介绍 objdump 命令的功能用法。
readelf 和 objdump 相比：
- objdump 可以对二进制文件根据调试符号表进行反汇编，但是 readelf 不行；
- 两者都会使用 build-id 和 gnu debuglink 机制从
/usr/lib/debug查找当前二进制的 debuginfo 文件，然后显示其内容；
通用选项：
-w/--wide：可以使输出宽度超过 80 字符。-j, --section=NAME：只显示执行 SECTION 的内容。
1 显示文件格式 #
objdump -a 显示文件格式（elf 也是一种归档 archive 文件格式）：
root@lima-ebpf-dev:~# objdump -w -a hello
hello: file format elf64-x86-64
hello
2 显示 ELF header #
objdump -f 显示 elf header 的简略概要：
root@lima-ebpf-dev:~# objdump -w -f hello
hello: file format elf64-x86-64
architecture: i386:x86-64, flags 0x00000150:
HAS_SYMS, DYNAMIC, D_PAGED
start address 0x0000000000001060
3 显示 Program headers #
objdump -p 显示 elf 文件中的 private-headers 列表：
- 包括：Program headers，Dynamic Section Headers
root@lima-ebpf-dev:~# objdump -w -p hello
hello: file format elf64-x86-64
Program Header:
PHDR off 0x0000000000000040 vaddr 0x0000000000000040 paddr 0x0000000000000040 align 2**3
filesz 0x00000000000002d8 memsz 0x00000000000002d8 flags r--
INTERP off 0x0000000000000318 vaddr 0x0000000000000318 paddr 0x0000000000000318 align 2**0
filesz 0x000000000000001c memsz 0x000000000000001c flags r--
LOAD off 0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**12
filesz 0x0000000000000628 memsz 0x0000000000000628 flags r--
LOAD off 0x0000000000001000 vaddr 0x0000000000001000 paddr 0x0000000000001000 align 2**12
filesz 0x0000000000000185 memsz 0x0000000000000185 flags r-x
LOAD off 0x0000000000002000 vaddr 0x0000000000002000 paddr 0x0000000000002000 align 2**12
filesz 0x0000000000000114 memsz 0x0000000000000114 flags r--
LOAD off 0x0000000000002db8 vaddr 0x0000000000003db8 paddr 0x0000000000003db8 align 2**12
filesz 0x0000000000000258 memsz 0x0000000000000260 flags rw-
DYNAMIC off 0x0000000000002dc8 vaddr 0x0000000000003dc8 paddr 0x0000000000003dc8 align 2**3
filesz 0x00000000000001f0 memsz 0x00000000000001f0 flags rw-
NOTE off 0x0000000000000338 vaddr 0x0000000000000338 paddr 0x0000000000000338 align 2**3
filesz 0x0000000000000030 memsz 0x0000000000000030 flags r--
NOTE off 0x0000000000000368 vaddr 0x0000000000000368 paddr 0x0000000000000368 align 2**2
filesz 0x0000000000000044 memsz 0x0000000000000044 flags r--
0x6474e553 off 0x0000000000000338 vaddr 0x0000000000000338 paddr 0x0000000000000338 align 2**3
filesz 0x0000000000000030 memsz 0x0000000000000030 flags r--
EH_FRAME off 0x000000000000200c vaddr 0x000000000000200c paddr 0x000000000000200c align 2**2
filesz 0x000000000000003c memsz 0x000000000000003c flags r--
STACK off 0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**4
filesz 0x0000000000000000 memsz 0x0000000000000000 flags rw-
RELRO off 0x0000000000002db8 vaddr 0x0000000000003db8 paddr 0x0000000000003db8 align 2**0
filesz 0x0000000000000248 memsz 0x0000000000000248 flags r--
Dynamic Section:
NEEDED libc.so.6
INIT 0x0000000000001000
FINI 0x0000000000001178
INIT_ARRAY 0x0000000000003db8
INIT_ARRAYSZ 0x0000000000000008
FINI_ARRAY 0x0000000000003dc0
FINI_ARRAYSZ 0x0000000000000008
GNU_HASH 0x00000000000003b0
STRTAB 0x0000000000000480
SYMTAB 0x00000000000003d8
STRSZ 0x000000000000008d
SYMENT 0x0000000000000018
DEBUG 0x0000000000000000
PLTGOT 0x0000000000003fb8
PLTRELSZ 0x0000000000000018
PLTREL 0x0000000000000007
JMPREL 0x0000000000000610
RELA 0x0000000000000550
RELASZ 0x00000000000000c0
RELAENT 0x0000000000000018
FLAGS 0x0000000000000008
FLAGS_1 0x0000000008000001
VERNEED 0x0000000000000520
VERNEEDNUM 0x0000000000000001
VERSYM 0x000000000000050e
RELACOUNT 0x0000000000000003
Version References:
required from libc.so.6:
0x09691a75 0x00 03 GLIBC_2.2.5
0x069691b4 0x00 02 GLIBC_2.34
4 显示 Section headers #
objdump -h 显示 Section Header 列表：
root@lima-ebpf-dev:~# objdump -h hello
hello: file format elf64-x86-64
