[PATCH bpf-next 2/2] arm64, bpf: support more atomic operations

[Daniel Borkmann]

On 1/21/22 2:56 PM, Hou Tao wrote:
> Atomics for eBPF patch series adds support for atomic[64]_fetch_add,
> atomic[64]_[fetch_]{and,or,xor} and atomic[64]_{xchg|cmpxchg}, but
> it only add support for x86-64, so support these atomic operations
> for arm64 as well.
> 
> Basically the implementation procedure is almost mechanical translation
> of code snippets in atomic_ll_sc.h & atomic_lse.h & cmpxchg.h located
> under arch/arm64/include/asm. An extra temporary register is needed
> for (BPF_ADD | BPF_FETCH) to save the value of src register, instead of
> adding TMP_REG_4 just use BPF_REG_AX instead.
> 
> For cpus_have_cap(ARM64_HAS_LSE_ATOMICS) case and no-LSE-ATOMICS case,
> both ./test_verifier and "./test_progs -t atomic" are exercised and
> passed correspondingly.

Please also make sure that lib/test_bpf.ko passes given it has the most
extensive tests around atomics.

Thanks,
Daniel