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