From: Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Cc: Kees Cook <keescook@chromium.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Jann Horn <jannh@google.com>,
Paul Kocialkowski <paul.kocialkowski@bootlin.com>,
Emese Revfy <re.emese@gmail.com>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] security: do not enable CONFIG_GCC_PLUGINS by default
Date: Fri, 14 Jun 2019 20:14:34 +0200 [thread overview]
Message-ID: <20190614201434.3fa4bb6d@primarylaptop.localdomain> (raw)
In-Reply-To: <20190614162811.o33yeq65ythjumrh@shell.armlinux.org.uk>
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On Fri, 14 Jun 2019 17:28:11 +0100
Russell King - ARM Linux admin <linux@armlinux.org.uk> wrote:
> I'm wondering whether this is sloppy wording or whether the author is
> really implying that they call the kernel decompressor with the MMU
> enabled, against the express instructions in
> Documentation/arm/Booting.
According to [1]
> If they are going against the express instructions, all bets are off.
More background on the decompressor patch:
- The "ANDROID: arm: decompressor: Flush tlb before swiching domain 0 to
client mode" patch is needed anyway since 3.4 in any case, and
according to the thread about it [1], the MMU is on at boot.
- There is a downstream u-boot port for the Galaxy SIII and other very
similar devices, which doesn't setup the MMU at boot, but I'm not
confident enough to test in on the devices I have. To test with
u-boot I'd need to find a new device.
- If I don't manage to find a new device to test on, since there is
already some setup code like arch/arm/boot/compressed/head-sa1100.S
that deal with MMU that are enabled with the bootloader, are patches
to add a new file like that still accepted? The big downside is that
using something like that is probably incompatible with
ARCH_MULTIPLATFORM.
References:
-----------
[1]http://lkml.iu.edu/hypermail/linux/kernel/1212.1/02099.html
[2]https://blog.forkwhiletrue.me/posts/an-almost-fully-libre-galaxy-s3/
Denis.
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next prev parent reply other threads:[~2019-06-14 18:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190614145755.10926-1-GNUtoo@cyberdimension.org>
2019-06-14 16:05 ` [PATCH] security: do not enable CONFIG_GCC_PLUGINS by default Jann Horn
2019-06-14 16:12 ` Denis 'GNUtoo' Carikli
2019-06-14 16:28 ` Russell King - ARM Linux admin
2019-06-14 18:14 ` Denis 'GNUtoo' Carikli [this message]
2019-06-14 18:54 ` Russell King - ARM Linux admin
2019-06-15 10:13 ` Paul Kocialkowski
2019-06-21 23:42 ` Denis 'GNUtoo' Carikli
2019-06-24 13:31 ` Paul Kocialkowski
2019-06-15 3:08 ` Kees Cook
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