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 copyrightnotice and this notice are preserved.  -->
<!-- This file was generated using the following file:/usr/src/linux/arch/x86/include/asm/unistd_64.hThe 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>

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 }

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

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 ?? ()