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 0000001c 0000000000000318 0000000000000318 00000318 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.gnu.property 00000030 0000000000000338 0000000000000338 00000338 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .note.gnu.build-id 00000024 0000000000000368 0000000000000368 00000368 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .note.ABI-tag 00000020 000000000000038c 000000000000038c 0000038c 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .gnu.hash 00000024 00000000000003b0 00000000000003b0 000003b0 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .dynsym 000000a8 00000000000003d8 00000000000003d8 000003d8 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .dynstr 0000008d 0000000000000480 0000000000000480 00000480 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .gnu.version 0000000e 000000000000050e 000000000000050e 0000050e 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .gnu.version_r 00000030 0000000000000520 0000000000000520 00000520 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .rela.dyn 000000c0 0000000000000550 0000000000000550 00000550 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .rela.plt 00000018 0000000000000610 0000000000000610 00000610 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
11 .init 0000001b 0000000000001000 0000000000001000 00001000 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .plt 00000020 0000000000001020 0000000000001020 00001020 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .plt.got 00000010 0000000000001040 0000000000001040 00001040 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
14 .plt.sec 00000010 0000000000001050 0000000000001050 00001050 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
15 .text 00000117 0000000000001060 0000000000001060 00001060 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
16 .fini 0000000d 0000000000001178 0000000000001178 00001178 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
17 .rodata 0000000b 0000000000002000 0000000000002000 00002000 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .eh_frame_hdr 0000003c 000000000000200c 000000000000200c 0000200c 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .eh_frame 000000cc 0000000000002048 0000000000002048 00002048 2**3
CONTENTS, ALLOC, LOAD, READONLY, DATA
20 .init_array 00000008 0000000000003db8 0000000000003db8 00002db8 2**3
CONTENTS, ALLOC, LOAD, DATA
21 .fini_array 00000008 0000000000003dc0 0000000000003dc0 00002dc0 2**3
CONTENTS, ALLOC, LOAD, DATA
22 .dynamic 000001f0 0000000000003dc8 0000000000003dc8 00002dc8 2**3
CONTENTS, ALLOC, LOAD, DATA
23 .got 00000048 0000000000003fb8 0000000000003fb8 00002fb8 2**3
CONTENTS, ALLOC, LOAD, DATA
24 .data 00000010 0000000000004000 0000000000004000 00003000 2**3
CONTENTS, ALLOC, LOAD, DATA
25 .bss 00000008 0000000000004010 0000000000004010 00003010 2**0
ALLOC
26 .comment 0000002b 0000000000000000 0000000000000000 00003010 2**0
CONTENTS, READONLY
27 .debug_aranges 00000030 0000000000000000 0000000000000000 0000303b 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
28 .debug_info 000000a6 0000000000000000 0000000000000000 0000306b 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
29 .debug_abbrev 0000005e 0000000000000000 0000000000000000 00003111 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
30 .debug_line 0000005f 0000000000000000 0000000000000000 0000316f 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
31 .debug_str 000000df 0000000000000000 0000000000000000 000031ce 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
32 .debug_line_str 00000011 0000000000000000 0000000000000000 000032ad 2**0
CONTENTS, READONLY, DEBUGGING, OCTETS
root@lima-ebpf-dev:~#
5 显示所有 Headers #
objdump -x 显示所有 header 列表：
root@lima-ebpf-dev:~# objdump -w -x hello
hello: file format elf64-x86-64
hello
architecture: i386:x86-64, flags 0x00000150:
HAS_SYMS, DYNAMIC, D_PAGED
start address 0x0000000000001060
Program Header:
