98 lines
2.6 KiB
NASM
98 lines
2.6 KiB
NASM
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; test source file for assembling to ELF shared library
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; build with:
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; nasm -f elf elfso.asm
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; ld -shared -o elfso.so elfso.o
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; test with:
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; gcc -o elfso elftest.c ./elfso.so
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; ./elfso
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; (assuming your gcc is ELF, and you're running bash)
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; This file should test the following:
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; [1] Define and export a global text-section symbol
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; [2] Define and export a global data-section symbol
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; [3] Define and export a global BSS-section symbol
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; [4] Define a non-global text-section symbol
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; [5] Define a non-global data-section symbol
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; [6] Define a non-global BSS-section symbol
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; [7] Define a COMMON symbol
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; [8] Define a NASM local label
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; [9] Reference a NASM local label
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; [10] Import an external symbol
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; [11] Make a PC-relative call to an external symbol
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; [12] Reference a text-section symbol in the text section
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; [13] Reference a data-section symbol in the text section
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; [14] Reference a BSS-section symbol in the text section
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; [15] Reference a text-section symbol in the data section
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; [16] Reference a data-section symbol in the data section
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; [17] Reference a BSS-section symbol in the data section
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BITS 32
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GLOBAL lrotate:function ; [1]
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GLOBAL greet:function ; [1]
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GLOBAL asmstr:data asmstr.end-asmstr ; [2]
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GLOBAL textptr:data 4 ; [2]
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GLOBAL selfptr:data 4 ; [2]
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GLOBAL integer:data 4 ; [3]
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EXTERN printf ; [10]
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COMMON commvar 4:4 ; [7]
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EXTERN _GLOBAL_OFFSET_TABLE_
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SECTION .text
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; prototype: long lrotate(long x, int num);
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lrotate: ; [1]
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push ebp
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mov ebp,esp
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mov eax,[ebp+8]
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mov ecx,[ebp+12]
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.label rol eax,1 ; [4] [8]
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loop .label ; [9] [12]
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mov esp,ebp
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pop ebp
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ret
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; prototype: void greet(void);
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greet push ebx ; we'll use EBX for GOT, so save it
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call .getgot
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.getgot: pop ebx
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add ebx,_GLOBAL_OFFSET_TABLE_ + $$ - .getgot wrt ..gotpc
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mov eax,[ebx+integer wrt ..got] ; [14]
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mov eax,[eax]
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inc eax
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mov [ebx+localint wrt ..gotoff],eax ; [14]
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mov eax,[ebx+commvar wrt ..got]
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push dword [eax]
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mov eax,[ebx+localptr wrt ..gotoff] ; [13]
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push dword [eax]
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mov eax,[ebx+integer wrt ..got] ; [1] [14]
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push dword [eax]
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lea eax,[ebx+printfstr wrt ..gotoff]
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push eax ; [13]
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call printf wrt ..plt ; [11]
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add esp,16
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pop ebx
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ret
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SECTION .data
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; a string
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asmstr db 'hello, world', 0 ; [2]
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.end
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; a string for Printf
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printfstr db "integer==%d, localint==%d, commvar=%d"
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db 10, 0
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; some pointers
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localptr dd localint ; [5] [17]
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textptr dd greet wrt ..sym ; [15]
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selfptr dd selfptr wrt ..sym ; [16]
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SECTION .bss
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; an integer
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integer resd 1 ; [3]
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; a local integer
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localint resd 1 ; [6]
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