Assembly PIC test

main.c

#include <stdio.h>

/* Assembly function, calls foo() */
extern int foo_proxy(int a, int b);

int myGlobalInteger = 0;

int foo(int a, int b) {
    return a + b;
}

int main(void) {
    int result = foo_proxy(5, 6);
    printf("result: %d\n", result);
    printf("global: %d\n", myGlobalInteger);

    return 0;
}

Makefile

CC=gcc
CFLAGS=-Wall -Wextra -Ofast -fPIC
LDFLAGS=

AS=nasm
ASFLAGS=-f elf64

.PHONY: all clean

all: asm-pic-test.out

clean:
	rm -f asm-pic-test.out main.o test.o

asm-pic-test.out: main.o test.o
	$(CC) $(CFLAGS) -shared -o $@ $^ $(LDFLAGS)

main.o: main.c
	$(CC) $(CFLAGS) -c -o $@ $<

test.o: test.asm
	$(AS) $(ASFLAGS) -o $@ $<

test.asm

; Same output with and without this line
default REL

section .text
    extern myGlobalInteger
    extern foo

global foo_proxy
foo_proxy:
    mov     [myGlobalInteger], rdi
    jmp     foo