PHDR off 0x0000000000000040 vaddr 0x0000000000000040 paddr 0x0000000000000040 align 2**3
filesz 0x00000000000002d8 memsz 0x00000000000002d8 flags r--
INTERP off 0x0000000000000318 vaddr 0x0000000000000318 paddr 0x0000000000000318 align 2**0
filesz 0x000000000000001c memsz 0x000000000000001c flags r--
LOAD off 0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**12
filesz 0x0000000000000628 memsz 0x0000000000000628 flags r--
LOAD off 0x0000000000001000 vaddr 0x0000000000001000 paddr 0x0000000000001000 align 2**12
filesz 0x0000000000000185 memsz 0x0000000000000185 flags r-x
LOAD off 0x0000000000002000 vaddr 0x0000000000002000 paddr 0x0000000000002000 align 2**12
filesz 0x0000000000000114 memsz 0x0000000000000114 flags r--
LOAD off 0x0000000000002db8 vaddr 0x0000000000003db8 paddr 0x0000000000003db8 align 2**12
filesz 0x0000000000000258 memsz 0x0000000000000260 flags rw-
DYNAMIC off 0x0000000000002dc8 vaddr 0x0000000000003dc8 paddr 0x0000000000003dc8 align 2**3
filesz 0x00000000000001f0 memsz 0x00000000000001f0 flags rw-
NOTE off 0x0000000000000338 vaddr 0x0000000000000338 paddr 0x0000000000000338 align 2**3
filesz 0x0000000000000030 memsz 0x0000000000000030 flags r--
NOTE off 0x0000000000000368 vaddr 0x0000000000000368 paddr 0x0000000000000368 align 2**2
filesz 0x0000000000000044 memsz 0x0000000000000044 flags r--
0x6474e553 off 0x0000000000000338 vaddr 0x0000000000000338 paddr 0x0000000000000338 align 2**3
filesz 0x0000000000000030 memsz 0x0000000000000030 flags r--
EH_FRAME off 0x000000000000200c vaddr 0x000000000000200c paddr 0x000000000000200c align 2**2
filesz 0x000000000000003c memsz 0x000000000000003c flags r--
STACK off 0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**4
filesz 0x0000000000000000 memsz 0x0000000000000000 flags rw-
RELRO off 0x0000000000002db8 vaddr 0x0000000000003db8 paddr 0x0000000000003db8 align 2**0
filesz 0x0000000000000248 memsz 0x0000000000000248 flags r--
Dynamic Section:
NEEDED libc.so.6
INIT 0x0000000000001000
FINI 0x0000000000001178
INIT_ARRAY 0x0000000000003db8
INIT_ARRAYSZ 0x0000000000000008
FINI_ARRAY 0x0000000000003dc0
FINI_ARRAYSZ 0x0000000000000008
GNU_HASH 0x00000000000003b0
STRTAB 0x0000000000000480
SYMTAB 0x00000000000003d8
STRSZ 0x000000000000008d
SYMENT 0x0000000000000018
DEBUG 0x0000000000000000
PLTGOT 0x0000000000003fb8
PLTRELSZ 0x0000000000000018
PLTREL 0x0000000000000007
JMPREL 0x0000000000000610
RELA 0x0000000000000550
RELASZ 0x00000000000000c0
RELAENT 0x0000000000000018
FLAGS 0x0000000000000008
FLAGS_1 0x0000000008000001
VERNEED 0x0000000000000520
VERNEEDNUM 0x0000000000000001
VERSYM 0x000000000000050e
RELACOUNT 0x0000000000000003
Version References:
required from libc.so.6:
0x09691a75 0x00 03 GLIBC_2.2.5
0x069691b4 0x00 02 GLIBC_2.34
Sections:
Idx Name Size VMA LMA File off Algn Flags
0 .interp 0000001c 0000000000000318 0000000000000318 00000318 2**0 CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.gnu.property 00000030 0000000000000338 0000000000000338 00000338 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .note.gnu.build-id 00000024 0000000000000368 0000000000000368 00000368 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .note.ABI-tag 00000020 000000000000038c 000000000000038c 0000038c 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .gnu.hash 00000024 00000000000003b0 00000000000003b0 000003b0 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .dynsym 000000a8 00000000000003d8 00000000000003d8 000003d8 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .dynstr 0000008d 0000000000000480 0000000000000480 00000480 2**0 CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .gnu.version 0000000e 000000000000050e 000000000000050e 0000050e 2**1 CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .gnu.version_r 00000030 0000000000000520 0000000000000520 00000520 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .rela.dyn 000000c0 0000000000000550 0000000000000550 00000550 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .rela.plt 00000018 0000000000000610 0000000000000610 00000610 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
