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From: Nicolas Pitre <nico@fluxnic.net>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Geert Uytterhoeven <geert+renesas@glider.be>,
	Arnd Bergmann <arnd@arndb.de>,
	Russell King <linux@armlinux.org.uk>,
	linux-arm-kernel@lists.infradead.org,
	Ard Biesheuvel <ardb@kernel.org>
Subject: Re: [PATCH 2/3] RFC: ARM: head: Save lr in r11 while setting up page tables
Date: Fri, 4 Sep 2020 10:53:38 -0400 (EDT)	[thread overview]
Message-ID: <nycvar.YSQ.7.78.906.2009041052180.4095746@knanqh.ubzr> (raw)
In-Reply-To: <20200904081949.5594-3-linus.walleij@linaro.org>

On Fri, 4 Sep 2020, Linus Walleij wrote:

> We might need to use lr as we want to be able to call
> the debug print functions, so save lr to r11 and restore
> lr from r11 in __create_page_tables.
> 
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
>  arch/arm/kernel/head.S | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
> index 2bfdf33aa74c..8b089c4c0d17 100644
> --- a/arch/arm/kernel/head.S
> +++ b/arch/arm/kernel/head.S
> @@ -171,10 +171,11 @@ ENDPROC(stext)
>   * r8 = phys_offset, r9 = cpuid, r10 = procinfo
>   *
>   * Returns:
> - *  r0, r3, r5-r7 corrupted
> + *  r0, r3, r5-r7, r11 corrupted
>   *  r4 = physical page table address
>   */
>  __create_page_tables:
> +	mov	r11, lr				@ we need to be able to call prints
>  	pgtbl	r4, r8				@ page table address
>  
>  	/*
> @@ -350,6 +351,7 @@ __create_page_tables:
>  #ifdef CONFIG_ARM_LPAE
>  	sub	r4, r4, #0x1000		@ point to the PGD table
>  #endif
> +	mov	lr, r11
>  	ret	lr

Here you could simply do "ret r11".




>  ENDPROC(__create_page_tables)
>  	.ltorg
> -- 
> 2.26.2
> 
> 

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  reply	other threads:[~2020-09-04 14:55 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-04  8:19 [PATCH 0/3] RFC: ARM section mapping debug prints Linus Walleij
2020-09-04  8:19 ` [PATCH 1/3] RFC: ARM: head: Use non-conditional instructions Linus Walleij
2020-09-04  8:19 ` [PATCH 2/3] RFC: ARM: head: Save lr in r11 while setting up page tables Linus Walleij
2020-09-04 14:53   ` Nicolas Pitre [this message]
2020-09-04  8:19 ` [PATCH 3/3] RFC: ARM: head: Debug prints for section mappings Linus Walleij
2020-09-04 15:51   ` Nicolas Pitre
2020-09-04 18:33     ` Nicolas Pitre

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