From: Christoffer Dall <christoffer.dall@linaro.org>
To: "Suzuki K. Poulose" <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
ard.biesheuvel@linaro.org, Marc.Zyngier@arm.com,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 03/15] arm64: Introduce helpers for page table levels
Date: Wed, 7 Oct 2015 10:26:52 +0200 [thread overview]
Message-ID: <20151007082652.GM9011@cbox> (raw)
In-Reply-To: <1442331684-28818-4-git-send-email-suzuki.poulose@arm.com>
Hi Suzuki,
On Tue, Sep 15, 2015 at 04:41:12PM +0100, Suzuki K. Poulose wrote:
> From: "Suzuki K. Poulose" <suzuki.poulose@arm.com>
>
> Introduce helpers for finding the number of page table
> levels required for a given VA width, shift for a particular
> page table level.
>
> Convert the existing users to the new helpers. More users
> to follow.
>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will.deacon@arm.com>
> Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
> Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
> arch/arm64/include/asm/pgtable-hwdef.h | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h
> index 24154b0..ce18389 100644
> --- a/arch/arm64/include/asm/pgtable-hwdef.h
> +++ b/arch/arm64/include/asm/pgtable-hwdef.h
> @@ -16,13 +16,21 @@
> #ifndef __ASM_PGTABLE_HWDEF_H
> #define __ASM_PGTABLE_HWDEF_H
>
> +/*
> + * Number of page-table levels required to address 'va_bits' wide
> + * address, without section mapping
> + */
> +#define ARM64_HW_PGTABLE_LEVELS(va_bits) (((va_bits) - 4) / (PAGE_SHIFT - 3))
I don't understand the '(va_bits) - 4' here, can you explain it (and add a
comment to that effect) ?
> +#define ARM64_HW_PGTABLE_LEVEL_SHIFT(level) \
> + ((PAGE_SHIFT - 3) * (level) + 3)
> +
While this change is clearly correct, if you can explain the math here
in a comment as well, that would be helpful.
Thanks,
-Christoffer
> #define PTRS_PER_PTE (1 << (PAGE_SHIFT - 3))
>
> /*
> * PMD_SHIFT determines the size a level 2 page table entry can map.
> */
> #if CONFIG_PGTABLE_LEVELS > 2
> -#define PMD_SHIFT ((PAGE_SHIFT - 3) * 2 + 3)
> +#define PMD_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(2)
> #define PMD_SIZE (_AC(1, UL) << PMD_SHIFT)
> #define PMD_MASK (~(PMD_SIZE-1))
> #define PTRS_PER_PMD PTRS_PER_PTE
> @@ -32,7 +40,7 @@
> * PUD_SHIFT determines the size a level 1 page table entry can map.
> */
> #if CONFIG_PGTABLE_LEVELS > 3
> -#define PUD_SHIFT ((PAGE_SHIFT - 3) * 3 + 3)
> +#define PUD_SHIFT ARM64_HW_PGTABLE_LEVEL_SHIFT(3)
> #define PUD_SIZE (_AC(1, UL) << PUD_SHIFT)
> #define PUD_MASK (~(PUD_SIZE-1))
> #define PTRS_PER_PUD PTRS_PER_PTE
> @@ -42,7 +50,8 @@
> * PGDIR_SHIFT determines the size a top-level page table entry can map
> * (depending on the configuration, this level can be 0, 1 or 2).
> */
> -#define PGDIR_SHIFT ((PAGE_SHIFT - 3) * CONFIG_PGTABLE_LEVELS + 3)
> +#define PGDIR_SHIFT \
> + ARM64_HW_PGTABLE_LEVEL_SHIFT(CONFIG_PGTABLE_LEVELS)
> #define PGDIR_SIZE (_AC(1, UL) << PGDIR_SHIFT)
> #define PGDIR_MASK (~(PGDIR_SIZE-1))
> #define PTRS_PER_PGD (1 << (VA_BITS - PGDIR_SHIFT))
> --
> 1.7.9.5
>
> _______________________________________________
> kvmarm mailing list
> kvmarm@lists.cs.columbia.edu
> https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2015-10-07 8:26 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-15 15:41 [PATCHv2 00/15] arm64: 16K translation granule support Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 01/15] arm64: Move swapper pagetable definitions Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 02/15] arm64: Handle section maps for swapper/idmap Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 03/15] arm64: Introduce helpers for page table levels Suzuki K. Poulose
2015-10-07 8:26 ` Christoffer Dall [this message]
2015-10-07 9:26 ` Marc Zyngier
2015-10-07 9:48 ` Suzuki K. Poulose
2015-10-08 14:45 ` Christoffer Dall
2015-10-08 17:22 ` Suzuki K. Poulose
2015-10-08 17:28 ` Catalin Marinas
2015-10-09 9:22 ` Suzuki K. Poulose
2015-10-07 9:51 ` Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 04/15] arm64: Calculate size for idmap_pg_dir at compile time Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 05/15] arm64: Handle 4 level page table for swapper Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 06/15] arm64: Clean config usages for page size Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 07/15] arm64: Kconfig: Fix help text about AArch32 support with 64K pages Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 08/15] arm64: Check for selected granule support Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 09/15] arm64: Add page size to the kernel image header Suzuki K. Poulose
2015-10-02 15:49 ` Catalin Marinas
2015-10-02 16:31 ` Catalin Marinas
2015-10-02 16:50 ` Marc Zyngier
2015-10-05 15:43 ` Christoffer Dall
2015-10-05 13:02 ` Suzuki K. Poulose
2015-10-05 13:22 ` Ard Biesheuvel
2015-10-10 17:22 ` Christoffer Dall
2015-09-15 15:41 ` [PATCH 10/15] arm64: kvm: Fix {V}TCR_EL2_TG0 mask Suzuki K. Poulose
2015-10-08 15:17 ` Christoffer Dall
2015-09-15 15:41 ` [PATCH 11/15] arm64: Cleanup VTCR_EL2 computation Suzuki K. Poulose
2015-10-07 10:11 ` Marc Zyngier
2015-10-07 10:23 ` Suzuki K. Poulose
2015-10-10 17:22 ` Christoffer Dall
2015-09-15 15:41 ` [PATCH 12/15] arm: kvm: Move fake PGD handling to arch specific files Suzuki K. Poulose
2015-10-07 10:23 ` Marc Zyngier
2015-10-10 17:22 ` Christoffer Dall
2015-09-15 15:41 ` [PATCH 13/15] arm64: kvm: Rewrite fake pgd handling Suzuki K. Poulose
2015-10-07 11:13 ` Marc Zyngier
2015-10-07 12:21 ` Suzuki K. Poulose
2015-10-10 14:52 ` Christoffer Dall
2015-10-12 9:55 ` Suzuki K. Poulose
2015-10-13 15:39 ` Christoffer Dall
2015-10-13 16:04 ` Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 14/15] arm64: Add 16K page size support Suzuki K. Poulose
2015-09-15 15:41 ` [PATCH 15/15] arm64: 36 bit VA Suzuki K. Poulose
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