/>
  <syscall name="remap_file_pages" number="216" groups="memory"/>
  <syscall name="getdents64" number="217" groups="descriptor"/>
  <syscall name="set_tid_address" number="218"/>
  <syscall name="restart_syscall" number="219"/>
  <syscall name="semtimedop" number="220" groups="ipc"/>
  <syscall name="fadvise64" number="221" groups="descriptor"/>
  <syscall name="timer_create" number="222"/>
  <syscall name="timer_settime" number="223"/>
  <syscall name="timer_gettime" number="224"/>
  <syscall name="timer_getoverrun" number="225"/>
  <syscall name="timer_delete" number="226"/>
  <syscall name="clock_settime" number="227"/>
  <syscall name="clock_gettime" number="228"/>
  <syscall name="clock_getres" number="229"/>
  <syscall name="clock_nanosleep" number="230"/>
  <syscall name="exit_group" number="231" groups="process"/>
  <syscall name="epoll_wait" number="232" groups="descriptor"/>
  <syscall name="epoll_ctl" number="233" groups="descriptor"/>
  <syscall name="tgkill" number="234" groups="signal"/>
  <syscall name="utimes" number="235" groups="file"/>
  <syscall name="vserver" number="236"/>
  <syscall name="mbind" number="237" groups="memory"/>
  <syscall name="set_mempolicy" number="238" groups="memory"/>
  <syscall name="get_mempolicy" number="239" groups="memory"/>
  <syscall name="mq_open" number="240"/>
  <syscall name="mq_unlink" number="241"/>
  <syscall name="mq_timedsend" number="242"/>
  <syscall name="mq_timedreceive" number="243"/>
  <syscall name="mq_notify" number="244"/>
  <syscall name="mq_getsetattr" number="245"/>
  <syscall name="kexec_load" number="246"/>
  <syscall name="waitid" number="247" groups="process"/>
  <syscall name="add_key" number="248"/>
  <syscall name="request_key" number="249"/>
  <syscall name="keyctl" number="250"/>
  <syscall name="ioprio_set" number="251"/>
  <syscall name="ioprio_get" number="252"/>
  <syscall name="inotify_init" number="253" groups="descriptor"/>
  <syscall name="inotify_add_watch" number="254" groups="descriptor"/>
  <syscall name="inotify_rm_watch" number="255" groups="descriptor"/>
  <syscall name="migrate_pages" number="256" groups="memory"/>
  <syscall name="openat" number="257" groups="descriptor,file"/>
  <syscall name="mkdirat" number="258" groups="descriptor,file"/>
  <syscall name="mknodat" number="259" groups="descriptor,file"/>
  <syscall name="fchownat" number="260" groups="descriptor,file"/>
  <syscall name="futimesat" number="261" groups="descriptor,file"/>
  <syscall name="newfstatat" number="262" groups="descriptor,file"/>
  <syscall name="unlinkat" number="263" groups="descriptor,file"/>
  <syscall name="renameat" number="264" groups="descriptor,file"/>
  <syscall name="linkat" number="265" groups="descriptor,file"/>
  <syscall name="symlinkat" number="266" groups="descriptor,file"/>
  <syscall name="readlinkat" number="267" groups="descriptor,file"/>
  <syscall name="fchmodat" number="268" groups="descriptor,file"/>
  <syscall name="faccessat" number="269" groups="descriptor,file"/>
  <syscall name="pselect6" number="270" groups="descriptor"/>
  <syscall name="ppoll" number="271" groups="descriptor"/>
  <syscall name="unshare" number="272" groups="process"/>
  <syscall name="set_robust_list" number="273"/>
  <syscall name="get_robust_list" number="274"/>
  <syscall name="splice" number="275" groups="descriptor"/>
  <syscall name="tee" number="276" groups="descriptor"/>
  <syscall name="sync_file_range" number="277" groups="descriptor"/>
  <syscall name="vmsplice" number="278" groups="descriptor"/>
  <syscall name="move_pages" number="279" groups="memory"/>
  <syscall name="utimensat" number="280" groups="descriptor,file"/>
  <syscall name="epoll_pwait" number="281" groups="descriptor"/>
  <syscall name="signalfd" number="282" groups="descriptor,signal"/>
  <syscall name="timerfd_create" number="283" groups="descriptor"/>
  <syscall name="eventfd" number="284" groups="descriptor"/>
  <syscall name="fallocate" number="285" groups="descriptor"/>
  <syscall name="timerfd_settime" number="286" groups="descriptor"/>
  <syscall name="timerfd_gettime" number="287" groups="descriptor"/>
  <syscall name="accept4" number="288" groups="network"/>
  <syscall name="signalfd4" number="289" groups="descriptor,signal"/>
  <syscall name="eventfd2" number="290" groups="descriptor"/>
  <syscall name="epoll_create1" number="291" groups="descriptor"/>
  <syscall name="dup3" number="292" groups="descriptor"/>
  <syscall name="pipe2" number="293" groups="descriptor"/>
  <syscall name="inotify_init1" number="294" groups="descriptor"/>
  <syscall name="preadv" number="295" groups="descriptor"/>
  <syscall name="pwritev" number="296" groups="descriptor"/>
</syscalls_info>

