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; test source file for assembling to ELF64 shared library
; build with:
; nasm -f elf64 elf64so.asm
; ld -shared -o elf64so.so elf64so.o
; test with:
; gcc -o elf64so elftest64.c ./elf64so.so
; ./elf64so
; 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 64
GLOBAL lrotate:function ; [1]
GLOBAL greet_s:function ; [1]
GLOBAL greet_m:function ; [1]
GLOBAL asmstr:data asmstr.end-asmstr ; [2]
GLOBAL textptr:data 8 ; [2]
GLOBAL selfptr:data 8 ; [2]
GLOBAL useless:data 8 ; [3]
GLOBAL integer:data 8 ; [3]
EXTERN printf ; [10]
COMMON commvar 8:8 ; [7]
EXTERN _GLOBAL_OFFSET_TABLE_
SECTION .text
; prototype: long lrotate(long x, int num);
lrotate: ; [1]
push rbp
mov rbp,rsp
mov rax,rdi
mov rcx,rsi
.label rol rax,1 ; [4] [8]
loop .label ; [9] [12]
mov rsp,rbp
pop rbp
ret
;; prototype: void greet_*(void);
;;
;; Arguments are: rdi - rsi - rdx - rcx - r8 - r9
;; Registers: rbx, rbp, r12-r15 are saved
;; greet_s() is Small PIC model, greet_m() is Medium PIC model
;; (Large model cannot be linked with other code)
;;
greet_s:
;; This instruction is useless, this is only a test...
cmp qword [rel integer wrt ..got],0
mov rax,[rel commvar wrt ..got] ; &commvar
mov rcx,[rax] ; commvar
mov rax,[rel integer wrt ..got] ; &integer
mov rsi,[rax]
lea rdx,[rsi+1]
mov [rel localint],rdx ; localint = integer+1
mov rax,[rel localptr] ; localptr
mov rdx,[rax] ; *localptr = localint
lea rdi,[rel printfstr]
xor eax,eax ; No fp arguments
jmp printf wrt ..plt ; [10]
greet_m:
push r15 ; Used by convention...
lea r15,[rel _GLOBAL_OFFSET_TABLE_]
mov rax,[rel commvar wrt ..got] ; &commvar
mov rcx,[rax] ; commvar
mov rax,[rel integer wrt ..got] ; &integer
mov rsi,[rax]
lea rdx,[rsi+1]
mov rax,localint wrt ..gotoff ; &localint - r15
mov [rax+r15],rdx ; localint = integer+1
mov rax,localptr wrt ..gotoff ; &localptr - r15
mov rax,[rax+r15] ; localptr
mov rdx,[rax] ; *localptr = localint
mov rdi,printfstr wrt ..gotoff ; &printfstr - r15
add rdi,r15 ; &printfstr
xor eax,eax ; No fp arguments
pop r15
jmp printf wrt ..plt ; [10]
SECTION .data
; a string
asmstr db 'hello, world', 0 ; [2]
.end:
; a string for Printf
printfstr db "integer=%ld, localint=%ld, commvar=%ld", 10, 0
; some pointers
localptr dq localint ; [5] [17]
textptr dq greet_s wrt ..sym ; [15]
selfptr dq selfptr wrt ..sym ; [16]
SECTION .bss
; a useless symbol
useless resq 1
; an integer
integer resq 1 ; [3]
; a local integer
localint resq 1 ; [6]
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