1 ; test source file for assembling to ELF shared library 2 ; build with: 3 ; nasm -f elf elfso.asm 4 ; ld -shared -o elfso.so elfso.o 5 ; test with: 6 ; gcc -o elfso elftest.c ./elfso.so 7 ; ./elfso 8 ; (assuming your gcc is ELF, and you're running bash) 9 10 ; This file should test the following: 11 ; [1] Define and export a global text-section symbol 12 ; [2] Define and export a global data-section symbol 13 ; [3] Define and export a global BSS-section symbol 14 ; [4] Define a non-global text-section symbol 15 ; [5] Define a non-global data-section symbol 16 ; [6] Define a non-global BSS-section symbol 17 ; [7] Define a COMMON symbol 18 ; [8] Define a NASM local label 19 ; [9] Reference a NASM local label 20 ; [10] Import an external symbol 21 ; [11] Make a PC-relative call to an external symbol 22 ; [12] Reference a text-section symbol in the text section 23 ; [13] Reference a data-section symbol in the text section 24 ; [14] Reference a BSS-section symbol in the text section 25 ; [15] Reference a text-section symbol in the data section 26 ; [16] Reference a data-section symbol in the data section 27 ; [17] Reference a BSS-section symbol in the data section 28 29 BITS 32 30 GLOBAL lrotate:function ; [1] 31 GLOBAL greet:function ; [1] 32 GLOBAL asmstr:data asmstr.end-asmstr ; [2] 33 GLOBAL textptr:data 4 ; [2] 34 GLOBAL selfptr:data 4 ; [2] 35 GLOBAL integer:data 4 ; [3] 36 EXTERN printf ; [10] 37 COMMON commvar 4:4 ; [7] 38 EXTERN _GLOBAL_OFFSET_TABLE_ 39 40 SECTION .text 41 42 ; prototype: long lrotate(long x, int num); 43 lrotate: ; [1] 44 push ebp 45 mov ebp,esp 46 mov eax,[ebp+8] 47 mov ecx,[ebp+12] 48 .label rol eax,1 ; [4] [8] 49 loop .label ; [9] [12] 50 mov esp,ebp 51 pop ebp 52 ret 53 54 ; prototype: void greet(void); 55 greet push ebx ; we'll use EBX for GOT, so save it 56 call .getgot 57 .getgot: pop ebx 58 add ebx,_GLOBAL_OFFSET_TABLE_ + $$ - .getgot wrt ..gotpc 59 mov eax,[ebx+integer wrt ..got] ; [14] 60 mov eax,[eax] 61 inc eax 62 mov [ebx+localint wrt ..gotoff],eax ; [14] 63 mov eax,[ebx+commvar wrt ..got] 64 push dword [eax] 65 mov eax,[ebx+localptr wrt ..gotoff] ; [13] 66 push dword [eax] 67 mov eax,[ebx+integer wrt ..got] ; [1] [14] 68 push dword [eax] 69 lea eax,[ebx+printfstr wrt ..gotoff] 70 push eax ; [13] 71 call printf wrt ..plt ; [11] 72 add esp,16 73 pop ebx 74 ret 75 76 SECTION .data 77 78 ; a string 79 asmstr db 'hello, world', 0 ; [2] 80 .end 81 82 ; a string for Printf 83 printfstr db "integer==%d, localint==%d, commvar=%d" 84 db 10, 0 85 86 ; some pointers 87 localptr dd localint ; [5] [17] 88 textptr dd greet wrt ..sym ; [15] 89 selfptr dd selfptr wrt ..sym ; [16] 90 91 SECTION .bss 92 93 ; an integer 94 integer resd 1 ; [3] 95 96 ; a local integer 97 localint resd 1 ; [6] 98
