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] The patch introduces a call to a `sign_extend()` function that is undeclared and undefined, resulting in a compilation failure.
--

--- Patch [1]: [PATCH bpf-next] riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args ---
commit 47567ad8c96e02d677f1ae5123565efa9cf1b55f
Author: Pu Lehui <pulehui@huawei.com>

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

This commit updates the RISC-V BPF JIT to sign-extend 1-byte and 2-byte
kfunc arguments as required by the RV64 ABI. This addresses an issue exposed
by recent state pruning liveness analysis changes.

> 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]
Is sign_extend() declared in this context?

It appears this function might be missing from this file or requires an
unapplied prerequisite patch. Looking through the source, there doesn't
appear to be a sign_extend() function defined in the RISC-V BPF JIT code
that matches this 5-argument signature. Will this cause a build failure due
to an undeclared function?

>  			}
>  		}
>

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260814064726.3607615-1-pulehui@huaweicloud.com?part=1