11 .init 0000001b 0000000000001000 0000000000001000 00001000 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .plt 00000020 0000000000001020 0000000000001020 00001020 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .plt.got 00000010 0000000000001040 0000000000001040 00001040 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE
14 .plt.sec 00000010 0000000000001050 0000000000001050 00001050 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE
15 .text 00000117 0000000000001060 0000000000001060 00001060 2**4 CONTENTS, ALLOC, LOAD, READONLY, CODE
16 .fini 0000000d 0000000000001178 0000000000001178 00001178 2**2 CONTENTS, ALLOC, LOAD, READONLY, CODE
17 .rodata 0000000b 0000000000002000 0000000000002000 00002000 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .eh_frame_hdr 0000003c 000000000000200c 000000000000200c 0000200c 2**2 CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .eh_frame 000000cc 0000000000002048 0000000000002048 00002048 2**3 CONTENTS, ALLOC, LOAD, READONLY, DATA
20 .init_array 00000008 0000000000003db8 0000000000003db8 00002db8 2**3 CONTENTS, ALLOC, LOAD, DATA
21 .fini_array 00000008 0000000000003dc0 0000000000003dc0 00002dc0 2**3 CONTENTS, ALLOC, LOAD, DATA
22 .dynamic 000001f0 0000000000003dc8 0000000000003dc8 00002dc8 2**3 CONTENTS, ALLOC, LOAD, DATA
23 .got 00000048 0000000000003fb8 0000000000003fb8 00002fb8 2**3 CONTENTS, ALLOC, LOAD, DATA
24 .data 00000010 0000000000004000 0000000000004000 00003000 2**3 CONTENTS, ALLOC, LOAD, DATA
25 .bss 00000008 0000000000004010 0000000000004010 00003010 2**0 ALLOC
26 .comment 0000002d 0000000000000000 0000000000000000 00003010 2**0 CONTENTS, READONLY
27 .gnu_debuglink 00000010 0000000000000000 0000000000000000 00003040 2**2 CONTENTS, READONLY
SYMBOL TABLE:
0000000000000000 l df *ABS* 0000000000000000 Scrt1.o
000000000000038c l O .note.ABI-tag 0000000000000020 __abi_tag
0000000000000000 l df *ABS* 0000000000000000 crtstuff.c
0000000000001090 l F .text 0000000000000000 deregister_tm_clones
00000000000010c0 l F .text 0000000000000000 register_tm_clones
0000000000001100 l F .text 0000000000000000 __do_global_dtors_aux
0000000000004010 l O .bss 0000000000000001 completed.0
0000000000003dc0 l O .fini_array 0000000000000000 __do_global_dtors_aux_fini_array_entry
0000000000001140 l F .text 0000000000000000 frame_dummy
0000000000003db8 l O .init_array 0000000000000000 __frame_dummy_init_array_entry
0000000000000000 l df *ABS* 0000000000000000 test.c
0000000000000000 l df *ABS* 0000000000000000 crtstuff.c
0000000000002110 l O .eh_frame 0000000000000000 __FRAME_END__
0000000000000000 l df *ABS* 0000000000000000
0000000000003dc8 l O .dynamic 0000000000000000 _DYNAMIC
000000000000200c l .eh_frame_hdr 0000000000000000 __GNU_EH_FRAME_HDR
0000000000003fb8 l O .got 0000000000000000 _GLOBAL_OFFSET_TABLE_
0000000000000000 F *UND* 0000000000000000 __libc_start_main@GLIBC_2.34
0000000000000000 w *UND* 0000000000000000 _ITM_deregisterTMCloneTable
0000000000004000 w .data 0000000000000000 data_start
0000000000000000 F *UND* 0000000000000000 puts@GLIBC_2.2.5
0000000000004010 g .data 0000000000000000 _edata
0000000000001178 g F .fini 0000000000000000 .hidden _fini
0000000000001149 g F .text 000000000000001a hello
0000000000004000 g .data 0000000000000000 __data_start
0000000000000000 w *UND* 0000000000000000 __gmon_start__
0000000000004008 g O .data 0000000000000000 .hidden __dso_handle
0000000000002000 g O .rodata 0000000000000004 _IO_stdin_used
0000000000004018 g .bss 0000000000000000 _end
0000000000001060 g F .text 0000000000000026 _start
0000000000004010 g .bss 0000000000000000 __bss_start
