[PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[Hardevsinh Palaniya]

The condition 'if (ARC_CC_AL)' is always true, as ARC_CC_AL is a constant 
integer. This makes the check redundant, so it is safe to remove.

Signed-off-by: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
---
 arch/arc/net/bpf_jit_arcv2.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/arch/arc/net/bpf_jit_arcv2.c b/arch/arc/net/bpf_jit_arcv2.c
index 4458e409ca0a..19792ce952be 100644
--- a/arch/arc/net/bpf_jit_arcv2.c
+++ b/arch/arc/net/bpf_jit_arcv2.c
@@ -2916,10 +2916,7 @@ bool check_jmp_32(u32 curr_off, u32 targ_off, u8 cond)
 	addendum = (cond == ARC_CC_AL) ? 0 : INSN_len_normal;
 	disp = get_displacement(curr_off + addendum, targ_off);
 
-	if (ARC_CC_AL)
-		return is_valid_far_disp(disp);
-	else
-		return is_valid_near_disp(disp);
+	return is_valid_far_disp(disp);
 }
 
 /*
-- 
2.43.0

Re: [PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[Vadim Fedorenko]

On 11/11/2024 14:19, Hardevsinh Palaniya wrote:
> The condition 'if (ARC_CC_AL)' is always true, as ARC_CC_AL is a constant
> integer. This makes the check redundant, so it is safe to remove.
> 
> Signed-off-by: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
> ---
>   arch/arc/net/bpf_jit_arcv2.c | 5 +----
>   1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/arch/arc/net/bpf_jit_arcv2.c b/arch/arc/net/bpf_jit_arcv2.c
> index 4458e409ca0a..19792ce952be 100644
> --- a/arch/arc/net/bpf_jit_arcv2.c
> +++ b/arch/arc/net/bpf_jit_arcv2.c
> @@ -2916,10 +2916,7 @@ bool check_jmp_32(u32 curr_off, u32 targ_off, u8 cond)
>   	addendum = (cond == ARC_CC_AL) ? 0 : INSN_len_normal;
>   	disp = get_displacement(curr_off + addendum, targ_off);
>   
> -	if (ARC_CC_AL)
> -		return is_valid_far_disp(disp);
> -	else
> -		return is_valid_near_disp(disp);
> +	return is_valid_far_disp(disp);
>   }
>   
>   /*

The original code is obviously optimized out, but the intention, I
believe, was to check if the jump is conditional or not.

So the proper fix should change the code to check cond:

-	if (ARC_CC_AL)
+	if (cond == ARC_CC_AL)

Re: [PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[Shahab Vahedi]

Vadim Fedorenko wrote:
 
> The original code is obviously optimized out, but the intention, I
> believe, was to check if the jump is conditional or not.
> So the proper fix should change the code to check cond:
> 
> - if (ARC_CC_AL)
> + if (cond == ARC_CC_AL)

That is absolutely correct. If a new patch is not submitted soon
I'll try to fix it myself.

Cheers,
Shahab

Re: [PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[Hardevsinh Palaniya]

Hi Vadim , Shahab

Thanks for the feedback 

> > The original code is obviously optimized out, but the intention, I
> > believe, was to check if the jump is conditional or not.
> > So the proper fix should change the code to check cond:
> >
> > - if (ARC_CC_AL)
> > + if (cond == ARC_CC_AL)

Okay 

> That is absolutely correct. If a new patch is not submitted soon
> I'll try to fix it myself.

if you are okay with that then I can proceed by submitting version 2
of the patch with the proposed changes included 

Best Regards,
Hardev
________________________________________
From: Shahab Vahedi <list+bpf@vahedi.org>
Sent: Wednesday, November 13, 2024 7:41 AM
To: Vadim Fedorenko <vadim.fedorenko@linux.dev>; Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>; ast@kernel.org <ast@kernel.org>; andrii@kernel.org <andrii@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>; Martin KaFai Lau <martin.lau@linux.dev>; Eduard Zingerman <eddyz87@gmail.com>; Song Liu <song@kernel.org>; Yonghong Song <yonghong.song@linux.dev>; John Fastabend <john.fastabend@gmail.com>; KP Singh <kpsingh@kernel.org>; Stanislav Fomichev <sdf@fomichev.me>; Hao Luo <haoluo@google.com>; Jiri Olsa <jolsa@kernel.org>; Vineet Gupta <vgupta@kernel.org>; bpf@vger.kernel.org <bpf@vger.kernel.org>; linux-snps-arc@lists.infradead.org <linux-snps-arc@lists.infradead.org>; linux-kernel@vger.kernel.org <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check
 
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Vadim Fedorenko wrote:

> The original code is obviously optimized out, but the intention, I
> believe, was to check if the jump is conditional or not.
> So the proper fix should change the code to check cond:
>
> - if (ARC_CC_AL)
> + if (cond == ARC_CC_AL)

That is absolutely correct. If a new patch is not submitted soon
I'll try to fix it myself.

Cheers,
Shahab

Re: [PATCH] ARC: bpf_jit_arcv2: Remove redundant condition check

[Shahab Vahedi]

Hardev wrote:

> Shahab wrote: 
> >  
> > Vadim wrote:
> > > 
> > > 
> > > The original code is obviously optimized out, but the intention, I
> > > believe, was to check if the jump is conditional or not.
> > > So the proper fix should change the code to check cond:
> > >
> > >   - if (ARC_CC_AL)
> > >   + if (cond == ARC_CC_AL)
> >
> > 
> > That is absolutely correct. If a new patch is not submitted soon
> > I'll try to fix it myself.
>
> if you are okay with that then I can proceed by submitting version 2
> of the patch with the proposed changes included

Of course. Please go ahead. To be clear, What I meant by "soon" was
something around a week time.


Cheers,
Shahab