[PATCH v2 10/10] powerpc/bpf ppc32: Fix BPF_SUB when imm == 0x80000000

[Christophe Leroy]

Le 05/10/2021 à 22:25, Naveen N. Rao a écrit :
> Special case handling of the smallest 32-bit negative number for BPF_SUB.
> 
> Fixes: 51c66ad849a703 ("powerpc/bpf: Implement extended BPF on PPC32")
> 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_comp32.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c
> index 68dc8a8231de04..0da31d41d41310 100644
> --- a/arch/powerpc/net/bpf_jit_comp32.c
> +++ b/arch/powerpc/net/bpf_jit_comp32.c
> @@ -357,7 +357,7 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, struct codegen_context *
>   				PPC_LI32(_R0, imm);
>   				EMIT(PPC_RAW_ADDC(dst_reg, dst_reg, _R0));
>   			}
> -			if (imm >= 0)
> +			if (imm >= 0 || (BPF_OP(code) == BPF_SUB && imm == 0x80000000))
>   				EMIT(PPC_RAW_ADDZE(dst_reg_h, dst_reg_h));
>   			else
>   				EMIT(PPC_RAW_ADDME(dst_reg_h, dst_reg_h));
>