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3.设置系统函数mmap catchpoint实例 （mmap对应编号9）

1 #include <cstdio>
2 
3 int main(void){
4   int num = 100;
5 
6   printf("num = %d\n", num);
7   return 0;
8 }

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9

调试方式一：系统函数名调试

(gdb) catch syscall mmap
Catchpoint 1 (syscall 'mmap' [9])
(gdb) r
Starting program: /home/meek/demo/C/111/test 

Catchpoint 1 (call to syscall mmap), __mmap64 (offset=0, fd=-1, flags=34, prot=3, len=8192, addr=0x0) at ../sysdeps/unix/sysv/linux/mmap64.c:58
58	../sysdeps/unix/sysv/linux/mmap64.c: 没有那个文件或目录.
(gdb) c
Continuing.

Catchpoint 1 (returned from syscall mmap), __mmap64 (offset=0, fd=-1, flags=34, prot=3, len=8192, addr=0x0) at ../sysdeps/unix/sysv/linux/mmap64.c:58
58	in ../sysdeps/unix/sysv/linux/mmap64.c
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调试方式二：编号调试(mmap函数对应编号9）

(gdb) catch syscall 9
Catchpoint 2 (syscall 'mmap' [9])
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n) y
Starting program: /home/meek/demo/C/111/test 

Catchpoint 1 (call to syscall mmap), __mmap64 (offset=0, fd=-1, flags=34, prot=3, len=8192, addr=0x0) at ../sysdeps/unix/sysv/linux/mmap64.c:58
58	../sysdeps/unix/sysv/linux/mmap64.c: 没有那个文件或目录.
(gdb) c
Continuing.

Catchpoint 1 (returned from syscall mmap), __mmap64 (offset=0, fd=-1, flags=34, prot=3, len=8192, addr=0x0) at ../sysdeps/unix/sysv/linux/mmap64.c:58
58	in ../sysdeps/unix/sysv/linux/mmap64.c
//查看当前堆栈信息
(gdb) bt
#0  __mmap64 (offset=0, fd=3, flags=2050, prot=1, len=2260560, addr=0x0) at ../sysdeps/unix/sysv/linux/mmap64.c:58
#1  __mmap64 (addr=0x0, len=len@entry=2260560, prot=prot@entry=1, flags=flags@entry=2050, fd=fd@entry=3, offset=0) at ../sysdeps/unix/sysv/linux/mmap64.c:46
#2  0x00007ffff7fcbf1c in _dl_map_segment (fd=3, maplength=2260560, mappref=<optimized out>, c=0x7fffffffc700) at ./dl-map-segments.h:29
#3  _dl_map_segments (loader=0x4, has_holes=false, maplength=2260560, nloadcmds=<optimized out>, loadcmds=0x7fffffffc700, type=3, header=<optimized out>, fd=3, l=0x7ffff7fbb160) at ./dl-map-segments.h:102
#4  _dl_map_object_from_fd (name=name@entry=0x5555555544a9 "libc.so.6", origname=origname@entry=0x0, fd=<optimized out>, fbp=<optimized out>, realname=<optimized out>, loader=loader@entry=0x7ffff7ffe2e0, l_type=<optimized out>, 
    mode=<optimized out>, stack_endp=<optimized out>, nsid=<optimized out>) at ./elf/dl-load.c:1258
#5  0x00007ffff7fcd601 in _dl_map_object (loader=0x7ffff7ffe2e0, name=0x5555555544a9 "libc.so.6", type=1, trace_mode=0, mode=0, nsid=<optimized out>) at ./elf/dl-load.c:2327
#6  0x00007ffff7fc6495 in openaux (a=a@entry=0x7fffffffd4c0) at ./elf/dl-deps.c:64
#7  0x00007ffff7fe036a in _dl_catch_exception (exception=exception@entry=0x7fffffffd4a0, operate=operate@entry=0x7ffff7fc6460 <openaux>, args=args@entry=0x7fffffffd4c0) at ./elf/dl-error-skeleton.c:208
#8  0x00007ffff7fc6c7c in _dl_map_object_deps (map=map@entry=0x7ffff7ffe2e0, preloads=preloads@entry=0x0, npreloads=npreloads@entry=0, trace_mode=<optimized out>, open_mode=open_mode@entry=0) at ./elf/dl-deps.c:248
#9  0x00007ffff7fe63c0 in dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at ./elf/rtld.c:1970
#10 0x00007ffff7fe285c in _dl_sysdep_start (start_argptr=start_argptr@entry=0x7fffffffdd70, dl_main=dl_main@entry=0x7ffff7fe4900 <dl_main>) at ../elf/dl-sysdep.c:256
#11 0x00007ffff7fe45b8 in _dl_start_final (arg=0x7fffffffdd70) at ./elf/rtld.c:507
#12 _dl_start (arg=0x7fffffffdd70) at ./elf/rtld.c:596
#13 0x00007ffff7fe32b8 in _start () from /lib64/ld-linux-x86-64.so.2
#14 0x0000000000000001 in ?? ()
#15 0x00007fffffffe118 in ?? ()
#16 0x0000000000000000 in ?? ()
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