This document discusses linking and loaders. It covers topics like object file formats (COFF, ELF, a.out), sections and segments, the linking process, dynamic linking using the procedure linkage table and global offset table, and relocation. Key terms discussed include loaders, linkers, sections like .text, .data, .bss, and dynamic linking concepts like position independent code.

1. ó ì?Ø
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Gdutor@gmail.com
TAIR
2012.02.05

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7. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
8I©‡
¹ •¹= &E
¹ ~„‚ªIO
¹ a.out/ELF‚ª©Û
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8. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
•¹= &E
¹ ©‡Þ
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9. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
~„‚ªIO
¹ COFF, Common Object File Format
¹ COM!PE, Portable Executable
¹ a.out
¹ ELF, Executable Linkable Format
[… Linkers

10. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
©‡ÞÜ
¹ Žê!©‡a.
¹ e !i!S!éàâÝ
¹ •/Œ
¹ §SÞ ˜!Œ !‡ê
¹ «ãÞ ˜!Œ !‡ê
Section vs. Segment
Section§«ãµÜ6 §¡•ó ì
Segment§ãµÔn §¡•1ì
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11. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
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¹ «ã¶¡!a.
¹ «ãIP
¹ «ãŒ !3©‡¥ £þ
¹ L‘Œ
¹ §SÞ ˜!Œ !‡ê
¹ éàâÝ
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12. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
«ãa.
¹ PROGBITS: .text, .data, .rodata
¹ NOBITS: .bss
¹ SYSTAB, DYNSYM: .symtab, .dynsym
¹ STRTAB: .strtab
¹ REL: .rel.txt, .rel.data, .rel.rodata
¹ DYNAMIC, HASH: .dynamic, .hash
¹ AÏ«ã: .got, .plt, .init, .fini, .interp, .line
[… Linkers

13. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K •¹ &E ~„‚ª ELF©Û
-½ ‘!ÎÒL
¹ -½ ‘
¸ I‡-½ ÎÒ
¸ I‡-½ /Œ
¸ /Œ°Ý
¸ ÎÒa.µSÜ/ Ü
¹ ÎÒL‘
¸ ÎÒ3iÎGL¥ ¢Ú
¸ ÎÒa.: ÛÜ/ Û/fÎÒ
¸ ´Ä½Â
¸ ÎÒŠ: ƒé/ýé/Œ
[… Linkers

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¹ •¡éà
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ÎÒ)Û
¹ ó ìÎÒL
¸ hashL
¸ õ«ÎÒL
¹ ¬L
¸ ^r ¬
¸ ¥ ¬
¹ AÏÎÒ
¸ .etext, .edata, .end
¸ fÎÒ
[… Linkers

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-½
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¸ M‡/^‡-½
¸ •-/êâ-½
¹ -½ žÅ
¸ ó ž-½
¸ 1ž-½
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18. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K · ¥/Ä ¥ Ä ó
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¹ •Ÿo¦^§S¥
¸ “èE^
¸ !Ž˜m
¹ ¥ «a
¸ · ¥
¸ Ä ¥
¸ •¥
[… Linkers

19. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K · ¥/Ä ¥ Ä ó
· ¥/Ä ¥
¹ ó •ª
¹ ©‡‚ª
[… Linkers

20. ƒ'¯K 8I©‡ ó L§ §S¥ ¢S¯K · ¥/Ä ¥ Ä ó
Ä ó n
¹ ˜Ã'“è: PIC
¹ Û £þL: GOT
¹ L§ó L: PLT
[… Linkers

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¹ CX¥¥ ÎÒ
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22. √
Thanks !
♥