Relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `my_fn'

Can some one help to solve the error -

have the following code in one file, got linker error of: “undefined reference to main_fn' relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol my_fn’”

… #![feature(global_asm)] … global_asm!( r#"

.section .text … bl main_fn lp_nop: nop b lp_nop "# );

pub unsafe fn my_fn()
{
let mut addr: u32 = 0xf7113000;
let _raw_mut = &mut addr as *mut u32;
while true {
unsafe { *_raw_mut = 88; }
}
}