mcsemaissue, undefined reference to `main'

test.c

#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include <stdint.h>
#include <string.h>

int getMemoryPermission(void*);
void smcInit(void*);

int main(){

	smcInit(main);
	uint8_t mcode[] = {'\xe9','\x00','\x00','\x00','\x00'};
	uint8_t mcode2[] = {'\x90', '\x90', '\x90', '\x90', '\x90'};
	memcpy(&&_branch, mcode2, 5); // this line make undefined `main' problem.
	// memcpy(mcode, mcode2, 5);

_branch:
	__asm__ __volatile__("_branch:\n"
	"jmp _end");


_deadblock:
	__asm__ __volatile__("_deadblock:\n"
	"nop\n"
	"nop\n"
	"nop\n"
	"nop\n"
	"nop\n"
);
	printf("Here is Dead Block.\n");
	printf("'jmp end' is relative 5bytes jmp instruction.\n");
	printf("code is modifed.\n");
	__asm__ __volatile__("jmp _return\n");


_end:	
	__asm__ __volatile__("_end:");
	printf("Not Modifed.\n");


_return:
	__asm__ __volatile__("_return:");
	return 0;
}

int getMemoryPermission(void *addr){
	// Move the pointer to the page boundary
	int page_size = getpagesize();
	addr -= (unsigned long)addr % page_size;

	if (mprotect(addr, page_size, PROT_READ | PROT_WRITE | PROT_EXEC) == -1)
	{
		return -1;
	}

	return 0;
}

void smcInit(void *addr){
	if(getMemoryPermission(addr)==-1){printf("Faield!\n");}
}