linux-kernel - Re: [PATCH v3 14/21] arm64: [re]define SWAPPER_TABLE

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Date:	Mon, 11 Jan 2016 14:26:28 +0100
From:	Ard Biesheuvel <ard.biesheuvel@...aro.org>
To:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	kernel-hardening@...ts.openwall.com,
	Will Deacon <will.deacon@....com>,
	Catalin Marinas <catalin.marinas@....com>,
	Mark Rutland <mark.rutland@....com>,
	Leif Lindholm <leif.lindholm@...aro.org>,
	Kees Cook <keescook@...omium.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Stuart Yoder <stuart.yoder@...escale.com>,
	Sharma Bhupesh <bhupesh.sharma@...escale.com>,
	Arnd Bergmann <arnd@...db.de>,
	Marc Zyngier <marc.zyngier@....com>,
	Christoffer Dall <christoffer.dall@...aro.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>
Subject: Re: [PATCH v3 14/21] arm64: [re]define SWAPPER_TABLE_[SHIFT|SIZE] for
 use in asm code

Please disregard this patch, I accidentally sent out two versions of
14/21, and this is the wrong one.


On 11 January 2016 at 14:19, Ard Biesheuvel <ard.biesheuvel@...aro.org> wrote:
> The current definition of SWAPPER_TABLE_SHIFT can only be used in
> asm code if the configured number of translation levels defines
> PUD_SHIFT and/or PMD_SHIFT natively (4KB and 16KB/64KB granule,
> respectively). Otherwise, it depends on the nopmd/nopud fixup
> headers, which can only be included in C code.
>
> So redefine SWAPPER_TABLE_SHIFT in a way that is independent of the
> number of configured translation levels. Define SWAPPER_TABLE_SIZE
> as well, we will need it later.
>
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> ---
>  arch/arm64/include/asm/kernel-pgtable.h | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kernel-pgtable.h b/arch/arm64/include/asm/kernel-pgtable.h
> index daa8a7b9917a..eaac46097359 100644
> --- a/arch/arm64/include/asm/kernel-pgtable.h
> +++ b/arch/arm64/include/asm/kernel-pgtable.h
> @@ -57,13 +57,14 @@
>  #if ARM64_SWAPPER_USES_SECTION_MAPS
>  #define SWAPPER_BLOCK_SHIFT    SECTION_SHIFT
>  #define SWAPPER_BLOCK_SIZE     SECTION_SIZE
> -#define SWAPPER_TABLE_SHIFT    PUD_SHIFT
>  #else
>  #define SWAPPER_BLOCK_SHIFT    PAGE_SHIFT
>  #define SWAPPER_BLOCK_SIZE     PAGE_SIZE
> -#define SWAPPER_TABLE_SHIFT    PMD_SHIFT
>  #endif
>
> +#define SWAPPER_TABLE_SHIFT    (SWAPPER_BLOCK_SHIFT + PAGE_SHIFT - 3)
> +#define SWAPPER_TABLE_SIZE     (1 << SWAPPER_TABLE_SHIFT)
> +
>  /* The size of the initial kernel direct mapping */
>  #define SWAPPER_INIT_MAP_SIZE  (_AC(1, UL) << SWAPPER_TABLE_SHIFT)
>
> --
> 2.5.0
>