Re: [PATCH v3 2/5] LoongArch: BPF: Add the default case in emit_atomic() and rename it

[Hengqi Chen]

On Mon, Apr 13, 2026 at 12:05 PM Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> wrote:
>
> Like the other archs such as x86 and riscv, add the default case
> in emit_atomic() to print an error message for the invalid opcode
> and return -EINVAL , then make its return type as int.
>
> While at it, given that all of the instructions in emit_atomic()
> are only read-modify-write instructions, rename emit_atomic() to
> emit_atomic_rmw() to make it clear, because there will be a new
> function emit_atomic_ld_st() for load-acquire and store-release
> instructions in the later patch.
>
> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx>
> ---

Acked-by: Hengqi Chen <hengqi.chen@xxxxxxxxx>

>  arch/loongarch/net/bpf_jit.c | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
> index 9cb796e16379..fefda4050a20 100644
> --- a/arch/loongarch/net/bpf_jit.c
> +++ b/arch/loongarch/net/bpf_jit.c
> @@ -344,7 +344,7 @@ static int emit_bpf_tail_call(struct jit_ctx *ctx, int insn)
>  #undef jmp_offset
>  }
>
> -static void emit_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
> +static int emit_atomic_rmw(const struct bpf_insn *insn, struct jit_ctx *ctx)
>  {
>         const u8 t1 = LOONGARCH_GPR_T1;
>         const u8 t2 = LOONGARCH_GPR_T2;
> @@ -448,7 +448,12 @@ static void emit_atomic(const struct bpf_insn *insn, struct jit_ctx *ctx)
>                         emit_zext_32(ctx, r0, true);
>                 }
>                 break;
> +       default:
> +               pr_err_once("bpf-jit: invalid atomic read-modify-write opcode %02x\n", imm);
> +               return -EINVAL;
>         }
> +
> +       return 0;
>  }
>
>  static bool is_signed_bpf_cond(u8 cond)
> @@ -1256,7 +1261,9 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx, bool ext
>
>         case BPF_STX | BPF_ATOMIC | BPF_W:
>         case BPF_STX | BPF_ATOMIC | BPF_DW:
> -               emit_atomic(insn, ctx);
> +               ret = emit_atomic_rmw(insn, ctx);
> +               if (ret)
> +                       return ret;
>                 break;
>
>         /* Speculation barrier */
> --
> 2.42.0
>