From: Chris.Brandt@renesas.com (Chris Brandt)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2] ARM: proc-v7.S: Adjust stack address when XIP_KERNEL
Date: Tue, 16 Feb 2016 18:53:46 +0000 [thread overview]
Message-ID: <HK2PR06MB0561B01AAD9BA5DAC043B6AC8AAD0@HK2PR06MB0561.apcprd06.prod.outlook.com> (raw)
In-Reply-To: <20160216173225.GE19428@n2100.arm.linux.org.uk>
On 16 Feb 2016, Russell King - ARM Linux wrote:
> I keep looking at this patch, and I really find that I detest this
> PHYS_OFFSET_FIXUP thing - it's really not obvious what's going on here.
> It's taken a _long_ time to work this out, which _really_ isn't good
> going forward.
>
> Let's instead change things to make it much more obvious - see the
> patch below.
>
>
> diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
> index ebdaaf7dd19f..593e5613184d 100644
> --- a/arch/arm/include/asm/memory.h
> +++ b/arch/arm/include/asm/memory.h
> @@ -135,11 +135,18 @@
> #define PLAT_PHYS_OFFSET UL(CONFIG_PHYS_OFFSET)
>
> #ifdef CONFIG_XIP_KERNEL
> -#define PHYS_OFFSET_FIXUP \
> - ( XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) - PAGE_OFFSET + \
> - PLAT_PHYS_OFFSET - CONFIG_XIP_PHYS_ADDR )
> +/*
> + * When referencing data in RAM from the XIP region in a relative
> +manner
> + * with the MMU off, we need the relative offset between the two
> +physical
> + * addresses. The macro below achieves this, which is:
> + * __pa(v_data) - __xip_pa(v_text)
> + */
> +#define PHYS_RELATIVE(v_data, v_text) \
> + (((v_data) - PAGE_OFFSET + PLAT_PHYS_OFFSET) - \
> + ((v_text) - XIP_VIRT_ADDR(CONFIG_XIP_PHYS_ADDR) + \
> + CONFIG_XIP_PHYS_ADDR))
> #else
> -#define PHYS_OFFSET_FIXUP 0
> +#define PHYS_RELATIVE(v_data, v_text) (v_data) - (v_text)
> #endif
>
> #ifndef __ASSEMBLY__
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index
> 1595fb29ec12..0f8963a7e7d9 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -487,7 +487,7 @@ __errata_finish:
>
> .align 2
> __v7_setup_stack_ptr:
> - .word __v7_setup_stack - . + PHYS_OFFSET_FIXUP
> + .word PHYS_RELATIVE(__v7_setup_stack, .)
> ENDPROC(__v7_setup)
>
> .bss
>
This works fine for me (comes up with the same number either way).
Just tested it with my XIP_KERNEL ARMv7 system.
Chris
next prev parent reply other threads:[~2016-02-16 18:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-29 22:11 [PATCH] ARM: proc-v7.S: Adjust stack address when XIP_KERNEL Chris Brandt
2016-01-31 23:20 ` Arnd Bergmann
2016-02-01 14:08 ` Chris Brandt
2016-02-01 14:08 ` [PATCH v2] " Chris Brandt
2016-02-01 21:15 ` Nicolas Pitre
2016-02-16 17:32 ` Russell King - ARM Linux
2016-02-16 18:53 ` Chris Brandt [this message]
2016-02-16 20:16 ` Nicolas Pitre
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