0000000000001163 g F .text 0000000000000014 main
0000000000004010 g O .data 0000000000000000 .hidden __TMC_END__
0000000000000000 w *UND* 0000000000000000 _ITM_registerTMCloneTable
0000000000000000 w F *UND* 0000000000000000 __cxa_finalize@GLIBC_2.2.5
0000000000001000 g F .init 0000000000000000 .hidden _init
6 反汇编可执行 Sections #
objdump -d 反汇编所有可执行 executable sections 的内容：
root@lima-ebpf-dev:~# objdump -w -d hello
hello: file format elf64-x86-64
Disassembly of section .init:
0000000000001000 <_init>:
1000: f3 0f 1e fa endbr64
1004: 48 83 ec 08 sub $0x8,%rsp
1008: 48 8b 05 d9 2f 00 00 mov 0x2fd9(%rip),%rax # 3fe8 <__gmon_start__@Base>
100f: 48 85 c0 test %rax,%rax
1012: 74 02 je 1016 <_init+0x16>
1014: ff d0 call *%rax
1016: 48 83 c4 08 add $0x8,%rsp
101a: c3 ret
Disassembly of section .plt:
0000000000001020 <.plt>:
1020: ff 35 9a 2f 00 00 push 0x2f9a(%rip) # 3fc0 <_GLOBAL_OFFSET_TABLE_+0x8>
1026: f2 ff 25 9b 2f 00 00 bnd jmp *0x2f9b(%rip) # 3fc8 <_GLOBAL_OFFSET_TABLE_+0x10>
102d: 0f 1f 00 nopl (%rax)
1030: f3 0f 1e fa endbr64
1034: 68 00 00 00 00 push $0x0
1039: f2 e9 e1 ff ff ff bnd jmp 1020 <_init+0x20>
103f: 90 nop
Disassembly of section .plt.got:
0000000000001040 <__cxa_finalize@plt>:
1040: f3 0f 1e fa endbr64
1044: f2 ff 25 ad 2f 00 00 bnd jmp *0x2fad(%rip) # 3ff8 <__cxa_finalize@GLIBC_2.2.5>
104b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
Disassembly of section .plt.sec:
0000000000001050 <puts@plt>:
1050: f3 0f 1e fa endbr64
1054: f2 ff 25 75 2f 00 00 bnd jmp *0x2f75(%rip) # 3fd0 <puts@GLIBC_2.2.5>
105b: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
Disassembly of section .text:
0000000000001060 <_start>:
1060: f3 0f 1e fa endbr64
1064: 31 ed xor %ebp,%ebp
1066: 49 89 d1 mov %rdx,%r9
1069: 5e pop %rsi
106a: 48 89 e2 mov %rsp,%rdx
106d: 48 83 e4 f0 and $0xfffffffffffffff0,%rsp
1071: 50 push %rax
1072: 54 push %rsp
1073: 45 31 c0 xor %r8d,%r8d
1076: 31 c9 xor %ecx,%ecx
1078: 48 8d 3d e4 00 00 00 lea 0xe4(%rip),%rdi # 1163 <main>
107f: ff 15 53 2f 00 00 call *0x2f53(%rip) # 3fd8 <__libc_start_main@GLIBC_2.34>
1085: f4 hlt
1086: 66 2e 0f 1f 84 00 00 00 00 00 cs nopw 0x0(%rax,%rax,1)
0000000000001090 <deregister_tm_clones>:
1090: 48 8d 3d 79 2f 00 00 lea 0x2f79(%rip),%rdi # 4010 <__TMC_END__>
1097: 48 8d 05 72 2f 00 00 lea 0x2f72(%rip),%rax # 4010 <__TMC_END__>
109e: 48 39 f8 cmp %rdi,%rax
10a1: 74 15 je 10b8 <deregister_tm_clones+0x28>
10a3: 48 8b 05 36 2f 00 00 mov 0x2f36(%rip),%rax # 3fe0 <_ITM_deregisterTMCloneTable@Base>
10aa: 48 85 c0 test %rax,%rax
10ad: 74 09 je 10b8 <deregister_tm_clones+0x28>
10af: ff e0 jmp *%rax
10b1: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
10b8: c3 ret
10b9: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
00000000000010c0 <register_tm_clones>:
10c0: 48 8d 3d 49 2f 00 00 lea 0x2f49(%rip),%rdi # 4010 <__TMC_END__>
10c7: 48 8d 35 42 2f 00 00 lea 0x2f42(%rip),%rsi # 4010 <__TMC_END__>
10ce: 48 29 fe sub %rdi,%rsi
10d1: 48 89 f0 mov %rsi,%rax
10d4: 48 c1 ee 3f shr $0x3f,%rsi
10d8: 48 c1 f8 03 sar $0x3,%rax
10dc: 48 01 c6 add %rax,%rsi
10df: 48 d1 fe sar %rsi
10e2: 74 14 je 10f8 <register_tm_clones+0x38>
10e4: 48 8b 05 05 2f 00 00 mov 0x2f05(%rip),%rax # 3ff0 <_ITM_registerTMCloneTable@Base>
10eb: 48 85 c0 test %rax,%rax
10ee: 74 08 je 10f8 <register_tm_clones+0x38>
10f0: ff e0 jmp *%rax
10f2: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
10f8: c3 ret
10f9: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0000000000001100 <__do_global_dtors_aux>:
1100: f3 0f 1e fa endbr64
1104: 80 3d 05 2f 00 00 00 cmpb $0x0,0x2f05(%rip) # 4010 <__TMC_END__>
110b: 75 2b jne 1138 <__do_global_dtors_aux+0x38>
110d: 55 push %rbp
110e: 48 83 3d e2 2e 00 00 00 cmpq $0x0,0x2ee2(%rip) # 3ff8 <__cxa_finalize@GLIBC_2.2.5>
1116: 48 89 e5 mov %rsp,%rbp
1119: 74 0c je 1127 <__do_global_dtors_aux+0x27>
111b: 48 8b 3d e6 2e 00 00 mov 0x2ee6(%rip),%rdi # 4008 <__dso_handle>
