Re: [PATCH bpf-next] riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] bpf: build failure due to missing sign_extend() definition in RISC-V JIT
--

commit 6d703d57a8b42af3d4a88a2137eead18963e0c3c
Author: Pu Lehui <pulehui@huawei.com>

riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

This commit modifies the RISC-V BPF JIT to perform sign-extension for 1-byte
and 2-byte kfunc arguments to comply with the RV64 ABI.

> diff --git a/arch/riscv/net/bpf_jit_comp64.c b/arch/riscv/net/bpf_jit_comp64.c
> index 10e01ff06312d..0c6de02eb33a8 100644
> --- a/arch/riscv/net/bpf_jit_comp64.c
> +++ b/arch/riscv/net/bpf_jit_comp64.c
> @@ -1784,9 +1784,10 @@ int bpf_jit_emit_insn(const struct bpf_insn *insn, struct rv_jit_context *ctx,
>  
>  			for (idx = 0; idx < fm->nr_args; idx++) {
>  				u8 reg = bpf_to_rv_reg(BPF_REG_1 + idx, ctx);
> +				bool sign = fm->arg_flags[idx] & BTF_FMODEL_SIGNED_ARG;
>  
> -				if (fm->arg_size[idx] == sizeof(int))
> -					emit_sextw(reg, reg, ctx);
> +				if (sign_extend(reg, reg, fm->arg_size[idx], sign, ctx))
> +					return -EINVAL;

[Severity: Low]
Does this introduce a build regression?

Compiling the kernel with RISC-V BPF JIT enabled triggers an implicit
declaration and subsequent linker error because the sign_extend function
is not defined for this usage in bpf_jit_emit_insn.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260923144154.934674-1-pulehui@huaweicloud.com?part=1