[PATCH v2 03/10] powerpc/bpf: Fix BPF_MOD when imm == 1

[Christophe Leroy]

Le 05/10/2021 à 22:25, Naveen N. Rao a écrit :
> Only ignore the operation if dividing by 1.
> 
> Acked-by: Song Liu <songliubraving at fb.com>
> Acked-by: Johan Almbladh <johan.almbladh at anyfinetworks.com>
> Tested-by: Johan Almbladh <johan.almbladh at anyfinetworks.com>
> Fixes: 156d0e290e969c ("powerpc/ebpf/jit: Implement JIT compiler for extended BPF")
> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>

Reviewed-by: Christophe Leroy <christophe.leroy at csgroup.eu>

> ---
>   arch/powerpc/net/bpf_jit_comp64.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c
> index f06c62089b1457..d67f6d62e2e1ff 100644
> --- a/arch/powerpc/net/bpf_jit_comp64.c
> +++ b/arch/powerpc/net/bpf_jit_comp64.c
> @@ -391,8 +391,14 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
>   		case BPF_ALU64 | BPF_DIV | BPF_K: /* dst /= imm */
>   			if (imm == 0)
>   				return -EINVAL;
> -			else if (imm == 1)
> -				goto bpf_alu32_trunc;
> +			if (imm == 1) {
> +				if (BPF_OP(code) == BPF_DIV) {
> +					goto bpf_alu32_trunc;
> +				} else {
> +					EMIT(PPC_RAW_LI(dst_reg, 0));
> +					break;
> +				}
> +			}
>   
>   			PPC_LI32(b2p[TMP_REG_1], imm);
>   			switch (BPF_CLASS(code)) {
>