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From: Linus Walleij <linus.walleij@linaro.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: cuigaosheng <cuigaosheng1@huawei.com>,
	Russell King - ARM Linux <linux@armlinux.org.uk>,
	Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
	Andrew Lunn <andrew@lunn.ch>,
	Gregory CLEMENT <gregory.clement@bootlin.com>,
	Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	Viresh Kumar <vireshk@kernel.org>,
	Shiraz Hashim <shiraz.linux.kernel@gmail.com>,
	SoC Team <soc@kernel.org>, Ard Biesheuvel <ardb@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	"moderated list:ARM/SAMSUNG EXYNOS ARM ARCHITECTURES" 
	<linux-samsung-soc@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	gongruiqi1@huawei.com, wangweiyang2@huawei.com
Subject: Re: [PATCH -next 0/3] replace open coded VA->PA calculation
Date: Wed, 22 Dec 2021 03:31:10 +0100	[thread overview]
Message-ID: <CACRpkdaNv7850mOyXRMgmPf8TQxiM-C5VEkGnLfd+wvffW8FAg@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a0aNoU693ft3pHCPJOcGubZ1dMFyOmWozO0N_8-F_JkLQ@mail.gmail.com>

On Tue, Dec 21, 2021 at 10:16 AM Arnd Bergmann <arnd@arndb.de> wrote:

> I think for CPUs that can use LPAE, we want to eventually move to the 4G:4G
> memory model, which in turn depends on having the kernel in vmalloc space, as
> implemented by Linus Walleij in
> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git/log/?h=kernel-in-vmalloc-v5.14-rc1

Yeah I'm still working on this series. The 4/4 split works pretty well,
but it breaks KASan and I was in the process of fixing that when I left
for parental leave.

The reason it breaks would be related to KASan not expecting
executable code in the vmalloc area, and since the shadowing
algorithm is a simple pointer offset, and since we go to lengths
to chisel shadow memory out of lowmem at a fixed offset from
TEXT_OFFSET, we have a problem.

The patch "KASAN horror" shows what I am trying to do to fix it,
it's "just" some hard work missing.

Yours,
Linus Walleij

WARNING: multiple messages have this Message-ID (diff)
From: Linus Walleij <linus.walleij@linaro.org>
To: Arnd Bergmann <arnd@arndb.de>
Cc: cuigaosheng <cuigaosheng1@huawei.com>,
	 Russell King - ARM Linux <linux@armlinux.org.uk>,
	 Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
	Andrew Lunn <andrew@lunn.ch>,
	 Gregory CLEMENT <gregory.clement@bootlin.com>,
	 Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
	Viresh Kumar <vireshk@kernel.org>,
	 Shiraz Hashim <shiraz.linux.kernel@gmail.com>,
	SoC Team <soc@kernel.org>,  Ard Biesheuvel <ardb@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	 "moderated list:ARM/SAMSUNG EXYNOS ARM ARCHITECTURES"
	<linux-samsung-soc@vger.kernel.org>,
	 Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	gongruiqi1@huawei.com, wangweiyang2@huawei.com
Subject: Re: [PATCH -next 0/3] replace open coded VA->PA calculation
Date: Wed, 22 Dec 2021 03:31:10 +0100	[thread overview]
Message-ID: <CACRpkdaNv7850mOyXRMgmPf8TQxiM-C5VEkGnLfd+wvffW8FAg@mail.gmail.com> (raw)
In-Reply-To: <CAK8P3a0aNoU693ft3pHCPJOcGubZ1dMFyOmWozO0N_8-F_JkLQ@mail.gmail.com>

On Tue, Dec 21, 2021 at 10:16 AM Arnd Bergmann <arnd@arndb.de> wrote:

> I think for CPUs that can use LPAE, we want to eventually move to the 4G:4G
> memory model, which in turn depends on having the kernel in vmalloc space, as
> implemented by Linus Walleij in
> https://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-integrator.git/log/?h=kernel-in-vmalloc-v5.14-rc1

Yeah I'm still working on this series. The 4/4 split works pretty well,
but it breaks KASan and I was in the process of fixing that when I left
for parental leave.

The reason it breaks would be related to KASan not expecting
executable code in the vmalloc area, and since the shadowing
algorithm is a simple pointer offset, and since we go to lengths
to chisel shadow memory out of lowmem at a fixed offset from
TEXT_OFFSET, we have a problem.

The patch "KASAN horror" shows what I am trying to do to fix it,
it's "just" some hard work missing.

Yours,
Linus Walleij

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-12-22  2:31 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-18  8:58 [PATCH -next 0/3] replace open coded VA->PA calculation Gaosheng Cui
2021-12-18  8:58 ` Gaosheng Cui
2021-12-18  8:58 ` [PATCH -next 1/3] arm-soc: exynos: replace open coded VA->PA conversions Gaosheng Cui
2021-12-18  8:58   ` Gaosheng Cui
2021-12-18  8:58 ` [PATCH -next 2/3] arm-soc: mvebu: replace open coded VA->PA conversion Gaosheng Cui
2021-12-18  8:58   ` Gaosheng Cui
2021-12-18  8:58 ` [PATCH -next 3/3] arm-soc: various: replace open coded VA->PA calculation Gaosheng Cui
2021-12-18  8:58   ` Gaosheng Cui
2021-12-20 15:39 ` [PATCH -next 0/3] " Arnd Bergmann
2021-12-20 15:39   ` Arnd Bergmann
2021-12-20 18:06   ` Andrew Lunn
2021-12-20 18:06     ` Andrew Lunn
2021-12-20 18:16     ` Ard Biesheuvel
2021-12-20 18:16       ` Ard Biesheuvel
2021-12-21  1:41   ` cuigaosheng
2021-12-21  1:41     ` cuigaosheng
2021-12-21  9:15     ` Arnd Bergmann
2021-12-21  9:15       ` Arnd Bergmann
2021-12-22  2:31       ` Linus Walleij [this message]
2021-12-22  2:31         ` Linus Walleij
2021-12-22  9:29         ` Ard Biesheuvel
2021-12-22  9:29           ` Ard Biesheuvel
2021-12-24  4:05           ` Linus Walleij
2021-12-24  4:05             ` Linus Walleij

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