Error: the BPF_PROG_LOAD syscall failed.

[Godones]

When I used a variable initialized to 0 in the program, an error occurred while loading the ebpf program.
The test code is as follows：

static mut MASK: usize = 1;
static mut MASK2: usize = 0;
#[kprobe]
pub fn myapp(ctx: ProbeContext) -> u32 {
    unsafe {
        MASK += 1;
        MASK2 +=1;
    }
    0
}

The error message is as follows：

Error: the BPF_PROG_LOAD syscall failed. Verifier output: 0: R1=ctx(off=0,imm=0) R10=fp0
0: (18) r1 = 0xffff8e21015e6f10       ; R1_w=map_value(off=0,ks=4,vs=8,imm=0)
2: (79) r2 = *(u64 *)(r1 +0)          ; R1_w=map_value(off=0,ks=4,vs=8,imm=0) R2_w=scalar()
3: (07) r2 += 1                       ; R2_w=scalar()
4: (7b) *(u64 *)(r1 +0) = r2          ; R1_w=map_value(off=0,ks=4,vs=8,imm=0) R2_w=scalar()
5: (18) r1 = 0xffff8e21015e5a00       ; R1_w=map_ptr(off=0,ks=4,vs=8,imm=0)
7: (79) r2 = *(u64 *)(r1 +0)          ; R1_w=map_ptr(off=0,ks=4,vs=8,imm=0) R2_w=ptr_bpf_map_ops(off=0,imm=0)
8: (07) r2 += 1                       ; R2_w=ptr_bpf_map_ops(off=1,imm=0)
9: (7b) *(u64 *)(r1 +0) = r2
only read from bpf_array is supported
verification time 16 usec
stack depth 0
processed 8 insns (limit 1000000) max_states_per_insn 0 total_states 0 peak_states 0 mark_read 0

[harry-xm]

only read from bpf_array is supported

You are trying to access a static item, which is not supported in BPF. You will need to maintain state in a BPF map:

The eBPF Virtual Machine, where our eBPF programs will be run, is a constrained runtime environment:

• There is only 512 bytes of stack (or 256 bytes if we are using tail calls).
• There is no access to heap space and data must instead be written to maps.

https://aya-rs.dev/book/#ebpf-program-constraints