x/56wx：w 代表 4 字节，x 代表 16 进制显示，56 代表显示 56 个 4 字节。显示效果为：每行 4 列（16 Byte），共 14 行。
The hook function hook-stop is a special definition that GDB calls at every breakpoint event. This means that you can use it to call your user-defined functions each time GDB stops (after a breakpoint, after each next/nexti, etc.).---ref
gdb里的hook函数与某些事件绑定，当绑定事件发生时，该函数被触发执行。类似的还有hook-run、hook-continue函数。
程序执行时忽略SIGUSR1信号引起的运行停止
(gdb) define hook-run
> handle SIGUSR1 nostop
> end
汇编调试时, 跟踪显示汇编以及指定寄存器的信息
(gdb) define hook-stop
Type commands for definition of "hook-stop".
End with a line saying just "end".
>p /x $eax
>p /x $ebx
>disas $rip + 5
>end
(gdb) info inferiors
Num Description Executable
* 1 process 2782 /home/sirius/competitive-programming/a.out
示例程序
#include <stdio.h>
int array[(1<<30)];
int main()
{
printf( "hello world\n");
return 0;
}- 使用
info proc mappings
(gdb) info proc mappings
process 2782
Mapped address spaces:
Start Addr End Addr Size Offset objfile
0x8000000 0x8001000 0x1000 0x0 /home/sirius/competitive-programming/a.out
0x8001000 0x8002000 0x1000 0x1000 /home/sirius/competitive-programming/a.out
0x8002000 0x8003000 0x1000 0x2000 /home/sirius/competitive-programming/a.out
0x8003000 0x8004000 0x1000 0x2000 /home/sirius/competitive-programming/a.out
0x8004000 0x8005000 0x1000 0x3000 /home/sirius/competitive-programming/a.out
0x8005000 0x108005000 0x100000000 0x0
0x7fffff5b0000 0x7fffff5d5000 0x25000 0x0 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff5d5000 0x7fffff74d000 0x178000 0x25000 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff74d000 0x7fffff797000 0x4a000 0x19d000 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff797000 0x7fffff798000 0x1000 0x1e7000 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff798000 0x7fffff79b000 0x3000 0x1e7000 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff79b000 0x7fffff79e000 0x3000 0x1ea000 /usr/lib/x86_64-linux-gnu/libc-2.31.so
0x7fffff79e000 0x7fffff7a2000 0x4000 0x0
0x7fffff7b0000 0x7fffff7b1000 0x1000 0x0 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b1000 0x7fffff7b3000 0x2000 0x1000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b3000 0x7fffff7b4000 0x1000 0x3000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b4000 0x7fffff7b5000 0x1000 0x4000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b5000 0x7fffff7b6000 0x1000 0x5000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b6000 0x7fffff7b7000 0x1000 0x6000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b7000 0x7fffff7b8000 0x1000 0x7000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7b8000 0x7fffff7c6000 0xe000 0x8000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7c6000 0x7fffff7c7000 0x1000 0x16000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7c7000 0x7fffff7c8000 0x1000 0x17000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7c8000 0x7fffff7d3000 0xb000 0x18000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7d3000 0x7fffff7d4000 0x1000 0x23000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7d4000 0x7fffff7db000 0x7000 0x24000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7db000 0x7fffff7dc000 0x1000 0x2b000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7dd000 0x7fffff7de000 0x1000 0x2c000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7de000 0x7fffff7df000 0x1000 0x2d000 /usr/lib/x86_64-linux-gnu/ld-2.31.so
0x7fffff7df000 0x7fffff7e2000 0x3000 0x0
0x7fffff7ef000 0x7ffffffef000 0x800000 0x0 [stack]
0x7ffffffef000 0x7fffffff0000 0x1000 0x0 [vdso]
- 使用
cat /proc/<pid>/maps
(gdb) !cat /proc/2782/maps
08000000-08001000 r--p 00000000 00:00 323488 /home/sirius/competitive-programming/a.out
08001000-08002000 rwxp 00001000 00:00 323488 /home/sirius/competitive-programming/a.out
08002000-08003000 r--p 00002000 00:00 323488 /home/sirius/competitive-programming/a.out
08003000-08004000 r--p 00002000 00:00 323488 /home/sirius/competitive-programming/a.out
08004000-08005000 rw-p 00003000 00:00 323488 /home/sirius/competitive-programming/a.out
08005000-108005000 rw-p 00000000 00:00 0
7fffff5b0000-7fffff5d5000 r--p 00000000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff5d5000-7fffff74d000 r-xp 00025000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff74d000-7fffff797000 r--p 0019d000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff797000-7fffff798000 ---p 001e7000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff798000-7fffff79b000 r--p 001e7000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff79b000-7fffff79e000 rw-p 001ea000 00:00 85659 /usr/lib/x86_64-linux-gnu/libc-2.31.so
7fffff79e000-7fffff7a2000 rw-p 00000000 00:00 0