1122: e8 19 ff ff ff call 1040 <__cxa_finalize@plt>
1127: e8 64 ff ff ff call 1090 <deregister_tm_clones>
112c: c6 05 dd 2e 00 00 01 movb $0x1,0x2edd(%rip) # 4010 <__TMC_END__>
1133: 5d pop %rbp
1134: c3 ret
1135: 0f 1f 00 nopl (%rax)
1138: c3 ret
1139: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
0000000000001140 <frame_dummy>:
1140: f3 0f 1e fa endbr64
1144: e9 77 ff ff ff jmp 10c0 <register_tm_clones>
0000000000001149 <hello>:
1149: f3 0f 1e fa endbr64
114d: 55 push %rbp
114e: 48 89 e5 mov %rsp,%rbp
1151: 48 8d 05 ac 0e 00 00 lea 0xeac(%rip),%rax # 2004 <_IO_stdin_used+0x4>
1158: 48 89 c7 mov %rax,%rdi
115b: e8 f0 fe ff ff call 1050 <puts@plt>
1160: 90 nop
1161: 5d pop %rbp
1162: c3 ret
0000000000001163 <main>:
1163: f3 0f 1e fa endbr64
1167: 55 push %rbp
1168: 48 89 e5 mov %rsp,%rbp
116b: e8 d9 ff ff ff call 1149 <hello>
1170: b8 00 00 00 00 mov $0x0,%eax
1175: 5d pop %rbp
1176: c3 ret
Disassembly of section .fini:
0000000000001178 <_fini>:
1178: f3 0f 1e fa endbr64
117c: 48 83 ec 08 sub $0x8,%rsp
1180: 48 83 c4 08 add $0x8,%rsp
1184: c3 ret
root@lima-ebpf-dev:~#
objdump –disassemble=<sym> 反汇编指定 symbol 的内容：
root@lima-ebpf-dev:~# objdump -w --disassemble=hello hello
hello: file format elf64-x86-64
Disassembly of section .init:
Disassembly of section .plt:
Disassembly of section .plt.got:
Disassembly of section .plt.sec:
Disassembly of section .text:
0000000000001149 <hello>:
1149: f3 0f 1e fa endbr64
114d: 55 push %rbp
114e: 48 89 e5 mov %rsp,%rbp
1151: 48 8d 05 ac 0e 00 00 lea 0xeac(%rip),%rax # 2004 <_IO_stdin_used+0x4>
1158: 48 89 c7 mov %rax,%rdi
115b: e8 f0 fe ff ff call 1050 <puts@plt>
1160: 90 nop
1161: 5d pop %rbp
1162: c3 ret
Disassembly of section .fini:
root@lima-ebpf-dev:~#
objdump -S/–source 反汇编时显示源文件的内容：
- -S 使用的是 build-id 而非 gnu debug link 机制，必须将 debug file 放到
/usr/lib/debug/.build-id目录下时，才会显示源文件内容。
root@lima-ebpf-dev:~# strace -e openat objdump -S hello |& grep /usr/lib/debug
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 4
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 5
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 5
openat(AT_FDCWD, "/usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/root/hello.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/root/hello.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
root@lima-ebpf-dev:~#
root@lima-ebpf-dev:~# objdump -S --disassemble=hello hello
hello: file format elf64-x86-64
Disassembly of section .init:
Disassembly of section .plt:
Disassembly of section .plt.got:
Disassembly of section .plt.sec:
Disassembly of section .text:
0000000000001149 <hello>:
1149: f3 0f 1e fa endbr64
114d: 55 push %rbp
114e: 48 89 e5 mov %rsp,%rbp
1151: 48 8d 05 ac 0e 00 00 lea 0xeac(%rip),%rax # 2004 <_IO_stdin_used+0x4>
1158: 48 89 c7 mov %rax,%rdi
115b: e8 f0 fe ff ff call 1050 <puts@plt>
1160: 90 nop
1161: 5d pop %rbp
1162: c3 ret
Disassembly of section .fini:
root@lima-ebpf-dev:~# mv /usr/lib/debug/hello.debug /usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug
root@lima-ebpf-dev:~# objdump -S --disassemble=hello hello
hello: file format elf64-x86-64
Disassembly of section .init:
Disassembly of section .plt:
Disassembly of section .plt.got:
Disassembly of section .plt.sec:
Disassembly of section .text:
0000000000001149 <hello>:
#include <stdio.h>
void hello(void){
1149: f3 0f 1e fa endbr64
114d: 55 push %rbp
114e: 48 89 e5 mov %rsp,%rbp
printf("hello!\n");
1151: 48 8d 05 ac 0e 00 00 lea 0xeac(%rip),%rax # 2004 <_IO_stdin_used+0x4>
1158: 48 89 c7 mov %rax,%rdi
115b: e8 f0 fe ff ff call 1050 <puts@plt>
}
1160: 90 nop
1161: 5d pop %rbp
1162: c3 ret
Disassembly of section .fini:
root@lima-ebpf-dev:~#
7 显示 Sections 内容 #
objdump -s 十六进制显示对象文件各 Section 的内容：
root@lima-ebpf-dev:~# objdump -s hello |tail
3fe8 00000000 00000000 00000000 00000000 ................
