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From: Daniel Thompson <daniel.thompson@linaro.org>
To: Christopher Covington <cov@codeaurora.org>
Cc: "Russell King" <linux@arm.linux.org.uk>,
	"Will Deacon" <will.deacon@arm.com>,
	"Mark Rutland" <mark.rutland@arm.com>,
	"Nicolas Pitre" <nico@linaro.org>,
	"Jon Medhurst (Tixy)" <tixy@linaro.org>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Wang Nan" <wangnan0@huawei.com>,
	"Nathan Lynch" <nathan_lynch@mentor.com>,
	"Stephen Boyd" <sboyd@codeaurora.org>,
	"Yingjoe Chen" <yingjoe.chen@mediatek.com>,
	"Masahiro Yamada" <yamada.m@jp.panasonic.com>,
	"Gregory CLEMENT" <gregory.clement@free-electrons.com>,
	"Arnd Bergmann" <arnd@arndb.de>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Kees Cook" <keescook@chromium.org>,
	"Florian Fainelli" <f.fainelli@gmail.com>,
	"Maxime Coquelin stm32" <mcoquelin.stm32@gmail.com>,
	"Linus Walleij" <linus.walleij@linaro.org>,
	"Paul Bolle" <pebolle@tiscali.nl>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm: Handle starting up in secure mode
Date: Thu, 27 Aug 2015 17:17:11 +0100	[thread overview]
Message-ID: <55DF3807.40506@linaro.org> (raw)
In-Reply-To: <1440424572-27116-1-git-send-email-cov@codeaurora.org>

On 24/08/15 14:55, Christopher Covington wrote:
> ARM Linux appears to have never been made aware of the ARMv7 security
> extensions. When CONFIG_ARM_SEC_EXT=y, have it probe for its security
> state by checking whether CNTFRQ is writeable and potentially make
> mode changes based on the information. The most features are available
> from hypervisor (HYP) mode, so switch to it possible. Failing that,
> prefer non-secure supervisor (SVC) mode to secure supervisor mode.

If there is no hypervisor mode available what benefit do we get from 
transitioning to non-secure mode?

When running in secure mode we retain access to some potentially useful 
features such as having access to FIQ.


Daniel.


      parent reply	other threads:[~2015-08-27 16:17 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-24 13:55 Christopher Covington
2015-08-26 10:37 ` Ard Biesheuvel
2015-08-26 10:39 ` Dave Martin
2015-08-26 10:48   ` Russell King - ARM Linux
2015-08-26 14:19     ` Christopher Covington
2015-08-27 15:28       ` Dave Martin
2015-09-08 13:21   ` Linus Walleij
2015-08-26 10:46 ` Russell King - ARM Linux
2015-08-27 16:17 ` Daniel Thompson [this message]

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