linux-kernel - Re: [PATCH] arm32: simplify ARM_MMU

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Message-ID: <1811814.VLH7GnMWUR@devpool47.emlix.com>
Date: Wed, 18 Dec 2024 13:13:24 +0100
From: Rolf Eike Beer <eb@...ix.com>
To: Russell King <linux@...linux.org.uk>, Arnd Bergmann <arnd@...db.de>,
 Yuntao Liu <liuyuntao12@...wei.com>, Linus Walleij <linus.walleij@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm32: simplify ARM_MMU_KEEP usage

On Montag, 7. Oktober 2024 15:11:40 Mitteleuropäische Normalzeit Rolf Eike 
Beer wrote:
> All current users need to add a KEEP() around the argument so the value is
> actually kept, which doesn't feel very natural and is prone to upcoming bugs
> as the name suggests that this macro alone already keeps things. Move that
> directly into the definition.
> 
> Signed-off-by: Rolf Eike Beer <eb@...ix.com>
> ---

Ping?

> I'm unsure if ARM_MMU_DISCARD() needs the same treatment for the non-MMU
> case. I suspect noone has tried dead code elimination for non-MMU?
> 
>  arch/arm/include/asm/vmlinux.lds.h | 2 +-
>  arch/arm/kernel/vmlinux-xip.lds.S  | 2 +-
>  arch/arm/kernel/vmlinux.lds.S      | 2 +-
>  3 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/include/asm/vmlinux.lds.h
> b/arch/arm/include/asm/vmlinux.lds.h index d60f6e83a9f7..89697f204715
> 100644
> --- a/arch/arm/include/asm/vmlinux.lds.h
> +++ b/arch/arm/include/asm/vmlinux.lds.h
> @@ -19,7 +19,7 @@
>  #endif
> 
>  #ifdef CONFIG_MMU
> -#define ARM_MMU_KEEP(x)		x
> +#define ARM_MMU_KEEP(x)		KEEP(x)
>  #define ARM_MMU_DISCARD(x)
>  #else
>  #define ARM_MMU_KEEP(x)
> diff --git a/arch/arm/kernel/vmlinux-xip.lds.S
> b/arch/arm/kernel/vmlinux-xip.lds.S index 5eddb75a7174..f2e8d4fac068 100644
> --- a/arch/arm/kernel/vmlinux-xip.lds.S
> +++ b/arch/arm/kernel/vmlinux-xip.lds.S
> @@ -63,7 +63,7 @@ SECTIONS
>  	. = ALIGN(4);
>  	__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
>  		__start___ex_table = .;
> -		ARM_MMU_KEEP(KEEP(*(__ex_table)))
> +		ARM_MMU_KEEP(*(__ex_table))
>  		__stop___ex_table = .;
>  	}
> 
> diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S
> index de373c6c2ae8..d592a203f9c6 100644
> --- a/arch/arm/kernel/vmlinux.lds.S
> +++ b/arch/arm/kernel/vmlinux.lds.S
> @@ -74,7 +74,7 @@ SECTIONS
>  	. = ALIGN(4);
>  	__ex_table : AT(ADDR(__ex_table) - LOAD_OFFSET) {
>  		__start___ex_table = .;
> -		ARM_MMU_KEEP(KEEP(*(__ex_table)))
> +		ARM_MMU_KEEP(*(__ex_table))
>  		__stop___ex_table = .;
>  	}


-- 
Rolf Eike Beer

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