3ff8 00000000 00000000 ........
Contents of section .data:
4000 00000000 00000000 08400000 00000000 .........@......
Contents of section .comment:
0000 4743433a 20285562 756e7475 2031312e GCC: (Ubuntu 11.
0010 332e302d 31756275 6e747531 7e32322e 3.0-1ubuntu1~22.
0020 30342e31 29203131 2e332e30 00 04.1) 11.3.0.
Contents of section .gnu_debuglink:
0000 68656c6c 6f2e6465 62756700 a3c55b6a hello.debug...[j
通过添加 -j SECTION 来只显示指定 SECTION 的内容：
root@lima-ebpf-dev:~# objdump -s hello -j .comment
hello: file format elf64-x86-64
Contents of section .comment:
0000 4743433a 20285562 756e7475 2031312e GCC: (Ubuntu 11.
0010 342e302d 31756275 6e747531 7e32322e 4.0-1ubuntu1~22.
0020 30342920 31312e34 2e3000 04) 11.4.0.
8 显示符号表 #
objdump -t/–syms 显示符号表：
- 会在 /usr/lib/debug 目录下查找 hello.debug 或者使用 .build-id 来查找 debug 文件，然后提取符号表。所以，即使二进制本身被 strip，只要有 debug 文件，也能显示符号表。
root@lima-ebpf-dev:~# objdump -t hello
hello: file format elf64-x86-64
SYMBOL TABLE:
0000000000000000 l df *ABS* 0000000000000000 Scrt1.o
000000000000038c l O .note.ABI-tag 0000000000000020 __abi_tag
0000000000000000 l df *ABS* 0000000000000000 crtstuff.c
0000000000001090 l F .text 0000000000000000 deregister_tm_clones
00000000000010c0 l F .text 0000000000000000 register_tm_clones
0000000000001100 l F .text 0000000000000000 __do_global_dtors_aux
0000000000004010 l O .bss 0000000000000001 completed.0
0000000000003dc0 l O .fini_array 0000000000000000 __do_global_dtors_aux_fini_array_entry
0000000000001140 l F .text 0000000000000000 frame_dummy
0000000000003db8 l O .init_array 0000000000000000 __frame_dummy_init_array_entry
0000000000000000 l df *ABS* 0000000000000000 test.c
0000000000000000 l df *ABS* 0000000000000000 crtstuff.c
0000000000002110 l O .eh_frame 0000000000000000 __FRAME_END__
0000000000000000 l df *ABS* 0000000000000000
0000000000003dc8 l O .dynamic 0000000000000000 _DYNAMIC
000000000000200c l .eh_frame_hdr 0000000000000000 __GNU_EH_FRAME_HDR
0000000000003fb8 l O .got 0000000000000000 _GLOBAL_OFFSET_TABLE_
0000000000000000 F *UND* 0000000000000000 __libc_start_main@GLIBC_2.34
0000000000000000 w *UND* 0000000000000000 _ITM_deregisterTMCloneTable
0000000000004000 w .data 0000000000000000 data_start
0000000000000000 F *UND* 0000000000000000 puts@GLIBC_2.2.5
0000000000004010 g .data 0000000000000000 _edata
0000000000001178 g F .fini 0000000000000000 .hidden _fini
0000000000001149 g F .text 000000000000001a hello
0000000000004000 g .data 0000000000000000 __data_start
0000000000000000 w *UND* 0000000000000000 __gmon_start__
0000000000004008 g O .data 0000000000000000 .hidden __dso_handle
0000000000002000 g O .rodata 0000000000000004 _IO_stdin_used
0000000000004018 g .bss 0000000000000000 _end
0000000000001060 g F .text 0000000000000026 _start
0000000000004010 g .bss 0000000000000000 __bss_start
0000000000001163 g F .text 0000000000000014 main
0000000000004010 g O .data 0000000000000000 .hidden __TMC_END__
0000000000000000 w *UND* 0000000000000000 _ITM_registerTMCloneTable
0000000000000000 w F *UND* 0000000000000000 __cxa_finalize@GLIBC_2.2.5
