netdev - Re: [PATCH V2 14/15] ARM: bpf: cleanup cppcheck shifting error

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Message-ID: <20190624140035.36md6cp5ikniluwv@shell.armlinux.org.uk>
Date:   Mon, 24 Jun 2019 15:00:35 +0100
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Phong Tran <tranmanphong@...il.com>
Cc:     acme@...nel.org, alexander.shishkin@...ux.intel.com,
        alexander.sverdlin@...il.com, allison@...utok.net, andrew@...n.ch,
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Subject: Re: [PATCH V2 14/15] ARM: bpf: cleanup cppcheck shifting error

On Mon, Jun 24, 2019 at 08:51:04PM +0700, Phong Tran wrote:
> [arch/arm/net/bpf_jit_32.c:618]: (error) Shifting signed 32-bit value by
> 31 bits is undefined behaviour
> 
> Signed-off-by: Phong Tran <tranmanphong@...il.com>
> ---
>  arch/arm/net/bpf_jit_32.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
> index adff54c312bf..4e8ad26305ca 100644
> --- a/arch/arm/net/bpf_jit_32.c
> +++ b/arch/arm/net/bpf_jit_32.c
> @@ -612,7 +612,7 @@ static inline void emit_a32_mov_se_i64(const bool is64, const s8 dst[],
>  				       const u32 val, struct jit_ctx *ctx) {
>  	u64 val64 = val;
>  
> -	if (is64 && (val & (1<<31)))
> +	if (is64 && (val & (BIT(31))))

Extra parens are not necessary, please remove.

>  		val64 |= 0xffffffff00000000ULL;
>  	emit_a32_mov_i64(dst, val64, ctx);
>  }
> -- 
> 2.11.0
> 
> 

-- 
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