linux-kernel - Re: [PATCH 2/2] arm64: KVM: hyp: debug-sr: Mark expected switch fall-through

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Message-ID: <86d0hxnfif.wl-marc.zyngier@arm.com>
Date:   Fri, 26 Jul 2019 13:31:52 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Anders Roxell <anders.roxell@...aro.org>
Cc:     catalin.marinas@....com, will@...nel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] arm64: KVM: hyp: debug-sr: Mark expected switch fall-through

On Fri, 26 Jul 2019 12:27:10 +0100,
Anders Roxell <anders.roxell@...aro.org> wrote:
> 
> When fall-through warnings was enabled by default the following warnings
> was starting to show up:
> 
> ../arch/arm64/kvm/hyp/debug-sr.c: In function ‘__debug_save_state’:
> ../arch/arm64/kvm/hyp/debug-sr.c:20:19: warning: this statement may fall
>  through [-Wimplicit-fallthrough=]
>   case 15: ptr[15] = read_debug(reg, 15);   \
> ../arch/arm64/kvm/hyp/debug-sr.c:113:2: note: in expansion of macro ‘save_debug’
>   save_debug(dbg->dbg_bcr, dbgbcr, brps);
>   ^~~~~~~~~~
> ../arch/arm64/kvm/hyp/debug-sr.c:21:2: note: here
>   case 14: ptr[14] = read_debug(reg, 14);   \
>   ^~~~
> ../arch/arm64/kvm/hyp/debug-sr.c:113:2: note: in expansion of macro ‘save_debug’
>   save_debug(dbg->dbg_bcr, dbgbcr, brps);
>   ^~~~~~~~~~
> ../arch/arm64/kvm/hyp/debug-sr.c:21:19: warning: this statement may fall
>  through [-Wimplicit-fallthrough=]
>   case 14: ptr[14] = read_debug(reg, 14);   \
> ../arch/arm64/kvm/hyp/debug-sr.c:113:2: note: in expansion of macro ‘save_debug’
>   save_debug(dbg->dbg_bcr, dbgbcr, brps);
>   ^~~~~~~~~~
> ../arch/arm64/kvm/hyp/debug-sr.c:22:2: note: here
>   case 13: ptr[13] = read_debug(reg, 13);   \
>   ^~~~
> ../arch/arm64/kvm/hyp/debug-sr.c:113:2: note: in expansion of macro ‘save_debug’
>   save_debug(dbg->dbg_bcr, dbgbcr, brps);
>   ^~~~~~~~~~
> 
> Rework to add a 'break;' where the compiler warned about
> fall-through.

That's not what this patch does, I'm afraid.

Thanks,

	M.

> 
> Fixes: d93512ef0f0e ("Makefile: Globally enable fall-through warning")
> Signed-off-by: Anders Roxell <anders.roxell@...aro.org>
> ---
>  arch/arm64/kvm/hyp/debug-sr.c | 30 ++++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
> 
> diff --git a/arch/arm64/kvm/hyp/debug-sr.c b/arch/arm64/kvm/hyp/debug-sr.c
> index 26781da3ad3e..0fc9872a1467 100644
> --- a/arch/arm64/kvm/hyp/debug-sr.c
> +++ b/arch/arm64/kvm/hyp/debug-sr.c
> @@ -18,40 +18,70 @@
>  #define save_debug(ptr,reg,nr)						\
>  	switch (nr) {							\
>  	case 15:	ptr[15] = read_debug(reg, 15);			\
> +			/* Fall through */				\
>  	case 14:	ptr[14] = read_debug(reg, 14);			\
> +			/* Fall through */				\
>  	case 13:	ptr[13] = read_debug(reg, 13);			\
> +			/* Fall through */				\
>  	case 12:	ptr[12] = read_debug(reg, 12);			\
> +			/* Fall through */				\
>  	case 11:	ptr[11] = read_debug(reg, 11);			\
> +			/* Fall through */				\
>  	case 10:	ptr[10] = read_debug(reg, 10);			\
> +			/* Fall through */				\
>  	case 9:		ptr[9] = read_debug(reg, 9);			\
> +			/* Fall through */				\
>  	case 8:		ptr[8] = read_debug(reg, 8);			\
> +			/* Fall through */				\
>  	case 7:		ptr[7] = read_debug(reg, 7);			\
> +			/* Fall through */				\
>  	case 6:		ptr[6] = read_debug(reg, 6);			\
> +			/* Fall through */				\
>  	case 5:		ptr[5] = read_debug(reg, 5);			\
> +			/* Fall through */				\
>  	case 4:		ptr[4] = read_debug(reg, 4);			\
> +			/* Fall through */				\
>  	case 3:		ptr[3] = read_debug(reg, 3);			\
> +			/* Fall through */				\
>  	case 2:		ptr[2] = read_debug(reg, 2);			\
> +			/* Fall through */				\
>  	case 1:		ptr[1] = read_debug(reg, 1);			\
> +			/* Fall through */				\
>  	default:	ptr[0] = read_debug(reg, 0);			\
>  	}
>  
>  #define restore_debug(ptr,reg,nr)					\
>  	switch (nr) {							\
>  	case 15:	write_debug(ptr[15], reg, 15);			\
> +			/* Fall through */				\
>  	case 14:	write_debug(ptr[14], reg, 14);			\
> +			/* Fall through */				\
>  	case 13:	write_debug(ptr[13], reg, 13);			\
> +			/* Fall through */				\
>  	case 12:	write_debug(ptr[12], reg, 12);			\
> +			/* Fall through */				\
>  	case 11:	write_debug(ptr[11], reg, 11);			\
> +			/* Fall through */				\
>  	case 10:	write_debug(ptr[10], reg, 10);			\
> +			/* Fall through */				\
>  	case 9:		write_debug(ptr[9], reg, 9);			\
> +			/* Fall through */				\
>  	case 8:		write_debug(ptr[8], reg, 8);			\
> +			/* Fall through */				\
>  	case 7:		write_debug(ptr[7], reg, 7);			\
> +			/* Fall through */				\
>  	case 6:		write_debug(ptr[6], reg, 6);			\
> +			/* Fall through */				\
>  	case 5:		write_debug(ptr[5], reg, 5);			\
> +			/* Fall through */				\
>  	case 4:		write_debug(ptr[4], reg, 4);			\
> +			/* Fall through */				\
>  	case 3:		write_debug(ptr[3], reg, 3);			\
> +			/* Fall through */				\
>  	case 2:		write_debug(ptr[2], reg, 2);			\
> +			/* Fall through */				\
>  	case 1:		write_debug(ptr[1], reg, 1);			\
> +			/* Fall through */				\
>  	default:	write_debug(ptr[0], reg, 0);			\
>  	}
>  
> -- 
> 2.20.1
> 

-- 
Jazz is not dead, it just smells funny.