Re: [PATCH] arm: Handle starting up in secure mode

From	Daniel Thompson <daniel.thompson@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] arm: Handle starting up in secure mode
Date	2015-08-27 18:20 +0200
Message-ID	<q284a-18X-7@gated-at.bofh.it> (permalink)
References	<q10BI-1vm-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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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.

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[PATCH] arm: Handle starting up in secure mode Christopher Covington <cov@codeaurora.org> - 2015-08-24 16:10 +0200
  Re: [PATCH] arm: Handle starting up in secure mode Dave Martin <Dave.Martin@arm.com> - 2015-08-26 12:40 +0200
    Re: [PATCH] arm: Handle starting up in secure mode Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-08-26 12:50 +0200
      Re: [PATCH] arm: Handle starting up in secure mode Christopher Covington <cov@codeaurora.org> - 2015-08-26 16:20 +0200
        Re: [PATCH] arm: Handle starting up in secure mode Dave Martin <Dave.Martin@arm.com> - 2015-08-27 17:30 +0200
  Re: [PATCH] arm: Handle starting up in secure mode Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-08-26 12:40 +0200
  Re: [PATCH] arm: Handle starting up in secure mode Russell King - ARM Linux <linux@arm.linux.org.uk> - 2015-08-26 12:50 +0200
  Re: [PATCH] arm: Handle starting up in secure mode Daniel Thompson <daniel.thompson@linaro.org> - 2015-08-27 18:20 +0200

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