7fffff7b0000-7fffff7b1000 r--p 00000000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b1000-7fffff7b3000 r-xp 00001000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b3000-7fffff7b4000 rwxp 00003000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b4000-7fffff7b5000 rwxp 00004000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b5000-7fffff7b6000 r-xp 00005000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b6000-7fffff7b7000 rwxp 00006000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b7000-7fffff7b8000 rwxp 00007000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7b8000-7fffff7c6000 r-xp 00008000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7c6000-7fffff7c7000 rwxp 00016000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7c7000-7fffff7c8000 rwxp 00017000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7c8000-7fffff7d3000 r-xp 00018000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7d3000-7fffff7d4000 r-xp 00023000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7d4000-7fffff7db000 r--p 00024000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7db000-7fffff7dc000 r--p 0002b000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7dd000-7fffff7de000 r--p 0002c000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7de000-7fffff7df000 rw-p 0002d000 00:00 85366 /usr/lib/x86_64-linux-gnu/ld-2.31.so
7fffff7df000-7fffff7e2000 rw-p 00000000 00:00 0
7fffff7ef000-7ffffffef000 rw-p 00000000 00:00 0 [stack]
7ffffffef000-7fffffff0000 r-xp 00000000 00:00 0 [vdso]
- 使用
pmap <pid>
(gdb) !pmap 2782
2782: /home/sirius/competitive-programming/a.out
0000000008000000 4K r---- a.out
0000000008001000 4K rwx-- a.out
0000000008002000 4K r---- a.out
0000000008003000 4K r---- a.out
0000000008004000 4K rw--- a.out
0000000008005000 4194304K rw--- [ anon ]
00007fffff5b0000 148K r---- libc-2.31.so
00007fffff5d5000 1504K r-x-- libc-2.31.so
00007fffff74d000 296K r---- libc-2.31.so
00007fffff797000 4K ----- libc-2.31.so
00007fffff798000 12K r---- libc-2.31.so
00007fffff79b000 12K rw--- libc-2.31.so
00007fffff79e000 16K rw--- [ anon ]
00007fffff7b0000 4K r---- ld-2.31.so
00007fffff7b1000 8K r-x-- ld-2.31.so
00007fffff7b3000 4K rwx-- ld-2.31.so
00007fffff7b4000 4K rwx-- ld-2.31.so
00007fffff7b5000 4K r-x-- ld-2.31.so
00007fffff7b6000 4K rwx-- ld-2.31.so
00007fffff7b7000 4K rwx-- ld-2.31.so
00007fffff7b8000 56K r-x-- ld-2.31.so
00007fffff7c6000 4K rwx-- ld-2.31.so
00007fffff7c7000 4K rwx-- ld-2.31.so
00007fffff7c8000 44K r-x-- ld-2.31.so
00007fffff7d3000 4K r-x-- ld-2.31.so
00007fffff7d4000 28K r---- ld-2.31.so
00007fffff7db000 4K r---- ld-2.31.so
00007fffff7dd000 4K r---- ld-2.31.so
00007fffff7de000 4K rw--- ld-2.31.so
00007fffff7df000 12K rw--- [ anon ]
00007fffff7ef000 8192K rw--- [ anon ]
00007ffffffef000 4K r-x-- [ anon ]
total 4204708K
- 使用readelf读取 Type为LOAD的行，offset代表在文件偏移，VirtAddr每个段的虚拟起始地址，FileSiz代表该段在目标文件所占的大小，MemSiz代表该段在内存空间所占大小。
(gdb) !readelf -l a.out
Elf file type is DYN (Shared object file)
Entry point 0x1060
There are 13 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
PHDR 0x0000000000000040 0x0000000000000040 0x0000000000000040
0x00000000000002d8 0x00000000000002d8 R 0x8
INTERP 0x0000000000000318 0x0000000000000318 0x0000000000000318
0x000000000000001c 0x000000000000001c R 0x1
[Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x00000000000005f8 0x00000000000005f8 R 0x1000
LOAD 0x0000000000001000 0x0000000000001000 0x0000000000001000
0x00000000000001f5 0x00000000000001f5 R E 0x1000
LOAD 0x0000000000002000 0x0000000000002000 0x0000000000002000
0x0000000000000160 0x0000000000000160 R 0x1000
LOAD 0x0000000000002db8 0x0000000000003db8 0x0000000000003db8
0x0000000000000258 0x0000000100000288 RW 0x1000
DYNAMIC 0x0000000000002dc8 0x0000000000003dc8 0x0000000000003dc8
0x00000000000001f0 0x00000000000001f0 RW 0x8
NOTE 0x0000000000000338 0x0000000000000338 0x0000000000000338
0x0000000000000020 0x0000000000000020 R 0x8
NOTE 0x0000000000000358 0x0000000000000358 0x0000000000000358
0x0000000000000044 0x0000000000000044 R 0x4
GNU_PROPERTY 0x0000000000000338 0x0000000000000338 0x0000000000000338
0x0000000000000020 0x0000000000000020 R 0x8
GNU_EH_FRAME 0x0000000000002010 0x0000000000002010 0x0000000000002010
0x0000000000000044 0x0000000000000044 R 0x4
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RW 0x10
GNU_RELRO 0x0000000000002db8 0x0000000000003db8 0x0000000000003db8
0x0000000000000248 0x0000000000000248 R 0x1
Section to Segment mapping:
Segment Sections...
00
01 .interp
02 .interp .note.gnu.property .note.gnu.build-id .note.ABI-tag .gnu.hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt
03 .init .plt .plt.got .plt.sec .text .fini
04 .rodata .eh_frame_hdr .eh_frame
05 .init_array .fini_array .dynamic .got .data .bss
06 .dynamic
07 .note.gnu.property
08 .note.gnu.build-id .note.ABI-tag
09 .note.gnu.property
10 .eh_frame_hdr
11
12 .init_array .fini_array .dynamic .got
(gdb) help info proc
Show /proc process information about any running process.
Specify any process id, or use the program being debugged by default.
Specify any of the following keywords for detailed info:
mappings -- list of mapped memory regions.
stat -- list a bunch of random process info.
status -- list a different bunch of random process info.
all -- list all available /proc info.