Re: [PATCH] LoongArch: BPF: Fix uninitialized symbol 'retval_off'

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Tue, Aug 19, 2025 at 4:21 AM Huacai Chen <chenhuacai@loongson.cn> wrote:
>
> In __arch_prepare_bpf_trampoline(), retval_off is meaningful only when
> save_ret is not 0, so the current logic is correct. But it may cause a
> build warning:
>
> arch/loongarch/net/bpf_jit.c:1547 __arch_prepare_bpf_trampoline() error: uninitialized symbol 'retval_off'.
>
> So initialize retval_off unconditionally to fix it.
>
> Fixes: f9b6b41f0cf3 ("LoongArch: BPF: Add basic bpf trampoline support")
> Closes: https://lore.kernel.org/r/202508191020.PBBh07cK-lkp@intel.com/
> Reported-by: kernel test robot <lkp@intel.com>
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
> ---
>  arch/loongarch/net/bpf_jit.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>

Is this something that should go through loongarch-specific tree?

> diff --git a/arch/loongarch/net/bpf_jit.c b/arch/loongarch/net/bpf_jit.c
> index abfdb6bb5c38..a73f6ea4ed4a 100644
> --- a/arch/loongarch/net/bpf_jit.c
> +++ b/arch/loongarch/net/bpf_jit.c
> @@ -1504,11 +1504,10 @@ static int __arch_prepare_bpf_trampoline(struct jit_ctx *ctx, struct bpf_tramp_i
>         stack_size += 16;
>
>         save_ret = flags & (BPF_TRAMP_F_CALL_ORIG | BPF_TRAMP_F_RET_FENTRY_RET);
> -       if (save_ret) {
> -               /* Save BPF R0 and A0 */
> -               stack_size += 16;
> -               retval_off = stack_size;
> -       }
> +       if (save_ret)
> +               stack_size += 16; /* Save BPF R0 and A0 */
> +
> +       retval_off = stack_size;
>
>         /* Room of trampoline frame to store args */
>         nargs = m->nr_args;
> --
> 2.47.3
>
>