Моя машина - Ubuntu 16.04. И я хочу понять связь между разделом .bss и памятью. Поэтому я печатаю
readelf -e /usr/bin/find
и получите
ELF Header:
Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
Class: ELF64
Data: 2's complement, little endian
Version: 1 (current)
OS/ABI: UNIX - System V
ABI Version: 0
Type: DYN (Shared object file)
Machine: Advanced Micro Devices X86-64
Version: 0x1
Entry point address: 0x7340
Start of program headers: 64 (bytes into file)
Start of section headers: 219912 (bytes into file)
Flags: 0x0
Size of this header: 64 (bytes)
Size of program headers: 56 (bytes)
Number of program headers: 9
Size of section headers: 64 (bytes)
Number of section headers: 29
Section header string table index: 28
Section Headers:
[Nr] Name Type Address Offset
Size EntSize Flags Link Info Align
[ 0] NULL 0000000000000000 00000000
0000000000000000 0000000000000000 0 0 0
[ 1] .interp PROGBITS 0000000000000238 00000238
000000000000001c 0000000000000000 A 0 0 1
[ 2] .note.ABI-tag NOTE 0000000000000254 00000254
0000000000000020 0000000000000000 A 0 0 4
[ 3] .note.gnu.build-i NOTE 0000000000000274 00000274
0000000000000024 0000000000000000 A 0 0 4
[ 4] .gnu.hash GNU_HASH 0000000000000298 00000298
0000000000000164 0000000000000000 A 5 0 8
[ 5] .dynsym DYNSYM 0000000000000400 00000400
0000000000001200 0000000000000018 A 6 2 8
[ 6] .dynstr STRTAB 0000000000001600 00001600
0000000000000751 0000000000000000 A 0 0 1
[ 7] .gnu.version VERSYM 0000000000001d52 00001d52
0000000000000180 0000000000000002 A 5 0 2
[ 8] .gnu.version_r VERNEED 0000000000001ed8 00001ed8
00000000000000a0 0000000000000000 A 6 2 8
[ 9] .rela.dyn RELA 0000000000001f78 00001f78
0000000000004c38 0000000000000018 A 5 0 8
[10] .rela.plt RELA 0000000000006bb0 00006bb0
0000000000000048 0000000000000018 AI 5 24 8
[11] .init PROGBITS 0000000000006bf8 00006bf8
000000000000001a 0000000000000000 AX 0 0 4
[12] .plt PROGBITS 0000000000006c20 00006c20
0000000000000040 0000000000000010 AX 0 0 16
[13] .plt.got PROGBITS 0000000000006c60 00006c60
0000000000000470 0000000000000000 AX 0 0 8
[14] .text PROGBITS 00000000000070d0 000070d0
000000000001ebc9 0000000000000000 AX 0 0 16
[15] .fini PROGBITS 0000000000025c9c 00025c9c
0000000000000009 0000000000000000 AX 0 0 4
[16] .rodata PROGBITS 0000000000025cc0 00025cc0
00000000000064e6 0000000000000000 A 0 0 32
[17] .eh_frame_hdr PROGBITS 000000000002c1a8 0002c1a8
0000000000000fc4 0000000000000000 A 0 0 4
[18] .eh_frame PROGBITS 000000000002d170 0002d170
00000000000059cc 0000000000000000 A 0 0 8
[19] .init_array INIT_ARRAY 0000000000233188 00033188
0000000000000008 0000000000000000 WA 0 0 8
[20] .fini_array FINI_ARRAY 0000000000233190 00033190
0000000000000008 0000000000000000 WA 0 0 8
[21] .jcr PROGBITS 0000000000233198 00033198
0000000000000008 0000000000000000 WA 0 0 8
[22] .data.rel.ro PROGBITS 00000000002331a0 000331a0
00000000000016e0 0000000000000000 WA 0 0 32
[23] .dynamic DYNAMIC 0000000000234880 00034880
0000000000000210 0000000000000010 WA 6 0 8
[24] .got PROGBITS 0000000000234a90 00034a90
0000000000000570 0000000000000008 WA 0 0 8
[25] .data PROGBITS 0000000000235000 00035000
00000000000009c8 0000000000000000 WA 0 0 32
[26] .bss NOBITS 00000000002359e0 000359c8
00000000000012b0 0000000000000000 WA 0 0 32
[27] .gnu_debuglink PROGBITS 0000000000000000 000359c8
0000000000000034 0000000000000000 0 0 1
[28] .shstrtab STRTAB 0000000000000000 000359fc
0000000000000106 0000000000000000 0 0 1
Key to Flags:
W (write), A (alloc), X (execute), M (merge), S (strings), l (large)
I (info), L (link order), G (group), T (TLS), E (exclude), x (unknown)
O (extra OS processing required) o (OS specific), p (processor specific)
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
PHDR 0x0000000000000040 0x0000000000000040 0x0000000000000040
0x00000000000001f8 0x00000000000001f8 R E 8
INTERP 0x0000000000000238 0x0000000000000238 0x0000000000000238
0x000000000000001c 0x000000000000001c R 1
[Requesting program interpreter: /lib64/ld-linux-x86-64.so.2]
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000032b3c 0x0000000000032b3c R E 200000
LOAD 0x0000000000033188 0x0000000000233188 0x0000000000233188
0x0000000000002840 0x0000000000003b08 RW 200000
DYNAMIC 0x0000000000034880 0x0000000000234880 0x0000000000234880
0x0000000000000210 0x0000000000000210 RW 8
NOTE 0x0000000000000254 0x0000000000000254 0x0000000000000254
0x0000000000000044 0x0000000000000044 R 4
GNU_EH_FRAME 0x000000000002c1a8 0x000000000002c1a8 0x000000000002c1a8
0x0000000000000fc4 0x0000000000000fc4 R 4
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RW 10
GNU_RELRO 0x0000000000033188 0x0000000000233188 0x0000000000233188
0x0000000000001e78 0x0000000000001e78 R 1
Section to Segment mapping:
Segment Sections...
00
01 .interp
02 .interp .note.ABI-tag .note.gnu.build-id .gnu.hash .dynsym .dynstr .gnu.version .gnu.version_r .rela.dyn .rela.plt .init .plt .plt.got .text .fini .rodata .eh_frame_hdr .eh_frame
03 .init_array .fini_array .jcr .data.rel.ro .dynamic .got .data .bss
04 .dynamic
05 .note.ABI-tag .note.gnu.build-id
06 .eh_frame_hdr
07
08 .init_array .fini_array .jcr .data.rel.ro .dynamic .got
И мой вопрос: почему FileSiz сегмента данных плюс размер .bss не равен MemSiz сегмента данных (0x2840 + 0x12B0 = 0x3AF0！ = 0x3B08)?
Я также пытаюсь добавить все разделы сегмента данных (.init_array .fini_array .jcr .data.rel.ro .dynamic .got .data .bss) и получить 0x3AF0.
Где находится память байтов 0x18 (0x3B08-0x3AF0)?