x64なHello World

hello.c

#include <unistd.h>
#include <sys/mman.h>

static const unsigned char code[] =
  // mov $0x01,%rax
  "\x48\xc7\xc0\x01\x00\x00\x00"
  // mov $0x0d,%edx
  "\xba\x0d\x00\x00\x00"
  // mov $0x01,%edi
  "\xbf\x01\x00\x00\x00"
  // callq
  "\xe8\x0a\x00\x00\x00"
  // add $0x0f,%rsi
  "\x48\x81\xc6\x0f\x00\x00\x00"
  // syscall
  "\x0f\x05"
  // ret
  "\xc3"
  // (%rsp),%rsi
  "\x48\x8b\x34\x24"
  // ret
  "\xc3"
  "Hello World!\n";


int
main(void)
{
  unsigned long page_size = (unsigned long) (sysconf(_SC_PAGESIZE) - 1);
  mprotect((void *) code, (sizeof(code) + page_size) & ~page_size, PROT_READ | PROT_EXEC);
  ((void (*)()) (unsigned char *) code)();
  return 0;
}