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From: Steve Capper <Steve.Capper@arm.com>
To: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: "ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	"jcm@redhat.com" <jcm@redhat.com>,
	Will Deacon <Will.Deacon@arm.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>, nd <nd@arm.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW
Date: Thu, 6 Dec 2018 12:24:59 +0000	[thread overview]
Message-ID: <20181206122448.GA17473@capper-debian.cambridge.arm.com> (raw)
In-Reply-To: <20181205173651.GD27881@arrakis.emea.arm.com>

On Wed, Dec 05, 2018 at 05:36:52PM +0000, Catalin Marinas wrote:
> 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>

Thanks!

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WARNING: multiple messages have this Message-ID (diff)
From: Steve Capper <Steve.Capper@arm.com>
To: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>,
	Will Deacon <Will.Deacon@arm.com>,
	"jcm@redhat.com" <jcm@redhat.com>,
	"ard.biesheuvel@linaro.org" <ard.biesheuvel@linaro.org>,
	nd <nd@arm.com>
Subject: Re: [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW
Date: Thu, 6 Dec 2018 12:24:59 +0000	[thread overview]
Message-ID: <20181206122448.GA17473@capper-debian.cambridge.arm.com> (raw)
In-Reply-To: <20181205173651.GD27881@arrakis.emea.arm.com>

On Wed, Dec 05, 2018 at 05:36:52PM +0000, Catalin Marinas wrote:
> 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>

Thanks!

  reply	other threads:[~2018-12-06 12:28 UTC|newest]

Thread overview: 34+ 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 ` 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   ` Steve Capper
2018-12-05 16:41 ` [PATCH V4 2/6] arm64: mm: Introduce DEFAULT_MAP_WINDOW Steve Capper
2018-12-05 16:41   ` Steve Capper
2018-12-05 17:36   ` Catalin Marinas
2018-12-05 17:36     ` Catalin Marinas
2018-12-06 12:24     ` Steve Capper [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   ` Steve Capper
2018-12-05 16:41 ` [PATCH V4 4/6] arm64: mm: Offset TTBR1 to allow 52-bit PTRS_PER_PGD Steve Capper
2018-12-05 16:41   ` Steve Capper
2018-12-06 11:50   ` Catalin Marinas
2018-12-06 11:50     ` Catalin Marinas
2018-12-06 12:27     ` Steve Capper
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 16:41   ` Steve Capper
2018-12-05 18:22   ` Suzuki K Poulose
2018-12-05 18:22     ` Suzuki K Poulose
2018-12-06 12:26     ` Steve Capper
2018-12-06 12:26       ` Steve Capper
2018-12-06 14:35       ` Suzuki K Poulose
2018-12-06 14:35         ` Suzuki K Poulose
2018-12-06 14:52         ` Steve Capper
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
2018-12-05 16:41   ` Steve Capper
2018-12-06 11:51   ` Catalin Marinas
2018-12-06 11:51     ` Catalin Marinas
2018-12-06 12:28     ` Steve Capper
2018-12-06 12:28       ` Steve Capper

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