From: Catalin Marinas <catalin.marinas@arm.com>
To: Steve Capper <steve.capper@arm.com>
Cc: linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
will.deacon@arm.com, jcm@redhat.com, ard.biesheuvel@linaro.org
Subject: Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW
Date: Wed, 5 Dec 2018 17:36:52 +0000 [thread overview]
Message-ID: <20181205173651.GD27881@arrakis.emea.arm.com> (raw)
In-Reply-To: <20181205164145.24568-3-steve.capper@arm.com>
On Wed, Dec 05, 2018 at 04:41:41PM +0000, Steve Capper wrote:
> We wish to introduce a 52-bit virtual address space for userspace but
> maintain compatibility with software that assumes the maximum VA space
> size is 48 bit.
>
> In order to achieve this, on 52-bit VA systems, we make mmap behave as
> if it were running on a 48-bit VA system (unless userspace explicitly
> requests a VA where addr[51:48] != 0).
>
> On a system running a 52-bit userspace we need TASK_SIZE to represent
> the 52-bit limit as it is used in various places to distinguish between
> kernelspace and userspace addresses.
>
> Thus we need a new limit for mmap, stack, ELF loader and EFI (which uses
> TTBR0) to represent the non-extended VA space.
>
> This patch introduces DEFAULT_MAP_WINDOW and DEFAULT_MAP_WINDOW_64 and
> switches the appropriate logic to use that instead of TASK_SIZE.
>
> Signed-off-by: Steve Capper <steve.capper@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
next prev parent reply other threads:[~2018-12-05 17:36 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-05 16:41 [PATCH V4 0/6] 52-bit userspace VAs Steve Capper
2018-12-05 16:41 ` [PATCH V4 1/6] mm: mmap: Allow for "high" userspace addresses Steve Capper
2018-12-05 16:41 ` [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW Steve Capper
2018-12-05 17:36 ` Catalin Marinas [this message]
2018-12-06 12:24 ` Steve Capper
2018-12-05 16:41 ` [PATCH V4 3/6] arm64: mm: Define arch_get_mmap_end, arch_get_mmap_base Steve Capper
2018-12-05 16:41 ` [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD Steve Capper
2018-12-06 11:50 ` Catalin Marinas
2018-12-06 12:27 ` Steve Capper
2018-12-05 16:41 ` [PATCH V4 5/6] arm64: mm: introduce 52-bit userspace support Steve Capper
2018-12-05 18:22 ` Suzuki K Poulose
2018-12-06 12:26 ` Steve Capper
2018-12-06 14:35 ` Suzuki K Poulose
2018-12-06 14:52 ` Steve Capper
2018-12-05 16:41 ` [PATCH V4 6/6] arm64: mm: Allow forcing all userspace addresses to 52-bit Steve Capper
2018-12-06 11:51 ` Catalin Marinas
2018-12-06 12:28 ` Steve Capper
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