0000000000001000 g F .init 0000000000000000 .hidden _init
root@lima-ebpf-dev:~#
root@lima-ebpf-dev:~# strace -f -e open,openat objdump -t hello |& grep /lib/debug/
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 4
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 5
openat(AT_FDCWD, "/usr/lib/debug/hello.debug", O_RDONLY) = 5
openat(AT_FDCWD, "/usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/usr/lib/debug/usr/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug", O_RDONLY) = -1 ENOENT (No such file or directory)
objdump -T/–dynamic-syms： 显示动态符号表：
root@lima-ebpf-dev:~# objdump -T hello
hello: file format elf64-x86-64
DYNAMIC SYMBOL TABLE:
0000000000000000 DF *UND* 0000000000000000 (GLIBC_2.34) __libc_start_main
0000000000000000 w D *UND* 0000000000000000 Base _ITM_deregisterTMCloneTable
0000000000000000 DF *UND* 0000000000000000 (GLIBC_2.2.5) puts
0000000000000000 w D *UND* 0000000000000000 Base __gmon_start__
0000000000000000 w D *UND* 0000000000000000 Base _ITM_registerTMCloneTable
0000000000000000 w DF *UND* 0000000000000000 (GLIBC_2.2.5) __cxa_finalize
root@lima-ebpf-dev:~#
9 显示调试符号表 DWARF #
objdump -g/-W 显示文件的 DWARF 格式的 debug 信息：
- 直接从文件中读，或者根据 debug-link/build-id 从系统
/usr/lib/debug读取 debug 文件。root@lima-ebpf-dev:~# objdump -w -g hello Contents of the .debug_aranges section (loaded from /usr/lib/debug/hello.debug): Length: 44 Version: 2 Offset into .debug_info: 0x0 Pointer Size: 8 Segment Size: 0 Address Length 0000000000001149 000000000000002e 0000000000000000 0000000000000000 Contents of the .debug_info section (loaded from /usr/lib/debug/hello.debug): Compilation Unit @ offset 0x0: Length: 0xa2 (32-bit) Version: 5 Unit Type: DW_UT_compile (1) Abbrev Offset: 0x0 Pointer Size: 8 <0><c>: Abbrev Number: 2 (DW_TAG_compile_unit) <d> DW_AT_producer : (strp) (offset: 0x35): GNU C17 11.3.0 -mtune=generic -march=x86-64 -g -fasynchronous-unwind-tables -fstack-protector-strong -fstack-clash-protection -fcf-protection <11> DW_AT_language : (data1) 29 (C11) <12> DW_AT_name : (line_strp) (offset: 0x0): test.c <16> DW_AT_comp_dir : (line_strp) (offset: 0x7): /root <1a> DW_AT_low_pc : (addr) 0x1149 <22> DW_AT_high_pc : (data8) ... Contents of the .gnu_debuglink section (loaded from hello): Separate debug info file: hello.debug CRC value: 0x6a5bc5a3 root@lima-ebpf-dev:~#
objdump –dwarf 可以指定要打印的 DWARF 内容类型，支持如下参数：-W, –dwarf[a/=abbrev, A/=addr, r/=aranges, c/=cu_index, L/=decodedline, f/=frames, F/=frames-interp, g/=gdb_index, i/=info, o/=loc, m/=macro, p/=pubnames, t/=pubtypes, R/=Ranges, l/=rawline, s/=str, O/=str-offsets, u/=trace_abbrev, T/=trace_aranges, U/=trace_info]
例如打印内存地址和源码行之间的关系；
root@lima-ebpf-dev:~# objdump --dwarf=decodedline hello
Contents of the .debug_line section (loaded from /usr/lib/debug/.build-id/7e/31292c839740f24092f371f1e85cd9ad74a79b.debug):
test.c:
File name Line number Starting address View Stmt
test.c 3 0x1149 x
test.c 4 0x1151 x
test.c 5 0x1160 x
test.c 6 0x1163 x
test.c 7 0x116b x
test.c 8 0x1170 x
test.c 9 0x1175 x
test.c - 0x1177
hello: file format elf64-x86-64
root@lima-ebpf-dev:~#